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Sample records for zeolita hzsm5 modificada

  1. SÍNTESIS SELECTIVA DE BENZALDEHÍDO USANDO ZEOLITAS MODIFICADAS CON METALES DE TRANSICIÓN

    Directory of Open Access Journals (Sweden)

    Clara Saux

    2012-01-01

    Full Text Available Se estudió la oxidación selectiva de estireno para la obtención de benzaldehído sobre zeolitas ZSM-5 modificadas con diferentes metales de transición (cromo, cobalto, hierro, zinc, manganeso y cobre y utilizando peróxido de hidrógeno como oxidante. Dado que los mejores resultados se obtuvieron utilizando Cr-ZSM-5, estos materiales se estudiaron evaluando el efecto del tiempo de reacción, la masa de catalizador, la relación molar estireno/hidroperóxido, la naturaleza del solvente y la temperatura de reacción. Los mejores resultados de las condiciones evaluadas se obtuvieron trabajando con una relación molar sustrato/oxidante de 0,45 y utilizando acetonitrilo como solvente, dado su carácter aprótico y de mayor polaridad de los solventes evaluados (acetonitrilo, acetona, 2-butanol y 2-propanol. El aumento en la temperatura de reacción mostró un incremento en la conversión de estireno, el cual se desaceleró al superar los 60 oC por descomposición térmica del peróxido de hidrógeno.

  2. Re/HZSM-5: a new catalyst for ethane aromatization with improved stability

    DEFF Research Database (Denmark)

    Krogh, Anne; Hansen, Thomas W.; Christensen, Claus Hviid

    2003-01-01

    Rhenium-impregnated HZSM-5 is found to be a promising catalyst for ethane aromatization. The Re–HZSM-5 catalyst deactivates significantly slower than well-known ethane aromatization Zn–HZSM-5 catalyst. Product selectivities for the two catalysts are similar, indicating that the shape selectivity...

  3. Upgrading pyrolysis bio-oil to biofuel over bifunctional Co-Zn/HZSM-5 catalyst in supercritical methanol

    International Nuclear Information System (INIS)

    Cheng, Shouyun; Wei, Lin; Julson, James; Muthukumarappan, Kasiviswanathan; Kharel, Parashu Ram

    2017-01-01

    Highlights: • Integration of Co-Zn/HZSM-5 and supercritical methanol was used for bio-oil hydrodeoxygenation. • Co-Zn/HZSM-5 exhibited higher effectiveness than Co/HZSM-5 or Zn/HZSM-5. • 15%Co5%Zn/HZSM-5 produced biofuel with the highest hydrocarbons content at 35.33%. • Loading of Co and/or Zn did not change crystalline structure of HZSM-5. • Hydrogenation and esterification are main reactions in bio-oil hydrodeoxygenation. - Abstract: The role of catalyst is essential in processes of upgrading biomass pyrolysis bio-oil into hydrocarbon biofuel. While the majority of heterogeneous catalytic processes are conducted in the presence of gas (nearly ideal) or liquid phase, a growing number of processes are utilizing supercritical fluids (SCFs) as reaction media. Although hydrodeoxygenation (HDO) is proven a promising process for pyrolysis bio-oil upgrading to hydrocarbon biofuel, catalyst efficiency remains a challenge. Integrating heterogeneous catalysts with SCFs in a bio-oil HDO process was investigated in this study. Bifunctional Co-Zn/HZSM-5 catalysts were firstly used to upgrade bio-oil to biofuel in supercritical methanol. The loading of Co and Zn did not change HZSM-5 crystalline structure. Physicochemical properties of biofuel produced by Co and/or Zn loaded HZSM-5 catalysts such as water content, total acid number, viscosity and higher heating value improved. Bimetallic Co-Zn/HZSM-5 catalysts showed enhanced reactions of decarboxylation and decarbonylation that resulted in higher yields of CO and CO 2 . Bimetallic Co-Zn/HZSM-5 catalysts were more effective for bio-oil HDO than monometallic Co/HZSM-5 or Zn/HZSM-5 catalyst , which was attributed to the synergistic effect of Co and Zn on HZSM-5 support. Bimetallic Co-Zn/HZSM-5 catalysts increased biofuel yields and hydrocarbons contents in biofuels in comparison with monometallic Co/HZSM-5 and Zn/HZSM-5 catalysts. 5%Co15%Zn/HZSM-5 catalyst generated the highest biofuel yield at 22.13 wt.%, and 15%Co5

  4. Study on antimony oxide self-assembled inside HZSM-5

    International Nuclear Information System (INIS)

    Li Bin; Li Shijie; Wang Yingxia; Li Neng; Liu Xiyao; Lin Bingxiong

    2005-01-01

    Sb/ZSM-5 was obtained by solid-state reaction with the mixture of Sb 2 O 3 and zeolite HZSM-5 under a dry nitrogen flow at 773K. Characterization of the treated zeolite was undertaken with XRD, 27 Al MAS NMR, BET, TGA and FT-IR. The results revealed that part of the antimony oxides migrated into the channels of zeolite, and decreased the Bronsted acid sites in Sb/ZSM-5 remarkably. The other part of antimony oxides together with the amorphous alumino-silicate in the products distributed on the external surface of zeolite ZSM-5 and modified it, while the framework of ZSM-5 in crystal phase was retained. The structure of occluded antimony oxide inside the channels of ZSM-5 was studied by XRD Rietveld method. The result showed that their structure can be described as a chain of non-perfect [Sb 5 O 5 (H 2 O) 2 ] n 5n+ , which is parallel to the straight channel of ZSM-5. There is about 0.6 [Sb 5 O 5 (H 2 O) 2 ] 5+ unit in every cell of the ZSM-5 on an average

  5. Catalytic dehydration of ethanol to ethylene over HMOR HZSM-5 modified with copper and iron

    Directory of Open Access Journals (Sweden)

    José Luis Agudelo

    2005-09-01

    Full Text Available Catalytic dehydration of ethanol to ethylene on HMOR (Si/Al = 6.5, HZSM-5 (Si/Al = 29, Cu-HZSM-5 (Si/Al = 98 and Fe-HZSM-5 (Si/Al = 151 was studied at atmospheric pressure and 120oC - 300ºC. ZSM-5 supported catalysts were active at temperatures over 260ºC, achieving more than 60% conversion. Ethylene was predominantly produced as a dehydration product. Incorporating Cu did not significantly improve catalytic activity compared to HZSM-5. H-MOR was very active at low temperatures but deactivated rapidly at 240ºC, most probably due to coke formation.

  6. Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts

    KAUST Repository

    Alabi, Wahab

    2012-07-01

    A kinetic study of toluene alkylation with methanol was performed over pure HZSM-5, mordenite/ZSM-5 (hybrid of mordenite and HZSM-5), and ZM13 (composite mixture of HZSM-5 and MCM-41 at pH 13). Experimental runs were conducted using a batch fluidized bed reactor at temperatures of 300, 350 and 400 °C and reaction times of 3, 5, 7, 10, 13, 15 and 20. s. The rate of toluene methylation and toluene disproportionation were studied on the three catalysts (toluene alkylation is usually accompanied by toluene disproportionation on acid catalyst). Based on the results obtained, a simplified power law kinetic model consisting of three reactions was developed to estimate the activation energies of toluene methylation and disproportionation simultaneously. Coke formation on catalysts was accounted for using both reaction time and reactant conversion decay functions. All parameters were estimated based on quasi-steady state approximation. Estimated kinetic parameters were in good agreement with experimental results. The order of alkylation ability of the catalysts was found to be ZM13 > HZSM-5 > mordenite/ZSM-5, while the reverse is for toluene disproportionation (mordenite/ZSM-5 > HZSM-5 > ZM13). Thus, alkylation of toluene is most favorable on ZM13 due to combined effect of mesoporosity induced through its synthetic route and acid content. Toluene/MeOH molar ratio of 1:1 was most suitable for toluene alkylation reaction. © 2012 Elsevier B.V.

  7. Hydrodeoxygenation of Methyl Laurate over Ni Catalysts Supported on Hierarchical HZSM-5 Zeolite

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    Nana Li

    2017-12-01

    Full Text Available The hierarchical HZSM-5 zeolite was prepared successfully by a simple NaOH treatment method. The concentration of NaOH solution was carefully tuned to optimal the zeolite acidity and pore structure. Under NaOH treatment conditions, a large number of mesopores, which interconnected with the retained micropores, were created to facilitate mass transfer performance. There are very good correlations between the decline of the relative zeolite crystallinity and the loss of micropores volume. The Ni nanoclusters were uniformly confined in the mesopores of hierarchical HZSM-5 by the excessive impregnation method. The direct deoxygenation in N2 and hydrodeoxygenation in H2 of the methyl laurate were compared respectively over the Ni/HZSM-5 catalysts. In the N2 atmosphere, the deoxygenation rate of the methyl laurate on the Ni/HZSM-5 catalyst is relatively slow. In the presence of H2, the synergistic effect between the hydrogenation function of the metal and the acid function of the zeolite supports can make the deoxygenation level more obvious. The yield of hydrocarbon products gradually reached the maximum with the appropriate treatment concentration of 1M NaOH, which could be attributed to the improved mass transfer in the hierarchical HZSM-5 supports.

  8. Fuels by Waste Plastics Using Activated Carbon, MCM-41, HZSM-5 and Their Mixture

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    Miskolczi Norbert

    2016-01-01

    Full Text Available Waste material was pyrolyzed in a horizontal tubular reactor at 530-540°C using different catalysts, such as activated carbon, MCM-41, HZSM-5 and their mixtures. Products were investigated by gas-chromatography, EDXRFS and standardized methods. Catalysts significantly affected the yields of volatiles; e.g. HZSM-5 catalyst increased especially the yield of gaseous hydrocarbons, while MCM-41 catalyst was responsible for increasing the pyrolysis oil yield. Synergistic effects were found using mixtures of different catalysts. Furthermore the catalysts modified the main carbon frame of the products. Pyrolysis oil obtained over HZSM-5 catalyst contained large amounts of aromatics, while MCM-41 catalyst mainly isomerized the carbon frame. Regarding contaminants it was concluded, that the sulphur content could be significantly decreased by activated carbon, however it had only a slight effect to the other properties of the products.

  9. The Hydrocarbon Pool in Ethanol-to-Gasoline over HZSM-5 Catalysts

    DEFF Research Database (Denmark)

    Johansson, Roger; Hruby, S.L.; Hansen, Jeppe Rass

    2009-01-01

    It is shown that the conversion of ethanol-to-gasoline over an HZSM-5 catalyst yields essentially the same product distribution as for methanol-to-gasoline performed over the same catalyst. Interestingly, there is a significant difference between the identity of the hydrocarbon molecules trapped...... inside the HZSM-5 catalyst when ethanol is used as a feed instead of methanol. In particular, the hydrocarbon pool contains a significant amount of ethylsubstituted aromatics when ethanol is used as feedstock, but there remains only methyl-substituted aromatics in the product slate....

  10. In line wood plastic composite pyrolyses and HZSM-5 conversion of the pyrolysis vapors

    International Nuclear Information System (INIS)

    Lin, Xiaona; Zhang, Zhijun; Tan, Shun; Wang, Fengqiang; Song, Yongming; Wang, Qingwen; Pittman, Charles U.

    2017-01-01

    Graphical abstract: HZSM-5 can be used to catalytic convert Wood Fiber-Polypropylene or Wood Fiber-Polypropylene pyrolysis vapors into aromatic compounds in reasonable selectivities. This provides a recycling utilization WPCs wastes method. - Highlights: • Converting wood/plastic composites (WPC) wastes into aromatics. • Recycling WPC by fast pyrolysis coupled with vapor catalytic cracking. • Selective production of aromatics from WPCs and their components over HZSM-5. • Acid site concentration inside zeolite was critical for maximizing aromatic yield. • Synergistic effects between wood and plastics enhanced aromatics production. - Abstract: Wood powder-high density polyethylene (WPE) and wood powder-polypropylene (WPP) composites were pyrolyzed at 550 °C in the presence of HZSM-5 catalysts using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Immediately passing the pyrolysis vapors through the HZSM-5 changed the product distribution by producing aromatic hydrocarbons and eliminating tar formation. Zeolite HZSM-5 was employed with three different silica-to-alumina ratios (25, 50, 260). The influence of catalysts on the yields of aliphatic and aromatic hydrocarbons, furan derivatives, lignin-derived compounds and acetic acid was studied. High yields of aliphatic hydrocarbons formed in WPE or WPP pyrolysis alone. The highest yields of aromatic hydrocarbons from WPE or WPP pyrolysis vapors over HZSM-5 occurred with a zeolite framework Si/Al ratio of 25 (more acid sites), suggesting that the concentration of acid sites inside the zeolite was critical for maximizing aromatic yield. Exposing vapors to HZSM-5 increased the hydrocarbon yields and reduced the amount of acetic acid produced, resulting in increased calorific value. The yields of typical aromatics from catalytic pyrolysis of WPP mixture and composites were higher than those of the calculated values of poplar wood and PP catalytic pyrolysis individually, indicating that a

  11. Utilization of biomass: Conversion of model compounds to hydrocarbons over zeolite H-ZSM-5

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Holm, Martin Spangsberg

    2011-01-01

    Zeolite catalyzed deoxygenation of small oxygenates present in bio-oil or selected as model compounds was performed under Methanol-to-Hydrocarbons (MTH) like reaction conditions using H-ZSM-5 as the catalyst. Co-feeding of the oxygenates with methanol generally decreases catalyst lifetime due...

  12. KONVERSI KATALITIK MINYAK SAWIT UNTUK MENGHASILKAN BIOFUEL MENGGUNAKAN SILIKA ALUMINA DAN HZSM-5 SINTESIS

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    Nurjannah Nurjannah

    2012-02-01

    Full Text Available Terbatasnya sumber energi fosil menyebabkan perlunya pengembangan energi terbarukan yang berasal dari alam dan dapat diperbaharui. Penggunaan bahan bakar minyak bumi, baik dari penggunaan berupa alat transportasi maupun dari penggunaan oleh industri sangat mencemari lingkungan karena tingkat polusi yang ditimbulkan sangat tinggi sehingga perlu mencari bahan bakar alternatif pengganti bahan bakar gasoline, solar, dan kerosene dari minyak nabati. Penelitian dilakukan dalam dua tahapan yaitu sintesa katalis dan proses katalitik cracking. Silika alumina disintesa menggunakan metode Latourette dan HZSM-5 disintesa menggunakan metode Plank. Hasil sintesa dikarakterisasi dengan Penyerapan Spektroskopi Atomis (AAS menunjukkan bahwa silika alumina dan HZSM-5 mempunyai Si/Al 198 dan 243. Luas permukaan  silika alumina dan HZSM-5 diperoleh dari analisa Brunauer Emmet Teller (BET yaitu 149,91-213,35 m2.g-1 dan ukuran pori rata-rata adalah 13oA. Perengkahan katalitik dilakukan dalam suatu mikroreaktor fixed bed pada temperatur 350-500°C dan laju alir gas N2 100-160 ml.min-1 selama 120 min. Hasil perengkahan dianalisa dengan metode gas kromatografi. Hasil yang diperoleh untuk katalis HZSM-5 fraksi gasoline dengan yield tertinggi 28,87%, kerosene 16,70%, dan diesel 12,20%  pada suhu reaktor 4500C dan laju gas N2 100 ml/menit.

  13. Hydrogen/Denterium exchange during n.butane conversion on H-ZSM-5

    NARCIS (Netherlands)

    Narbeshuber, T.; Narbeshuber, Thomas F.; Stockenhuber, Michael; Brait, Axel; Brait, A.; Seshan, Kulathuiyer; Lercher, J.A.

    1996-01-01

    Steady-state isotope tracer studies and isotope transient response experiments ofn-butane conversion on H-ZSM-5 (Si/Al = 35) were carried out between 673 and 823 K. Among the three main reactions, the rate of H/D-exchange is at least one order of magnitude higher compared to the rates of cracking or

  14. Catalytic Fast Pyrolysis of Kraft Lignin over Hierarchical HZSM-5 and Hβ Zeolites

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    Yadong Bi

    2018-02-01

    Full Text Available The hierarchical HZSM-5 and Hβ zeolites were prepared by alkaline post-treatment methods adopting Na2CO3, TMAOH/NaOH mixture, and NaOH as desilication sources, respectively. More mesopores are produced over two kinds of zeolites, while the micropores portion is well preserved. The mesopores formed in hierarchical Hβ zeolites were directly related to the basicity of the alkaline solution, indicating that Hβ zeolite is more sensitive to the alkaline post-treatment. The hierarchical HZSM-5 and Hβ zeolites are more active than the parent one for catalytic fast pyrolysis (CFP of Kraft lignin. Hierarchical zeolites retained the function of acid catalysis, while additionally creating larger mesopores to ensure the entry of bulkier reactant molecules. The increase of the condensable volatiles yield can be attributed to the improvement of the mass transfer performance, which correlates well with the change of mesoporous surface area. In particular, the condensable volatiles yield for the optimized hierarchical Hβ reached approximately two times that of the parent Hβ zeolites. In contrast to the parent HZSM-5, the optimized hierarchical HZSM-5 zeolite significantly reduced the selectivity of oxygenates from 27.2% to 3.3%.

  15. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation

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    Achmad Roesyadi

    2013-03-01

    Full Text Available It is important to develop a renewable source of energy to overcome a limited source fossil energy. Palm oil is a potential alternative and environmental friendly energy resource in Indonesia due to high production capacity of this vegetable oil. The research studied effect of catalyst to selectivity of biofuel product from cracking of palm oil. The catalyst consisted of HZSM-5 catalyst with or without impregnation. The research was conducted in two steps, namely catalyst synthesized and catalytic cracking process. HZSM-5 was synthesized using Plank methods. The characterization of the synthesized catalysts used AAS (Atomic Absorption Spectroscopy and BET (Brunaueur Emmet Teller. The cracking was carried out in a fixed bed microreactor with diameter of 1 cm and length of 16 cm which was filled with 0.6 gram catalyst. The Zn/HZSM-5 catalyst was recommended for cracking palm oil for the high selectivity to gasoline. © 2013 BCREC UNDIP. All rights reserved.(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 28th September 2012; Revised: 19th November 2012; Accepted: 20th December 2012[How to Cite: A. Roesyadi, D. Hariprajitno, N. Nurjannah, S.D. Savitri, (2013. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 185-190.(doi:10.9767/bcrec.7.3.4045.185-190][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4045.185-190 ] View in  |

  16. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation

    OpenAIRE

    Achmad Roesyadi; Danawati Hariprajitno; Nurjannah Nurjannah; Santi Dyah Savitri

    2013-01-01

    It is important to develop a renewable source of energy to overcome a limited source fossil energy. Palm oil is a potential alternative and environmental friendly energy resource in Indonesia due to high production capacity of this vegetable oil. The research studied effect of catalyst to selectivity of biofuel product from cracking of palm oil. The catalyst consisted of HZSM-5 catalyst with or without impregnation. The research was conducted in two steps, namely catalyst synthesized and cata...

  17. Catalytic Fast Pyrolysis of Cellulose by Integrating Dispersed Nickel Catalyst with HZSM-5 Zeolite

    Science.gov (United States)

    Lei, Xiaojuan; Bi, Yadong; Zhou, Wei; Chen, Hui; Hu, Jianli

    2018-01-01

    The effect of integrating dispersed nickel catalyst with HZSM-5 zeolite on upgrading of vapors produced from pyrolysis of lignocellulosic biomass was investigated. The active component nickel nitrate was introduced onto the cellulose substrate by impregnation technique. Based on TGA experimental results, we discovered that nickel nitrate first released crystallization water, and then successively decomposed into nickel oxide which was reduced in-situ to metallic nickel through carbothermal reduction reaction. In-situ generated nickel nanoparticles were found highly dispersed over carbon substrate, which were responsible for catalyzing reforming and cracking of tars. In catalytic fast pyrolysis of cellulose, the addition of nickel nitrate caused more char formation at the expense of the yield of the condensable liquid products. In addition, the selectivity of linear oxygenates was increased whereas the yield of laevoglucose was reduced. Oxygen-containing compounds in pyrolysis vapors were deoxygenated into aromatics using HZSM-5. Moreover, the amount of condensable liquid products was decreased with the addition of HZSM-5.

  18. Produksi Biofuel dari Minyak Kelapa Sawit dengan Katalis Au/HZSM-5 dan Kompositnya

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    Tillotama Anindita Sari

    2012-09-01

    Full Text Available Semakin meningkatnya kebutuhan dan konsumsi bahan bakar minyak menyebabkan cadangan minyak bumi semakin menipis sehingga perlu adanya pengembangan bahan lain sebagai sumber bahan bakar alternatif yang dapat menggantikannya. Salah satu produk energi alternatif yang ramah lingkungan dan dapat diperbaharui adalah biofuel. Perubahan minyak sawit menjadi biofuel salah satunya adalah dengan proses perengkahan katalitik. Penelitian ini bertujuan untuk mengatasi masalah tersebut dimana dalam penelitian ini akan dipelajari kondisi operasi dan  unjuk kerja katalis Au/HZSM-5 sintetis dan kompositnya pada reaksi perengkahan minyak sawit menjadi biofuel. Penelitian ini diharapakan mampu menghasilkan teknologi pembuatan katalis baru dan teknologi proses baru dalam proses produksi biofuel pada proses perengkahan katalitik asam palmitat dari minyak sawit. Pada penelitian ini biofuel telah berhasil diperoleh pada proses perengkahan minyak sawit menggunakan katalis Au/HZSM-5 sintetis dan kompositnya pada berbagai temperatur dan laju alir gas N2. Penelitian dilakukan dengan tiga tahapan yaitu sintesa katalis, karakterisasi katalis dan proses perengkahan katalitik. Au/HZSM-5 disintesa dengan metode Plank dan katalis komposit disentesa berdasarkan penelitian yang telah dilakukan oleh Qjang Tang et all. Hasil yang telah berhasil disintesa dikarakterisasi dengan Energy Difraction X-Ray (EDX, X-Ray Difraction (XRD dan Brunaur Emmet Teller (BET. Dari hasil karakterisasi dapat disimpulkan bahwa katalis yang telah disintetis telah memenuhi syarat untuk digunakan sebagai katalis pada proses perengkahan. Proses perengkahan katalitik dilakukan dalam suatu mikroreaktor fixed bed dengan berat katalis yang digunakan sebanyak 2 gram dan proses perengkahan dimulai saat gas N2 dialirkan selama 60 menit. Proses perengkahan dilakukan pada variasi temperatur 350-550 °C dan laju alir gas N2 90-400 ml/min. Hasil perengkahan dianalisa dengan metode gas kromatografi. Hasil yang

  19. Hydrocracking of Cerbera manghas Oil with Co-Ni/HZSM-5 as Double Promoted Catalyst

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    Lenny Marlinda

    2017-05-01

    Full Text Available The effect of various reaction temperature on the hydrocracking of Cerbera manghas oil to produce a paraffin-rich mixture of hydrocarbons with Co-Ni/HZSM-5 as doubled promoted catalyst were studied. The Co-Ni/HZSM-5 catalyst with various metal loading and metal ratio was prepared by incipient wetness impregnation. The catalysts were characterized by XRD, AAS, and N2 adsorption-desorption. Surface area, pore diameter, and pore volume of catalysts decreased with the increasing of metals loading. The hydrocracking process was conducted under hydrogen initial pressure in batch reactor equipped with a mechanical stirrer. The reaction was carried out at a temperature of 300-375 oC for 2 h.  Depending on the experimental condition, the reaction pressure changed between 10 bar and 15 bar.   Several parameters were used to evaluate biofuel produced, including oxygen removal, hydrocarbon composition and gasoline/kerosene/diesel yields. Biofuel was analyzed by Fourier Transform Infrared Spectroscopic (FTIR and gas chromatography-mass spectrometry (GC-MS. The composition of hydrocarbon compounds in liquid products was similar to the compounds in the gasoil sold in unit of Pertamina Gas Stations, namely pentadecane, hexadecane, heptadecane, octadecane, and nonadecane with different amounts for each biofuel produced at different reaction temperatures. However, isoparaffin compounds were not formed at all operating conditions. Pentadecane (n-C15 and heptadecane (n-C17 were the most abundant composition in gasoil when Co-Ni/HZSM-5 catalyst was used. Cerbera Manghas oil can be recommended as the source of non-edible vegetable oil to produce gasoil as an environmentally friendly transportation fuel. Copyright © 2017 BCREC Group. All rights reserved Received: 20th May 2016; Revised: 30th January 2017; Accepted: 10th February 2017 How to Cite: Marlinda, L., Al-Muttaqii, M., Gunardi, I., Roesyadi, A., Prajitno, D.H. (2017. Hydrocracking of Cerbera manghas Oil

  20. Zn-Mo/HZSM-5 Catalyst for Gasoil Range Hydrocarbon Production by Catalytic Hydrocracking of Ceiba pentandra oil

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    Yustia Wulandari Mirzayanti

    2018-01-01

    Full Text Available Biofuel from vegetable oil becomes one of the most suitable and logical alternatives to replace fossil fuel. The research focused on various metal ratio Zinc/Molybdenum/HZSM-5 (Zn-Mo/HZSM-5 catalyst to produce liquid hydrocarbon via catalytic hydrocracking of Ceiba penandra oil. The catalytic hydrocracking process has been applied in this study to crack Ceiba pentandra oil into a gasoil range hydrocarbon using Zn-Mo/HZSM-5 as a catalyst. The effect of various reaction temperature on the catalytic hydrocracking of Ceiba pentandra oil were studied. The Zn-Mo/HZSM-5 catalyst with metal ratio was prepared by incipient wetness impregnation method. This process used slurry pressure batch reactor with a mechanical stirrer. A series of experiments were carried out in the temperature range from 300-400 oC for 2 h at pressure between 10-15 bar. The conversion and selectivity were estimated. The liquid hydrocarbon product were identified to gasoline, kerosene, and gas oil. The results show that the use of Zn-Mo/HZSM-5 can produce gas oil as the most component in the product. Overall, the highest conversion and selectivity of gas oil range hydrocarbon was obtained when the ZnMo/HZSM-5 metal ratio was Zn(2.86 wt.%-Mo(5.32 wt.%/HZSM-5 and the name is Zn-Mo/HZSM-5_102. The highest conversion was obtained at 63.31 % and n-paraffin (gas oil range selectivity was obtained at 90.75 % at a temperature of 400 oC. Ceiba pentandra oil can be recommended as the source of inedible vegetable oil to produce gasoil as an environmentally friendly transportation fuel. Copyright © 2018 BCREC Group. All rights reserved Received: 8th September 2017; Revised: 9th September 2017; Accepted: 17th September 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Mirzayanti, Y.W., Kurniawansyah, F., Prajitno, D.H., Roesyadi, A. (2018. Zn-Mo/HZSM-5 Catalyst for Gasoil Range Hydrocarbon Production by Catalytic Hydrocracking of Ceiba pentandra

  1. Production of liquid alkanes by controlling reactivity of sorbitol hydrogenation with a Ni/HZSM-5 catalyst in water

    International Nuclear Information System (INIS)

    Zhang, Qing; Wang, Tiejun; Xu, Ying; Zhang, Qi; Ma, Longlong

    2014-01-01

    Graphical abstract: MCM-41-modified Ni/HZSM-5 catalyst was developed by impregnation method with high catalytic performance for sorbitol hydrogenation in water. Appropriate amount of MCM-41 addition can distinctly promote the improvement in the surface structure and modulation of acidic sites of the catalyst. The scission of C–O bond in the sorbitol molecule into liquid alkanes was easily carried out on the catalyst containing more Lewis acidic sites. - Highlights: • Ni/HZSM-5 promoted with MCM-41 is active for sorbitol hydrogenation to liquid alkanes. • Lewis acidic sites of Ni/HZSM-5 can be modulated by pure silica MCM-41. • MCM-41 added can distinctly decrease carbon deposition on the catalyst surface. - Abstract: Liquid fuels derived from renewable biomass are of great importance on the potential substitution for diminishing fossil fuels. The conversion of sorbitol (a product of biomass-derived glucose hydrogenation) into liquid alkanes such as pentane and hexane over the Ni/HZSM-5 catalysts with or without MCM-41 addition was investigated in the presence of hydrogen in water medium. The production distribution of sorbitol hydrogenation can be controlled by adjusting the acidity of the catalyst. The scission of C–C bond in the sorbitol molecule into light C 1 –C 4 alkanes was mainly carried out over Ni/HZSM-5 containing strong Brønsted acid sites, while C–O bond scission into heavier alkanes was dominated over the catalysts added by MCM-41 containing weak Lewis acid sites. The sorbitol conversion and total liquid alkanes selectivity were found to be 67.1% and 98.7% over 2%Ni/HZSM-5 modified by 40 wt% of MCM-41, whereas the corresponding value was 40% and 35.6% over 2%Ni/HZSM-5 in the absence of MCM-41. The effect of MCM-41 on the structure, acidity, and reducibility of Ni/HZSM-5 was investigated by using XRD, Py-IR, IR, and H 2 -TPR. Meanwhile, the resistance of carbon deposition over the catalyst modified by MCM-41 was studied by using TG

  2. Catalytic hydrothermal liquefaction (HTL of biomass for bio-crude production using Ni/HZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Shouyun Cheng

    2017-04-01

    Full Text Available Hydrothermal liquefaction (HTL is an effective method that can convert biomass into bio-crude, but direct use of bio-crude derived from biomass HTL remains a challenge due to the lower quality. In this study, bifunctional Ni/HZSM-5 catalysts and zinc hydrolysis were combined to produce upgraded bio-crude in an in-situ HTL process. The K2CO3 and HZSM-5 catalysts with different Ni loading ratios were tested. The effects of different catalysts on the yield and quality of bio-crude and gas were investigated. The results indicated that the catalysts improved bio-crude and gas yields, compared to pine sawdust liquefaction without catalyst. The catalysts reduced the contents of undesirable oxygenated compounds such as acids, ketones, phenols, alcohols and esters in bio-crude products while increased desirable hydrocarbons content. K2CO3 produced highest bio-crude yield and lowest solid residue yield among all catalysts. Compared to parent HZSM-5 catalyst, bifunctional Ni/HZSM-5 catalysts exhibited higher catalyst activity to improve quality of upgraded bio-crude due to its integration of cracking and hydrodeoxygenation reactions. 6%Ni/HZSM-5 catalyst produced the bio-crude with the highest hydrocarbons content at 11.02%. This catalyst can be a candidate for bio-crude production from biomass HTL.

  3. Removal of gas phase low-concentration toluene over Mn, Ag and Ce modified HZSM-5 catalysts by periodical operation of adsorption and non-thermal plasma regeneration.

    Science.gov (United States)

    Wang, Wenzheng; Wang, Honglei; Zhu, Tianle; Fan, Xing

    2015-07-15

    Ag/HZSM-5, Mn/HZSM-5, Ce/HZSM-5, Ag-Mn/HZSM-5 and Ce-Mn/HZSM-5 were prepared by impregnation method. Both their adsorption capacity and catalytic activity were investigated for the removal of gas phase low-concentration toluene by periodical operation of adsorption and non-thermal plasma regeneration. Results show that catalysts loaded with Ag (Ag/HZSM-5 and Ag-Mn/HZSM-5) had larger adsorption capacity for toluene than the other catalysts. And Ag-Mn/HZSM-5 displayed the best catalytic performance for both toluene oxidation by non-thermal plasma and byproducts suppression. On the other hand, the deactivated catalyst can be fully regenerated by calcining in air stream when its adsorption capacity and catalytic activity of the Ag-Mn/HZSM-5 catalyst was found to be decreased after 10 cycles of periodical adsorption and non-thermal regeneration. Copyright © 2015. Published by Elsevier B.V.

  4. Characterization of Cr/Bentonite and HZSM-5 Zeolite as Catalysts for Ethanol Conversion to Biogasoline

    Directory of Open Access Journals (Sweden)

    Robert Ronal Widjaya

    2012-04-01

    Full Text Available In this research it has been done characterization on Cr/Bentonit and Zeolit HZSM-5 catalysts for ethanol catalytic process to biogasoline (equal to gasoline. Cr/Bentonit has high acidity and resistant to a lot of moisture, so in addition to being able to processing feed which a lot of moisture (>15% from ethanol-water mixture, also it is not easy deactivated. Cr/Bentonit which is then used as the catalyst material on the process of ethanol conversion to be biogasoline and the result was compared with catalyst HZSM-5 zeolite. Several characterization methods: X-ray diffraction, Brunauer Emmett Teller (BET, thermogravimetry analysis (TGA, and catalyst activity tests using catalytic Muffler instrument and gas chromatography-mass spectrometry (GC-MS for product analysis were performed on both catalysts. From acidity measurement, it is known that acidity level of Cr/Bentonit is the highest and also from XRD result, it is known there is shift for 2theta in Cr/Bentonit, which indicates that Cr-pillar in the Bentonite can have interaction. It is also supported by BET data that shows the addition of specific surface are in Cr/Bentonite compared with natural Bentonite before pillarization. Futhermore catalyst activity test produced the results, analyzed by GC-MS, identified as butanol and also possibly formed hexanol, decane, dodecane, undecane, which are all included in gasoline range (C4 until C12.

  5. Conversion of n-Butane to iso-Butene on Gallium/HZSM-5 Catalysts

    Directory of Open Access Journals (Sweden)

    S.M. Gheno

    2002-07-01

    Full Text Available The conversion of n-butane to iso-butene on gallium/HZSM-5 catalysts at 350ºC and WHSV=2.5h8-1 was studied. The catalysts were prepared by ion exchange from a Ga(NO32 solution and further submitted to calcination in air at 530ºC. TEM analysis with an EDAX detector and TPR-H2 data showed that after calcination the Ga species were present mainly as Ga2O3, which are reduced to Ga2O at temperatures near 610ºC. The specific acid activity (SAA of the catalysts increased with the increase in aluminum content in the zeolite, and for a fixed Si/Al ratio, the SAA increased with Ga content. Values for specific hydro/dehydrogenation activity (SH/DHA were significantly higher than those for SAA, indicating that the catalytic process is controlled by the kinetics on acid sites. Moreover, the production of iso-butene with a selectivity higher than 25% was a evidence that in gallium/HZSM-5-based catalysts the rate of the hydrogenation reaction is lower than that of the dehydrogenation reaction; this behavior confirmed the dehydrogenation nature of gallium species, thereby showing great promise for iso-butene production.

  6. Relevance of the Mo-precursor state in H-ZSM-5 for methane dehydroaromatization

    KAUST Repository

    Vollmer, Ina

    2018-01-04

    Although the local geometry of Mo in Mo/HZSM-5 has been characterized before, we present a systematic way to manipulate the configuration of Mo and link it to its catalytic properties. The location and geometry of cationic Mo-complexes, the precursor of the active metal site for methane dehydroaromatization, are altered by directing the way they anchor to the framework of the zeolite. The feature used to direct the anchoring of Mo is the location of Al in the zeolite framework. According to DFT calculations, the local geometry of Mo should change, while UV-vis and pyridine FTIR spectroscopy indicated differences in the dispersion of Mo. Both aspects, however, did not influence the catalytic behavior of Mo/HZSM-5, indicating that as long as enough isolated Mo species are present inside the pores of the zeolite, the catalytic behavior is unaffected. This paves the way to better understand how the Mo oxo precursor transforms into the active phase under the reaction conditions.

  7. Efficient Hydrogenolysis of Guaiacol over Highly Dispersed Ni/MCM-41 Catalyst Combined with HZSM-5

    Directory of Open Access Journals (Sweden)

    Songbai Qiu

    2016-09-01

    Full Text Available A series of MCM-41 supported Ni catalysts with high metal dispersion was successfully synthesized by simple co-impregnation using proper ethylene glycol (EG. The acquired Ni-based catalysts performed the outstanding hydrogenolysis activity of guaiacol. The effects of the synthesis parameters including drying temperature, calcination temperature, and metal loading on the physical properties of NiO nanoparticles were investigated through the use of X-ray diffraction (XRD. The drying temperature was found to significantly influence the particle sizes of NiO supported on MCM-41, but the calcination temperature and metal loading had less influence. Interestingly, the small particle size (≤3.3 nm and the high dispersion of NiO particles were also obtained for co-impregnation on the mixed support (MCM-41:HZSM-5 = 1:1, similar to that on the single MCM-41 support, leading to excellent hydrogenation activity at low temperature. The guaiacol conversion could reach 97.9% at 150 °C, and the catalytic activity was comparative with that of noble metal catalysts. The hydrodeoxygenation (HDO performance was also promoted by the introduction of acidic HZSM-5 zeolite and an 84.1% yield of cyclohexane at 240 °C was achieved. These findings demonstrate potential applications for the future in promoting and improving industrial catalyst performance.

  8. Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Lercher, Johannes A. [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Dept. of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 Garching 85748 Germany

    2016-10-06

    Aqueous phase dehydration of 1-propanol over H-ZSM-5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulation of the mimicking aqueous phase H-ZSM-5 zeolite unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol-propanol, the propanol-water complex, and the trimeric propanol-propanol-water are formed at high propanol concentrations, which provide a kinetically feasible dehydration reaction channel of 1-propanol to propene. However, calculation results also indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration reaction. This work was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.

  9. Rate Parameter Distributions for Isobutane Dehydrogenation and Isobutene Dimerization and Desorption over HZSM-5

    Directory of Open Access Journals (Sweden)

    Trevor C. Brown

    2013-11-01

    Full Text Available Deconvolution of the evolved isobutene data obtained from temperature-programmed, low-pressure steady-state conversion of isobutane over HZSM-5 has yielded apparent activation energies for isobutane dehydrogenation, isobutene dimerization and desorption. Intrinsic activation energies and associated isobutane collision frequencies are also estimated. A combination of wavelet shrinkage denoising, followed by time-varying flexible least squares of the evolved mass-spectral abundance data over the temperature range 150 to 450 °C, provides accurate, temperature-dependent, apparent rate parameters. Intrinsic activation energies for isobutane dehydrogenation range from 86 to 235.2 kJ mol−1 (average = 150 ± 42 kJ mol−1 for isobutene dimerization from 48.3 to 267 kJ mol−1 (average = 112 ± 74 kJ mol−1 and for isobutene desorption from 64.4 to 97.8 kJ mol−1 (average = 77 ± 12 kJ mol−1. These wide ranges reflect the heterogeneity and acidity of the zeolite surface and structure. Seven distinct locations and sites, including Lewis and Brønsted acid sites can be identified in the profiles. Isobutane collision frequencies range from 10−0.4 to 1022.2 s−1 and are proportional to the accessibility of active sites, within the HZSM-5 micropores or on the external surface.

  10. Relevance of the Mo-precursor state in H-ZSM-5 for methane dehydroaromatization

    KAUST Repository

    Vollmer, Ina; Li, Guanna; Yarulina, Irina; Kosinov, Nikolay; Hensen, Emiel J.; Houben, Klaartje; Mance, Deni; Baldus, Marc; Gascon, Jorge; Kapteijn, Freek

    2018-01-01

    Although the local geometry of Mo in Mo/HZSM-5 has been characterized before, we present a systematic way to manipulate the configuration of Mo and link it to its catalytic properties. The location and geometry of cationic Mo-complexes, the precursor of the active metal site for methane dehydroaromatization, are altered by directing the way they anchor to the framework of the zeolite. The feature used to direct the anchoring of Mo is the location of Al in the zeolite framework. According to DFT calculations, the local geometry of Mo should change, while UV-vis and pyridine FTIR spectroscopy indicated differences in the dispersion of Mo. Both aspects, however, did not influence the catalytic behavior of Mo/HZSM-5, indicating that as long as enough isolated Mo species are present inside the pores of the zeolite, the catalytic behavior is unaffected. This paves the way to better understand how the Mo oxo precursor transforms into the active phase under the reaction conditions.

  11. Experimental study of polyethylene pyrolysis and combustion over HZSM-5, HUSY, and MCM-41.

    Science.gov (United States)

    Huang, Que; Liu, Changcheng; Wei, Ruichao; Wang, Jian

    2017-07-05

    The effects of temperatures, catalysts, and catalyst contents on polyethylene (PE) pyrolysis were investigated by using single-photon ionization time-of-flight mass spectrometry (SPI-TOFMS). The mass spectra of pyrolyzed PE and PE/catalysts from 300°C to 800°C illustrate that the pyrolysis reactions were apparently promoted and varied by introducing HZSM-5, HUSY, and MCM-41. As microporous catalysts, HZSM-5 and HUSY were found to accelerate the BTX formation at 400°C, which could not be observed for pure PE until 800°C. With the existence of MCM-41, only alkenes were produced below 600°C. The pyrolysis processes could to be accelerated by adding catalysts. Principal components analysis (PCA) was finally employed to identify the main factors with influence on the products distribution. Analytical results showed that the yield of the majority of products could be affected by different experimental conditions, that the type of catalysts makes the most significant influence. The impact of different types of catalysts on fire hazard of PE was studied by using the cone calorimeter. The results indicated that the time to ignition (TTI) and the peak heat release rate (pHRR) were changed remarkably. It is worth noting that with the addition of MCM-41, the pHRR is the minimum. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

    Directory of Open Access Journals (Sweden)

    Xiangjin Kong

    Full Text Available The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

  13. Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

    Science.gov (United States)

    Kong, Xiangjin; Liu, Junhai

    2014-01-01

    The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

  14. Multinuclear MAS NMR studies on coked zeolites H-ZSM-5

    International Nuclear Information System (INIS)

    Ernst, H.; Freude, D.; Hunger, M.; Pfeifer, H.

    1991-01-01

    During the cracking process carbonaceous materials are deposited on the outer or inner surface of the catalyst. These deposits are in many cases the main cause of catalyst deactivation. Magic angle spinning (MAS) NMR investigations and catalytic n-hexane cracking were carried out on H-ZSM-5 zeolites after a mild hydrothermal de-alumination. By 13 C CP MAS NMR it could be shown that the enhanced catalytic activity does not enhance the coke formation and that the chemical nature of these deposits is essentially aromatic. From 1 H MAS NMR studies performed on shallow-bed activated sealed samples and 27 Al and 29 Si MAS NMR on rehydrated samples it follows that for high coke concentrations the catalyst deactivation is caused mainly by blocking of Broensted acid sites. (author). 27 refs.; 3 figs.; 2 tabs

  15. Hexane cracking over steamed phosphated zeolite H-ZSM-5 : Promotional effect on catalyst performance and stability

    NARCIS (Netherlands)

    Van Der Bij, Hendrik E.; Meirer, Florian; Kalirai, Samanbir; Wang, Jian; Weckhuysen, Bert M.

    2014-01-01

    The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of 27Al and 31P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3

  16. Selective dehydration of bio-ethanol to ethylene catalyzed by lanthanum-phosphorous-modified HZSM-5: influence of the fusel.

    Science.gov (United States)

    Hu, Yaochi; Zhan, Nina; Dou, Chang; Huang, He; Han, Yuwang; Yu, Dinghua; Hu, Yi

    2010-11-01

    Bio-ethanol dehydration to ethylene is an attractive alternative to oil-based ethylene. The influence of fusel, main byproducts in the fermentation process of bio-ethanol production, on the bio-ethanol dehydration should not be ignored. We studied the catalytic dehydration of bio-ethanol to ethylene over parent and modified HZSM-5 at 250°C, with weight hourly space velocity (WHSV) equal to 2.0/h. The influences of a series of fusel, such as isopropanol, isobutanol and isopentanol, on the ethanol dehydration over the catalysts were investigated. The 0.5%La-2%PHZSM-5 catalyst exhibited higher ethanol conversion (100%), ethylene selectivity (99%), and especially enhanced stability (more than 70 h) than the parent and other modified HZSM-5. We demonstrated that the introduction of lanthanum and phosphorous to HZSM-5 could weaken the negative influence of fusel on the formation of ethylene. The physicochemical properties of the catalysts were characterized by ammonia temperature-programmed desorption (NH(3)-TPD), nitrogen adsorption and thermogravimetry (TG)/differential thermogravimetry (DTG)/differential thermal analysis (DTA) (TG/DTG/DTA) techniques. The results indicated that the introduction of lanthanum and phosphorous to HZSM-5 could inhibit the formation of coking during the ethanol dehydration to ethylene in the presence of fusel. The development of an efficient catalyst is one of the key technologies for the industrialization of bio-ethylene.

  17. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  18. Elastic behavior of MFI-type zeolites: Compressibility of H-ZSM-5 in penetrating and non-penetrating media

    International Nuclear Information System (INIS)

    Quartieri, Simona; Montagna, Gabriele; Arletti, Rossella; Vezzalini, Giovanna

    2011-01-01

    The elastic behavior of H-ZSM-5 was investigated by in-situ synchrotron X-ray powder diffraction, using both silicone oil (s.o.) and (16:3:1) methanol:ethanol:water (m.e.w.) as 'non-penetrating' and 'penetrating' pressure transmitting media, respectively. From P amb to 6.2 GPa the volume reduction observed in s.o. is 16.6%. This testifies that H-ZSM-5 is one of the most flexible microporous materials up to now compressed in s.o. Volume reduction observed in m.e.w. up to 7.6 GPa is 14.6%. A strong increase in the total electron number of the extraframework system, due to the penetration of water/alcohol molecules in the pores, is observed in m.e.w. This effect is the largest up to now observed in zeolites undergoing this phenomenon without cell volume expansion. The higher compressibility in s.o. than in m.e.w. can be ascribed to the penetration of the extra-water/alcohol molecules, which stiffen the structure and contrast the channel deformations. - Graphical abstract: High-pressure behavior of H-ZSM-5 compressed in (16:3:1) methanol:ethanol:water: (a) projection of the structure along the [0 1 0] direction at P amb , 2 GPa and after pressure release to original ambient conditions (P amb (rev)), and (b) P-dependence of the extraframework content expressed as total number of electrons (gray square represents the number of the extraframework electrons at P amb after decompression). Highlights: → X-ray powder diffraction study of H-ZSM-5 compressibility. → H-ZSM-5 is one of the softest porous material compressed in silicon oil. → Penetration of additional water/alcohol molecules upon compression in m.e.w. → Extra molecules contribute to stiffen the structure and to contrast HP effects.

  19. Chemistry of Furan Conversion into Aromatics and Olefins over HZSM-5: A Model Biomass Conversion Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yu-Ting; Huber, George W.

    2011-06-03

    The conversion of furan (a model of cellulosic biomass) over HZSM-5 was investigated in a thermogravimetric analysis–mass spectrometry system, in situ Fourier transform infrared analysis, and in a continuous-flow fixed-bed reactor. Furan adsorbed as oligomers at room temperature with a 1.73 of adsorbed furan/Al ratio. These oligomers were polycyclic aromatic compounds that were converted to CO, CO₂, aromatics, and olefins at temperatures from 400 to 600 °C. Aromatics (e.g., benzene, toluene, and naphthalene), oligomer isomers (e.g., benzofuran, 2,2-methylenebisfuran, and benzodioxane), and heavy oxygenates (C₁₂{sub +} oligomers) were identified as intermediates formed inside HZSM-5 at different reaction temperatures. During furan conversion, graphite-type coke formed on the catalyst surface, which caused the aromatics and olefins formation to deactivate within the first 30 min of time on-stream. We have measured the effects of space velocity and temperature for furan conversion to help us understand the chemistry of biomass conversion inside zeolite catalysts. The major products for furan conversion included CO, CO₂, allene, C₂–C₆ olefins, benzene, toluene, styrene, benzofuran, indene, and naphthalene. The aromatics (benzene and toluene) and olefins (ethylene and propylene) selectivity decreased with increasing space velocity. Unsaturated hydrocarbons such as allene, cyclopentadiene, and aromatics selectivity increased with increasing space velocity. The product distribution was selective to olefins and CO at high temperatures (650 °C) but was selective to aromatics (benzene and toluene) at intermediate temperatures (450–600 °C). At low temperatures (450 °C), benzofuran and coke contributed 60% of the carbon selectivity. Several different reactions were occurring for furan conversion over zeolites. Some important reactions that we have identified in this study include Diels–Alder condensation (e.g., two furans form benzofuran and water

  20. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    International Nuclear Information System (INIS)

    Ding, Weiping; Meitzner, George D.; Marler, David O.; Iglesia, Enrique

    2001-01-01

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5

  1. The role of zeolites in the deactivation of multifunctional fischer-tropsch synthesis catalysts: the interaction between HZSM-5 and Fe-based Ft-catalysts

    Directory of Open Access Journals (Sweden)

    P. C. Zonetti

    2013-12-01

    Full Text Available In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis.

  2. The role of zeolites in the deactivation of multifunctional Fischer-Tropsch Synthesis catalysts: the interaction between HZSM-5 and Fe-based FT-catalysts

    International Nuclear Information System (INIS)

    Zonetti, P.C.; Gaspar, A.B.; Mendes, F.M.T.; Appel, L.G.; Avillez, R. R. de; Sousa-Aguiar, E.F.

    2013-01-01

    In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis. (author)

  3. The role of zeolites in the deactivation of multifunctional Fischer-Tropsch Synthesis catalysts: the interaction between HZSM-5 and Fe-based FT-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zonetti, P.C.; Gaspar, A.B.; Mendes, F.M.T.; Appel, L.G., E-mail: lucia.appel@int.gov.br [Instituto Nacional de Tecnologia (INT/MCT), Rio de Janeiro, RJ (Brazil); Avillez, R. R. de [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil); Sousa-Aguiar, E.F. [Centro de Pesquisa Leopoldo Americo Miguez de Mello (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2013-10-15

    In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis. (author)

  4. Rekayasa Katalis Ni/Zn-HZSM-5 untuk Memproduksi Biofuel dari Minyak Bintaro

    Directory of Open Access Journals (Sweden)

    Muhammad Iqbal

    2014-09-01

    Full Text Available Sumber energi alternatif terbarukan sangat diperlukan pada masa kini, sebab penggunaan sumber energi fosil tidak dapat menjadi andalan untuk masa depan. Hal ini karena sumber energi fosil semakin menipis dan penggunaannya menghasilkan emisi CO2 yang tidak ramah lingkungan. Salah satu sumber energi alternatif yang menjanjikan adalah biofuel. Biofuel merupakan sumber energi terbarukan dan ramah lingkungan. Penelitian ini bertujuan untuk mempelajari pengaruh katalis berpromotor ganda Ni/Zn-HZSM-5 dan suhu terhadap proses perengkahan minyak bintaro untuk memproduksi biofuel. Variabel yang digunakan adalah perbandingan massa Ni terhadap Zn, perbandingan massa logam terhadap katalis total serta suhu. Parameter kualitas biofuel dapat dilihat dari nilai selektivitas. Selektivitas maksimum gasoline sebesar 52,42% tercapai pada suhu 350°C dan selektivitas maksimum kerosene sebesar 86,72% tercapai pada suhu 400°C pada pengguunaan katalis dengan perbandingan Ni:Zn sebesar 1:1 dengan logam 2% massa total katalis. Diperlukan penelitian yang lebih lanjut untuk memproduksi biofuel yang lebih berkualitas pada suhu yang lebih tinggi dan massa katalis yang lebih besar.

  5. SYNTHESIS OF PROPYLENE FROM ETHANOL USING PHOSPHORUS-MODIFIED HZSM-5

    Directory of Open Access Journals (Sweden)

    R. S. Costa

    Full Text Available Abstract Effects of phosphorus addition to HZSM-5 on ethanol conversion to propylene were evaluated. Catalysts were characterized by XRF, XRD, nitrogen adsorption, 27Al and 31P MAS NMR, n-propylamine and ammonia TPD. Increasing P content decreased the strength and density of acid total sites. Ethanol dehydration was carried out in a fixed bed reactor operating at atmospheric pressure. Conversion was around 100% for all catalysts. 1.2 wt% of P catalyst showed the highest propylene yield, and was used to evaluate temperature and ethanol partial pressure effects on the product distribution. The highest propylene accumulated productivity was obtained for an ethanol partial pressure of 0.4 atm. Propylene formation was favored in the temperature range 475-500 °C. Significant changes in the product distribution as a function of time on stream were observed at higher temperatures, suggesting stronger catalyst deactivation. The ethylene yield decreased up to 500 °C, rising significantly at 550 °C, possibly due to heavier product cracking reactions.

  6. Ethanol dehydration in HZSM-5 studied by density functional theory: evidence for a concerted process.

    Science.gov (United States)

    Kim, Seonah; Robichaud, David J; Beckham, Gregg T; Paton, Robert S; Nimlos, Mark R

    2015-04-16

    Dehydration over acidic zeolites is an important reaction class for the upgrading of biomass pyrolysis vapors to hydrocarbon fuels or to precursors for myriad chemical products. Here, we examine the dehydration of ethanol at a Brønsted acid site, T12, found in HZSM-5 using density functional theory (DFT). The geometries of both cluster and mixed quantum mechanics/molecular mechanics (QM:MM) models are prepared from the ZSM-5 crystal structure. Comparisons between these models and different DFT methods are conducted to show similar results among the models and methods used. Inclusion of the full catalyst cavity through a QM:MM approach is found to be important, since activation barriers are computed on average as 7 kcal mol(-1) lower than those obtained with a smaller cluster model. Two different pathways, concerted and stepwise, have been considered when examining dehydration and deprotonation steps. The current study shows that a concerted dehydration process is possible with a lower (4-5 kcal mol(-1)) activation barrier while previous literature studies have focused on a stepwise mechanism. Overall, this work demonstrates that fairly high activation energies (∼50 kcal mol(-1)) are required for ethanol dehydration. A concerted mechanism is favored over a stepwise mechanism because charge separation in the transition state is minimized. QM:MM approaches appear to provide superior results to cluster calculations due to a more accurate representation of charges on framework oxygen atoms.

  7. Hydronium-Ion-Catalyzed Elimination Pathways of Substituted Cyclohexanols in Zeolite H-ZSM5

    Energy Technology Data Exchange (ETDEWEB)

    Hintermeier, Peter H. [Department; Eckstein, Sebastian [Department; Mei, Donghai [Institute; Olarte, Mariefel V. [Institute; Camaioni, Donald M. [Institute; Baráth, Eszter [Department; Lercher, Johannes A. [Department; Institute

    2017-10-02

    Hydronium ions in the pores of zeolite H-ZSM5 show high catalytic activity in the elimination of water from cyclohexanol in aqueous phase. Substitution induces subtle changes in rates and reaction pathways, which are concluded to be related to steric effects. Exploring the reaction pathways of 2-, 3-, and 4-methylcyclohexanol (2-McyOH, 3-McyOH, and 4-McyOH), 2- and 4-ethylcyclohexanol (2-EcyOH and 4-EcyOH), 2-n-propylcyclohexanol (2-PcyOH), and cyclohexanol (CyOH) it is shown that the E2 character increases with closer positioning of the alkyl and hydroxyl groups. Thus, 4-McyOH dehydration proceeds via an E1-type elimination, while cis-2-McyOH preferentially reacts via an E2 pathway. The entropy of activation decreased with increasing alkyl chain length (ca. 20 J mol-1 K-1 per CH2 unit) for 2-substituted alcohols, which is concluded to result from constraints influencing the configurational entropy of the transition states.

  8. Performance of modified H-ZSM-5 zeolite for dehydration of methanol to dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Hassanpour, Samaneh; Taghizadeh, Majid [Department of chemical engineering, Babol University of Technology, P.O. Box 484, 4714871167 Babol (Iran); Yaripour, Fereydoon [Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, Tehran (Iran)

    2010-10-15

    The conversion of methanol to dimethyl ether was carried out over various commercial zeolites and modified H-ZSM-5 catalysts to evaluate their catalytic performance. A series of commercially available zeolite samples were used for vapor-phase dehydration of methanol to DME. Catalyst screening tests were performed in a fixed-bed reactor under the same operating conditions (T = 300 S, P = 16 barg, WHSV = 3.8 h{sup -1}). It was found that all the H-form zeolite catalysts in this study were active and selective for DME synthesis. According to the experimental results MDHC-1 catalyst exhibited the highest activity in dehydration of methanol. After finding the most active catalyst, the H-MFI90 zeolite was modified with Na content varying from 0 to 120 mol%, via wet-impregnation method to further improve its selectivity. All of catalysts were characterized by BET, XRD, NH{sub 3}-TPD, ICP, TGA, SEM, FT-IR and TPH techniques. It was found that these materials affected activity of MDHC-1 zeolite by changing its acidity. Ultimately, among all the catalysts studied, Na{sub 100}-modified H-MFI90 zeolite exhibited optimum activity, selectivity and stability at methanol dehydration reaction. (author)

  9. Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

    Science.gov (United States)

    Zhokh, Alexey A.; Strizhak, Peter E.

    2018-01-01

    H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

  10. Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

    Science.gov (United States)

    Zhokh, Alexey A.; Strizhak, Peter E.

    2018-07-01

    H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

  11. Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Ahmed K. Aboul-Gheit

    2012-12-01

    Full Text Available H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm and the smallest pores (0.4–1.7 nm. The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give Ea and ΔS∗ values compatible with the characterization data of the catalysts.

  12. Influence of the desilication process on the acidity of HZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Rac, Vladislav, E-mail: vrac@ffh.bg.ac.rs [Faculty of Agriculture, Department of Chemistry, University of Belgrade, Belgrade (Serbia); Rakić, Vesna [Faculty of Agriculture, Department of Chemistry, University of Belgrade, Belgrade (Serbia); Miladinović, Zoran [Institute of General and Physical Chemistry, Belgrade (Serbia); Stošić, Dušan; Auroux, Aline [Institut de Recherches sur la Catalyse et l’Environnement de Lyon (IRCELYON), Villeurbanne (France)

    2013-09-10

    Highlights: ► Mesopore creation in three different HZSM-5 zeolites was performed via desilication. ► Acidity was assessed by microcalorimetric and thermokinetic data. ► ZSM-5 with SiO{sub 2}/Al{sub 2}O{sub 3} = 23 proved to be the least susceptable to mesopore creation. ► Acidity of samples with SiO{sub 2}/Al{sub 2}O{sub 3} = 50 and 80 remained mostly unchanged by desilication, while the surface diffusion was improved. - Abstract: The influence of the alkaline treatment on the acidity of zeolite ZSM-5 (SiO{sub 2}/Al{sub 2}O{sub 3} = 23, 50 and 80) modified by desilication was investigated. The samples were characterized by X-ray diffraction, low temperature adsorption of nitrogen and solid-state {sup 27}Al MAS NMR. Acidity of the samples was investigated using microcalorimetry-volumetry of ammonia adsorption at 423 K. Acid sites accessibility and intracrystalline diffusion were estimated by the thermokinetic parameter. The desilication process was shown to be Si/Al ratio dependant. Relative enhancement of mesopore surface decreased in the following order of SiO{sub 2}/Al{sub 2}O{sub 3}: 50 > 8 0 >23. Pore size distribution broadened and mesopore sizes increased with increasing Si/Al ratio. For samples with SiO{sub 2}/Al{sub 2}O{sub 3} = 50 and 80 almost full preservation of acid sites strength and distribution was achieved. Significant alteration of the acidity was found for the mesoporous sample with SiO{sub 2}/Al{sub 2}O{sub 3} = 23. Thermokinetic parameter values indicate facilitated intracristalline diffusion for mesoporous samples.

  13. High Yield of Liquid Range Olefins Obtained by Converting i-Propanol over Zeolite H-ZSM-5

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Shunmugavel, Saravanamurugan; Hruby, S.L.

    2009-01-01

    Methanol, ethanol, and i-propanol were converted under methanol-to-gasoline (MTH)-like conditions (400 degrees C, 1-20 bar) over zeolite H-ZSM-5. For methanol and ethanol, the catalyst lifetimes and conversion capacities are comparable, but when i-propanol is used as the reactant, the catalyst...... lifetime is increased dramatically. In fact, the total conversion capacity (calculated as the total amount of alcohol converted before deactivation in g(alcohol)/g(zeolite)) is more than 25 times higher for i-propanol compared to the lower alcohols. Furthermore, when i-propanol is used as the reactant...

  14. [Optimization of ethylene production from ethanol dehydration using Zn-Mn-Co/HZSM-5 by response surface methodology].

    Science.gov (United States)

    Wang, Wei; Cheng, Keke; Xue, Jianwei; Zhang, Jian'an

    2011-03-01

    The effects of reaction temperature, ethanol concentration and weight hourly space velocity (WHSV) on the ethylene production from ethanol dehydration using zinc, manganese and cobalt modified HZSM-5 catalyst were investigated by response surface methodology (RSM). The results showed that the most significant effect among factors was reaction temperature and the factors had interaction. The optimum conditions were found as 34.4% ethanol concentration, 261.3 0 degrees C of reaction temperature and 1.18 h(-1) of WHSV, under these conditions the yield of ethylene achieved 98.69%.

  15. Jet-Fuel Range Hydrocarbons from Biomass-Derived Sorbitol over Ni-HZSM-5/SBA-15 Catalyst

    Directory of Open Access Journals (Sweden)

    Yujing Weng

    2015-12-01

    Full Text Available Aromatics and cyclic-hydrocarbons are the significant components of jet fuel with high energy-density. However, conventional technologies for bio-fuel production cannot produce these products without further aromatization and isomerization. In this work, renewable liquid fuel with high content of aromatics and cyclic-hydrocarbons was obtained through aqueous catalytic conversion of biomass sorbitol over Ni-HZSM-5/SBA-15 catalyst. Texture characteristics of the catalyst were determined by physisorption of N2, which indicated its bimodal pore structures were microporous (HZSM-5, pore width: 0.56 nm and mesoporous (SBA-15, pore width: 8 nm. The surface acidity included weak and strong acid sites, predominantly Lewis type, and was further confirmed by the NH3-TPD and Py-IR analysis. The catalytic performances were tested in a fixed-bed reactor under the conditions of 593 K, WHSV of 0.75 h−1, GHSV of 2500 h−1 and 4.0 MPa of hydrogen pressure, whereby oil yield of 40.4 wt. % with aromatics and cyclic-hydrocarbons content of 80.0% was obtained.

  16. HZSM-5 CATALYST FOR CRACKING PALM OIL TO BIODIESEL: A COMPARATIVE STUDY WITH AND WITHOUT PT AND PD IMPREGNATION

    Directory of Open Access Journals (Sweden)

    Agus Budianto

    2014-05-01

    Full Text Available The Needs of healthy environment and green energy poses a great demand for alternative energy. Biofuel is one of the alternative energy products that are environmentally friendly. Biofuel can be made from plant oils, especially palm oil. Cracking of palm oil into biofuel is constrained by the availability of catalysts. Moreover the available catalyst still gives a low yield. This research aims to study the effect of Pt and Pd impregnation into HZSM-5 catalyst on the catalytic properties. Another aim is to obtain the operating conditions of the catalytic cracking process of palm oil into biofuel which gives the highest yield and selectivity, especially for biodiesel and biogasoline fractions. Catalytic cracking process was carried out in a micro fixed bed reactor with diameter of 1 cm and length of 16 cm. The reactor was filled with a catalyst. The results of the study successfully prove that Pt and Pd impregnated into HZSM-5 catalyst can increase the yield and selectivity of biodiesel. Pd and Pt are highly recommended to increase the yield and selectivity of biodiesel.

  17. Adsorption and diffusion of fructose in zeolite HZSM-5: selection of models and methods for computational studies

    International Nuclear Information System (INIS)

    Cheng, L.; Curtiss, L.A.; Assary, R.S.; Greeley, J.; Kerber, T.; Sauer, J.

    2011-01-01

    The adsorption and protonation of fructose in HZSM-5 have been studied for the assessment of models for accurate reaction energy calculations and the evaluation of molecular diffusivity. The adsorption and protonation were calculated using 2T, 5T, and 46T clusters as well as a periodic model. The results indicate that the reaction thermodynamics cannot be predicted correctly using small cluster models, such as 2T or 5T, because these small cluster models fail to represent the electrostatic effect of a zeolite cage, which provides additional stabilization to the ion pair formed upon the protonation of fructose. Structural parameters optimized using the 46T cluster model agree well with those of the full periodic model; however, the calculated reaction energies are in significant error due to the poor account of dispersion effects by density functional theory. The dispersion effects contribute -30.5 kcal/mol to the binding energy of fructose in the zeolite pore based on periodic model calculations that include dispersion interactions. The protonation of the fructose ternary carbon hydroxyl group was calculated to be exothermic by 5.5 kcal/mol with a reaction barrier of 2.9 kcal/mol using the periodic model with dispersion effects. Our results suggest that the internal diffusion of fructose in HZSM-5 is very likely to be energetically limited and only occurs at high temperature due to the large size of the molecule.

  18. The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil

    Directory of Open Access Journals (Sweden)

    Amalia Putri Purnamasari

    2017-10-01

    Full Text Available Transesterification of used cooking oil was carried out over calcium oxide supported on mesoporous H-ZSM-5 prepared from kaolin as solid base catalysts. Solid basic catalysts investigated in this study were characterized by XRD, FTIR spectroscopy, and N2 adsorption-desorption techniques. The XRD pattern showed peaks corresponding to the CaO and mesoporous ZSM-5 in the sample. The peak intensity of the CaO increased as CaO loading in ZSM-5 was increased. The characterization based on FTIR spectroscopy revealed that CaO/H-ZSM-5 solids have functional groups characteristics of both CaO and mesoporous H-ZSM-5 which appeared in the band at around  550 cm-1 and 480 cm-1. The isotherm of N2 adsorption-desorption of CaO/H-ZSM-5 indicated the type IV isotherm with the presence of hysteresis loop. For the catalytic activity, the biodiesel yield using catalyst of 10 % CaO/HZSM-5 (100 %, 30 % CaO/HZSM-5 (100 %, 50 % CaO/HZSM-5 (100 % were 24.34, 27.37, and 29.73 %, respectively. It also related with the basic active site, when loading CaO increased, the basic active site also increased. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 8th March 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Purnamasari, A.P., Sari, M.E.F., Kusumaningtyas, D.T., Suprapto, S., Hamid, A., Prasetyoko, D. (2017. The Effect of Mesoporous H-ZSM-5 Crystallinity as a CaO Support on the Transesterification of Used Cooking Oil. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 329-336 (doi:10.9767/bcrec.12.3.802.329-336

  19. Influence of the particle size of zeolite HZSM-5 on the catalytic performance in the ethene-to-propene reaction

    Energy Technology Data Exchange (ETDEWEB)

    Follmann, S.; Ernst, S. [Kaiserslautern Univ. (Germany). Dept. of Chemistry; Vetter, A.; Ripperger, S. [Kaiserslautern Univ. (Germany). Dept. of Mechanical and Process Engineering

    2013-11-01

    In this study, HZSM-5-type zeolites with comparable nSi/nAl-ratios but different crystallite sizes (6 {mu}m, 27 {mu}m, 40 {mu}m and 62 {mu}m) were synthesized and their physicochemical properties characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and nitrogen physisorption. Their catalytic properties were explored in the acid-catalyzed conversion of ethene to propene (and higher hydrocarbons). The results show that there is a significant influence of the crystallite size of the zeolite catalyst on the activity and time-on-steam stability. While the yields of short-chain olefins do not significantly differ for all materials investigated, the formation of aromatics is significantly suppressed over the catalyst with the largest crystallite size. (orig.)

  20. High Selectively Catalytic Conversion of Lignin-Based Phenols into para-/m-Xylene over Pt/HZSM-5

    Directory of Open Access Journals (Sweden)

    Guozhu Liu

    2016-01-01

    Full Text Available High selectively catalytic conversion of lignin-based phenols (m-cresol, p-cresol, and guaiacol into para-/m-xylene was performed over Pt/HZSM-5 through hydrodeoxygenation and in situ methylation with methanol. It is found that the p-/m-xylene selectivity is uniformly higher than 21%, and even increase up to 33.5% for m-cresol (with phenols/methanol molar ratio of 1/8. The improved p-/m-xylene selectivity in presence of methanol is attributed to the combined reaction pathways: methylation of m-cresol into xylenols followed by HDO into p-/m-xylene, and HDO of m-cresol into toluene followed by methylation into p-/m-xylene. Comparison of the product distribution over a series of catalysts indicates that both metals and supporters have distinct effect on the p-/m-xylene selectivity.

  1. The Catalytic Conversion of Thiophenes over Large H-ZSM-5 Crystals: An X-Ray, UV/Vis, and Fluorescence Microspectroscopic Study

    NARCIS (Netherlands)

    Kox, M.H.F.; Mijovilovich, A.E.; S ättler, J.J.H.B.; Stavitski, I.; Weckhuysen, B.M.

    2013-01-01

    X-ray absorption, UV/Vis, and fluorescence microspectroscopy have been used to characterize the catalytic conversion of thiophene derivatives within the micropores of an individual H-ZSM-5 zeolite crystal. Space-resolved information into the Si/ Al ratios and sulfur content was provided by X-ray

  2. Coke formation during the methanol-to-olefin conversion: in situ microspectroscopy on individual H-ZSM-5 crystals with different Brønsted acidity

    NARCIS (Netherlands)

    Mores, D.; Kornatowski, J.; Olsbye, U.; Weckhuysen, B.M.

    2011-01-01

    Coke formation during the methanol-to-olefin (MTO) conversion has been studied at the single-particle level with in situ UV/Vis and confocal fluorescence microscopy. For this purpose, large H-ZSM-5 crystals differing in their Si/Al molar ratio have been investigated. During MTO, performed at 623 and

  3. Fast microwave-assisted catalytic co-pyrolysis of corn stover and scum for bio-oil production with CaO and HZSM-5 as the catalyst.

    Science.gov (United States)

    Liu, Shiyu; Xie, Qinglong; Zhang, Bo; Cheng, Yanling; Liu, Yuhuan; Chen, Paul; Ruan, Roger

    2016-03-01

    This study investigated fast microwave-assisted catalytic co-pyrolysis of corn stover and scum for bio-oil production with CaO and HZSM-5 as the catalyst. Effects of reaction temperature, CaO/HZSM-5 ratio, and corn stover/scum ratio on co-pyrolysis product fractional yields and selectivity were investigated. Results showed that co-pyrolysis temperature was selected as 550°C, which provides the maximum bio-oil and aromatic yields. Mixed CaO and HZSM-5 catalyst with the weight ratio of 1:4 increased the aromatic yield to 35.77 wt.% of feedstock, which was 17% higher than that with HZSM-5 alone. Scum as the hydrogen donor, had a significant synergistic effect with corn stover to promote the production of bio-oil and aromatic hydrocarbons when the H/C(eff) value exceeded 1. The maximum yield of aromatic hydrocarbons (29.3 wt.%) were obtained when the optimal corn stover to scum ratio was 1:2. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. On the impact of olefins and aromatics in the methanol-to-hydrocarbon conversion over H-ZSM-5 catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.; Mueller, S.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen, Garching (Germany). Dept. of Chemistry

    2012-07-01

    Methanol-to-hydrocarbons processes using HZSM-5 archetype acidic zeolites or zeotype SAPO-34 catalysts are regarded as a vital suite of conversion technologies to bypass petroleum-based routes for the production of specific fuels and petrochemical commodities. Special significance of the methanol chemistry originates from its versatility enabling selective transformations towards various products. Industry demonstrated successfully implementations of Methanol-To-Gasoline, Methanol-To-Olefin, and Methanol-To-Propylene processes, although the typical single-pass selectivity remained limited and recycling is necessary. Considerable fundamental research efforts both from experimental and computational sides contributed to unravel the underlying complex reaction mechanism. The indirect hydrocarbon pool mechanism, in which Broensted acid sites combined with adsorbed light olefins or lower methylbenzenes act as active centers, is generally accepted to explain the formation of light olefins. As olefin and aromatics populated catalytic sites show different reactivity in terms of activity and selectivity to ethylene or propylene, one could envision optimizing the product distribution by suitable co-feeding of specific hydrocarbons. The present work addresses three questions with an experimental study conducted under realistic MTP operation conditions: (1) How are ethylene and propylene formed at molecular level? (2) Which reaction pathway leads to the formation of undesired hydrogen transfer products? (3) Does olefin or aromatics co-feeding change the selectivity to ethylene or propylene? Xylenes and various olefins were co-fed with methanol to achieve a detailed understanding of the reaction mechanism over acidic HZSM-5 zeolites. Results suggest, that an olefin homologation/cracking route (olefin cycle) accounts for the autocatalytic (-like) nature and the majority of methanol consumption rather than the route involving aromatic intermediates (aromatics cycle). Co

  5. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    International Nuclear Information System (INIS)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo; Chang, Jong San; Qiu, Fa Li; Park, Sang Eon

    2004-01-01

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl 4 , was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl 4 with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl 4 was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis

  6. Incorporation of Titanium into H-ZSM-5 Zeolite via Chemical Vapor Deposition: Effect of Steam Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Cheng Hua; Jin, Tai Huan; Jhung, Sung Hwa; Hwang, Jin Soo [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Chang, Jong San; Qiu, Fa Li [Chinese Academy of Sciences(CAS), Chengdu (China); Park, Sang Eon [Inha University, Incheon (Korea, Republic of)

    2004-05-15

    Ti-ZSM-5 prepared by secondary synthesis, from the reaction of H-ZSM-5 with vapor phase TiCl{sub 4}, was characterized with several physicochemical techniques including FT-IR and UV/VIS-DRS. It was found that zeolite structure, surface area and pore volume did not change, and the framework aluminum could not be replaced by titanium atom during the secondary synthesis of Ti-ZSM-5. The incorporation of titanium into the framework might be due to reaction of TiCl{sub 4} with the silanol groups associated with defects or surface sites. The formation of extra-framework titanium could not be avoided, unless the samples were further treated by water vapor at 550 .deg. C or higher temperature. High temperature steam treatment of Ti-ZSM-5 prepared by chemical vapor deposition with TiCl{sub 4} was efficient to prevent the formation of non-framework titanium species. Ti-ZSM-5 zeolites prepared in this work contained only framework titanium species and exhibited improved catalytic property close to TS-1 prepared by hydrothermal synthesis.

  7. Theoretical study on the nitration of methane by acyl nitrate catalyzed by H-ZSM5 zeolite.

    Science.gov (United States)

    Silva, Alexander Martins; Nascimento, Marco Antonio Chaer

    2008-09-25

    A theoretical study on the nitration of methane by acyl nitrate catalyzed by HZSM-5 zeolite is reported. The zeolite was represented by a "double ring" 20T cluster. The calculations were performed at the DFT/X3LYP/6-31G** and MP2/6-31G** levels. The first step of the mechanism involves the protonation of the acyl nitrate by the zeolite and the formation of a nitronium-like ion. The reaction proceeds through a concerted step with the attack of the methane molecule by the nitronium-like ion and the simultaneous transfer of a proton from the methane molecule to the zeolite, thus reconstructing the acidic site. The activation energies for the first and second steps of this reaction are, respectively, 14.09 and 10.14 kcal/mol at X3LYP/6-31G** level and 16.68 and 13.85 kcal/mol at the MP2/6-31G**.

  8. Preparation of HZSM-5 membrane packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles for catalysing carbon dioxide hydrogenation to dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rong; Tian, Haifeng; Yang, Aimei; Zha, Fei, E-mail: zhafei@nwnu.edu.cn; Ding, Jian; Chang, Yue

    2015-08-01

    Highlights: • CuO–ZnO–Al{sub 2}O{sub 3} composite nanoparticles were successfully prepared using carbon sphere as template. • HZSM-5@CuO–ZnO–Al{sub 2}O{sub 3} capsule catalyst was prepared hydrothermally. • Zeolite capsule catalysts exhibited an extremely good selectivity for DME compared with the conventional hybrid catalyst. - Abstract: Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu{sup 2+}, Zn{sup 2+} and Al{sup 3+} ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles hydrothermally to form HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles were used as catalysts for the CO{sub 2} hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL g{sub cat}{sup −1} h{sup −1}, volume ratio of CO{sub 2}/H{sub 2} to 1:3 and temperature at 270 °C, the conversion of CO{sub 2} could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively.

  9. Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5.

    Science.gov (United States)

    Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

    2016-08-25

    We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

  10. Conversion of methanol to hydrocarbons over conventional and mesoporous H-ZSM-5 and H-Ga-MFI: Major differences in deactivation behavior

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie; Højholt, Karen Thrane; Holm, Martin Spangsberg

    2012-01-01

    . In the methanol-to-hydrocarbons (MTH) process, H-ZSM-5 is subjected to coke formation leading to catalyst deactivation. Here we show that when the gallium containing zeotypes are employed in the MTH process, only insignificant amounts of coke are present in the deactivated catalysts, indicating distinct...... (hydrolysis) of the Ga&sbnd;O bonds in the zeolite structure rather than coke deposition....

  11. Deactivation of Zeolite Catalyst H-ZSM-5 during Conversion of Methanol to Gasoline: Operando Time- and Space-Resolved X-ray Diffraction.

    Science.gov (United States)

    Rojo-Gama, Daniel; Mentel, Lukasz; Kalantzopoulos, Georgios N; Pappas, Dimitrios K; Dovgaliuk, Iurii; Olsbye, Unni; Lillerud, Karl Petter; Beato, Pablo; Lundegaard, Lars F; Wragg, David S; Svelle, Stian

    2018-03-15

    The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion of methanol to hydrocarbons was monitored by high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution was achieved by continuous scanning along the axial length of a capillary fixed bed reactor with a time resolution of 10 s per scan. Using real structural parameters obtained from XRD, we can track the development of coke at different points in the reactor and link this to a kinetic model to correlate catalyst deactivation with structural changes occurring in the material. The "burning cigar" model of catalyst bed deactivation is directly observed in real time.

  12. Diagramas de eslabilidad de zeolitas. I. Zeolitas en ambientes confinados alcalinos

    Directory of Open Access Journals (Sweden)

    La Iglesia, A.

    1989-12-01

    Full Text Available The stability fieds of zeolites in saline alkaline-lake deposits has been studied. Thermodynamical equilibriums were calculed by ussing a method of stimating the Gibbs free energies of formation of zeolites. We have studied the following stability fields: - Diagram c1inoptilolite-erionite-phillipsite.- Diagram analcime-clinoptilolite-chabazite-erionite-mordenite-phillipsite.- Diagram K-feldspar-zeolites in saline alkaline-lake deposits.The obtained stability diagrams show the influence of silica activity, water activity and alkaline ions activity on equilibrium relationship between analcime and alkalic silicic zeolites, and or feldspar and zeolites. pH influence on the solubility zeolites has been also studied. These results show, at pH below 10, that the most silicic zeolites (clinoptilolite and mordenite are more stable than low silicic ones (analcime and chabazite. However, at pH above 10, the low silicic zeolites are the most stable phases.Se estudia la estabilidad de las zeolitas que aparecen en ambientes confinados salinos. Los cálculos de equilibrio se realizan usando valores de energía libre de Gibbs estimados teóricamente. En este artículo se presentan los siguientes diagramas de estabilidad:- Diagrama clinoptiloita-erionita-phillipsita.- Diagrama aoalcima-clinoptilolita-chabazita-eriooita-mordenita-phillipsita.- Diagrama feldespato potásico-zeolitas depósitos salinos.Los diagramas calculados ponen de manifiesto la influencia de las actividades de los iones alcalinos, alcalinotérreos, agua y sílice en el equilibrio entre las distintas zeolitas y entre estas y el feldespato potásico. Se estudia también la influencia del pH en la solubilidad de las zeolitas. Los resultados obtenidos demuestran que las zeolitas muy silícicas (clinoptilolita y mordenita son las más estables a pH inferiores a 10. Por el contrario, las zeolitas de bajo contenido en sílice (analcima y chabazita son las más estables a pH superiores a 10.

  13. Catalytic Upgrading of Biomass-Derived Compounds via C-C Coupling Reactions. Computational and Experimental Studies of Acetaldehyde and Furan Reactions in HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong [Argonne National Lab. (ANL), Argonne, IL (United States); Evans, Tabitha J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cheng, Lei [Argonne National Lab. (ANL), Argonne, IL (United States); Nimlos, Mark R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mukarakate, Calvin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Robichaud, David J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Assary, Rajeev S. [Argonne National Lab. (ANL), Argonne, IL (United States); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-10-02

    These catalytic C–C coupling and deoxygenation reactions are essential for upgrading of biomass-derived oxygenates to fuel-range hydrocarbons. Detailed understanding of mechanistic and energetic aspects of these reactions is crucial to enabling and improving the catalytic upgrading of small oxygenates to useful chemicals and fuels. Using periodic density functional theory (DFT) calculations, we have investigated the reactions of furan and acetaldehyde in an HZSM-5 zeolite catalyst, a representative system associated with the catalytic upgrading of pyrolysis vapors. Comprehensive energy profiles were computed for self-reactions (i.e., acetaldehyde coupling and furan coupling) and cross-reactions (i.e., acetaldehyde + furan) of this representative mixture. Major products proposed from the computations are further confirmed using temperature controlled mass spectra measurements. Moreover, the computational results show that furan interacts with acetaldehyde in HZSM-5 via an alkylation mechanism, which is more favorable than the self-reactions, indicating that mixing furans with aldehydes could be a promising approach to maximize effective C–C coupling and dehydration while reducing the catalyst deactivation (e.g., coke formation) from aldehyde condensation.

  14. Two-step fast microwave-assisted pyrolysis of biomass for bio-oil production using microwave absorbent and HZSM-5 catalyst.

    Science.gov (United States)

    Zhang, Bo; Zhong, Zhaoping; Xie, Qinglong; Liu, Shiyu; Ruan, Roger

    2016-07-01

    A novel technology of two-step fast microwave-assisted pyrolysis (fMAP) of corn stover for bio-oil production was investigated in the presence of microwave absorbent (SiC) and HZSM-5 catalyst. Effects of fMAP temperature and catalyst-to-biomass ratio on bio-oil yield and chemical components were examined. The results showed that this technology, employing microwave, microwave absorbent and HZSM-5 catalyst, was effective and promising for biomass fast pyrolysis. The fMAP temperature of 500°C was considered the optimum condition for maximum yield and best quality of bio-oil. Besides, the bio-oil yield decreased linearly and the chemical components in bio-oil were improved sequentially with the increase of catalyst-to-biomass ratio from 1:100 to 1:20. The elemental compositions of bio-char were also determined. Additionally, compared to one-step fMAP process, two-step fMAP could promote the bio-oil quality with a smaller catalyst-to-biomass ratio. Copyright © 2016. Published by Elsevier B.V.

  15. Effects of Coke Deposits on the Catalytic Performance of Large Zeolite H-ZSM-5 Crystals during Alcohol-to-Hydrocarbons Reactions as Investigated by a Combination of Optical Spectroscopy and Microscopy

    DEFF Research Database (Denmark)

    Nordvang, Emily Catherine; Borodina, Elena; Ruiz-Martínez, Javier

    2015-01-01

    The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ...... single crystal UV/Vis and confocal fluorescence micro-spectroscopy, allowing the observation of the spatiotemporal formation of intermediates and coke species during the MTO and ETO conversions. It was observed that rapid deactivation at elevated temperatures was due to the fast formation of aromatics...... at the periphery of the H-ZSM-5 crystals, which are transformed into more poly-aromatic coke species at the external surface, preventing the diffusion of reactants and products into and out of the H-ZSM-5 crystal. Furthermore, we were able to correlate the operando UV/Vis spectroscopy results observed during...

  16. Ungüento ZZ, antiséptico elaborado con una zeolita natural modificada

    Directory of Open Access Journals (Sweden)

    Iliana Perdomo López

    1998-12-01

    Full Text Available Se realizó el diseño del ungüento ZZ a partir del producto activo zeolítico ZZ, el cual posee una marcada actividad antimicrobiana en el tratamiento de las micosis y afecciones bacterianas. Se elaboraron 3 formulaciones las cuales se evaluaron mediante determinaciones físico-químicas. La formulación I respondió a la utilización del ungüento hidrófilo como base, la II a la crema secante y la III a una base emulsionada aceite en agua. Se obtuvo como resultado la no utilización de las formulaciones I y II por la interacción del principio activo con el laurilsulfato de sodio y con el monoestearato de glicerilo, respectivamente. La formulación III resultó muy adecuada desde el punto de vista tecnológico y se le realizaron estudios toxicológicos de irritabilidad dérmica que resultaron favorables, ya que no hubo irritación de las zonas tratadas.ZZ oinment was designed from an active zeolite product which has a marked antimicrobial effect in the treatment of micosis and bacterial affections. Three different formulations were evaluated for the product through physicial-chemical determinations. Formulation I used hidrophil oinment as a base; formulation II used drying cream and Formulation III chose an oil-in-water emulsified base. As a result of this assessment, formulations I and II were not chosen because of the interaction of the active agent with sodium laurylsulphate and with glyceril monostereate respectively. Formulation III turned out to be the most suitable from the technological viewpoint. Toxicological studies were performed on this formulation to observe skin irritability but the results were favourable since there was no trace of irritation in the treated areas.

  17. A mechanistic basis for the effect of aluminum content on ethene selectivity in methanol-to-hydrocarbons conversion on HZSM-5

    KAUST Repository

    Khare, Rachit; Liu, Zhaohui; Han, Yu; Bhan, Aditya

    2017-01-01

    Increasing crystallize size or aluminum content in MFI-type zeolites independently enhances the propagation of the aromatics-based methylation/dealkylation cycle relative to that of the olefins-based methylation/cracking cycle in methanol-to-hydrocarbons (MTH) conversion and consequentially results in higher ethene selectivity. Ethene selectivity increases monotonically with increasing aluminum content for HZSM-5 samples with nearly identical crystallite size consequent to an increase in the intracrystalline contact time analogous to our recent report detailing the effects of crystallite size (Khare et al., 2015) on MTH selectivity. The confected effects of crystallite size and site density on MTH selectivity can therefore, be correlated using a descriptor that represents the average number of acid sites that an olefin-precursor will interact with before elution.

  18. Synthesis of DME by CO2 hydrogenation over La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Zhang Yajing

    2017-01-01

    Full Text Available A series of La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts were prepared by an oxalate co-precipitation method. The catalysts were fully characterized by X-ray diffraction (XRD, N2 adsorption-desorption, hydrogen temperature pro-grammed reduction (H2-TPR, ammonia temperature programmed desorption (NH3-TPD, and X-ray photoelectron spectroscopy (XPS techniques. The effect of the La2O3 content on the structure and performance of the catalysts was thoroughly investigated. The catalysts were evaluated for the direct synthesis of dimethyl ether (DME from CO2 hydrogenation. The results displayed that La2O3 addition enhanced catalytic performance, and the maximal CO2 conversion (34.3% and DME selectivity (57.3% were obtained over the catalyst with 1% La2O3, which due to the smaller size of Cu species and a larger ratio of Cu+/Cu.

  19. Radioisotope tracer study of co-reactions of methanol with ethanol using 11C-labelled methanol over alumina and H-ZSM-5

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Salmi, T.; Murzin, D.Yu

    2005-01-01

    Complete text of publication follows. The transformation of methanol has been investigated over alumina and H-ZSM-5 in our previous experiments by 11 C-radioisotope tracing. The main product in methanol conversion over alumina was dimethyl ether due to Lewis acid sites while over H-ZSM-5 mostly hydrocarbons were formed due to both Lewis and Brrnsted acid sites. With increasing temperature first the ethanol was dehydrated to diethyl ether followed by ethene formation over alumina and H-ZSM-5. In this work, 11 C-labelled methanol as radioisotope tracer was added to non-radioactive methanol for investigation of co-reaction with non-radioactive ethanol over alumina and H- ZSM-5. The 11 C-methanol tracer was used to distinguish the methanol derivates and co-reaction derivates of methanol with ethanol against non-radioactive ethanol derivates. The yield of methyl ethyl ether as mixed ether and the influence of ethanol for the yields of C 1 -C 5 hydrocarbons were studied as a function of reaction temperature and contact time. The 11 C-methanol was formed by a radiochemical process from 11 CO 2 produced at cyclotron. The mixture of methanol and ethanol was added to 11 C-methanol and injected to the catalyst. The catalysis was carried out in a glass tube fixed-bed reactor after its pretreatment. The derivates were analyzed by radio-gas chromatography (gas chromatograph with thermal conductivity detector coupled on-line with a radioactivity detector). The comparative analysis of yields of radioactive and non-radioactive products as a function of reaction temperature gives information about the reaction pathways. Over alumina the yields of dimethyl ether and methyl ethyl ether (co-product) as radioactive and diethyl ether with ethene as non-radioactive main products were monitored as a function of reaction temperature and reaction time in the range of 513-593 K. Alongside ethanol derivates the ethene turns into main product in contrast with methyl ethyl ether and diethyl ether at higher temperature. In co-reaction over H-modified ZSM-5, while the ethanol was transformed to an olefin (ethene) at lower temperature, methanol reacted to hydrocarbons at higher temperature. Above 553 K, dimethyl ether and lower amounts of methyl ethyl ether were formed compared to these products over alumina, while higher yields of C 3 -C 6 hydrocar- bons were obtained in comparison with single methanol conversion. This result proves the influence of ethanol (reacting immediately to ethene) in the co-reaction to produce higher yields of C 3 -C 5 olefins. It can be concluded that the single methanol transformation was modified by ethanol reactant producing new derivates i.e. mixed ether over alumina and also C 3 -C 5 hydrocarbon co-products over H-ZSM-5. (author)

  20. A mechanistic basis for the effect of aluminum content on ethene selectivity in methanol-to-hydrocarbons conversion on HZSM-5

    KAUST Repository

    Khare, Rachit

    2017-03-20

    Increasing crystallize size or aluminum content in MFI-type zeolites independently enhances the propagation of the aromatics-based methylation/dealkylation cycle relative to that of the olefins-based methylation/cracking cycle in methanol-to-hydrocarbons (MTH) conversion and consequentially results in higher ethene selectivity. Ethene selectivity increases monotonically with increasing aluminum content for HZSM-5 samples with nearly identical crystallite size consequent to an increase in the intracrystalline contact time analogous to our recent report detailing the effects of crystallite size (Khare et al., 2015) on MTH selectivity. The confected effects of crystallite size and site density on MTH selectivity can therefore, be correlated using a descriptor that represents the average number of acid sites that an olefin-precursor will interact with before elution.

  1. Effects of Coke Deposits on the Catalytic Performance of Large Zeolite H-ZSM-5 Crystals during Alcohol-to-Hydrocarbon Reactions as Investigated by a Combination of Optical Spectroscopy and Microscopy

    NARCIS (Netherlands)

    Nordvang, Emily C.; Borodina, Elena; Ruiz-Martinez, Javier; Fehrmann, Rasmus; Weckhuysen, Bert M.

    2015-01-01

    The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ

  2. Study of (Fe/HZM-5) catalyst be used in the Fischer-Tropsch synthesis: preparation and characterization; Estudo do catalisador (Fe/HZSM-5) a ser utilizado na sintese de Fischer-Tropsch: preparacao e caracterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Gonzaga, Arthur C. [Universidade Estadual do Maranhao (UEMA0), MA (Brazil); Sousa, Bianca V. de; Lima, Wellington S.; Rodrigues, Meiry G.F. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica

    2008-07-01

    In this work it was developed an iron catalyst supported on the ZSM-5 zeolite to be used in the Fischer-Tropsch Synthesis (FTS). The NH{sub 4}{sup +}ZSM-5 zeolitic support was submitted to the wet impregnation, using the 0.1 M of the Fe(NO{sub 3}){sub 3}.9H{sub 2}O solution to obtain the Fe/NH{sub 4}{sup +}ZSM-5 sample in the content of iron 5% wt. After, the material was submitted for the drying process and in the following, for the calcination one, obtaining the Fe/HZSM-5 form. The EDS characterization analyses showed that in the Fe/HZSM-5 sample the iron is in the Fe{sub 2}O{sub 3} form and that the impregnation and calcination processes did not cause significant exchanges in the zeolitic support framework. The results of the N{sub 2} physical adsorption of the 5% Fe/HZSM-5 showed the presence of the micropores and mesopores. From these results, the obtained material (5% Fe/HZSM-5) presents a great potential to be used like a catalyst in the FTS. (author)

  3. Catalytic fast co-pyrolysis of bamboo residual and waste lubricating oil over an ex-situ dual catalytic beds of MgO and HZSM-5: Analytical PY-GC/MS study

    International Nuclear Information System (INIS)

    Wang, Jia; Zhang, Bo; Zhong, Zhaoping; Ding, Kuan; Deng, Aidong; Min, Min; Chen, Paul; Ruan, Roger

    2017-01-01

    Highlights: • Catalytic co-pyrolysis of bamboo residual and waste lubricating oil was conducted. • MgO was beneficial to deacidification via ketonization and aldol condensation. • Dual catalytic bed system exhibited prominent deoxygenation and aromatization. • A HZSM-5/MgO mass ratio of 3:2 largely increased the yield of aromatics. • Waste lubricating oil leads hydrocarbon pool towards the formation of hydrocarbons. - Abstract: Catalytic fast co-pyrolysis (co-CFP) of bamboo residual (BR) and waste lubricating oil (WLO) over dual catalytic beds of MgO and HZSM-5 were carried out in an analytical PY-GC/MS. The effects of pyrolysis temperature, catalyst types, HZSM-5/MgO mass ratio and WLO percentage on products distribution and selectivities of aromatics were investigated. Experimental results revealed that 600 °C promoted the total peak area of volatile matters and accelerated the yields of furans and phenols. Compared to HZSM-5, MgO exhibited pronounced deacidification via ketonization and aldol condensation reactions as the minimum yield of acids (2.116%) and the maximum yield of ketones (28.805%) could be obtained. Furthermore, given the selectivity of phenols, MgO not only spurred the increase of overall phenols yield, but also facilitated the selectivity of light phenols like phenol and 4-methyl-phenol. With respect to the co-CFP of BR and WLO, a HZSM-5/MgO mass ratio of 3:2 largely accelerated the yield of aromatics via Diels-Alder reaction. Simultaneously, the WLO percentage played a vital role in the yield of hydrocarbons (i.e. aromatics + olefins & alkanes), and the maximum yield (70.305%) could be attained at the percentage of 60% as a function of significant activation of hydrocarbon pool.

  4. One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: insights into the major reaction pathways.

    Science.gov (United States)

    Xing, Shiyou; Lv, Pengmei; Wang, Jiayan; Fu, Junying; Fan, Pei; Yang, Lingmei; Yang, Gaixiu; Yuan, Zhenhong; Chen, Yong

    2017-01-25

    For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C 6 -C 8 olefins over the catalysts' Brønsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C 6 -C 8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Brønsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.

  5. Water-assisted and thermally-enhanced protonic conduction in HZSM-5, effect of gamma-irradiation on the electric properties. [Zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Higazy, A.A.; Kassem, M.E. (Qatar Univ. (Qatar). Physics Dept.); Sayed, M.B. (Qatar Univ. (Qatar). Chemistry Dept.)

    1992-01-01

    Analysis of the a.c. conductivity of the zeolite HZSM-5, in the 0.1-100 kHz frequency region and the 300-700 K temperature range, reveals semiconducting features based predominantly on an ionic mechanism. This is reflected in a low-frequency Cole-Cole dependence of the Z''(Z') impedance and in a linear dependence of the {epsilon}''(''epsilon''') dielectric constant throughout the temperature range. The zeolite Broensted sites are the active centers responsible for the ionic conduction. As the conductivity drops to 373 K, sorbed water seems to participate in the conduction as a vehicle assisting the proton mobility. Above 373 K, the conductivity continues to rise as an indication of critical transition into a thermally enhanced ionic conduction. Both low-temperature sorbed water and high-temperature thermal motion are necessary to ensure a firm contact at the aggregate surfaces, where conduction takes place. Gamma-irradiation also participates in the conduction by creating new sites sensitive to the same parameters governing the conduction mechanism. (author).

  6. Formation of hydrocarbon compounds during the hydrocracking of non-edible vegetable oils with cobalt-nickel supported on hierarchical HZSM-5 catalyst

    Science.gov (United States)

    Marlinda, L.; Al-Muttaqii, M.; Roesyadi, A.; Prajitno, D. H.

    2017-05-01

    The hierarchical Co-Ni/HZSM-5 catalyst with hierarchical pore structure was prepared by desilication and incipient wetness impregnation. Hydrocracking of non-edible vegetable oils at temperature of 400 °C, 20±5 bar for 2 h was performed in the presence of this type of catalyst under hydrogen initial pressure in pressured batch reactor. Non-edible vegetable oils, such as Reutealis trisperma (Blanco) airy shaw (sunan candlenut) and Hevea brasiliensis (rubber seed) were chosen to study the effect of the degree of saturation and lateral chain length on hydrocarbon compounds obtained through hydrocracking. Cerbera manghas oil was also tested for comparison because the composition of fatty acid was different with the other oils The hydrocracking test indicated that liquid product produced has a similar hydrocarbon compounds with petroleum diesel. The most abundant hydrocarbon is pentadecane (n-C15) and heptadecane (n-C17). The high aromatic compounds were found in liquid product produced in hydrocracking of Sunan candlenut oil.

  7. Pyrolysis of soybean oil with H-ZSM5 (Proton-exchange of Zeolite Socony Mobil 5) and MCM41 (Mobil Composition of Matter No. 41) catalysts in a fixed-bed reactor

    International Nuclear Information System (INIS)

    Ngo, Thanh-An; Kim, Jinsoo; Kim, Sun Kuk; Kim, Seung-Soo

    2010-01-01

    Soybean oil was pyrolyzed with various catalysts in a fixed-bed reactor under nitrogen flow at 420 and 450 o C. The H-ZSM5 catalysts (molar ratio SiO 2 /Al 2 O 3 = 28, 40, and 180) and 2 wt% (Ga, Al or Cu) impregnated MCM41 catalysts were used in order to investigate the effect of catalysts during the pyrolysis process. The gas products in all experiments were mainly methane, ethane and propylene. The liquid products in the presence of H-ZSM5 catalysts were mainly aromatic components while those with metal/MCM41 catalysts were a mixture of alkanes, alkenes, alkadienes, aromatic and carboxylic acids. The highest coke yield of 4.4 wt% was obtained with Ga/MCM41 catalyst at the pyrolysis temperature of 420 o C. The effect of catalysts on product yield and composition was systematically investigated.

  8. Ultrasound assisted co-precipitation of nanostructured CuO-ZnO-Al2O3 over HZSM-5: effect of precursor and irradiation power on nanocatalyst properties and catalytic performance for direct syngas to DME.

    Science.gov (United States)

    Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

    2014-03-01

    Nanostructured CuO-ZnO-Al2O3/HZSM-5 was synthesized from nitrate and acetate precursors using ultrasound assisted co-precipitation method under different irradiation powers. The CuO-ZnO-Al2O3/HZSM-5 nanocatalysts were characterized using XRD, FESEM, BET, FTIR and EDX Dot-mapping analyses. The results indicated precursor type and irradiation power have significant influences on phase structure, morphology, surface area and functional groups. It was observed that the acetate formulated CuO-ZnO-Al2O3/HZSM-5 nanocatalyst have smaller CuO crystals with better dispersion and stronger interaction between components in comparison to nitrate based nanocatalysts. Ultrasound assisted co-precipitation synthesis method resulted in nanocatalyst with more uniform morphology compared to conventional method and increasing irradiation power yields smaller particles with better dispersion and higher surface area. Additionally the crystallinity of CuO is lower at high irradiation powers leading to stronger interaction between metal oxides. The nanocatalysts performance were tested at 200-300 °C, 10-40 bar and space velocity of 18,000-36,000 cm(3)/g h with the inlet gas composition of H2/CO = 2/1 in a stainless steel autoclave reactor. The acetate based nanocatalysts irradiated with higher levels of power exhibited better reactivity in terms of CO conversion and DME yield. While there is an optimal temperature for CO conversion and DME yield in direct synthesis of DME, CO conversion and DME yield both increase with the pressure increase. Furthermore ultrasound assisted co-precipitation method yields more stable CuO-ZnO-Al2O3/HZSM-5 nanocatalyst while conventional precipitated nanocatalyst lost their activity ca. 18% and 58% in terms of CO conversion and DME yield respectively in 24 h time on stream test.

  9. Highly efficient synthesis of dimethyl ether from syngas over the admixed catalyst of CuO-ZnO-Al{sub 2}O{sub 3} and antimony oxide modified HZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Mao Dongsen, E-mail: dsmao1106@yahoo.com.c [Research Institute of Applied Catalysis, Department of Chemical Engineering, Shanghai Institute of Technology, Shanghai 200235 (China); Xia Jianchao; Zhang Bin [Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208 (China); Lu Guanzhong [Research Institute of Applied Catalysis, Department of Chemical Engineering, Shanghai Institute of Technology, Shanghai 200235 (China)

    2010-06-15

    A series of HZSM-5 zeolites modified with various contents of antimony oxide (0-30 wt.%) were prepared by solid state ion reaction at 500 deg. C, and the acidities of the resulted materials were characterized by temperature-programmed desorption of NH{sub 3}. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the admixed catalysts of an industrial CuO-ZnO-Al{sub 2}O{sub 3} methanol synthesis catalyst and the parent and antimony oxide modified HZSM-5 zeolites under pressurized fixed-bed continuous flow conditions. The results indicated that modification of HZSM-5 with suitable amount of antimony oxide significantly decreased the selectivity for undesired byproducts like hydrocarbons and carbon dioxide from 9.3% and 32.4% to less than 1% and 28%, respectively, so the selectivity for DME was enhanced greatly from 55% to 69% under temperature of 260 deg. C, pressure of 4 MPa and gas hourly space velocity of 1500 mL h{sup -1} g{sub cat}{sup -1}. The decrease in the formation of hydrocarbons and carbon dioxide can be attributed to the significant decline in the amount of strong acid sites of the HZSM-5 zeolite induced by antimony oxide modification. Additionally, the influences of the operating parameters on the performance of the most efficient catalyst were also investigated. The results showed that high reaction temperature and high gas hourly space velocity resulted in both lower carbon monoxide conversion and lower dimethyl ether selectivity, so they should be no higher than 280 deg. C and 3000 mL h{sup -1} g{sub cat}{sup -1}, respectively.

  10. Highly efficient synthesis of dimethyl ether from syngas over the admixed catalyst of CuO-ZnO-Al{sub 2}O{sub 3} and antimony oxide modified HZSM-5 zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Dongsen Mao; Guanzhong Lu [Research Institute of Applied Catalysis, Department of Chemical Engineering, Shanghai Institute of Technology, Shanghai 200235 (China); Jianchao Xia; Bin Zhang [Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208 (China)

    2010-06-15

    A series of HZSM-5 zeolites modified with various contents of antimony oxide (0-30 wt.%) were prepared by solid state ion reaction at 500 C, and the acidities of the resulted materials were characterized by temperature-programmed desorption of NH{sub 3}. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the admixed catalysts of an industrial CuO-ZnO-Al{sub 2}O{sub 3} methanol synthesis catalyst and the parent and antimony oxide modified HZSM-5 zeolites under pressurized fixed-bed continuous flow conditions. The results indicated that modification of HZSM-5 with suitable amount of antimony oxide significantly decreased the selectivity for undesired byproducts like hydrocarbons and carbon dioxide from 9.3% and 32.4% to less than 1% and 28%, respectively, so the selectivity for DME was enhanced greatly from 55% to 69% under temperature of 260 C, pressure of 4 MPa and gas hourly space velocity of 1500 mL h{sup -1} g{sub cat}{sup -1}. The decrease in the formation of hydrocarbons and carbon dioxide can be attributed to the significant decline in the amount of strong acid sites of the HZSM-5 zeolite induced by antimony oxide modification. Additionally, the influences of the operating parameters on the performance of the most efficient catalyst were also investigated. The results showed that high reaction temperature and high gas hourly space velocity resulted in both lower carbon monoxide conversion and lower dimethyl ether selectivity, so they should be no higher than 280 C and 3000 mL h{sup -1} g{sub cat}{sup -1}, respectively. (author)

  11. La Tuberculosis, Una Enfermedad Modificada*

    Directory of Open Access Journals (Sweden)

    Valentin Malagón Castro

    1993-12-01

    Full Text Available

    Con ocasión de un estudio de revisión que hemos llevado a cabo recientemente sobre la tuberculosis osteoarticular, *** se ha apreciado un cambio notable en las características y manifestaciones de esta enfermedad.

    Hemos sido testigos del comportamiento de la tuberculosis en los últimos 40 años. Realizamos la tesis profesional en el Hospital de niños de la Misericordia de Bogotá en el año 1950 (86, basada en el análisis de más de 300 enfermos de Mal de Pott tratados con pobres resultados en esa institución en la época prequimioterápica. Efectuamos estudios de control del tratamiento quirúrgico de esa afección en el Hospital Infantil Lorencita Villegas de Santos y publicamos sus resultados en los años 1975,1980 Y1987 (85-87-88. Los pacientes correspondientes a estas nuevas series, ya en la época de la quimioterapia moderna, presentaban un mejor pronóstico vital y funcional. Cuadro 1A.

    En el decenio 1978-1988 asistimos al descenso espectacular de la frecuencia de tuberculosis osteoarticular en las salas de nuestros hospitales. Posteriormente hemos sido igualmente testigos de su lenta y progresiva reaparición.

    El estudio actual nos ha mostrado profundos cambios, como ya se ha dicho, en el comportamiento de la entidad, por lo que estamos de acuerdo en denominarla: La tuberculosis, una enfermedad modificada, diferente a la que hasta hace un década parecía derrotada, vencida por las nuevas drogas y las recientes técnicas quirúrgicas.

    La actual es una enfermedad diferente que ha tomado una fuerza avasalladora que amenaza con volverse resistente al tratamiento específico y dar lugar a una pandemia de incalculables proporciones y de terribles consecuencias para la humanidad.

    El objeto de publicar este estudio es recordar a nuestros colegas, en especial a aquellos de las nuevas promociones que quizás no han tenido la oportunidad de estar en contacto con pacientes de tuberculosis osteoarticular, de

  12. Effect of irradiation power and time on ultrasound assisted co-precipitation of nanostructured CuO–ZnO–Al2O3 over HZSM-5 used for direct conversion of syngas to DME as a green fuel

    International Nuclear Information System (INIS)

    Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

    2014-01-01

    Graphical abstract: Nanostructured CuO–ZnO–Al 2 O 3 /HZSM-5 catalyst has been prepared by an ultrasound-assisted co-precipitation hybrid method. Effect of power and irradiation time have been studied by changing the time (30–45–60 min) and power of sonication (50–100–150 W) during the synthesis which lead to different physiochemical properties of the catalyst. The XRD, FESEM, EDX, FTIR and BET analyses exhibited smaller particles with higher surface area and less population of particle aggregates at longer and highly irradiated catalysts. Study on the performance of investigated catalysts in direct synthesis of DME from syngas showed ultrasound-assisted co-precipitated synthesized catalysts have superior reactivity and stability compared with non-sonicated catalyst. Among sonicated catalysts, with increasing power and time of irradiation, the catalyst represents higher activity and DME selectivity. - Highlights: • Synthesis of CuO–ZnO–Al 2 O 3 /HZSM-5 by ultrasound assisted co-precipitation method. • Significant changes in morphology and surface area after ultrasound irradiations. • Smaller dispersed particle aggregates in longer and more intense irradiated catalysts. • Improvement in reactivity and stability of the longer and more intense ultrasound irradiated CZAZ catalyst. - Abstract: Nanostructured CuO–ZnO–Al 2 O 3 /HZSM-5 catalyst has been prepared by an ultrasound-assisted co-precipitation hybrid method. The effect of irradiation power and irradiation time have been studied by changing time (30, 45, 60 min) and power of the sonication (50, 100, 150 W) during the synthesis which led to different physiochemical properties of the nanocatalyst. The XRD, FESEM, EDX, FTIR and BET analyses exhibited smaller particles with higher surface area and less population of particle aggregates at longer and highly irradiated nanocatalysts. The nanocatalyst irradiated at 150 W for 60 min (the longest irradiation time and the most intense power

  13. Empaque de alimentos en atmosferas modificadas

    OpenAIRE

    Restrepo Molina, Diego Alonso

    2003-01-01

    Resumen: Las técnicas usadas para reducir el oxígeno alrededor del alimento son conocidas como Modified Atmosphere Packaging (MAP) e incluyen el empacado en atmosfera controlada y el “verdadero” empacado en atmosfera modificada. Teniendo en cuenta que la refrigeración es considerada, en el ámbito de los alimentos, como uno de los métodos de conservación de mayor impacto, ya que retarda el deterioro de los alimentos almacenados por periodos importantes de tiempo, la combinación de la disminuci...

  14. Captación de amonio en zeolita al incubar gallinaza y residuos de codorniz

    Directory of Open Access Journals (Sweden)

    Sarai Guadalupe Valerio Luna

    2016-04-01

    Full Text Available Con la finalidad de conocer el efecto de la zeolita en la volatilización del dióxido de carbono (CO2 y amoniaco (NH3, se estableció un ensayo de incubación durante 20 días en condiciones controladas de humedad y temperatura, para lo cual se realizaron mezclas entre residuos orgánicos de aves y cantidades de zeolita utilizando un diseño factorial 24, teniendo un total de 8 tratamientos donde se evaluaron cada día las emisiones de CO2 y NH3. Los datos obtenidos fueron sometidos a un análisis de varianza y a una prueba de Tukey. Los resultados mostraron que la zeolita ayuda a la disminución de emisiones de NH3, y no afectó la actividad microbiana presente, se concluye que la zeolita atrapó el ion amonio en su estructura y no permitió su transformación a NH3.

  15. ESTUDIO SOBRE LA INFLUENCIA DE LA INCORPORACIÓN DE CATIÓN METÁLICO EN LA ACTIVIDAD CATALÍTICA Y COMPORTAMIENTO MAGNÉTICO DE ZEOLITAS ZSM-5

    Directory of Open Access Journals (Sweden)

    Clara Saux

    2011-01-01

    Full Text Available Se sintetizaron zeolitas ZSM-5 con relación molar Si/Al 17 por el método hidrotérmico, las que fueron modificadas con cobalto y cromo por la técnica de impregnación por vía húmeda en un 3 % p/p del metal. Los resultados obtenidos por DRX, indican que la incorporación de ambos metales de transición no altera la estructura, ni la cristalinidad de la matriz original. Se detecta la presencia de especies Co3O4 para Co-ZSM-5 y Cr2O3 para el caso de Cr-ZSM-5. De las medidas de magnetización a temperatura ambiente se observa el efecto de los metales de transición sobre el comportamiento netamente diamagnético de la matriz zeolítica con la aparición de ciclos de histéresis que no saturan por presentar una componente paramagnética. Ambos materiales fueron probados como catalizadores para la reacción de oxidación selectiva de estireno con peróxido de hidrógeno, presentando buenos resultados en actividad con una elevada selectividad (superior al 70 % hacia benzaldehído.

  16. ELIMINACIÓN DE COLORANTES CATIÓNICOS USANDO OZONO, ZEOLITA NATURAL Y OZONO/ZEOLITA CATIONIC DYES REMOVAL USING OZONE, NATURAL ZEOLITE, AND OZONE/ZEOLITE

    Directory of Open Access Journals (Sweden)

    Héctor Valdés

    2009-12-01

    Full Text Available En este trabajo se comparan resultados experimentales de remoción azul de metileno (MB utilizando tratamientos basados en la oxidación con ozono (O3, la adsorción con zeolita natural (ZN, y tratamiento simultáneo de adsorción y oxidación con ozono en presencia de zeolita natural (O3/ZN. Se evalúa, a escala de laboratorio, el efecto del pH (2-8 y la presencia de sustancias atrapadoras radicales libres (iones acetatos en la velocidad de remoción y en la eficiencia de los procesos. Los experimentos se realizaron en un reactor diferencial compuesto por un estanque de 1 dm³ y una columna de 19 cm³ de capacidad. El ozono fue generado a razón de 5 g O3/h. Los resultados mostraron que el sistema simultáneo de oxidación/adsorción O3/ZN incrementa la velocidad de remoción del MB con respecto a los procesos separados de ozonización y adsorción con zeolita. En presencia de sustancias atrapadoras de radicales, se observó un 70% de disminución en la velocidad de remoción de MB cuando se empleó el tratamiento con O3 y sólo un 25% cuando se utiliza el tratamiento combinado O3/ZN. Los resultados sugieren que la reacción de oxidación del MB en el sistema tiene lugar fundamentalmente sobre la superficie de la zeolita.This paper compares experimental results on methylene blue (MB removal systems based on ozone oxidation, zeolite adsorption, and simultaneous adsorption-oxidation using ozone in the presence of natural zeolite. The effect of pH (2-8, and the presence of radical scavengers (sodium acetate on process rates and removal efficiencies are assessed at laboratory scale. The experimental system consisted of a 1L differential circular flow reactor and an ozone generator rated at 5 g O3/h. Results show that ozone oxidation combined with zeolite adsorption increases the overall MB oxidation rate with respect to ozonation process and zeolite adsorption. In presence of free radical scavenger, only a 25% of reduction on MB removal rate are

  17. REMOCIÓN DE COBRE Y NÍQUEL POR INTERCAMBIO CATIÓNICO CON UNA ZEOLITA NATURAL

    Directory of Open Access Journals (Sweden)

    Arnoldy Estupiñan

    2010-10-01

    Full Text Available Se empleó la zeolita natural clinoptilolita, para remover cobre y níquel de aguas residuales de una industria de galvanotecnia. La capacidad de intercambio determinada para la zeolita transformada al estado homoiónico sódico, fue de 0,794 meq/g para cobre y 0,447 meq/g para níquel. Se realizaron ensayos en cochada y en columna, alcanzando éste último un mayor acercamiento al equilibrio. En los ensayos de regeneración, la zeolita sódica concentró el cobre hasta 23,5 veces con respecto al valor que presenta en los enjuagues de los baños de recubrimiento en medio ácido, mostrando su potencialidad para usarla en el tratamiento de estos residuos, por su efectividad y bajo costo.

  18. A cluster DFT study of NH{sub 3} and NO adsorption on the (MoO{sub 2}){sup 2+}/HZSM-5 surface: Lewis versus Brønsted acid sites

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhifeng [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Zuo, Zhijun [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Li, Zhe, E-mail: lizhe@tyut.edu.cn [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Zhang, Jinshan [College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

    2014-12-01

    Graphical abstract: - Highlights: • NH{sub 3} adsorption is found to be more favorable energetically than NO adsorption on both Lewis and Brønsted acid sites. • Lewis and Brønsted acid sites are competitive energetically for NH{sub 3} adsorption. • Reduced-state Mo{sup 5+} is suggested to play a key role in adsorption and activation of NO{sub x} together with the adsorbed NH{sub 4}{sup +}. - Abstract: A systematic DFT study was carried out to investigate NH{sub 3} and NO adsorption on both Lewis and Brønsted acid sites of (MoO{sub 2}){sup 2+}/HZSM-5 catalyst by using cluster models. The adsorption energy results indicate that NH{sub 3} could strongly adsorb on both Lewis and Brønsted acid sites in the form of coordinated NH{sub 3} and NH{sub 4}{sup +}, respectively, whereas NO represents poorer adsorption ability. It is also found that Lewis and Brønsted acid sites are competitive energetically for NH{sub 3} adsorption. According to the difference in the proposed mechanisms for NH{sub 3} adsorption on different acid sites, particular attention has been focused on the first dissociation of coordinated NH{sub 3} for Lewis acid site and the effect of Mo site on the introduction of NO for Brønsted acid site. For the coordinated NH{sub 3} on Lewis acid site, the more electron donation from NH{sub 3} is, the greater its adsorption stability is and the higher active its H atoms are. In addition, DOS results show that stability of the H atoms is enhanced by interacting with framework oxygen and especially the H atoms chemical-bonded with framework oxygen. For the NH{sub 4}{sup +} on Brønsted acid site, reduced-state Mo{sup 5+} holds stronger reducibility and oxidizability than terminal oxygen, which is suggested to play a key role in adsorption and activation of NO{sub x} together with the adsorbed NH{sub 4}{sup +}.

  19. La zeolita y su efecto en la eficiencia del nitrógeno en arroz y maíz

    Directory of Open Access Journals (Sweden)

    Miguel Soca

    2014-12-01

    Full Text Available Este trabajo evaluó el efecto de la zeolita en las reducciones de volatilización del nitrógeno amoniacal (RVNA y volumen de lixiviados (RVL así como en rendimientos de arroz Oryza sativa L. y maíz Zea mays L. En el primer experimento bajo un Diseño Completamente al Azar (DCA se evaluó el tamaño de partícula de zeolita (< 1 mm, 1 - 2 mm, 2 - 3 mm y 3-5 mm en RVNA. El segundo experimento, consistió en evaluar RVL con la aplicación de cuatro tratamientos: testigo (T, zeolita (Z, urea (U y urea + zeolita (UZ. El tercer experimento se desarrolló en un cultivo de arroz, donde se evaluaron dos métodos de aplicación (al voleo y trasplante con cuatro tratamientos (T, U, UZ10% y UZ15% y su efecto en el rendimiento del cultivo. El cuarto experimento realizado en un campo de maíz con dos tratamientos (U y UZ15% evaluó el rendimiento del cultivo en dos suelos (aluvial y esquelético. Los tamaños de partícula entre 3 y 5 mm obtuvieron RVNA del 50% y RVL del 48%. La aplicación de zeolita en arroz obtuvo RVNA de 60% y mejoró los rendimientos sin encontrar diferencias entre método de aplicación. También su aplicación mejoró el peso de grano por mazorca y el peso seco de grano de maíz. La zeolita mejoró la eficiencia de la fertilización nitrogenada.

  20. Metodología de los trabajos de campo para la prospección de zeolitas naturales

    OpenAIRE

    Costafreda Mustelier, Jorge Luis

    2011-01-01

    Los yacimientos de zeolitas naturales, como cualquier otro, están sujetos a normas de investigación que varían en dependencia de las necesidades del momento. En los últimos seis años, por citar un ejemplo, el estudio y la explotación de los recursos no metálicos en España, incluyendo las zeolitas naturales, ha experimentado un fuerte declive que ubica la demanda muy por debajo de las cifras conocidas antes del 2008, fecha en que se destapó la verdadera cara de la llamada “burbuja inmobiliaria...

  1. Synthesis and characterization of zeolite from coal ashes modified by cationic surfactant; Sintese e caracterizacao de zeolita de cinzas de carvao modificada por surfactante cationico

    Energy Technology Data Exchange (ETDEWEB)

    Fungaro, D.A.; Borrely, S.I., E-mail: dfungaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-01-15

    Zeolite synthesized from coal fly ash was modified with different concentrations (2 and 20 mmol.L{sup -1}) of hexadecyltrimethylammonium bromide (HDTMA-Br). The Non-Modified Zeolite (NMZ) and Surfactant-Modified Zeolites (SMZ) were characterized by X-ray fluorescence spectrometry, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetric analysis, among others. The SMS presented negative charge probably due to the formation of a partial bilayer of HDTMA on exchangeable active sites on the external surface of NMZ. A decrease in surface area was observed for SMZ as compared to NMZ indicating zeolite surface coverage with HDTMA-Br molecules. The crystalline nature of the zeolite remained intact after adsorption of surfactant and heating for drying. FTIR analysis indicated that there were no significant changes in the structure of the zeolite after adsorption of surfactant. (author)

  2. Zeolites modified with silver for the development of a water disinfection system; Zeolitas modificadas con plata para el desarrollo de un sistema de desinfeccion de agua

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio V, S.

    2013-07-01

    In spite of great strides that have been taken in sanitation technologies, there still exist health problems due to microbiological contamination by water. The waterborne diseases have not been completely eradicated and are a big problem of economic interest and health. Moreover, the microbicidal properties of silver have been used for a long time. The use of silver as a disinfectant has many advantages; for example it inhibits a wide spectrum of microorganisms, it has oligo dynamic properties and owing its mechanisms of cell inactivation, it also does not allow the emergence of new resistant strains. In the present research, the kinetics of water disinfection with silver has been investigated, to develop small system for water disinfection, based in silver modified Mexican clinoptilolite. The chemical species of silver play a significant role in the disinfection processes. For this reason, in this work, were both the Ag{sup +} and nanoparticles of Ag{sup ο} considered. The synthesis of nanoparticles of Ag{sup ο} woes performed by thermal and chemical reduction. It was found that the chemical reduction of Ag{sup +} to Ag{sup ο} was more efficient because it presented more defined nano structures and better distribution than those of thermal reduction. Clinoptilolite of Taxco (Guerrero) was chosen to exchange the native ions from the clinoptilolite by Ag{sup +} from the aqueous medium, or to deposit the nanoparticles of Ag{sup ο} on this surface. These silver modified zeolitic materials were characterized by scanning electron microscopy (Sem), elemental analyses (EDS), X-ray diffraction (XRD) and neutron activation analysis (NAA). The results showed that the crystallographic structure of the clinoptilolite did not change during thermal and chemical reduction treatments of Ag{sup +} to obtain the nanoparticles of Ag{sup ο}. The bactericide activity of the silver modified zeolitic materials (with Ag{sup +} or nanoparticles of Ag{sup ο}) was evaluated on Escherichia coli Atcc 8739, in both distilled water and well water. Disinfection kinetic parameters demonstrated that the bactericide efficiency of clinoptilolite with Ag{sup +} (Z Ag-1 and Z Ag-2) was higher than those with nanoparticles of Ag{sup ο} (ZAgNps-1 and ZAgNps-2). The Ag desorbed from Z Ag-1 and Z Ag-2 during the disinfection process was higher than from ZAgNps-1 and ZAgNps-2. Furthermore it was found that the decay rate of E. coli was higher in well water than in distilled water, however the concentration of silver in well water is lower. Experimental data suggested that the bactericide effect and Ag desorption from modified zeolitic materials are determined by the chemical characteristics of the aqueous media, the type of chemical species of Ag and the concentration of Ag{sup +} in the water. The results obtained from this investigation were taken in account to make a proposal of a water disinfection system considering the clinoptilolite with nanoparticles of Ag{sup ο} as the bactericide agent. (Author)

  3. Dyes adsorption blue vegetable and blue watercolor by natural zeolites modified with surfactants;Adsorcion de colorantes azul vegetal y azul acuarela por zeolitas naturales modificadas con surfactantes

    Energy Technology Data Exchange (ETDEWEB)

    Jardon S, C. C.; Olguin G, M. T. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Diaz N, M. C., E-mail: teresa.olguin@inin.gob.m [Instituto Tecnologico de Toluca, Av. Instituto Tecnologico s/n, Ex-Rancho la Virgen, 52140 Metepec, Estado de Mexico (Mexico)

    2009-07-01

    In this work was carried out the dyes removal blue vegetable and blue watercolor of aqueous solutions, to 20 C, at different times and using a zeolite mineral of Parral (Chihuahua, Mexico) modified with hexadecyl trimethyl ammonium bromide or dodecyl trimethyl ammonium bromide. The zeolite was characterized before and after of its adaptation with NaCl and later with HDTMABr and DTMABr. For the materials characterization were used the scanning electron microscopy of high vacuum; elementary microanalysis by X-ray spectroscopy of dispersed energy and X-ray diffraction techniques. It was found that the surfactant type absorbed in the zeolite material influences on the adsorption process of the blue dye. Likewise, the chemical structure between the vegetable blue dye and the blue watercolor, determines the efficiency of the color removal of the water, by the zeolites modified with the surfactants. (Author)

  4. Ácidos silícicos como catalizadores y fuente de silicio/metal para zeolitas

    OpenAIRE

    Barea Berzosa, Eva María

    2011-01-01

    Barea Berzosa, EM. (2005). Ácidos silícicos como catalizadores y fuente de silicio/metal para zeolitas [Tesis doctoral no publicada]. Universitat Politècnica de València. doi:10.4995/Thesis/10251/1868.

  5. REMOCIÓN DE PLOMO EN AGUA A PARTIR DE MATERIAL NANOESTRUCTURADO, NANOTUBOS DE CARBONO SOPORTADOS EN ZEOLITA NATURAL

    Directory of Open Access Journals (Sweden)

    Holanda I. Cruz

    2017-01-01

    Full Text Available En este trabajo se realizó la cinética de remoción de plomo en agua con un material nanoestructurado, nanotubos de carbono soportados en zeolita (NTC-ZN, y con zeolita natural (ZN. La zeolita utilizada proviene de los Valles Centrales de Oaxaca, México. El material nanoestructurado se sintetizó por el método de aspersión pirolítica bajo condiciones especificas; se caracterizó por microscopía electrónica de barrido y de transmisión (SEM y TEM y determinación de área superficial (BET. Los materiales se probaron con una solución de plomo a una concentración de 10 ppm bajo condiciones de agitación y filtrado a vacío. El filtrado se caracterizó por espectrometría de masas con plasma acoplado inductivamente (ICP-MS. Los porcentajes de remoción fueron de 99.96% para NTC-ZN y 99.27% para la zeolita natural en 120 minutos. Sin embargo un 94.5% de remoción se presenta en un tiempo 6 veces menor con el híbrido que con ZN.

  6. REMOCION DE CROMO Y MATERIA ORGANICA DISUELTA EN EFLUENTES INDUSTRIALES POR ADSORCIÓN E INTERCAMBIO IONICO EN ZEOLITA Y CARBON ACTIVADO.

    OpenAIRE

    COVARRUBIAS GALLARDO, CRISTIAN MAURICIO; COVARRUBIAS GALLARDO, CRISTIAN MAURICIO

    2005-01-01

    Se estudió la remoción de cromo y materia orgánica desde solución acuosa utilizando métodos de separación basados en el uso de zeolitas y carbón activado. Para este propósito se evaluó la operación de remoción de cromo en columnas empacadas de zeolita y c 175p.

  7. ISOMERIZACIÓN DEL 1-CICLOHEXILOCTANO EN ZEOLITAS H-ZSM-22 Y H-Y

    Directory of Open Access Journals (Sweden)

    Jorge Quintero

    2009-06-01

    Full Text Available En este trabajo presentamos los resultados de la evaluacion energetica de los intermediarios de la isomerización del 1-ciclohexiloctano en dos etapas. La primera etapa corresponde a la isomerización del 1-ciclohexiloctano en fase gaseosa vía carbocationes clásicos, usando el nivel de teoría DFT/B3LYP y conjunto de funciones base 6-31G.  En la segunda etapa se desarrolló la coordenada de reacción de la isomerización del 1-ciclohexiloctano en presencia de zeolitas ácidas H-ZSM-22 y H-Y empleando el método ONIOM, usando los niveles de teoría B3LYP/6-31G:UFF. Nuestros resultados muestran diferencias significativas entre las reacciones en fase gaseosa y condensada. Estas diferencias ponen de manifiesto la influencia del confinamiento cuántico que sufren las moléculas al interior de los sistemas microporosos del tipo zeolitas.

  8. Fenoloxidasa Modificada: Clave para identificar cepas de Cryptococcus neoformans

    Directory of Open Access Journals (Sweden)

    Carlos Canelo D

    2000-01-01

    Full Text Available Cryptococcus neoformans es la única levadura patógena capaz de sintetizar pigmentos como la melanina mediante la actividad de su enzima llamada fenoloxidasa. El objetivo del presente estudio fue implementar y estandarizar la prueba de la fenoloxidasa, como técnica complementaria en la identificación de cepas de C. neoformans. Se estudiaron 21 cepas, identificadas previamente con métodos convencionales. La prueba de la fenoloxidasa fue modificada debido a que su empleo originaba 9,6% (2/21 de falsa negatividad. Esta prueba modificada se optimizó a 28°C a partir de un medio con baja concentración de glucosa. Ningún aislamiento falso negativo fue encontrado luego de repetir tres veces el ensayo, y el pigmento melanina fue detectado con mayor rapidez.

  9. Función ventilatoria en obreros expuestos al polvo de zeolita

    Directory of Open Access Journals (Sweden)

    Guillermo López Espinosa

    2000-08-01

    Full Text Available El presente estudio descriptivo y prospectivo se realizó en la Mina-Planta Zeolita Tasajeras, ubicada en el municipio de Ranchuelo, provincia de Villa Clara, desde septiembre del año 1998 a 1999 con el objetivo de evaluar la función ventilatoria en un grupo de obreros expuestos al polvo del mineral. A los 37 trabajadores que llevan 2 o más años de labor en el centro se les aplicó un cuestionario y se efectuaron 2 estudios espirométricos con un intervalo de 1 año. La información se analizó y los resultados fueron: de los 16 pa-cientes con prueba funcional ventilatoria patológica en el año 1998 se extendió a 24 en el 1999. El 64,8 % con afectación espirométrica mantiene entre 6 a 10 años de exposición al polvo del mineral zeolita y el 58,3 % son fumadores. El patrón espirográfico que predominó fue el obstructivo (56,8 % y se aprecia en el 62,1 % de los estudiados una disminución del flujo espiratorio forzado al 25 % (Vmax 25/H/L/TThe present descriptive and prospective study was conducted in "Tasajeras" Zeolite Mine-Plant, located in the municipality of Ranchuelo, province of Villa Clara, from September, 1998, to September, 1999, aimed at evaluating the ventilatory function in a group of workers exposed to zeolite dust. 37 workers with 2 or more years in the center answered a questionnarie. 2 sperimotric studies were carried out with a one-year interval. The information was analyzed and the results were the following: the number of patients undergoing the pathological ventilatory functional test was increased from 16, in 1998, to 24, in 1999. 64.8% of those with spirometric affectation have been exposed between 6 and 10 years to zeolite dust and 58.3% are smokers. The obstructive spirographic pattern prevailed (56.8%. A reduction of the forced expiratory flow to 25% (Vmax 25/H/L/T was observed in 62.1% of the studied individuals

  10. Eliminación del arsénico en diferentes clases de aguas con zeolitas naturales

    OpenAIRE

    Lazo Camposano, Roberto

    2013-01-01

    Para el desarrollo del presente trabajo de Investigación se ha tenido Ia referencia sobre todo de las contaminaciones de las diferentes aguas sea este de origen natural, aguas subterráneas, aguas de rio, aguas procedentes de Iluvias, aguas de filtraciones, aguas de minas, etc, es decir toda clase de agua que contenga el arsénico que es perjudicial a la salud humana. En el presente trabajo se utilizará un medio adsorbente que consiste de zeolita natural (clinoptilolita) recubierta con óxido...

  11. ZEOLITAS EN LA FERTILIZACIÓN QUÍMICA DEL CACAO CCN-51 ASOCIADO CON CUATRO ESPECIES MADERABLES

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    Fernando David Sánchez Mora

    2014-05-01

    Full Text Available Se evaluó el efecto de dos zeolitas comerciales del tipo clinoptilolita: Roca Mágica® (RM y Zeolite C® (ZC, incluidas en la fertilización química sobre la producción y rentabilidad del cacao “CCN-51”, de origen sexual, asociado con cuatro especies maderables [Caoba de montaña (Colubrina arborescens (Mill. Sarg, fernánsanchez (Triplaris cumingiana F., guayacán blanco (Cybistax donell-smithii Rose y laurel prieto (Cordia macrantha Chadat]. En la fertilización fueron utilizados los dos tipos de zeolita (RM y ZC y dos niveles (25 y 30%, más un testigo (sin zeolita. La fertilización se fraccionó en tres partes aplicándose urea, MgSO4, K2O y P2O5. Se empleó un diseño de parcelas divididas con cuatro especies maderables, cinco subtratamientos (tipos y niveles de zeolita y un testigo, en cuatro repeticiones. Se utilizó la prueba de Tukey al 5% de probabilidad. Se midió la fenología del cacao (brotación, floración, fructificación, cherelles wilt, número de mazorcas sanas y producción de cacao en kg ha-1. El mayor número de brotes los emitieron las plantas de cacao asociadas con fernánsanchez en la época lluviosa, posiblemente por la menor cobertura aérea de esta especie. El cacao alcanzó su mayor fructificación en la época lluviosa con las asociaciones fernánsanchez y guayacán y, 30% de ZC. El mayor número de mazorcas sanas, y producción de cacao fue obtenido con la asociación fernánsanchez en la época seca. La mayor rentabilidad se encontró con fernánsanchez y 25% de RM.

  12. Síntesis de Zeolitas del tipo ZSM y su utilización en la producción de Hidrocarburos aromáticos a partir de Metanol

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    Jorge Bonilla

    2009-10-01

    Full Text Available Se sintetizaron las zeolitas ZSM-5 H *, ZSM- 8H * y ZSM-11H * y se utilizaron como catalizadores en la conversión de metanol a hidrocarburos y agua. La zeolita ZSM-5 presentó los mejores rendimientos de conversión a productos de punto de ebullición similares a los de la gasolina y en su mayoría aromáticos.

  13. Estudio sobre la incorporación y retención de plomo en zeolita natural

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    Abraham Mendoza Córdoba

    2014-12-01

    Full Text Available Las zeolitas son un grupo de minerales que corresponden a la clase de los silicatos (tectosilicatos, entre las diversas utilidades que tienen estos minerales está la resolución de problemas ambientales, particularmente en la eliminación de contaminantes, entre estos se encuentran los metales pesados, los cuales están presentes en los suelos de zonas industriales, en el agua potable, en los afluentes de aguas procedentes de la industria y de la actividad minera, o bien procedentes de mantos acuíferos. Su utilidad se debe en parte por tener una gran capacidad de intercambio iónico, así como también por tener una estructura con cavidades de dimensiones nanométricas, eso le da la capacidad de incorporar elementos ajenos al mineral dentro de dichas cavidades. En el presente trabajo se ha experimentado con Pb incorporándolo en zeolitas (chabazita como acetato de plomo (Pb(CH3COO2 3H2O con el fin de conocer, por una parte, la capacidad del mineral para alojar dicho metal después de activarla, y por otra parte, conocer la capacidad de retención del metal después de un proceso reversible a la incorporación de Pb (activación.

  14. ESTUDIO DEL IMPACTO TÉCNICO DE MEZCLAS DE CONCRETO HIDRÁULICO POR LA SUSTITUCIÓN PARCIAL DE CEMENTO POR ZEOLITA

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    I. Miranda Pasos

    2014-06-01

    Full Text Available La industria de la construcción cada vez más consciente de la necesidad de ejecutar obras con materiales que se obtengan y/o utilicen procesos industriales que minimicen la contaminación y, que contribuyan en el comportamiento de un producto como lo es el concreto hidráulico en la construcción, ha estado buscando alternativas de materiales que sustituyan total o parcialmente al cemento por otro cementante que contamine menos en su procesos de obtención y que conserve las propiedades o las mejore. Una alternativa para sustitución parcial del cemento es la zeolita, es un mineral que se obtiene por proceso de excavación y molienda de puzolana. La norma ASTM-618, define a las puzolanas como materiales silíceo o aluminio-silíceo que por sí solo poseen poco a ningún valor cementante, pero cuando se han dividido finamente y en presencia de agua e hidróxido de calcio (Cal reaccionan químicamente a temperatura ambiente para formar cementantes (Miranda, 2008. Recientemente se ha estudiado el efecto de adicionar mineral Cal-Zeolita para la elaboración del concreto, cuyos resultados son favorables al comportamiento mecánico y su durabilidad (Dopico J.J., et al. 2009. Para la elaboración de morteros para recubrimientos al incorporar arenas zeolíticas como sustituto de la arena tradicional (Tiburcio et al. 2008. El presente proyecto evaluó el comportamiento del concreto hidráulico en estado fresco y endurecido al sustituir de manera parcial cemento por zeolita. Se enfocó a la evaluación del comportamiento mecánico como al diseño de la mezcla de concreto hidráulico fabricado con cemento normal y con cemento-zeolita. Tomando en cuenta los resultados obtenidos, la zeolita incorporada en porcentajes entre el 5% y 10 % tiende a valores de resistencias muy cercanos al concreto normal, los modelos obtenidos así lo corroboran, por lo que se puede concluir la factibilidad de sustitución parcial de cemento por zeolita tomando en cuenta el

  15. Qualidade do abacate 'HASS' frigoarmazenado submetido a atmosferas modificadas ativas

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    Rogério Lopes Vieites

    2014-06-01

    Full Text Available O objetivo deste trabalho foi avaliar a conservação do abacate 'Hass'frigoarmazenado submetido a atmosferas modificadas ativas. Os frutos foram acondicionados em embalagem de náilon+polietileno e submetidos à injeção de mistura de gases, constituindo os tratamentos: I - mistura gasosa do ambiente (21,0 kPa de O2+0,03 kPa de CO2; II - 4,0 kPa de O2+5,0kPa de CO2 ; III - 4,0 kPa de O2+6,0 kPa de CO2 ; IV - 4,0 kPa de O2+7,0 kPa de CO2, e V- 4,0 kPa de O2+8,0 kPa de CO2. As embalagens contendo os frutos foram armazenadas em câmara frigorífica, a uma temperatura de 10±1ºC e umidade relativa de 90±5%, durante 25 dias, sendo as análises realizadas a cada 5 dias. As análises realizadas foram perda de massa, atividade respiratória, potencial hidrogeniônico (pH, firmeza, acidez titulável (AT, sólidos solúveis (SS e atividade das enzimas pectinametilesterase (PME e poligalacturonase (PG. O tratamento em que os frutos foram submetidos à pressão parcial de 4,0 kPa de O2+7,0 kPa de CO2 foi o mais efetivo na conservação dos frutos, principalmente pela menor perda de massa e baixa produção de CO2.

  16. Aumento de la producción de biogás mediante el uso de zeolita natural

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    Francisco Díaz Marrero

    2011-02-01

    Full Text Available El presente trabajo analiza la influencia de una zeolita natural sobre el proceso de digestión anaerobia, a partir de las evidencias existentes sobre el incremento de la degradación de la materia orgánica y la producción de biogás cuando se añaden a los digestores ciertos materiales en los que se incluyen compuestos arcillosos. Teniendo en cuenta estos antecedentes es objetivo del presente trabajo contribuir a la creación de un biocatalizadorque favorezca la producción de biogás a partir de materiales de relativo bajo costo. A partir de lo reseñado en la literatura sobre las características de absorción del amonio por la zeolita (Roque, 19871 y partiendo de la existencia en Cuba de importantes yacimientos de este mineral que tiene como base fundamental una estructura porosa de aluminio-silicato.Fueron estudiadas diferentes dosis de zeolitas para determinar su efecto sobre los procesos anaerobios adicionándoles a éstos nitrógeno en forma urea (H2N-CO-NH2, compuesto éste que en su hidrólisis produce amonio.  The presentA woPrk LanIalCyseAs thCe inIfOluenNce Eof Sa n aItNuraDl zeUolitSe onT thRe pIrAoceLss Eof aSnaerobic digestion, starting from the existent evidences on the increment of the degradation of theorganic matter and the biogas production when they are added to the material certain digesters in those that are included compound loamy. Keeping in mind these antecedents is objective of the present work to contribute to the creation of a biocatalizer that favours the biogas production starting from materials of relative low cost.Starting from that pointed out in the literature on the characteristics of adsorption of the ammonium for the zeolite (Roque, 1987 and leaving of the existence in Cuba of important locations of this mineral that has like fundamental base a porous structure of aluminumsilicate.Different zeolite doses were studied to determine its effect on the anaerobic processes adding these nitrogen in urea form

  17. Estimación de propiedades termodinámicas de silicatos. Construcción de diagramas de actividad de zeolitas

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    La Iglesia, A.

    1995-12-01

    Full Text Available In this paper we analyze the present methods of estimation of the thermodynamic properties of silicates with special emphasis on the free energy and enthalpy of zeolites. These data are not available in the literature, as these phases are chemically complexo The obtained values allow us to build the 10 following thermodynamic equilibrium diagrams: solubility of laumontite, chabazite, analcime, volcanic glass, zeolite A and zeolite X, and stability diagrams of chabazite-analcime-phillipsite-volcanic glass, clinoptilolite-phillipsite-erionite, prehnite-laumontite-heulandite, and kaolinite-metakaolinhidrosodalite-zeolite A. These diagrams can be useful to understand the genesis of these minerals and the processes that allow their formation in the laboratory.En este artículo se pasa revista a los métodos actuales de estimación de propiedades termodinámicas de silicatos, haciendo especial énfasis a los dedicados a la estimación de la energía libre de formación y de la entalpía de zeolitas, datos poco disponibles en la bibliografía debido a la complejidad química de estas fases. Los valores obtenidos han permitido construir los 10 diagramas de equilibrio termodinámico siguientes: diagramas de solubilidad de laumontita, chabazita, analcima, vidrio volcánico, zeolita A y zeolita X y los de estabilidad de chabazita-analcima-philipsitavidrio volcánico, clinoptilolita-philipsita-erionita, prehnita-laumontita-heulandita y caolinita-metacaolinita-hidrosodalita-zeolita A. Estos diagramas pueden explicar la génesis de los minerales o los procesos que dan lugar a su síntesis en el laboratorio.

  18. Evaluación del aparato respiratorio en trabajadores expuestos a polvo del mineral zeolita

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    Guillermo López Espinosa

    1999-01-01

    Full Text Available Se realizó un estudio observacional de tipo transversal en la Mina-Planta de Zeolita Tasajeras, que pertenece al municipio de Ranchuelo, Villa Clara, en el período comprendido entre junio y septiembre de 1997, con el objetivo de determinar el estado clínico y funcional ventilatorio de los trabajadores. A los 73 pacientes con 2 o más años en la fábrica se les aplicó un cuestionario, y se les realizó un examen físico y una prueba funcional ventilatoria. Los resultados más relevantes corroboran que los trabajadores del área de mayor exposición al polvo refieren un mayor número de síntomas respiratorios, sobre todo los fumadores. Sin embargo, el 94,5 % presenta un examen físico de tórax negativo, el 68,8 % de los pacientes con prueba funcional ventilatoria patológica integran el área planta, son fumadores el 62,5 %, y el 63,1 % no usa con frecuencia el filtro respiratorio como medio de protección individualA croos-sectional observational study was carried out at the mine-plant zeolite in Tasajeras, municipality of Ranchuelo, Villa Clara, from June to September, 1997, aimed at determining the clinical and functional ventilatory status of the workers. 73 patients with 2 or more years in the factory answered a questionnarie and underwent a physical examination and a functional ventilatory test. According to the results, those workers that were more exposed to dust had a higher number of respiratory symptoms, mainly smokers. However, 94,5 % had a negative chest physical examination. 68.8 % of the area patients with pathological functional ventilatory test work in the of the plant. 62.5 % are smokers and 63.1 % do not use frequently the respiratory filter as a menas of individual protection.

  19. Armazenamento de abacaxi 'smooth cayenne' minimamente processado sob refrigeração e atmosfera modificada

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    Prado Mônica Elisabeth Torres

    2003-01-01

    Full Text Available Estudou-se a influência de diferentes atmosferas modificadas durante o armazenamento de abacaxis da cv. Smooth Cayenne minimamente processados, por um período de oito dias, a 5º C e 85% UR. Foram realizadas as análises de acidez total titulável (ATT, sólidos solúveis totais (SST, pH, líquido drenado (LD, pectina total (PT, pectina solúvel (PS, firmeza e determinou-se a atividade das enzimas polifenoloxidase (PFO e poligalacturonase (PG da polpa dos frutos, a cada 2 dias. Os tratamentos utilizados foram: atmosferas modificadas com a injeção de 5% de O2 e 5% de CO2, com 2% de O2 e 10% de CO2 e o Controle (atmosfera modificada passivamente. As atmosferas modificadas ativas apresentaram ação injuriosa sobre os tecidos do abacaxi minimamente processado, estimulando a atividade da PFO. O uso de atmosferas modificadas proporcionou menor atividade da PG e, conseqüentemente, menor solubilização de substâncias pécticas. O abacaxi cv. Smooth Cayenne, minimamente processado, apresentou uma vida útil de 6 dias, pois, embora suas principais características físicas e físico-químicas não tenham sido comprometidas, as alterações químicas e bioquímicas não permitiram que o produto atingisse os 8 dias de armazenamento previstos.

  20. Evaluación de la zeolita natural utilizada como una tecnología productiva y limpia, aplicada al pasto Maralfalfa (Pennisetum sp) como un complemento en el uso de los fertilizantes nitrogenados

    OpenAIRE

    Pérez-Marín, Manuel Francisco

    2014-01-01

    Proyecto de Graduación (Maestría en Gestión de Recursos Naturales y Tecnologías de Producción) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Agroforestal, 2014. La necesidad de buscar alternativas para el aprovechamiento de fertilizantes en pastos de alta calidad como Maralfalfa (Pennisetum sp), lleva a investigar a la zeolita a modo de tecnología complementaria al programa de fertilización. Países como México, Colombia, Ecuador y Bolivia han utilizado la zeolita de tal forma ...

  1. Dyes removal of textile wastewater onto surfactant modified zeolite from coal ash and evaluation of the toxic effects; Remocao de corantes de efluente textil por zeolita de cinzas de carvao modificada por surfactante e avaliacao dos efeitos toxicos

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Patricia Cunico

    2015-07-01

    Zeolites synthesized from fly and bottom ashes and modified with hexadecyltrimethylammonium (HDTMA) were used as adsorbent to remove dyes - Solophenyl Navy (SN) and Solophenyl Turquoise (ST) and their hydrolysed forms Solophenyl Navy Hydrolysed (SNH) and Solophenyl Turquoise Hydrolysed (STH), from simulated textile wastewater. The HDTMA-modified fly zeolite (ZMF) and HDTMA-modified bottom zeolite (ZMB) were characterized by different techniques, as X-ray fluorescence spectrometry, X-ray diffraction and scanning electron microscopy, etc. The ZMF and ZMB presented negative charge probably due to the formation of a partial bilayer of HDTMA on exchangeable active sites on the external surface of unmodified zeolite. Initial dye concentration, contact time and equilibrium adsorption were evaluated. The adsorption kinetic for SN, ST, SNH and STH onto the zeolites followed the pseudo second-order model. The equilibrium time was 20 min for SN and ST and 30 min for SNH and STH, respectively. Langmuir, Freundlich and Temkin models were applied to describe the adsorption isotherms. Adsorption of the dyes were best described by the Langmuir model, with exception to SN/ZPM, SNH/ZPM and SNH/ZLM systems that followed Freundlich model. The maximum adsorption capacities were 3,64; 3,57; 2,91 e 4,93 for SN, ST, SNH e STH by ZLM, respectively and 0,235; 0,492; 1,26 e 1,86 by ZPM, in this order. The best performance for hydrolyzed dyes has been attributed to reduction of the size of dyes molecules during the hydrolysis process. Acute toxicity of the dyes to a different organism were evaluated by different test-organisms. Waterflea, Ceriodaphnia dubia showed EC50 value of 1,25; 54,5; 0,78 and 2,56 mgL{sup -1} for SN, ST, SNH and STH, respectively. The plant Lemna minor showed EC50 values of 18,9; 69,4; 10,9 and 70,9 mgL{sup -1} for SN, ST, SNH and STH, respectively. Midges larvae of Chironomus tepperi showed EC50 values of 119 and 440 mgL{sup -1} for SN and ST, respectively. Regarding the adsorption process, acute effects were substantially reduced after adsorption treatment of aqueous solution with SN and ST by ZMF, as well as their hydrolysed forms, showing no toxicity after removal of 100% of colour. After treatment with ZPM there was an increase of the toxicity, with exception of SHN and STH dyes that do not show toxicity after the treatment. Toxicity Identification Evaluation tests (TIE) were realized in order to identify what substances were causing the observed toxicity for the SN, ST and the leached of ZMF and ZMB. The acute effects were significantly reduced after manipulation with Solid-Phase Extraction (SPE) and Ethylenediaminetetraacetic acid (EDTA) for the leached of ZMB and ZMF. The dyes showed reduced in the toxicity after manipulation with EDTA indicating that the toxicants are mostly cationic metals. (author)

  2. Modelado de curvas de ruptura en la adsorción de agua sobre sílica gel y zeolita 4A

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    Andrés Rivera Guerrero

    2014-01-01

    Full Text Available Este artículo presenta el desarrollo de un modelo computacional para simular la adsorción de agua en un lecho empacado, comparando el desempeño de una zeolita 4A y una sílica gel tipo ‘A’. Se usó una variación de la isoterma de Langmuir para la zeolita 4A y la isoterma de Tóth para la sílica gel; se utilizó el modelo de fuerza motriz lineal (LDF para la velocidad de adsorción, con un coeficiente total dependiente de la temperatura. El modelo está constituido por cinco ecuaciones diferenciales parciales asociadas con las variables: fracción molar de agua, temperatura, presión, velocidad superficial y carga adsorbida de agua. Para resolver el sistema se empleó el método de líneas (MOL con el integrador ODE15S de Matlab ® . Se evaluaron como variables de respuesta el intervalo de tiempo característico de la curva de ruptura, la asimetría, la temperatura máxima y la caída de presión, mediante un esquema factorial de dos niveles. El tipo de adsorbente es la variable que más influencia tiene en las variables de respuesta. A la zeolita corresponde la mayor velocidad de adsorción, comportamiento que puede explicarse si se observa la forma de su isoterma de adsorción, aunque presenta una menor capacidad de retención de agua y mayor resistencia a la transferencia de masa.

  3. Cálculo por dinámica y mecánica molecular de sitios y calores de adsorción de Dipentenos sobre Zeolita Y

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    Cristian Blanco

    2011-06-01

    Full Text Available Hemos utilizado métodos de la mecánica molecular para estudiar la adsorción de R-limoneno, p-ment-1-eno, p-ment-8-eno y p-mentano sobre faujasita silícea y sobre zeolitas Y con relación Si/Al = 2 que contenían diferentes cationes en el sitio SII (Nal+, Fe2+, FeH y MnH. Los cálculos mostraron que la presencia de dobles enlaces en la molécula que se adsorbe y el tipo de catión en SIl determinan la estabilidad del complejo adsorbatozeolita. Las interacciones entre el huésped y la molécula adsorbida estuvieron dominadas por las contribuciones electrostáticas, las cuales aumentaron con la carga del catión en SII. La orientación de las moléculas insaturadas en la supercaja fue resultado del balance entre el aumento de repulsiones estéricas entre zeolita y molécula adsorbida y el aumento de atracciones electrostáticas como resultado de la minimización de dos grupos de distancias: las distancias entre el catión en SII y los carbonos Sp2 de la molécula adsorbida y las distancias entre los oxígenos estructurales de la zeolita y los hidrógenos de la molécula adsorbida.

  4. MODIFICACIONES DE LAS PROPIEDADES TEXTURALES Y ESTRUCTURALES DE UNA ZEOLITA USY Y DE SUS MEZCLAS CON "CAOLÍN CLAY" Y CLORHIDROL COMO CONSECUENCIA DEL TRATAMIENTO HIDROTÉRMICO

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    Yazmin Yaneth Agamez Pertuz

    2008-03-01

    Full Text Available El catalizador de FCC está constituido por partículas de composición compleja donde el componente activo es una zeolita Y. En este trabajo se presentan los resultados texturales y estructurales de una zeolita USY comercial lixiviada, de una serie de catalizadores con 7, 15, 25, 35 y 45% de material activo y los de estos materiales desactivados hidrotérmicamente. Las muestras se caracterizaron por fluorescencia de rayos X (FRX, difracción de rayos X (DRX, resonancia magnética nuclear de silicio (29Si RMN y fisiadsorción de nitrógeno a 77 K. A partir de estos resultados se hallaron correlaciones entre el volumen de microporo y el contenido de zeolita y entre el grado de cristalinidad y el porcentaje de zeolita. Además, se encontró que un tratamiento con sólo 20% de vapor de agua a 1033 K durante 16 horas destruye los grupos estructurales Si(2Al y Si(3Al como reflejo de la dealuminización drástica que sufre el material. 

  5. Natural Mexican zeolite, potential material for hydrogen storage; Zeolita natural mexicana, material para su posible uso en el almacenamiento de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe-Garcia, J. L.; Lopez Munoz, B. E. [Instituto Nacional de Investigaciones Nucleares (Mexico)]. E-mail: joseluis.iturbe@inin.gob.mx

    2009-09-15

    This work presents a study of the use of natural Mexican zeolite as a possible alternative for hydrogen storage. This zeolite material is from the state of Sonora. Its particle size was decreased using a grinding treatment with a mechanical alloying system for 5 hours. The mechanical alloying equipment was built in our Institute (Instituto Nacional de Investigaciones Nucleares, ININ). Later, zeolite in powder form was characterized with x-ray diffraction and sweep electron microscopy. It was heated in a micro-reactor at 350 degrees Celsius, which was simultaneously emptied over 2 hours to eliminate humidity and possible gases trapped in its structure. Next, the temperature was reduce to 10 degrees Celsius and it was placed in contact with ultra-high pure hydrogen at a pressure of 10 bars for 10 minutes. The analysis of hydrogen trapped in the zeolite was conducted with gas chromatography. The results of the chromatograms indicate that the zeolite absorbed and liberated the hydrogen in completely different conditions than those reported in the literature. That is, with our experimental conditions at low pressure and temperature, the hydrogen was absorbed in this type of material. [Spanish] En este trabajo se presenta un estudio sobre el uso de una zeolita natural de origen mexicano como posible alternativa para almacenar hidrogeno. Este material zeolitico procede del Estado de Sonora, al cual se le disminuyo el tamano de particula mediante un tratamiento de molienda con un sistema de aleado mecanico durante 5 horas. El equipo de aleado mecanico se construyo en nuestro Instituto (Instituto Nacional de Investigaciones Nucleares, ININ). Posteriormente, la zeolita en forma de polvo se caracterizo por medio de difraccion de rayos X y microscopia electronica de barrido. Se sometio a calentamiento en un micro-reactor a 350 grados Celsios y al mismo tiempo haciendo vacio durante 2 horas, para eliminar humedad y posibles gases que estuvieran atrapados en su estructura. En

  6. Zeolites of the Valle Central of Costa Rica and its outskirts; Zeolitas del Valle Central de Costa Rica y sus alrededores

    Energy Technology Data Exchange (ETDEWEB)

    Zeledon, Luis Alonso [Moravia, San Jose, (Costa Rica)

    2004-12-15

    19 different species of zeolites have been found in 25 outcrops in the Valle Central of Costa Rica and in the Siquirres region. All the zeolites are secondary minerals and crystallized in little veins and vesicles of the basalts and pyroclastics rocks of the La Cruz and Grifo Alto formations, belonging to the Aguacate Group and the alkaline igneous rocks of Guayacan. The most frequent species of zeolites are stibnite, chabasite, laumontite, mesolite/mordenite, thomsonite, and analcime. Natrolite only was found near to Siquirres. (Author) [Spanish] Se describen 19 especies diferentes de zeolitas procedentes de 25 afloramientos en los alrededores del Valle Central de Costa Rica y en la region de Siquirres. Todas las zeolitas descritas son de origen secundario y se presentan en vetillas y vesiculas de los basaltos y rocas piroclasticas de las formaciones La Cruz y Grifo Alto del Grupo Aguacate y en las rocas igneas alcalinas de Guayacan. Las especies mas frecuentes son estilbita, chabasita, laumontita, mesolita/modernita, thomsonita y analcima. La natrolita solo se encontro en los alrededores de Siquirres. (Autor)

  7. Simulación físico-matemática del secado de la zeolita con microondas. // Physical-mathematical simulation of the zeolite drying with microwaves.

    Directory of Open Access Journals (Sweden)

    G. Quesada Ramos

    2004-01-01

    Full Text Available Se realiza una simulación físico-matemática del secado de la zeolita sometida a radiaciones de microondas utilizando la leyde Lambert. Las ecuaciones se expresan en un esquema implícito unidimensional, y se emplea el método numérico dediferencias finitas. La solución del sistema de ecuaciones se realiza por medio del método iterativo de Gauss-Seidel. Losresultados teóricos se comparan con los obtenidos experimentalmente.Palabras claves: Simulación, secado, zeolita, microondas._______________________________________________________________________________AbstractA physical-mathematical simulation of the zeolite drying with microwaves using the Lambert`s law is made. The equationsare expressed in an unidimensional implicit scheme, and the finite differences numeric method is used. The solution of theequations system is carried out by using the Gauss-Seidel´s iterativ method. The theoretical results are compared with thoseexperimentally obtained.Key words: Physical-mathematical simulation, drying, zeolite, microwaves.

  8. Estudio teórico de formas inusuales y modificadas de los ácidos nucleicos

    OpenAIRE

    Faustino Pló, Ignacio

    2013-01-01

    1) Estudio teórico de nucleobases modificadas. Las modificaciones químicas de ácidos nucleicos tienen una amplia variedad de aplicaciones tanto en clínica, utilizadas como agentes antisentido, así como en el estudio de las estructuras de los propios ácidos nucleicos, las interacciones proteína DNA o en la catálisis de ácidos nucleicos por poner algunos ejemplos. Actualmente se sintetizan cientos de análogos de nucleósidos estándar en laboratorios farmacéuticos, algunos de ellos como, ...

  9. Almacenamiento refrigerado de cerezas : efecto de madurez y atmósfera modificada

    OpenAIRE

    Yommi, Alejandra; Godoy, Carlos; Horvitz, Sandra; López Camelo, Andrés

    2002-01-01

    Se estudió el efecto de cosechar cerezas en dos estados de madurez: rojo pálido y rojo maduro y la utilización de atmósferas modificadas, empleando PBD de 11 y 40 m, sobre la calidad de fruta almacenada a 0 °C y después de 3 días a temperatura ambiente. La calidad fue evaluada en términos de pérdida de peso (%), color (ángulo hue), firmeza, contenido de sólidos solubles, aspecto de los pedicelos y presen...

  10. Célula del SMF modificada genéticamente para sobreexpresar NGAL y su uso como medicamento

    OpenAIRE

    Hotter, Georgina; Jung, Michaela; Solà, Anna M.

    2009-01-01

    Célula del SMF modificada genéticamente para sobreexpresar NGAL y su uso como medicamento. La presente invención se encuadra dentro del campo de la biomedicina. Específicamente, la presente invención se refiere a una célula del Sistema Mononuclear Fagocítico o SMF, preferiblemente un monocito o un macrófago, modificada genéticamente para sobreexpresar la lipocalina asociada a gelatinasa de neutrófilos (NGAL, en sus siglas en inglés), a un método para su obtención y a s...

  11. Caracterização de argamassa modificada por particula vegetal para nivelamento de contrapiso

    OpenAIRE

    Francisca Julia França Ferreira de Melo

    2007-01-01

    Resumo: O presente trabalho se propõe desenvolver uma argamassa para nivelamento de contra piso modificada com partículas vegetais de Pinus caribaea e avaliar suas características físicas e mecânicas. Os resíduos de Pinus utilizados são provenientes do processo de fabricação de lápis. Os traços tiveram seu fator água/cimento determinado pela trabalhabilidade. As misturas foram elaboradas com Cimento Portland CPII-E 32, areia, adição de partículas vegetais de Pinus e água proporcional ao traço...

  12. Novos sensores quimicos preparados com silica gel modificada com o ion piridinio

    OpenAIRE

    Lilian de Lourdes Lorencetti Prado

    1995-01-01

    Resumo: A sílica gel, com área superficial específica de 500 m.g e diâmetro médio de poros de 6 nm, foi organofuncionalizada com o íon piridínio. Reagiu-se a sílica com 3-cloropropiltrimetoxisilano e piridina, usando como solvente o CCI4. A quantidade de íons cloreto disponíveis para reações de troca iônica foi de 0,36 mmol.g. O espectro na região de infravermelho da sílica modificada (daqui para frente designada como SiPyCI) confirmou a presença dos grupos funcionais na superfície da mesma, ...

  13. Tratamiento quirúrgico de la pancreatitis aguda con técnica de Puestow modificada

    OpenAIRE

    Vázquez Merayo, Enrique; Moreno Pissau, Francisco; Labrada Arjona, Eduardo; Vázquez Martínez, Yovany Enrique

    2014-01-01

    La pancreatitis crónica representa uno de los mayores desafíos de la Gastroenterología, y su etiología sigue siendo difícil de establecer en 10-30 % de los pacientes. Se presenta un paciente masculino, de 13 años, con diagnóstico de pancreatitis crónica de tipo inmunológico, con estenosis del conducto pancreático principal. Necesitó tratamiento quirúrgico pancreaticoyeyunostomía longitudinal en Y de Roux, conocido como técnica de Puestow modificada. Se logró mejoría clínica, normalidad de sus...

  14. Vida-de-prateleira de goiabas minimamente processadas acondicionadas em embalagens sob atmosfera modificada

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    Pereira Leila Mendes

    2003-01-01

    Full Text Available Goiabas (Psidium guajava L., variedade vermelha "Paluma", minimamente processadas por desidratação osmótica branda, foram acondicionadas em embalagens rígidas de polietileno tereftalato (PET e estocadas à temperatura de 5masculineC, com o objetivo de avaliar a influência da embalagem sob atmosfera modificada e do processo de desidratação osmótica na vida-de-prateleira do produto. Goiabas sem o tratamento osmótico, acondicionadas nas embalagens de PET e em ar atmosférico, foram utilizadas como controle. Durante a estocagem foram avaliadas a perda de peso, a contaminação microbiológica, as características físico-químicas do produto e as concentrações de O2 e CO2 no interior das embalagens. As goiabas foram submetidas também a uma análise sensorial de aceitação, acompanhada da avaliação da intenção de compra do produto pelo consumidor. Verificou-se que a combinação da temperatura de estocagem, da embalagem sob atmosfera modificada passiva e do processo de desidratação osmótica proporcionou às goiabas minimamente processadas uma vida-de-prateleira de 24 dias, resultando num produto mais estável à contaminação microbiológica e com características sensoriais superiores às amostras controle, apresentando, também, melhor aceitação pelo consumidor.

  15. ARCILLA BENTONÍTICA MODIFICADA CON QUITOSANO PARA MATERIALES COMPUESTOS BIODEGRADABLES

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    GUSTAVO NEIRA ARENAS

    2011-01-01

    Full Text Available Se estudió la modificación de una arcilla colombiana tipo montmorillonita con un biopolímero policatiónico -quitosano-, y se evaluó el efecto del peso molecular del modificante en la efectividad del tratamiento de modificación. Como material de partida se empleó una arcilla montmorillonítica sódica la cual se sometió a un procedimiento de modificación desarrollado para tal fin, empleando diferentes concentraciones de quitosano de bajo y alto peso molecular. Las muestras de arcilla modificada fueron analizadas mediante Difracción de Rayos X, Espectroscopía de Infrarrojo con Transformada de Fourier (FTIR, y Análisis Termogravimétrico (TGA con el fin de identificar los posibles efectos del tratamiento de modificación sobre la estructura de la arcilla. Los resultados mostraron una relación directa entre el incremento de la distancia interlaminar de la arcilla modifi cada y la concentración de quitosano, encontrándose un incremento máximo de 1,559 nm para la relación 2:1 en peso de quitosano de bajo peso molecular y arcilla. En general, se detectó una mayor separación interlaminar en la arcilla al emplear quitosano de bajo peso molecular como modificador, comparado con el quitosano de alto peso molecular, aunque en los dos casos se observó una integración efectiva del agente modificador a la estructura de la arcilla. El análisis IR de la arcilla modificada evidenció la presencia en la estructura de grupos CH, NH3+, CH y NH , provenientes del quitosano, mientras el análisis TG sugirió un cierto grado de hidrofobicidad asociada a la presencia de quitosano, siendo estos aspectos de gran importancia para la aplicación de estos materiales como refuerzos de películas poliméricas biodegradables.

  16. Radiação gama e atmosfera modificada passiva na qualidade de goiabas 'Pedro Sato'

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    André José de Campos

    2011-10-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito da irradiação gama associada à atmosfera modificada passiva na qualidade pós-colheita de goiabas 'Pedro Sato', verificando suas características físico-químicas. Foram utilizadas goiabas provenientes da região de Vista Alegre do Alto-SP,Brasil. Após a colheita, as goiabas foram imediatamente transportadas ao Laboratório de Frutas e Hortaliças, pertencente ao Departamento de Gestão e Tecnologia Agroindustrial, da Faculdade de Ciências Agronômicas - UNESP - Câmpus de Botucatu-SP, onde foram armazenadas a 10ºC e 90-95%UR, em câmara frigorífica, por 28 dias. Os tratamentos foram: controle 1 (sem embalagem e sem irradiação; controle 2 (embalagem de poliestireno (PS + polietileno de baixa densidade (PEBD e sem irradiação; tratamento 1 (PS+PEBD e 0,2kGy; tratamento 2 (PS+PEBD e 0,6kGy, e tratamento 3 (PS+PEBD e 1,0kGy. As análises realizadas foram: firmeza, sólidos solúveis (SS, acidez titulável (AT e índice de maturação. Foi utilizado o delineamento inteiramente casualizado, com esquema fatorial 5 x 5 (tratamento x tempo. Concluiu-se que as altas doses de irradiação promoveram efeito negativo nas características físico-químicas da goiaba 'Pedro Sato', e que apenas a menor dose utilizada (0,2kGy associada à atmosfera modificada conservou frutos com maior qualidade e aceitabilidade, indicado por maiores índice de maturação e teor de sólidos solúveis obtidos.

  17. FRIGOCONSERVACIÓN Y ATMÓSFERAS MODIFICADAS EN FRUTOS DE AGUACATE MÍNIMAMENTE PROCESADO

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    J. A. Zarazúa-Escobar

    2005-01-01

    Full Text Available Este estudio tuvo como objetivo evaluar el efecto de dos atmósferas modificadas, una generada por polietileno de baja densidad lineal y el uso de Vacum 300, a dos temperaturas de almacenamiento 5 y 20 °C, así como el uso de antioxidantes (B-tocoferol, ácido Lascórbico y butilhidroxi-tolueno en la prolongación de la vida de anaquel de aguacate mínimamente procesado. Se evaluó la pérdida fisiológica de peso, color, firmeza, daños por frío, potencial de obscurecimiento, compuestos fenólicos, actividad de la polifenoloxidasa, incidencia y severidad de enfermedades, y evaluación sensorial. El mejor tratamiento fue el de película para vacío, Vacum 300 con antioxidantes (B-tocoferol, ácido L-ascórbico y butilhidroxi-tolueno almacenado a 5 °C, el cual tuvo la capacidad de mantener un aroma y apariencia aceptables en las rebanadas de aguacate. También redujo de forma considerable la pérdida fisiológica de peso, aminoró los desórdenes causados por el frío y conservó al producto en perfectas condiciones (libre de hongos a lo largo de 13 días.

  18. Tratamiento quirúrgico de la pancreatitis aguda con técnica de Puestow modificada

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    Enrique Vázquez Merayo

    Full Text Available La pancreatitis crónica representa uno de los mayores desafíos de la Gastroenterología, y su etiología sigue siendo difícil de establecer en 10-30 % de los pacientes. Se presenta un paciente masculino, de 13 años, con diagnóstico de pancreatitis crónica de tipo inmunológico, con estenosis del conducto pancreático principal. Necesitó tratamiento quirúrgico pancreaticoyeyunostomía longitudinal en Y de Roux, conocido como técnica de Puestow modificada. Se logró mejoría clínica, normalidad de sus enzimas en una semana, no hubo complicaciones, tuvo evolución posoperatoria satisfactoria, y una estadía hospitalaria de 14 días. Actualmente se mantiene con 4 años de evolución satisfactoria. La técnica efectuada en el paciente es considerada por muchos como la ideal, por su baja incidencia de mortalidad (menos del 3 % y por el alivio del dolor en más del 75 % de los pacientes. Por ello, se considera que esta técnica quirúrgica pudiera ser una opción terapéutica eficaz para este tipo de paciente.

  19. Evaluación de la eficiencia de una batería de filtros empacados en zeolita en la remoción de metales pesados presentes en un licor mixto bajo condiciones de laboratorio

    OpenAIRE

    Acevedo Cifuentes, Diana Rocío; Builes Felizzola, Sandra Milena; Ordóñez Ante, Carlos Andrés; López Sánchez, Idalia Jacqueline

    2011-01-01

    En este artículo se muestran resultados de investigación obtenidos en la remoción de los metales pesados, plomo, níquel, cromo, cadmio y mercurio, presentes en una solución compuesta por licor mixto proveniente de la planta de tratamiento de aguas residuales de San Fernando y una solución preparada con metales pesados con una concentración conocida, mediante el uso de una batería de filtros empacados en zeolita clinoptilolita. La experimentación se desarrolló bajo condiciones controladas de c...

  20. Estudio del comportamiento agronómico de las zeolitas en la fertilización del cultivo de la sandía (citrullus vulgaris) en la zona de taura, Guayas

    OpenAIRE

    Idrovo, Jorge; Quilambaqui, Miguel

    2009-01-01

    Con el fin de evaluar el comportamiento y efecto de las zeolitas en la producción del cultivo de la sandía, se realizó un estudio agronómico en la zona de Taura, Guayas, Ecuador, donde se instaló un ensayo de campo, en un área experimental de 3300 m2. El diseño que se aplicó en este estudio fue de un Bloques Completos al Azar (DBCA), conformado por 7 tratamientos y 4 repeticiones, con un total de 28 unidades experimentales. Los tratamientos a evaluarse, fueron dosis total de fertilizantes con...

  1. Pirólise catalítica do PEBD usando como catalisador a vermiculita modificada

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    Franciel Aureliano Bezerra

    2016-01-01

    Full Text Available Resumo O polietileno de baixa densidade (PEBD é um dos polímeros mais usados atualmente, e a grande quantidade desse polímero produzida resulta em toneladas de resíduos, que necessitam ser tratados. Neste trabalho foi realizada a pirólise termocatalítica do PEBD usando como catalisador a argila vermiculita modificada, como alternativa para o tratamento dos resíduos. A argila foi tratada com solução de ácido nítrico a diferentes concentrações e calcinada a 400 °C. Os materiais foram caracterizados por técnicas de difratometria de raios X, termogravimetria, adsorção de nitrogênio e espectroscopia de energia dispersiva. A pirólise térmica e termocatalítica foi realizada em um micro reator acoplado com GC/MS, a 500 °C. O intuito da pirólise de resíduos poliméricos é a obtenção de hidrocarbonetos leves (C<16, que possam ser empregados na indústria química e petroquímica, através de quebras na cadeia polimérica. Os resultados foram satisfatórios, com aumento no rendimento para hidrocarbonetos leves ao empregar os catalisadores chegando a 71,4% de produtos com C<16, enquanto a pirólise térmica resultou apenas de 25,8%.

  2. Manejo do etileno em ameixas 'Laetitia' armazenadas sob atmosferas controlada e modificada ativa

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    Thais Roseli Corrêa

    2011-09-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de condições de atmosfera controlada (AC e atmosfera modificada (AM ativa (filme PEBD de 40 µm, com duas perfurações de 1,0 mm de diâmetro, associadas ao manejo do etileno, sobre a manutenção da qualidade em ameixas 'Laetitia'. Os tratamentos avaliados consistiram no armazenamento refrigerado (60 dias a 0,5±0,1ºC em: atmosfera refrigerada (AR; 21,0 kPa O2 + <0,03 kPa CO2; AM; AM + baixo etileno (BE; AC; e AC + 1-MCP (1,0 µL L-1. As pressões parciais de O2 + CO2 (kPa foram de 1,0 + 1,0 e 2,5 + <0,1, em AC e AM, respectivamente. Os frutos armazenados em AC, independentemente do tratamento com 1-MCP, apresentaram retardo no amadurecimento, quando comparados aos frutos em AR. Contudo, os melhores resultados para a manutenção da textura da polpa e da acidez titulável foram obtidos em AC + 1-MCP. Os tratamentos não interferiram para a incidência de podridões, rachaduras e degenerescência da fruta. Frutos dos tratamentos AM + BE e AC + 1-MCP apresentaram menor escurecimento da polpa e maior aceitabilidade quanto à cor e ao sabor na análise sensorial em relação àqueles armazenados em AR.

  3. Diseño de una planta de envasado de patatas en atmósfera modificada

    OpenAIRE

    Roldán Fernández, Rubén

    2012-01-01

    El proyecto pretende diseñar una planta de envasado de patatas, variedad Monalisa, para su comercialización y posterior distribución de este producto hortofrutícola. En dicha planta se realizarán las operaciones de lavado, pelado, selección, corte, secado y envasado en atmósfera modificada (CO2, O2 y N2). El producto envasado se almacenará en cámaras frigoríficas hasta su comercialización. Los españoles consumimos una media de 60,54 Kg de hortalizas frescas por persona y ...

  4. Nivel del PH salival en niños de 6 meses a 18 meses de edad con ingesta de leche evaporada modificada y leche materna

    OpenAIRE

    Flores Concha, Paulita

    2010-01-01

    RESUMEN Objetivo: Determinar el nivel del pH salival en niños de 6 meses a 18 meses de edad con ingesta de leche evaporada modificada y leche materna, en el Programa Nacional Wawa Wasi del distrito de Villa María del Triunfo, según el tiempo transcurrido. Material y método: La muestra estuvo conformada por 40 niños de 6 meses a 18 meses de edad, distribuidos en dos grupos: 20 que consumieron leche materna y 20 que ingirieron leche evaporada modificada. Se les dio a tomar la leche ...

  5. Utilización de la zeolita para disminuir los gases tóxicos de los motores de combustión interna. // The utilization of Cuban zeolites in the decrease of toxic gases emissions of internal combustion engines.

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    J. L. Reyes González

    2003-01-01

    Full Text Available En el trabajo se presentan los resultados obtenidos al utilizar la zeolita natural cubana para la disminución de los gasestóxicos que los motores de combustión interna MCI. envían a la atmósfera. Los experimentos fueron realizados en bancosde pruebas de MCI. tanto para motores de carburación como para motores diesel. Obteniéndose eficiencias de disminucióndel CO del 80 %, del CnHm del 50% y el humo negro en un 90%. Se demuestra la importancia de la granulometría de lazeolita para esta eliminación y para mantener la potencia del motor dentro de rangos aceptables.Palabras claves: Toxicidad, zeolita, medio ambiente, filtros, gases de escape._______________________________________________________________________________Abstract.In this paper are presented the results of the utilization of Cuban zeolites in the decrease of toxic gas emissions toatmosphere of internal combustion engines, (MCI. The experiments were carried out in test bank for gasoline and dieselengines. The efficiency in the decrement of CO was of 80%, CnHm in 50%, and 90 % in soot. The size of the zeolitesparticle importance in the efficiency is demonstrated.Key words: Toxicity, zeolite, enviroment, filters, gas emissions.

  6. BIOADSORCIÓN DE ARSÉNICO (III EN SOLUCIÓN ACUOSA POR LA BIOMASA MODIFICADA DE Aspergillus niger

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    Erik E. Santos

    2017-01-01

    Full Text Available Se analizó la capacidad de remoción de As (III en solución acuosa por la biomasa modificada de Aspergillus niger, mediante Espectrometría de Absorción Atómica. La mayor bioadsorción (66% con 1 mg/L del metaloide fue a las 24 horas, a pH de 6.0, 28oC y 1 g de biomasa modificada. Con respecto a la temperatura, la más alta remoción fue a los 28oC, con un 66% de remoción a las 24 horas. A las concentraciones de As (III analizadas, la biomasa mostró una buena capacidad de remoción. Al aumentar la concentración del bioadsorbente, la remoción es más eficiente (91.2% con 5 g de biomasa, además de remover eficientemente el metaloide (67% de remoción en agua natural contaminada con 1 mg/100 mL de As (III a las 24 horas con 5 g de biomasa, por lo que puede ser utilizado para eliminar aguas residuales industriales.

  7. Recubrimiento comestible basado en goma arábiga y carboximetilcelulosa para conservar frutas en atmósfera modificada

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    S. Valle-Guadarrama

    2008-01-01

    Full Text Available El objetivo de este estudio fue desarrollar un recubrimiento comestible a base de goma arábiga (GA, carboximetilcelulosa (CMC y glicerol (GL como plastificante, para valorar su potencial de uso en sistemas de conservación de frutos en atmósfera modificada, mediante la evaluación de sus propiedades mecánicas, de barrera a gases y de transmisión de luz. En una fase de diseño evolutivo se obtuvo una formulación aproximada del recubrimiento; con esta base se definieron rangos de concentraciones de GA (20 y 30 %, CMC (0.25, 0.50 y 0.75 % y GL (5, 10 y 15 % para caracterizar el material. La combinación de GA en proporción de 30 %, CMC en un rango de 0.25 a 0.50 % y GL en un rango de 5 a 10 %, presentó un potencial adecuado para uso en conservación de frutos mediante sistemas de atmósfera modificada. El cambio de las concentraciones en GA, CMC y GL permitió regular las permeabilidadesa O2 y CO2 y la resistencia mecánica, con una transparencia mayor a 80 %.

  8. Esternotomia mediana como via preferencial na anastomose de Blalock-Taussig modificada

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    Rogério ABRAHÃO

    1997-04-01

    Full Text Available A abordagem usual para a realização da anastomose de Blalock-Taussig modificada (ABTM tem sido a toracotomia lateral. Esta via acarreta necessariamente trauma ao parênquima pulmonar e acesso difícil por ocasião da operação definitiva. A esternotomia mediana (EM apresenta-se como uma alternativa com certas vantagens. Este trabalho visa avaliar a viabilidade técnica e os resultados da realização da ABTM por EM. Dez pacientes foram submetidos a esta técnica, interpondo-se enxertos de PTFE. A mortalidade imediata foi de 30%, e a tardia de 10%. Complicação imediata ocorreu em 10%. O tempo médio de internação foi 7,0 ± 0,5 dias. A variação da saturação da hemoglobina pré e pós-operatória foi 27,5 ± 11,7% (pThe usual approach for systemic-pulmonary shunts has been right or left thoracotomy and interposition of a PTFE vascular graft between the subclavian and pulmonary arteries. This approach, necessarily causes, trauma to the lungs and some difficulty for dissection and ligation later during definitive surgical correction. Median sternotomy has been used occasionally for right subclavian-pulmonary artery anastomosis with certain advantages over thoracotomy. In this series, 10 patients were submitted to systemic-pulmonary modified Blalock-Taussig shunts by median sternotomy as the first choice. There have been no technical difficulties. The grafts were anastomosed to the right subclavian artery or brachiocephalic trunk. The right pulmonary artery was preferred, but when infeasible, this side of the shunt was made to the pulmonary trunk or left pulmonary artery. There have been 3 early and 1 late death, unrelated to the shunt. Arterial saturation improved by 27.5 ± 11.7% (p<0.001 post-operatively. This technique is viable, with advantages over lateral approach due to easier access, avoiding lung trauma, permitting surgical alternatives and canulation if needed and may facilitate dissection for later ligation.

  9. Transformações bioquímicas de abacaxi minimamente processado armazenado sob atmosfera modificada Biochemical modifications of pineapple minimally processed under modified atmosphere

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    Mônica Elisabeth Torres Prado

    2004-12-01

    Full Text Available Realizou-se estudo sobre a influência da atmosfera modificada com diferentes concentrações de gases durante o armazenamento de abacaxi cv. Smooth cayennne minimamente processado, por oito dias, à temperatura de 5ºC e 85% de UR. Foram realizadas análises de açúcares neutros, celulose, hemicelulose e poliuronídeos totais na parede celular. O abacaxi minimamente processado foi acondicionado sob duas Atmosferas Modificadas Ativas, uma com 5% de O2 e 5% de CO2 (AM1,outra com 2% de O2 e 10% de CO2 (AM2,e uma Atmosfera Modificada Passiva (Controle durante 8 dias de armazenamento. O uso de atmosferas modificadas ativas permitiu que o abacaxi minimamente processado sofresse menor degradação da parede celular com menor solubilização das hemiceluloses. Abacaxis minimamente processados e armazenados sob atmosfera modificada obtiveram uma vida de prateleira média de 6 dias, a 5º C.Pineapples minimally processed were, stored eight days (5ºC and 85% RH under passive and active atmosphere (MA. Neutral sugars, cellulose, hemicellulose, and total polyuronide analysis in cell wall were done. Two different active MA were tested: 5% of O2 + 5% of CO2 (MA1 and 2% of O2 + 10% of CO2 (MA2 and one passive MA (Control; during eight days of storage. Pineapples minimally processed stored under active modified atmosphere showed degradation of cell wall and less solubilization of hemicelluloses, besides being more effective in control of ethanol production and formation of off flavours. Pineapples minimally processed stored under modified atmosphere, showed life average of 6 days under refrigeration at 5ºC.

  10. Síntesis de zeolita LTA sobre soportes de corindón: Evaluación preliminar para la eliminación de metales pesados de efluentes acuosos

    Directory of Open Access Journals (Sweden)

    Jacas, A.

    2012-10-01

    Full Text Available The effectiveness of materials based on LTA Zeolite as active phase, for their incorporation into systems aimed at the removal of heavy metals on waste water is evaluated in a preliminary way. This type of Zeolite with the main channel of a minimum free diameter of 0,41 nm and a low SiO2/Al2O3 ratio is an interesting molecular sieve, which in turn display a high ion exchange capacity. From this point of view, LTA Zeolite crystals were obtained “in situ” by hydrothermal synthesis and characterized by x ray diffraction (XRD and scanning electron microscopy (SEM. We have studied the effect of hydrothermal synthesis time at 378 K. Likewise, the removal capacity of heavy metal from the active phase was evaluated in as a first step on diluted solutions of cooper salts at slightly acidic pH (~ 4,7.

    En este trabajo se evalúa de forma preliminar la efectividad del empleo de materiales basados en zeolita LTA, como fase activa para su incorporación en sistemas orientados a la eliminación de metales pesados presentes en aguas residuales. Este tipo de zeolitas con el canal principal de un diámetro mínimo libre de 0,41 nm y una baja relación SiO2/Al2O3 se presenta como un tamiz molecular interesante, que a su vez manifiesta una gran capacidad de intercambio iónico. Partiendo de este punto de vista, cristales de zeolita LTA fueron obtenidos “in situ” por síntesis hidrotermal y caracterizados por difracción de rayos X (DRX, y microscopia electrónica de barrido (MEB. Se ha estudiado el efecto del tiempo de tratamiento hidrotermal a 378 K. Asimismo, la capacidad de eliminación de metales pesados de la fase activa de los sistemas obtenidos fue evaluada en una primera etapa en soluciones diluidas de sales de cobre a pH ácido (~ 4,7.

  11. Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts

    KAUST Repository

    Alabi, Wahab; Atanda, Luqman; Jermy, Rabindran; Al-Khattaf, Sulaiman

    2012-01-01

    fluidized bed reactor at temperatures of 300, 350 and 400 °C and reaction times of 3, 5, 7, 10, 13, 15 and 20. s. The rate of toluene methylation and toluene disproportionation were studied on the three catalysts (toluene alkylation is usually accompanied

  12. Catalytic cracking of fast and tail gas reactive pyrolysis bio-oils over HZSM-5

    Science.gov (United States)

    While hydrodeoxygenation (HDO) of pyrolysis oil is well understood as an upgrading method, the high processing pressures associated with it alone justify the exploration of alternative upgrading solutions, especially those that could adapt pyrolysis oils into the existing refinery infrastructure. Ca...

  13. Direct upgrading of fast pyrolysis lignin vapor over the HZSM-5 catalyst

    DEFF Research Database (Denmark)

    Zhou, Guofeng; Jensen, Peter Arendt; Le, Duy M.

    2016-01-01

    is reduced from 27.6 wt%daf without a catalyst to 5.7 wt%daf (600 °C catalyst temperature). The energy recovery in the liquid organics is 8.7% (600 °C catalyst temperature), compared to the 33.0% energy recovery in the organic liquid from the non-catalytic run. Oxygen is removed from the pyrolysis vapor...

  14. Envasado de Carne de Vacuno con Hueso y Grasa en Atmósfera Modificada con CO2 y CO

    OpenAIRE

    Aspé, Estrella R; Roeckel, Marlene D; Martí, Cristina; Jiménez, Romel

    2008-01-01

    Se evaluó el efecto de envasado en atmósfera modificada (MAP) con bajo contenido de CO (0.1% y 0.4%) y presencia de CO2 sobre el color rojo y la vida útil de carne de vacuno. Se determinaron características microbiológicas, fisicoquímicas, organolépticas-sensoriales y de color del músculo y se compararon los resultados con el MAP de 70%O2+30%CO2. La vida útil de las muestras con O2 fue de 30 días mientras que para las muestras en MAP la vida útil fue de 40 a 45 días y no dependió de la concen...

  15. Avaliação de diferentes tipos de atmosferas modificadas na vida útil de carambolas minimamente processadas

    OpenAIRE

    Neves,Leandro Camargo; Prill,Marcos André de Souza; Silva,Vanuza Xavier da; Benedette,Ronaldo Moreno; Vieites,Rogério Lopes

    2006-01-01

    Este trabalho teve por objetivo a avaliação da vida útil potencial de carambolas cv. Golden Star, minimamente processadas, armazenadas em diferentes tipos de embalagens plásticas, para a concepção da atmosfera modificada. Os frutos colhidos fisiologicamente maturos apresentaram coloração verde-amarelada, sólidos solúveis (SS) médios de 6,8 ºBrix e massa média de 185 g. Antes da aplicação dos tratamentos, os frutos foram selecionados, higienizados em solução de hipoclorito de sódio (NaOCl) a 1...

  16. ADSORCIÓN DE CROMO HEXAVALENTE EN LA CÁSCARA DE ARROZ MODIFICADA QUÍMICAMENTE

    OpenAIRE

    Nancy Eggs; Susana Salvarezza; Ricardo Azario; Nicolás Fernández; María del C. García

    2012-01-01

    El objetivo del presente estudio fue analizar los factores cinéticos que afectan la adsorción de cromo (VI) en solución empleando como bioadsorbente la cáscara de arroz modificada químicamente, con hidróxido de potasio 1% m/m o con ácido fosfórico 1M. Se estudió la adsorción de cromo (VI) considerando los siguientes parámetros pH, tiempo de incubación, masa del bioadsorbente y concentración inicial del tóxico. La determinación de cromo hexavalente y total se realizó por el método de la difeni...

  17. Desenvolvimento de massas alimenticias instantaneas de arroz, pelo processo de extrusão termoplastica, utilizando farinhas quimicamente modificadas

    OpenAIRE

    Elizabeth Harumi Nabeshima

    2007-01-01

    Resumo: Esta pesquisa consistiu em apresentar uma alternativa de utilização da farinha de arroz através da modificação química (fosfatação ou acetilação), agregando-lhe valor e possibilitando ampliar sua utilização como ingrediente alimentício, especialmente na produção de massas alimentícias instantâneas sem glúten. Inicialmente a farinha de arroz foi modificada quimicamente, sendo acetilada ou fosfatada, utilizando-se anidrido acético (0,465; 1,500; 4,000; 6,500 e 7,535g/100g farinha) ou ox...

  18. COMPORTAMIENTO DE UNA MEZCLA DENSA DE ASFALTO EN CALIENTE MODIFICADA CON DESECHO DE POLICLORURO DE VINILO (PVC

    Directory of Open Access Journals (Sweden)

    Hugo Alexander Rondón Quintana

    2008-01-01

    Full Text Available En el mundo la tecnología de los asfaltos modificados ha sido una técnicaampliamente utilizada para mejorar las características que presentan las mezclasasfálticas convencionales cuando experimentan niveles elevados de tránsito ygradientes de temperatura. Por lo general lo que se busca con este tipo detecnología es mejorar algunas de las propiedades mecánicas y reológicas de losasfaltos y las mezclas asfálticas convencionales tales como la susceptibilidad térmica, la rigidez, y la resistencia al envejecimiento, a las deformaciones plásticas ya la fatiga. El artículo presenta los resultados experimentales de ensayar una mezcla asfáltica densa en caliente modificada con desecho de policloruro de vinilo (el cual se denominará en el presente trabajo PVC. Para la evaluación del comportamiento de las mezclas asfálticas convencionales y modificadas se realizaron ensayos Marshall, módulo dinámico y deformación permanente. Para el cemento asfáltico (CA con y sin aditivo se realizaron ensayos de caracterización de asfaltos como penetración, punto de ablandamiento y viscosidad. La modificación de las mezclas se realizó por vía húmeda y seca. Adicionando desecho de PVC al cemento asfáltico y a las mezclas, se obtiene un material más rígido con mayor resistencia a la penetración y menor susceptibilidad térmica a fluir.

  19. Determinación de parámetros físicos aplicables en el escalamiento de la síntesis de zeolita NaA, a partir de geles aluminosilicatos

    OpenAIRE

    Carmen M. López; Adriana García; Miguel Ríos; Neyla Rondón; Luis García; Johliny Casanova; Kevin Contreras

    2016-01-01

    Se estudió el efecto de parámetros físicos que influyen en la preparación de la zeolita NaA, a fin de determinar condiciones favorables para realizar el escalamiento de esta síntesis. Partiendo de una mezcla de síntesis con composición fija y cristalización a 80 °C se estudiaron los siguientes parámetros: orden y velocidad de agregado de las soluciones de partida, velocidad y tiempo de agitación de la mezcla de síntesis, agitación durante la cristalización, tiempo de cristalización y reciclo ...

  20. Evaluación de la técnica modificada de Dennis para el diagnóstico de fasciolosis bovina

    Directory of Open Access Journals (Sweden)

    Stefanya Correa

    2016-04-01

    Conclusión. La validez y el desempeño de la técnica modificada de Dennis fueron superiores a los de la técnica tradicional, por lo que constituye una buena heramienta de tamización para el diagnóstico de la fasciolosis en estudios poblacionales y de prevalencia, así como en jornadas de salud animal.

  1. Evaluación de las Propiedades Mecánicas de una Mezcla Densa en Caliente Modificada con un Desecho de PVC

    Directory of Open Access Journals (Sweden)

    Hugo A. Rondón-Quintana

    2011-12-01

    Full Text Available El presente trabajo evaluó en laboratorio, la resistencia mecánica bajo carga monotónica, el módulo resiliente y la resistencia a la deformación permanente que experimenta una mezcla asfáltica cuando se modifica con un desecho de policloruro de vinilo (PVC por vía húmeda. Adicionalmente, fue evaluada durante 21 meses, la influencia del medio ambiente de la ciudad de Bogotá D.C. sobre las propiedades mecánicas de la mezcla modificada. De los resultados obtenidos se concluye que la resistencia mecánica de la mezcla asfáltica modificada es superior en comparación con la convencional. La tendencia general de las mezclas con el tiempo de exposición al medio ambiente de Bogotá D.C. es experimentar un aumento en los valores de rigidez debido principalmente a procesos de endurecimiento por envejecimiento del ligante asfáltico. Sin embargo, para el caso de las mezclas fabricadas con CA 60-70 y modificadas con PVC en los primeros 15 meses de exposición, la rigidez disminuye por efecto de micro-fisuración térmica.

  2. Synthesis of zeolites coal ash in surfactant modified in application and removal of orange 8 acid solution: study in batch, fixed bed column and evaluation ecotoxicological; Sintese de zeolitas de cinzas de carvao modificada por surfactante e aplicacao na remocao de acido laranja 8 de solucao aquosa: estudo em leito movel, coluna de leito fixo e avaliacao ecotoxicologica

    Energy Technology Data Exchange (ETDEWEB)

    Magdalena, Carina Pitwak

    2015-09-01

    In this study, synthesized zeolitic material from coal ash and modified cationic surfactant was used for removing the acid dye Orange 8 (AL8) by adsorption process using moving bed and fixed-bed column. The raw material and adsorbents were characterized by different techniques, such as X-ray diffraction, X-ray fluorescence spectroscopy, among others. The adsorption of AL8 was performed by moving bed in order to optimize the results when they are launched in a fixed bed. The effects of adsorption on zeolite AL8 were compared: (1) Effect of counterions Br{sup -} and Cl{sup -} surfactant used in the modification of the zeolite; (2) effect of type of coal ash used as raw material in the synthesis of zeolites (fly and bottom). The following adsorbents were used in the study: fly and bottom zeolite modified by surfactant hexadecyltrimethylammonium bromide (ZLMS-Br-Br and ZPMS-Br) and fly zeolite modified by surfactant hexadecyltrimethylammonium chloride (ZLMS-Cl). The pseudo-second-order kinetic described the adsorption of the dye on all adsorbents. The equilibrium time was reached 40, 60 and 120 min for ZLMS-Br, ZLMS-Cl and ZPMS-Br, respectively. The adsorption equilibrium was analyzed by the equations of the models of linear and nonlinear isotherms of Langmuir, Freundlich, Temkin and Dubinin- Radushkevivh (DR) and the criterion of best fit was evaluated using the error functions.The DR model was adjusted better to the experimental data for the system AL8 / ZLMS-Br, the Freundlich model for AL8 / ZLMS-Cl and Langmuir for AL8 / ZPMS. According to the Langmuir maximum adsorption capacity was 4.67, 1.48 and 1.38 mg g{sup -1} for ZLMS-Br, ZLMS-Cl and ZPMS-Br, in order. In studies employing fixed bed columns, the effects of inlet concentration (20- 30 mg L{sup -1}), flow rate (4.0 -5.3 mL min{sup -1}) and the bed height (5, 5 - 6.5 cm) above the breakthrough curves characteristics in the adsorption system were determined. The Adams-Bohart, Thomas, Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the parameters that characterize the column. The mathematical models of Thomas and Yoon-Nelson adjusted well to the data of breakthrough curves. The highest bed capacity of 5.3 mg g{sup -1} was obtained using 30 mg L{sup -1} inlet Acid Orange 8 concentration, 5.5 cm bed height and 5.3 mL min{sup -1} flow rate. Acute ecotoxicity tests using Daphnia similis microcrustacean with wastewater (AL8) and after treatment with surfactant modified zeolite were carried out with the purpose of evaluating evidence of possible contamination when launched on the receiving water body. The results of this study showed that samples AL8 dye in aqueous solution does not show any toxic effect, and the treated samples showed toxicity with ZLMS-Br. (author)

  3. ADSORCIÓN DE CROMO HEXAVALENTE EN LA CÁSCARA DE ARROZ MODIFICADA QUÍMICAMENTE

    Directory of Open Access Journals (Sweden)

    Nancy Eggs

    2012-01-01

    Full Text Available El objetivo del presente estudio fue analizar los factores cinéticos que afectan la adsorción de cromo (VI en solución empleando como bioadsorbente la cáscara de arroz modificada químicamente, con hidróxido de potasio 1% m/m o con ácido fosfórico 1M. Se estudió la adsorción de cromo (VI considerando los siguientes parámetros pH, tiempo de incubación, masa del bioadsorbente y concentración inicial del tóxico. La determinación de cromo hexavalente y total se realizó por el método de la difenilcarbazida y por espectrofotometría de absorción atómica, respectivamente. El tratamiento químico con hidróxido de potasio o con ácido fosfórico de la cáscara de arroz produjo un aumento en la adsorción del tóxico. El análisis cinético de la adsorción de cromo (VI sugiere que el proceso es favorable cuando se trabaja a pH ácido (inferior a 2, se incrementa con la masa de bioadsorbente y con el tiempo de contacto.

  4. Tratamiento de la incontinencia urinaria de esfuerzo en la mujer, por la técnica de Perrin modificada

    Directory of Open Access Journals (Sweden)

    Edilberto Borges Cárdenas

    1995-12-01

    Full Text Available Se realizó un estudio prospectivo en 21 mujeres que presentaron incontinencia urinaria de esfuerzo, las cuales recibieron tratamiento quirúrgico por la técnica de Perrin modificada, en el Hospital General Docente "Guillermo Domínguez", del municipio Puerto Padre, en los años 1990 y 1991. Estas pacientes se siguieron después de operadas por espacio de 1 año, para evaluar los resultados mediatos obtenidos al aplicar esta técnica. Como principales resultados y conclusiones se expresan: la incontinencia urinaria de esfuerzo fue más frecuente después de la cuarta década de la vida, estuvo relacionada con la multiparidad y con el tipo de parto transpelviano; se encontró asociada con diversos grados de relajación pelviana, y resultaron los ligeros y medianos esfuerzos los que con mayor frecuencia la provocaron. Las pruebas de esfuerzo presentaron un alto grado de positividad. Técnicas quirúrgicas fallidas por vía vaginal, se recogieron como un antecedente importante. La retención urinaria fue la complicación posoperatoria más frecuente. El 95 % de los resultados mediatos alcanzados se evaluaron de satisfactorios

  5. Caracterización de bentonitas y zeolitas sin tratamiento como refuerzo en materiales compuestos de matriz polimérica//Characterization of untreated zeolites and bentonites as reinforcement in polymer matrix composites

    Directory of Open Access Journals (Sweden)

    Francisco Jesús Mondelo‐García

    2014-01-01

    Full Text Available Las bentonitas con microestructuras compuestas de placas silicio aluminosas. Se logró el objetivo de caracterizar las bentonitas sódicas de Wyoming, USA, Patagonia de Argentina, nordeste de Brasil, así como las bentonitas policatiónicas de Brasil, la cálcica activada con sodio y zeolita de Cuba no organofilizadas para emplearlas como refuerzo en materiales compuestos de matriz polimérica. Estosmateriales se evaluaron usando técnicas físico-químicas como fluorescencia de rayos X, difracción de rayos X, microscopia electrónica de barrido, humedad, capacidad de intercambio catiónico, absorción e hinchabilidad en diluyente acuoso. Los resultados confirmaron rangos variables de intercambio catiónico,hinchamiento y absorciòn en agua entre las bentonitas analizadas, debido a su naturaleza química estructural en hidratación, logrando mayores valores las sódicas, luego la cálcica activada y con menor valor las policatiónicas, pero permiten usarlas como carga en polímeros.Palabras claves: bentonita, zeolita, matriz polimérica, organofilizada, materiales compuestos._____________________________________________________________________________AbstractBentonites with aluminous silicon microstructure composed of plates. The work accomplished to characterize the sodium bentonites in Wyoming USA, Patagonia Argentina, Northeast Brazil and the Brazilian polycationic bentonites, calcium-activated sodium zeolite from Cuba without organic modificationnot organophilized to employ as reinforcing in composite materials of polymer matrix. These materials were evaluated for physical and chemical assay techniques such as X-ray fluorescence, X-ray diffraction, scanning electron microscopy, moisture, cation exchange capacity, absorption and swelling aqueousdiluent. The results confirmed variables ranges of cationic exchange, swelling and water absorption from the bentonites tested, due to its chemical-structural hydration, achieving higher values nature

  6. Atmosfera modificada e controle de etileno para bananas 'Prata-Anã' cultivadas na Amazônia Setentrional Brasileira

    Directory of Open Access Journals (Sweden)

    Marcos André de Souza Prill

    2012-12-01

    Full Text Available O presente trabalho teve por objetivo avaliar o efeito da atmosfera modificada (AM pelo uso de embalagem plástica de polietileno de baixa densidade (PEBD, do vácuo e da adsorção de etileno, visando à manutenção da qualidade das bananas 'Prata-Anã' produzidas em Roraima. As análises foram realizadas em intervalos de 5 dias após a colheita, até 35 dias de armazenamento refrigerado (AR. Verificou-se que os frutos submetidos a embalagem de PEBD apresentaram as menores perdas de massa fresca quando comparados aos demais. Da mesma forma, os frutos embalados na presença do adsorvedor de etileno obtiveram a melhor manutenção na coloração da casca, atraso temporal, do pico climatérico, assim como o retardamento na degradação do amido, os menores incrementos de sólidos solúveis e acidez titulável, as menores concentrações de etileno nos interiores das embalagens e atraso temporal e a diminuição da atividade enzimática. Isso, possivelmente, proporcionou os maiores teores de pectina total e solúvel ao final do período experimental. A combinação do uso da embalagem de PEBD com o sachê de permanganato de potássio (KMnO4 resultou no retardamento do processo de maturação dos frutos de banana 'Prata-Anã', quando armazenada a 12 ºC. Pode-se atribuir esse efeito benéfico à presença do sachê na adsorção de etileno e, consequentemente, na ação do etileno no amadurecimento dos frutos, retardando a senescência das bananas 'Prata-Anã'.

  7. Evaluación de la eficiencia de una batería de filtros empacados en zeolita en la remoción de metales pesados presentes en un licor mixto bajo condiciones de laboratorio Evaluation of efficiency of a filter battery packaging zeolite in the removal of heavy metals in a mixed liquor under laboratory conditions

    OpenAIRE

    Diana Rocío Acevedo Cifuentes; Sandra Milena Builes Felizzola; Carlos Andrés Ordóñez Ante; Idalia Jacqueline López Sánchez

    2011-01-01

    En este artículo se muestran resultados de investigación obtenidos en la remoción de los metales pesados, plomo, níquel, cromo, cadmio y mercurio, presentes en una solución compuesta por licor mixto proveniente de la planta de tratamiento de aguas residuales de San Fernando y una solución preparada con metales pesados con una concentración conocida, mediante el uso de una batería de filtros empacados en zeolita clinoptilolita. La experimentación se desarrolló bajo condiciones controladas de c...

  8. Avaliação do tratamento cirúrgico da doença de Dupuytren pela técnica da palma aberta modificada

    Directory of Open Access Journals (Sweden)

    Thiago Almeida Guilhen

    2014-01-01

    Full Text Available Objetivo: avaliar o tratamento cirúrgico com o uso da técnica da palma aberta modificada para o tratamento das contraturas graves da doença de Dupuytren. Métodos: em quatro anos, foram submetidos ao tratamento cirúrgico 16 pacientes, que pertenciam aos estágios III e IV da classificação proposta por Tubiana et al. Foram feitas aferições do déficit de extensão das articulações metacarpofalangeanas e inferfalangeana proximal e distal nos períodos pré-operatório, pós-operatório (três meses e pós-operatório tardio (cinco a oito anos. Angulações maiores do que 30° nas articulações metacarpofalangeanas e 15° nas interfalangeanas proximais foram consideradas como recidiva cirúrgica. Resultados: obtivemos uma média de déficit de extensão de 6,3° ao nível da articulação metacarpofalangeana, 13,8° na interfalangeana proximal e 1,9° na interfalangeana distal. Conclusão: a técnica da palma aberta modificada é um método eficaz no tratamento cirúrgico das contraturas graves na doença de Dupuytren.

  9. Escala RIPASA para el diagnóstico de apendicitis aguda: comparación con la escala de Alvarado modificada

    Directory of Open Access Journals (Sweden)

    C.Z. Díaz-Barrientos

    2018-04-01

    Full Text Available Resumen: Introducción y objetivos: La apendicitis aguda es la primera causa de las urgencias quirúrgicas. Permanece como un diagnóstico difícil de establecer, particularmente entre jóvenes, ancianos y mujeres en edad reproductiva, en los cuales una serie de condiciones inflamatorias pueden presentar síntomas y signos similares a los de la apendicitis aguda. Diversos sistemas de puntuación se han creado con el fin de incrementar la certeza diagnóstica; estos son baratos, no invasivos y fáciles de usar o reproducir. La escala de Alvarado modificada es probablemente la más difundida y de mayor aceptación en los servicios de urgencias del mundo. Por otro lado, la escala RIPASA fue elaborada en 2010 con mejor sensibilidad y especificidad. En México se encuentran pocos estudios que comparen los diversos sistemas de puntuación en apendicitis. El objetivo es comparar la escala de Alvarado modificada y la escala RIPASA para el diagnóstico de pacientes con dolor abdominal y sospecha de apendicitis aguda. Material y métodos: Se realizó un estudio observacional, analítico y prolectivo, de julio de 2012 a febrero 2014 en el Hospital Universitario de Puebla. Las encuestas en proceso de evaluación fueron aplicadas a los pacientes con sospecha clínica de apendicitis. Resultados: Escala de RIPASA: curva ROC/PC 8.5 (área 0.595, sensibilidad (93.3%, especificidad (8.3%, VPP (91.8%, VPN (10.1%. Escala de Alvarado modificada: Curva ROC/PC 6 (área 0.719, sensibilidad (75%, especificidad (41.6%, VPP (93.7%, VPN (12.5%. Conclusiones: La escala de RIPASA contrastada con la escala de Alvarado modificada no mostró ventajas al aplicarse a pacientes con sospecha de apendicitis aguda. Abstract: Introduction and objectives: Acute appendicitis is the first cause of surgical emergencies. It is still a difficult diagnosis to make, especially in young persons, the elderly, and in reproductive-age women, in whom a series of inflammatory conditions can have

  10. Retention of chromium by modified Al-Bentonite Retenção de cromo por Al-bentonita modificada

    Directory of Open Access Journals (Sweden)

    C. Volzone

    2002-09-01

    Full Text Available Retention of chromium (III from a tanning wastewater by modified Al-bentonites was studied. One bentonite from San Juan province, Argentina, was used. Al-bentonite was prepared by contact of bentonite with hydrolyzed OH-Al solutions (0.10 M in Al for 24 hours. The modified Al-bentonites were obtained by: a treatment with 0.5 M sodium chloride; b with 0.5 M sodium chloride adjusted at pH 8; and c treatment with an hexametaphosphate solution after sodium addition. Then, the samples were dried at 100 °C and heated at 500 °C. The chromium (III retention by samples was carried out in batch system putting in contact the material with a 2000 ppm Cr tannery waste at different times. The retained chromium was characterized by analyzing the supernatant using UV-visible spectroscopy. The different chromium retention was correlated with structural characteristics of the solids.Foi estudada a retenção de cromo (III de águas residuais por meio de Al-bentonitas modificadas. Foi usada uma bentonita da província de San Juan, Argentina. As bentonitas-Al forma preparadas colocando-as em contato com soluções (0,10 M Al hydrolizadas de OH-Al durante 24 horas. As bentonitas-Al modidicadas foram obtidas por meio de: a tratamento com cloreto de sódio 0,5 M; b com cloreto de sódio 0,5 M sodium com pH ajustado para 8; e c tratamento com uma solução de hexametafosfato após a adição de sódio. As amostras foram então secas a 100 °C e aquecidas a 500 °C. A retenção do cromo (III pelas amostras foi feita em lotes colocando o material em contato em diferentes tempos com um resíduo contendo 2000 ppm de cromo. O cromo retido foi caracterizado por meio de análise do sobrenadante usando espectroscopia UV-visível. As diferentes retenções de cromo foram correlacionadas com características estruturais dos sólidos.

  11. Evaluación de bolsa atmósfera modificada y concentraciones de anhídrido sulfuroso aplicadas sobre frutos de arándano alto (Vaccinium corymbosum L. cv. Emerald

    Directory of Open Access Journals (Sweden)

    Mario Rodríguez Beraud

    2015-01-01

    Full Text Available Con el objetivo de evaluar las técnicas de atmósfera modificada y aplicación de anhídrido sulfuroso sobre parámetros de calidad de postcosecha en frutos de arándanos (Vaccinium corymbosum L. cv. Emerald, se realizó un experimento de seis tratamientos, dados por la combinación de dos factores, atmósfera modificada (con y sin, y diferentes concentraciones de anhídrido sulfuroso (generadas por 0, 1 y 2 g de metabisulfito de sodio durante 7, 14, 21 y 28 días a 0 °C. Con la dosis de 2 g de metabisulfito de sodio en atmósfera modificada no se presentaron pudriciones, a diferencia del tratamiento testigo que presentó un 4,86% luego de 28 días de almacenaje. Los resultados indican que la incidencia de pudrición gris disminuyó significativamente (p ≤ 0,05 con anhídrido sulfuroso en bolsa atmósfera modificada, existiendo un efecto de interacción entre ambos factores, no obstante, el gas causó daños de blanqueamiento de frutos, el que correspondió a un 11,66% con una dosis de 2 g de metabisulfito de sodio, luego de 28 días de almacenaje. El uso de bolsa de atmósfera modificada redujo significativamente (p ≤ 0,05 la pérdida de peso por deshidratación (en promedio un 4% respecto a los tratamientos donde esta tecnología no fue utilizada. La concentración de sólidos solubles no fue influenciada por los tratamientos, manteniéndose entre 13 y 14%.

  12. Qualidade da alface crespa minimamente processada acondicionada em atmosfera modificada Quality of minimally processed crisp head lettuce packaged under modified atmosphere

    Directory of Open Access Journals (Sweden)

    Rosana Mendes Roversi

    2004-08-01

    Full Text Available A alface Crespa (Lactuca sativa L.foi minimamente processada, tendo suas folhas destacadas e higienizadas, embalada em sacos plásticos de polietileno com modificação ativa da atmosfera dentro do pacote. Duas atmosferas foram aplicadas, variando-se o nível de CO2 em 10 e 15%, reduzindo nos dois casos o O2 a 5%. Após o acondicionamento, a alface foi imediatamente refrigerada. Comparou-se a qualidade da alface com e sem atmosfera modificada durante o armazenamento refrigerado. Monitoraram-se a variação da concentração de O2 e CO2 no interior das embalagens e a vida-útil da alface pela análise sensorial e microbiológica e a variação de sólidos solúveis. A influência da atmosfera modificada no crescimento de microrganismos e na variação de sólidos solúveis não foi relevante. Entretanto, essa tecnologia reduziu as taxas de respiração e, conseqüentemente, minimizou as perdas de qualidade sensorial da alface durante todo o armazenamento. A vida-útil da alface em atmosfera modificada foi estendida em até cinco dias além daquela alcançada pela alface acondicionada em atmosfera normal.The crisp head lettuce (Lactuca sativa L.was minimally processed, with the leaves being detached and cleaned, packaged in plastic bags made of polyethylene with modified atmosphere inside the bag. Two different atmospheres were applied: 10 and 15% of CO2, with the O2 level being reduced in both cases to 5%. After the packing, the lettuce was immediately refrigerated. The product quality with and without modified atmosphere was compared during the storage time. It was accompanied the changes in O2 and CO2 concentration inside the packaging and the product shelf life, through sensorial and microbiological analysis, and soluble solids variation. The influence of modified atmosphere in microorganisms grown and in soluble solids variation was not relevant. However this technology reduced the lettuce respiration rates and the quality sensorial loss

  13. Qualidade de mangas 'Tommy Atkins' armazenadas sob atmosfera modificada Quality of 'Tommy Atkins' mangoes stored under modified atmosphere

    Directory of Open Access Journals (Sweden)

    Elisangela Marques Jeronimo

    2007-08-01

    Full Text Available Objetivou-se com este trabalho avaliar a qualidade pós-colheita de mangas 'Tommy Atkins', durante o armazenamento refrigerado, utilizando diferentes tipos de embalagens. Os tratamentos foram: frutos acondicionados individualmente em bandejas de acetato transparente, revestidas com filme plástico de cloreto de polivinila (PVC esticável de 14 µm, sem e com sachê de permanganato de potássio, preparado utilizando-se vermiculita como substrato, impregnada com KmnO4 (10 g / 500 g de fruto; frutos acondicionados individualmente em sacos plásticos de polietileno de baixa densidade 25 µm de parede simples (PE confeccionado ou não com permanganato de potássio e frutos acondicionados, em grupos de 5, em caixas de papelão com tampa, revestidas internamente ou não, com filme plástico confeccionado com permanganato de potássio. Os frutos foram armazenados a 13 ± 1°C, 85-90% UR por 20 dias e então transferidos para as condições de ambiente de 24,4 °C, 70% UR. Foram avaliadas a perda de massa fresca, aparência, firmeza da polpa, teor de sólidos solúveis, acidez titulável e ácido ascórbico. Verificou-se que o melhor tratamento de atmosfera modificada foi o de acondicionamento individual dos frutos de manga em bandejas de acetato transparentes, recoberta com o filme de PVC esticável. O permanganato de potássio na forma utilizada neste estudo (sachê e impregnado em filme plástico não interferiu nos resultados obtidos para a conservação dos frutos.The objective of this experiment was to evaluate the post harvest quality of 'Tommy Atkins' mangoes during refrigerated storage, using different types of packing. The modified atmosphere corresponded to the following treatments: fruits conditioned individually in plastic trays, covered with plastic film of polivinil chloride (PVC of 14 µm, without and with sachet of potassium permanganate (10 g; fruits conditioned individually in low density simple wall polyethylene bag of 25 µm made

  14. Armazenamento de melão 'Orange Flesh' minimamente processado sob atmosfera modificada Storage of 'Orange Flesh' mellons minimally processed and packaged under modified atmosphere

    Directory of Open Access Journals (Sweden)

    Mônica Elisabeth Torres Prado

    2005-04-01

    Full Text Available O aumento da demanda por produtos minimamente processados traz um grande desafio para a ciência e tecnologia de alimentos, considerando-se a escassez de informações sobre a manutenção da qualidade desses produtos. O armazenamento desses em condições adequadas é um ponto fundamental para o sucesso dessa tecnologia. Objetivou-se com este trabalho avaliar o efeito da atmosfera modificada ativa na conservação do melão tipo Orange Flesh minimamente processado. Os frutos, após o processamento, foram embalados sob atmosfera modificada (AM Passiva- Controle, AM Ativa com 5% de CO2 e 5% de O2 e AM Ativa com 10% de CO2 e 2% de O2, armazenados em câmara fria (6 ± 1 ºC e UR 85 ± 5% durante 8 dias e as amostras retiradas para análises de pH, sólidos solúveis totais (SST, acidez total titulável (ATT, açúcares solúveis totais (AST, firmeza, pectina total (PT, pectina solúvel (PS, e as enzimas pectinametilesterase (PME e poligalacturonase (PG a cada 2 dias de armazenamento. A atmosfera modificada ativa pouco influenciou no comportamento das variáveis pH, acidez total titulável (ATT, firmeza e pectina total com relação á atmosfera modificada passiva. No entanto, menor solubilização de pectinas foi detectada nas amostras armazenadas sob atmosfera com 10% de CO2 e 2% de O2. Não foram detectadas atividades das enzimas pectinametilesterase e poligalacturonase nos tratamentos analisados.The increase of the demand for products minimally processed brings a great challenge for the food science and technology, considering the shortage of information about the maintenance of the quality of those products. The storage of those products in appropriate conditions is a fundamental point for the success of such technology. The objective of this work was to evaluate the effect of the active modified atmosphere on the quality and conservation of the 'Orange Flesh' melons processed minimally. The fruits, after the processing, were wrapped under

  15. Aceite de girasol, semillas y plantas con distribución modificada de ácidos grasos en la molécula de triacil-glicerol

    OpenAIRE

    Garcés Mancheño, Rafael; Martínez-Force, Enrique

    2003-01-01

    El objeto de la presente invención es un aceite de girasol que se obtiene directamente de la semilla de girasol con de 12-40,8% de ácido esteárico calculado en relación al contenido total de ácidos grasos y con una distribución de ácidos grasos modificada entre las posiciones sn-1 y sn-3 de la molécula de triacilglicerol (TAG) comparado con el aceite obtenido del tipo silvestre de semillas de girasol. La invención también se refiere a una planta de girasol y a semillas que contien...

  16. Qualidade de uva 'Isabel' tratada com cloreto de cálcio em pós-colheita e armazenada sob atmosfera modificada

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    Rosana Sousa da Silva

    2012-03-01

    Full Text Available Uvas 'Isabel' foram tratadas após a colheita com cloreto de cálcio (CaCl2 e submetidas a atmosfera modificada para avaliação da manutenção de sua qualidade durante o armazenamento, a 12±1 ºC e 85±2% de UR. O experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial 5 x 2 x 5, com 3 repetições, sendo cinco doses de CaCl2 (0,0; 0,5; 1,0; 2,0 e 4,0%, dois tipos de atmosfera [ambiente e modificada (AM] e cinco períodos, durante o armazenamento refrigerado. As avaliações foram acidez titulável (AT, sólidos solúveis (SS, relação SS/AT, pH, ácido ascórbico, incidência de podridão, perda de massa, aparência do engaço e índice de degrana. A AM reduziu a perda de massa, a incidência de podridão e manteve a aparência verde do engaço, ampliando a vida útil de uva 'Isabel' em seis dias. Doses de CaCl2 entre 0,5 e 2,0% reduziram a incidência de podridão. A aplicação de CaCl2 associado à AM reduziu a degrana em uva 'Isabel' durante o armazenamento refrigerado.

  17. Revisão: alimentos frescos minimamente processados embalados em atmosfera modificada Review: fresh, minimally processed foods packaged under modified atmosphere

    Directory of Open Access Journals (Sweden)

    Joana Silva Santos

    2012-03-01

    Full Text Available Os alimentos frescos, minimamente processados e embalados sob atmosfera modificada atraem os consumidores que procuram produtos frescos e saudáveis, e que, ao mesmo tempo, são fáceis de transportar e preparar. A atmosfera no interior das embalagens consiste numa mistura de gases que está otimizada para cada alimento, de modo a preservar as suas qualidades durante mais tempo. A manutenção da temperatura de refrigeração durante o processamento, o armazenamento, a distribuição e a comercialização é essencial, por causa da natureza perecível dos produtos frescos minimamente processados. Este trabalho discute o estado de arte dos alimentos frescos minimamente processados (frutas, vegetais, carnes e pescados embalados em atmosfera modificada, com uma descrição pormenorizada dos últimos desenvolvimentos nesse campo.Fresh, minimally processed foods packaged under modified atmospheres are attractive to consumers searching for fresh healthy products that are also easy to transport and prepare. The atmosphere inside the package is a blend of gases optimized for each type of food, such that the quality characteristics are preserved for longer. However, due to the perishable nature of minimally processed fresh foods, maintenance at refrigeration temperatures is essential during processing, storage, distribution and commercialization. This paper discusses the state of art of minimally processed fresh foods (fruit and vegetables, meat and fish packaged under modified atmosphere, with a detailed description of the latest developments in this field.

  18. H-ZSM-5 Zeolite Model Crystals: Structure-Diffusion-Activity Relationship in Methanol-to-Olefins Catalysis.

    Czech Academy of Sciences Publication Activity Database

    Losch, P.; Pinar, A.B.; Willinger, M.G.; Soukup, Karel; Chavan, S.; Vincent, B.; Pale, P.; Louis, B.

    2017-01-01

    Roč. 345, JAN 1 (2017), s. 11-23 ISSN 0021-9517 Grant - others:NRFL(LU) 5898454 Institutional support: RVO:67985858 Keywords : zeolite * methanol-to-olefins (MTO) * model catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 6.844, year: 2016

  19. Selective transformation of syngas into gasoline-range hydrocarbons over mesoporous H-ZSM-5-supported cobalt nanoparticles.

    Science.gov (United States)

    Cheng, Kang; Zhang, Lei; Kang, Jincan; Peng, Xiaobo; Zhang, Qinghong; Wang, Ye

    2015-01-26

    Bifunctional Fischer-Tropsch (FT) catalysts that couple uniform-sized Co nanoparticles for CO hydrogenation and mesoporous zeolites for hydrocracking/isomerization reactions were found to be promising for the direct production of gasoline-range (C5-11 ) hydrocarbons from syngas. The Brønsted acidity results in hydrocracking/isomerization of the heavier hydrocarbons formed on Co nanoparticles, while the mesoporosity contributes to suppressing the formation of lighter (C1-4 ) hydrocarbons. The selectivity for C5-11 hydrocarbons could reach about 70 % with a ratio of isoparaffins to n-paraffins of approximately 2.3 over this catalyst, and the former is markedly higher than the maximum value (ca. 45 %) expected from the Anderson-Schulz-Flory distribution. By using n-hexadecane as a model compound, it was clarified that both the acidity and mesoporosity play key roles in controlling the hydrocracking reactions and thus contribute to the improved product selectivity in FT synthesis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Fluidized bed catalytic pyrolysis of eucalyptus over hzsm-5: effect of acid density and gallium modification on catalyst deactivation

    Science.gov (United States)

    Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass to catalyst ratio (B/C) of 4/1 over extruded pellets of three different ZSM-5 catalys...

  1. H-ZSM-5 Zeolite Model Crystals: Structure-Diffusion-Activity Relationship in Methanol-to-Olefins Catalysis.

    Czech Academy of Sciences Publication Activity Database

    Losch, P.; Pinar, A.B.; Willinger, M.G.; Soukup, Karel; Chavan, S.; Vincent, B.; Pale, P.; Louis, B.

    2017-01-01

    Roč. 345, JAN 1 (2017), s. 11-23 ISSN 0021-9517 Grant - others:NRFL(LU) 5898454 Institutional support: RVO:67985858 Keywords : zeolite * methanol -to-olefins (MTO) * model catalyst Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 6.844, year: 2016

  2. Proton proximity – New key parameter controlling adsorption, desorption and activity in propene oligomerization over H-ZSM-5 zeolites

    Czech Academy of Sciences Publication Activity Database

    Bernauer, Milan; Tabor, Edyta; Pashková, Veronika; Kaucký, Dalibor; Sobalík, Zdeněk; Wichterlová, Blanka; Dědeček, Jiří

    2016-01-01

    Roč. 344, DEC 2016 (2016), s. 157-172 ISSN 0021-9517 R&D Projects: GA ČR GA15-13876S; GA MŠk(CZ) LM2015073 Institutional support: RVO:61388955 Keywords : ZSM-5 * Al siting * Single Al Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.844, year: 2016

  3. WEED CONTROL IN GENETICALLY MODIFIED GLYPHOSATE-TOLERANT SOYBEAN MANEJO DE PLANTAS DANINHAS EM SOJA GENETICAMENTE MODIFICADA TOLERANTE AO GLYPHOSATE

    Directory of Open Access Journals (Sweden)

    Júlio Cezar Durigan

    2011-04-01

    convencionais, exigem, além do controle químico, a adoção de outras estratégias de manejo de plantas daninhas. Objetivou-se, com este trabalho, avaliar o controle químico de plantas daninhas, em soja geneticamente modificada (transgênica tolerante ao herbicida glyphosate associado a coberturas vegetais, na entressafra. O experimento foi instalado em área experimental da FCAV/Unesp, Jaboticabal (SP. O delineamento experimental foi o de blocos ao acaso, em esquema de parcelas subdivididas, com quatro repetições. Nas parcelas, foram avaliadas as coberturas vegetais de Brachiaria brizantha (braquiarão cv. Marandu, Pennisetum americanum (milheto forrageiro cv. BN2 e vegetação espontânea, e, nas subparcelas, os herbicidas glyphosate, chlorimuron - ethyl + lactofen em mistura e fluazifop-p-butyl em aplicação sequencial, além de duas testemunhas sem aplicação. A cobertura com braquiarão contribuiu para o controle químico, exercendo supressão das plantas daninhas. A aplicação única de 720 g e.a. ha-1 de glyphosate, independentemente da cobertura vegetal utilizada na entressafra, foi suficiente para o controle adequado de Acanthospermum hispidum, Alternanthera tenella, Amaranthus sp., Bidens pilosa, Xanthium strumarium, Cenchrus echinatus, Digitaria sp. e Eleusine indica, com resultados similares ao tratamento (chlorimuron-ethyl + lactofen + fluazifop-p-buthyl. Comparados à testemunha capinada, os herbicidas testados não afetaram a altura das plantas, massa seca da parte aérea, massa de 100 grãos e a produtividade de grãos. As plantas de soja crescidas sobre os resíduos vegetais de braquiarão e milheto forrageiro apresentaram maior altura, porém, nenhuma outra característica avaliada na cultura foi influenciada pelas coberturas.

    PALAVRAS-CHAVE: Brachiaria brizantha; Pennisetum americanum; plantio direto

  4. Evaluación de bolsa atmósfera modificada y concentraciones de anhídrido sulfuroso aplicadas sobre frutos de arándano alto (Vaccinium corymbosum L.) cv. Emerald

    OpenAIRE

    Mario Rodríguez Beraud; Anddy Wyss Valdés; Nelson Hormazábal Vásquez

    2015-01-01

    Con el objetivo de evaluar las técnicas de atmósfera modificada y aplicación de anhídrido sulfuroso sobre parámetros de calidad de postcosecha en frutos de arándanos (Vaccinium corymbosum L.) cv. Emerald, se realizó un experimento de seis tratamientos, dados por la combinación de dos factores, atmósfera modificada (con y sin), y diferentes concentraciones de anhídrido sulfuroso (generadas por 0, 1 y 2 g de metabisulfito de sodio) durante 7, 14, 21 y 28 días a 0 °C. Con la dosis de 2 g de meta...

  5. Armazenamento em atmosfera modificada e controlada de banana 'Prata' com absorção de etileno Modified and controlled atmosphere storage of 'Prata' banana with ethylene scrubbing

    Directory of Open Access Journals (Sweden)

    Auri Brackmann

    2006-10-01

    Full Text Available Foram conduzidos dois experimentos com o objetivo de avaliar o efeito da absorção do etileno e de pressões parciais de O2 e CO2 sobre a qualidade da banana 'Prata'. Os tratamentos no experimento 1 foram: AR (armazenamento refrigerado; AR + AE (absorção de etileno; e AM (atmosfera modificada + AE. No experimento 2 os tratamentos foram: AR; AR + AE; AM + AE; 21,0 kPa O2 + 3,0 kPa CO2 + AE; 21,0 kPa O2 + 4,5 kPa CO2 + AE; 21,0 kPa O2 + 6,0 kPa CO2 + RA; 21,0 kPa O2 + 4,5 kPa CO2; e 2,0 kPa O2 + 4,5 kPa CO2 + AE. As temperaturas de armazenamento foram 25ºC e 12ºC para os experimentos 1 e 2, respectivamente. Para o armazenamento em atmosfera modificada foram utilizados filmes de polietileno de baixa densidade, com espessura de 16gama. No experimento 1, a absorção de etileno proporcionou frutos com maior firmeza de polpa e menor escurecimento da casca. A AM+AE proporcionou frutos com cor da epiderme mais verde. No experimento 2, verificou-se que todos tratamentos em atmosfera controlada com absorção de etileno apresentaram cor da casca mais verde e menor escurecimento da casca. A banana 'Prata' pode ser armazenada em atmosfera modificada durante 14 e 21 dias a 25ºC e 12ºC, respectivamente, e por 28 dias em atmosfera controlada a 12ºC, sempre com absorção do etileno.Two experiments were carried out with the objective to evaluate the effect of storage conditions and ethylene scrubbing on the quality of 'Prata' bananas. The treatments of experiment 1 were: cold storage (CS; CS + ES (ethylene scrubbing and MA (modified atmosphere + ES. In experiment 2 treatments were: CS; CS + ES; MA + ES; 21kPa O2 + 3kPa CO2 + ES; 21kPa O2 + 4.5kPa CO2 + ES; 21kPa O2 + 6kPa CO2 + ES; 21kPa O2 + 4.5kPa CO2; and 2kPa O2 + 4.5kPa CO2 + ES. The storage temperatures were 25ºC and 12ºC for the experiments 1 and 2, respectively. In experiment 1, ethylene scrubbing maintained higher flesh firmness and lower skin browning. MA+ES maintained greener peel color. In

  6. Evaluación de la eficiencia de una batería de filtros empacados en zeolita en la remoción de metales pesados presentes en un licor mixto bajo condiciones de laboratorio Evaluation of efficiency of a filter battery packaging zeolite in the removal of heavy metals in a mixed liquor under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Diana Rocío Acevedo Cifuentes

    2011-01-01

    Full Text Available En este artículo se muestran resultados de investigación obtenidos en la remoción de los metales pesados, plomo, níquel, cromo, cadmio y mercurio, presentes en una solución compuesta por licor mixto proveniente de la planta de tratamiento de aguas residuales de San Fernando y una solución preparada con metales pesados con una concentración conocida, mediante el uso de una batería de filtros empacados en zeolita clinoptilolita. La experimentación se desarrolló bajo condiciones controladas de caudal y pH, a temperatura ambiente. Se encontró que la eficiencia de los filtros bajo las condiciones específicas de diseño es significativamente alta en la remoción de los metales pesados evaluados en la solución acuosa. Se encontró, además, que sin importar el valor de la concentración inicial, se obtuvo una remoción importante en los contaminantes luego de pasar por los filtros con una mayor eficiencia en la remoción del mercurio.This article shows the research results on the removal of five heavy metals (lead, nickel, chromium, cadmium and mercury present in a liquor made of a mixture of wastewater from San Fernando wastewater treatment plant and a solution prepared with known concentrations of heavy metals, using a series of batery filters packed with zeolita clinoptilolita. The experiments were run under controlled conditions of flow and pH, at room temperature. It was found that the removal efficiency was significantly high under the specified design conditions; also, it was found an important removal of the contaminants after passing through the filters, independently of the initial concentration, with the highest observed removal for mercury.

  7. Avaliação da qualidade do abacaxi "Pérola" minimamente processado armazenado sob atmosfera modificada Evaluation of quality in fresh-cut 'Pérola' pineapple stored under modified atmosphere

    Directory of Open Access Journals (Sweden)

    Juliana Costa Bueno Santos

    2005-04-01

    Full Text Available Objetivou-se com este trabalho verificar o efeito da atmosfera modificada ativa sobre a qualidade do abacaxi minimamente processado. Assim, foram avaliadas as modificações físico-químicas, sensorial e microbiológica do abacaxi 'Pérola' minimamente processado submetido a diferentes atmosferas modificadas passiva e ativamente (controle - atmosfera modificada passiva; 5%O2 + 5%CO2 , 2%O2 + 10%CO2. A atmosfera com 2% O2 + 10% CO2 determinou menor perda de líquido drenado, embora tal perda tenha sido desprezível. A atmosfera modificada ativa preveniu o amaciamento do abacaxi minimamente processado, reduzindo a atividade da poligalacturonase e solubilização péctica. As variáveis pH e vitamina C não foram significativamente afetadas pela atmosfera modificada ativa. Maiores valores de sólidos solúveis totais (SST foram encontrados nos frutos sob atmosfera 5% O2 + 5% CO2 e no caso dos açúcares solúveis o tratamento com 2% O2 + 10% CO2 resultou em maiores teores. De acordo com análise sensorial, os frutos sob atmosfera modificada passiva se sobressaíram com relação ao sabor, aparência e cor. A análise microbiológica detectou valores insignificantes para fungos filamentosos, leveduras e coliformes a 35° e 45°C em todos os tratamentos. Conclui-se que o abacaxi 'Pérola' minimamente processado pode ser armazenado por 8 dias, a 5°C, sob atmosfera modificada passiva.The goal of this work was to verify the effect of active modified atmosphere on the quality of fresh-cut pineapple. Physical-chemical, sensory and microbiological changes of fresh-cut 'Pérola' pineapple treated with passive (control and active (5%O2 + 5%CO2; 2%O2 + 10%CO2 modified atmosphere were studied. The 2%O2 + 10%CO2 combination promoted the lowest loss of drained liquid, although they were negligible. Active modified atmosphere prevented the softening of fresh cut pineapples, reducing the poligalacturonase activity and pectin solubilization. The pH and ascorbic

  8. Análise de Sistemas de Geração de Energia Elétrica com Base na Pegada Ecológica Modificada

    Directory of Open Access Journals (Sweden)

    Bruno Silva de Carvalho

    2011-08-01

    Full Text Available O presente trabalho determina a Pegada Ecológica modificada e a Capacidade de Carga (Zhao et al., 2004 de três sistemas de geração de energia elétrica com uso de combustíveis renováveis e as compara. Foram estudados os sistemas de Utilização de Resíduos Sólidos Urbanos em um Aterro Sanitário na cidade de São Paulo (Frimaio, 2011, Estação de Tratamento de Efluentes na cidade de Uppsala na Suécia (Bjorklund, et al., 2001 e uma Usina Autônoma localizada em São Paulo (Silva, 2006. Os resultados obtidos apontam que o sistema de Aproveitamento de resíduos apresenta melhor performance com relação ao sistema de Estação de Tratamento de Esgoto a Usina Autônoma.

  9. Qualidade de mandioquinha-salsa minimamente processada e armazenada sob atmosfera modificada Quality of fresh-cut peruvian carrot: use of modified atmosphere

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    Elisângela Elena Nunes

    2009-10-01

    Full Text Available O objetivo deste trabalho foi verificar o efeito da atmosfera modificada, passiva e ativa, sobre a conservação de mandioquinha-salsa minimamente processada da cultivar 'Amarela de Senador Amaral', adquirida de lavoura comercial do Município de Lavras, Minas Gerais (MG. As raízes foram selecionadas, lavadas com detergente neutro e enxaguadas em água corrente. Em seguida, foram imersas em solução de hipoclorito de sódio 300mg L-1, por 15 minutos, e secas em temperatura ambiente. As raízes foram descascadas e cortadas em fatias de aproximadamente 1cm de espessura, imersas em solução de hipoclorito de sódio 50mg L-1, por 10 minutos, drenadas em peneiras plásticas e embaladas. As bandejas contendo as fatias de mandioquinha-salsa foram armazenadas em câmara fria (5±1°C e 98% UR por 15 dias. As seguintes análises foram realizadas a cada três dias: pH, acidez titulável, sólidos solúveis totais, firmeza, valores L* e b*, amido e avaliação sensorial (aparência e cor. O delineamento experimental foi inteiramente ao acaso (DIC, em esquema fatorial 3 x 6, sendo três tipos de atmosferas (passiva; ativa com injeção inicial das misturas: 2% O2 + 10% CO2 e 5% O2 + 5% CO2 e seis tempos de armazenamento (0, 3, 6, 9, 12 e 15 dias, com três repetições. Os valores médios de pH, acidez titulável, sólidos solúveis e firmeza encontrados neste trabalho foram 6,79, 0,13% de ácido málico, 4,04°Brix e 5,17N, respectivamente. A atmosfera modificada ativa (5% de O2 + 5% CO2 determinou maior valor L* às mandioquinhas-salsa minimamente processadas no sexto e no décimo segundo dia de armazenamento, quando comparada com a atmosfera (2% de O2 e 10% CO2. A atmosfera modificada ativa com 5% O2 + 5% CO2 determinou maiores valor b* e teores de amido às fatias de mandioquinha-salsa em comparação com as outras atmosferas. Conclui-se que a atmosfera modificada passiva, aliada à refrigeração e a boas práticas de fabricação, é suficiente

  10. El sistema de calificación cualitativa para la Prueba Gestáltica de Bender – Modificada. Estudio preliminar de sus propiedades psicométricas

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    César A. Merino Soto

    2010-01-01

    Full Text Available El presente artículo describe las propiedades psicométricaspreliminares del Sistema de CalificaciónCualitativa para la Prueba Gestáltica de Bender– Modificada, en un grupo de 97 niños que van a ingresar al primer grado de educación elemental en una escuela pública de Lima. Los niveles deconfiabilidad por consistencia interna y test-retestfueron más modestos que los del manual, aunque su rango potencial (por intervalos de confianzallega a niveles altos. La correlación con criterios de conducta orientada a la tarea, inteligencia fluida y el reporte parental de conductas de motricidad fina dan soporte a la validez y utilidad de este nuevo sistema en el contexto de la evaluación de niños de primer grado. Se discute su relevancia para la evaluación psicopedagógica y para la investigación educacional.

  11. Diseño y construcción de bobinas de Rogowski modificadas de bajo costo y alto desempeño

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    Diego Seuret Jiménez

    2014-01-01

    Full Text Available Las bobinas Rogowski son dispositivos sencillos, confiables y versátiles para hacer mediciones de corriente en una amplia gama de aplicaciones que van, desde dispositivos microelectrónicos hasta sistemas de alta potencia en instalaciones industriales. Se construyó una bobina de Rogowski y el circuito de acondicionamiento de la señal para poder hacer mediciones de su respuesta ante estímulos eléctricos y llevar a cabo un análisis cualitativo. Adicionalmente, a partir del modelo matemático de la bobina, se hizo una modificación en la estructura interna de la misma para obtener voltajes de mayor magnitud y facilitar la lectura en instrumentos de medición eléctrica. Estos resultados se compararon con una bobina comercial estándar y las mediciones del voltaje de salida de la bobina Rogowski modificada muestran una señal con menos ruido y de mayor magnitud. Al haber aumentado la relación señal ruido en el sistema, el circuito de integración y amplificación arrojan resultados esperados.

  12. Utilização de zeólitas modificadas CaX e MgX como adsorventes de compostos orgânicos

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    Denise Maria Malachini Miotto

    2002-04-01

    Full Text Available Neste trabalho, foi avaliada a capacidade de adsorção de zeólitas modificadas, CaX e MgX, em contato com uma solução do subproduto do processo de extração de esteviosídeo, um adoçante extraído das folhas de Stevia rebaudiana. Os efeitos do processo de adsorção na estrutura zeolítica foram avaliados por meio de diversas técnicas de caracterização. As análises térmicas mostraram que os compostos adsorvidos sofrem pequenas mudanças estruturais sob aquecimento. A partir da espectroscopia ao infravermelho, foi verificado que o processo de adsorção não modifica a estrutura da zeólita. As medidas de área superficial e volume de poros indicaram que a adsorção ocorre preferencialmente na superfície externa e nos mesoporos. Finalmente, os resultados de acidez indicaram que a adsorção dos compostos orgânicos coloridos ocorre principalmente nos cátions de compensação.

  13. Osteotomia em Chevron modificada: análise preliminar do comportamento baropodométrico Modified Chevron osteotomy: preliminary analysis of baropodometric behavior

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    Juliana Motta Costa

    2010-01-01

    Full Text Available OBJETIVO: Avaliar as características clínicas e baropodométricas da marcha de indivíduos com Hálux Valgo após a osteotomia em Chevron modificada, isolada ou em associação com a osteotomia de Weil. MÉTODOS: FORAM avaliados, antes e três meses após a cirurgia, 27 pés com deformidade leve e moderada. A avaliação clínica incluiu a pontuação da AOFAS e medidas radiográficas. A avaliação baropodométrica foi realizada através da Plataforma Emed-at. As variáveis Pico de Pressão, Integral Pressão-Tempo e Carga Relativa foram calculadas em 10 regiões: calcanhar, mediopé, 1-5º metatársicos, hálux, 2º, 3-5º dedos. RESULTADOS: Após a cirurgia houve aumento na pontuação da AOFAS e redução dos parâmetros radiográficos. A avaliação baropodométrica, após osteotomia em Chevron isolada, demonstrou redução da pressão e da força sob o 1º metatársico e hálux, assim como, aumento dessas variáveis nos metatársicos centrais e laterais. Após a osteotomia em Chevron/Weil ocorreram alterações significativas apenas na região do hálux e dos dedos. CONCLUSÃO: Em curto prazo, a técnica em Chevron modificada promoveu melhora das condições clínicas e dos parâmetros radiográficos. Em relação a avaliação baropodométrica constatou-se uma transferência de cargas da região medial para lateral do antepé, possivelmente pelo curto período de pós-operatório.OBJECTIVE: To evaluate the clinical and baropodometric characteristics of the gaits of individuals with a hallux valgus deformity after modified Chevron osteotomy, in isolation or in association with the Weil osteotomy. METHODS: Foot evaluation happened before and three months after surgery analyzing 27 mildly and moderately deformed feet. The clinical evaluation included the AOFAS score and radiographic measurements. The baropodometric evaluation was done with the Emed-at platform. Peak of Pressure, Pressure-Time Integral and Relative Load were calculated in

  14. Evaluación de las propiedades mecánicas de una mezcla densa en caliente modificada con asfaltita/Mechanical Properties Evaluation of a hot Asphalt Mixture Modified with Asphaltite

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    Hugo Alexander Rondón Quintana

    2012-12-01

    Full Text Available El trabajo evaluó en laboratorio la resistencia mecánica bajo carga monotónica, el módulo resiliente y la resistencia a la deformación permanente que experimenta una mezcla asfáltica cuando se modifica con una asfaltita. Adicionalmente, fue evaluada durante dos años, la influencia del medio ambiente de la ciudad de Bogotá D.C., sobre las propiedades mecánicas de la mezcla modificada. Se concluye que la resistencia mecánica de la mezcla asfáltica modificada incrementa en comparación con la convencional. La tendencia general de las mezclas con el tiempo de exposición al medio ambiente de Bogotá D.C., es experimentar un aumento en los valores de rigidez debido principalmente a procesos de endurecimiento por envejecimiento del ligante asfáltico. Sin embargo, para el caso de las mezclas modificadas y fabricadas con CA 60-70 en los primeros cinco meses de exposición, la rigidez disminuye.The strength under monotonic load, resilient modulus and rutting were evaluated on a hot-mix asphalt (HMAmodified with a natural sphaltite. Additionally, the influence of the environmental conditions of BogotáD.C., was evaluated during two years on the mechanical properties of a modified asphalt mixture. The results show that the mechanical properties evaluated were better for the HMA mixes modified in compared with those with neat asphalts. The asphaltite produces higher mechanical resistance in HMA. The general tendency of the mixtures is increase the modulus with time due to aging of the asphalt cement. However, modified mixtures with AC 60- 70, decrease in stiffness during the first months.

  15. Prueba de tolerancia oral a la glucosa modificada en puérperas como diagnóstico retrospectivo de diabetes gestacional

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    Joel Cárdenas

    2004-03-01

    Full Text Available Objetivo: Determinar la relación entre la prueba de tolerancia oral a la glucosa (PTOG en puérperas con macrosomia fetal y plantearla como método de diagnóstico retrospectivo para diabetes gestacional. Diseño de estudio: Estudio clínico, de corte transversal, analítico, casos y controles. Material y Métodos: Estudio de 142 puérperas, 71 con recién nacidos macrosómicos y 71 con recién nacidos con pesos en percentiles de la normalidad. Se realizó una PTOG modificada de dos horas (basal, 1h y 2 h, con 100 g de glucosa, entre las primeras 8 y 48 horas posparto (positivo si [glicemia 2h - basal] + [glicemia 1h - basal] 110 mg/dL. Se utilizó el SPSS 10,0 para crear la base de datos y realizar el análisis estadístico: análisis univariado, bivariado para evaluar la hipótesis, y finalmente un análisis multivariado. Resultados: La PTOG anormal resultó un factor de riesgo para macrosomia fetal, con un odds ratio ajustado de 5,9; IC95% 2,6-13,4. Se encontró asociación entre antecedente de macrosomia fetal, odds ratio 15,7; IC95% 1,9-123,6 y control prenatal odds ratio 5,7; IC95% 1,2-26,8. Conclusión: Existe relación entre la PTOG en puérperas y macrosomia fetal, que puede ser usada como prueba diagnóstica retrospectiva de diabetes gestacional.

  16. Efecto de variedades de algodón genéticamente modificadas sobre larvas de Spodoptera frugiperda Smith (Lepidoptera: Noctuidae

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    Sandra Jimena Valencia Cataño

    2014-01-01

    Full Text Available Spodoptera frugiperda es una plaga polífaga de importancia económica en países tropicales y subtropicales. En Colombia ataca el algodonero (Gossypium hirsutum L., cultivo que ha tomado importancia gracias a la adopción de variedades genéticamente modificadas (GM. En el estudio se determinaron los efectos subletales de algunas de estas variedades sobre larvas de este insecto. Para el efecto, en condiciones de laboratorio (27°C, 65 ± 10% HR y 12 h fotoperiodo se evaluaron las variedades NuOPAL RR (proteína Cry1Ac, DP141 B2RF (proteínas Cry1Ac+Cry2Ab y DeltaOPAL RR (no Bt. Los parámetros evaluados fueron: (a peso de larvas, (bpeso de heces, (c peso del alimento ofrecido y (d peso del alimento no consumido. Como índices de consumo y digestibilidad se calcularon la tasa relativa de consumo (TRCo, la tasa relativa de crecimiento (TRCr, la eficiencia de conversión del alimento ingerido (ECI y la digestibilidad aproximada (DA. Los índices mostraron actividad antialimentaria de la variedad DP141 B2RF (Cry1Ac+Cry2Ab que afecta de forma negativa la tasa de crecimiento y la conversión del alimento por parte de las larvas. El peso de las larvas alimentadas en DP141 B2RF (Cry1Ac+Cry2Ab fue 58.6% menor que en la variedad no Bt. Los resultados muestran un efecto adverso de la variedad DP141 B2RF (Cry1Ac+Cry2Ab en el desarrollo larval de S. frugiperda. Se confirman los efectos antibióticos de las variedades GM evaluadas que inciden en un menor desarrollo y en la supervivencia de las larvas.

  17. Aumento da vida útil e microbiologia da carne suína embalada em atmosfera modificada Shelf life extension and microbiology of pork meat packaged in modified atmosphere

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    Sérgio Borges Mano

    2002-01-01

    Full Text Available Com o objetivo de avaliar o efeito da embalagem de carne suína em atmosfera modificada, obteve-se assepticamente amostras de lombo (Longissimus dorsi de suíno de aproximadamente 3x3cm que depois de lavadas em solução salina (0,35% estéril, foram introduzidas em bolsas de plástico (Cryovac BB4L de baixa permeabilidade. Dividiram-se em 4 lotes e se embalaram com aproximadamente 1,0l de ar (100%, nitrogênio (100%, 20/80 e 40/60 CO2/O2 e se termo-selaram. Finalmente, cada lote se subdividiu em 2, armazenando-se a 1 e 7ºC. Durante o armazenamento tomaram-se amostras determinando-se a composição da atmosfera, o pH e a composição da microbiota (microbiota total, bactérias lácticas, Enterobacteriaceae, Brochothrix thermosphacta e contagens em ágar pseudomonas. Os parâmetros de crescimento (fase de latência e tempo de duplicação dos microrganismos foram determinados mediante a equação de Gompertz. Os resultados demonstraram que a vida útil da carne suína é prolongada quando se armazena em atmosferas modificadas. As atmosferas enriquecidas com CO2 e a 1ºC mostraram uma maior eficácia. As atmosferas com CO2, mantiveram o pH das amostras constante durante todo o período de armazenamento. A 1 e 7ºC, as fases de latência e os tempos de duplicação da microbiota total foram progressivamente maiores na seguinte ordem: atmosfera de ar (100%, N2 (100%, 20/80 e 40/60 CO2/O2. Pode-se concluir que, tanto a 1 como a 7ºC, a utilização das atmosferas modificadas retardou o crescimento das bactérias alterantes da carne suína, favorecendo o prolongamento da vida útil, principalmente nas atmosferas com CO2.The objective of the present study was to evaluate the effect of modified atmospheres on refrigerated pork meat (Longissimus dorsi. Pork meat was cut into ca. 1cm thick slices of 9cm², introduced in Cryovac type BB4L bags, characterized by its low gas permeability, and divided into four batches. The bags of each batch were filled

  18. Impacto intraoperatorio de la ultrafiltración modificada en pacientes pediátricos sometidos a cirugía cardíaca con circulación extracorpórea

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    Pedro José Curi-Curi

    2016-07-01

    Conclusiones: La ultrafiltración modificada puede beneficiar a los pacientes pediátricos no neonatales con cardiopatía congénita operados con bomba porque es capaz de disminuir la concentración sérica de IL-6, IL-10 y lactato post-CEC. Adicionalmente, puede ayudar a filtrar C4d y a remover el exceso de líquido que promovería una mayor hemoconcentración, por lo que se recomienda su uso rutinario cuando las condiciones hemodinámicas lo permitan.

  19. Avaliação da adição de emulsificantes do tipo lecitinas modificadas na cristalização de manteiga de cacau e de chocolate amargo

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    Eriksen Koji Miyasaki

    2013-01-01

    Resumo: As lecitinas modificadas de soja estão sendo introduzidas no processamento de chocolates como alternativa à lecitina padrão para melhorar as propriedades reológicas e de cristalização. A influência da adição de 0,2 a 0,8% (m/m) de lecitinas hidrolisada enzimaticamente, hidroxilada, em pó e acetilada na cristalização da manteiga de cacau foi avaliada. No chocolate, foram adicionadas as lecitinas hidrolisada enzimaticamente e hidroxilada nas concentrações de 0,1 a 0,3% (m/m). Os resulta...

  20. REMOCIÓN DE MICROORGANISMOS PATÓGENOS PRESENTES EN UN LICOR MIXTO BAJO CONDICIONES DE LABORATORIO EMPLEANDO FILTROS EMPACADOS EN ZEOLITA NATURAL REMOVAL OF PATHOGENIC MICROORGANISMS PRESENT IN MIXED LIQUOUR UNDER LABORATORY CONDITIONS BY USING FILTERS PACKED IN NATURAL ZEOLITE

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    Diana Rocío Acevedo Cifuentes

    2012-12-01

    Full Text Available En este artículo, se presentan los resultados obtenidos en la remoción de coliformes totales, coliformes fecales y salmonella-shigella, presentes en un licor mixto proveniente de la planta de tratamiento de aguas residuales San Fernando (Medellín, Colombia, mediante el uso de una batería de filtros empacados en zeolita clinoptilolita. La experimentación se desarrolló bajo condiciones controladas de caudal y pH, a temperatura ambiente. Se empleó zeolita natural tipo clinoptilolita la cual se activó con solución salina y secado, se empacó en una batería compuesta por dos filtros, uno de flujo descendente y otro de flujo ascendente, para facilitar el contacto de la solución contaminada y el material adsorbente (zeolita. Se realizaron cinco ensayos independientes y al final de cada uno de ellos se lavó y se activó el material zeolítico antes de comenzar el siguiente. En cada ensayo se tomaron tres muestras. Se encontró que la eficiencia de los filtros bajo las condiciones específicas de diseño fue significativamente alta en la remoción de los patógenos evaluados, y el porcentaje de remoción fue independiente del valor de la concentración a la entrada del filtro. Además, la eficiencia en la remoción de los patógenos evaluados no dependió del tipo de microorganismo.This article displays results obtained when total coliforms, fecal coliforms, and Salmonella shigella were removed from mixed liquor taken from San Fernando waste water treatment plant in Medellín, Colombia, by using a battery of filters packed in zeolite clinoptilolite. Experiments were developed under controlled conditions of flow and pH at room temperature. Natural clinoptilolite-type zeolite was used activated with saline solution and drying; it was packed in a battery consisting of two filters (a downward-flow filter and an upward-flow filter in order to make contact of contaminated solution and adsorbent material (zeolite easier. Five independent tests were

  1. Formas farmacêuticas de liberação modificada: polímeros hidrifílicos Modified release of drug delivery systems: hydrophilic polymers

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    Carla Martins Lopes

    2005-06-01

    Full Text Available Os sistemas de liberação de fármacos são parte integrante da investigação farmacêutica. A maioria dos sistemas de liberação oral de fármacos é baseada em matrizes poliméricas. Nas duas décadas passadas, as matrizes hidrofílicas tornaram-se muito populares na formulação de formas farmacêuticas de liberação modificada. A escolha do polímero hidrofílico na formulação da matriz pode fornecer uma combinação apropriada dos mecanismos de intumescimento, de dissolução ou de erosão e determinam a cinética de liberação in vitro. As matrizes de intumescimento são sistemas monolíticos preparados pela compressão de mistura de um polímero hidrofílico e de um fármaco. Elas representam sistemas da liberação em que os vários mecanismos podem ser adaptados ao programa de liberação. O sucesso desses sistemas está relacionado com a tecnologia de fabricação e com as características físicas e físico-químicas do polímero, responsáveis pelo mecanismo de liberação.Drug delivery systems (DDS became an integral part of pharmaceutical research. The majority of oral DDS are matrix-based systems. Hydrophilic matrices for the past two decades have been popular in the formulation of controlled release solid dosage forms. Swellable matrices are monolithic systems prepared by compression of a powdered mixture of a hydrophilic polymer and a drug. They represent a delivery system in which various mechanisms can be adapted to the delivery program. Their success is linked to the established tabletting technology of manufacture. The choice of the hydrophilic polymer in the matrix formulation can provide an appropriate combination of swelling, dissolution or erosion mechanisms to evaluate in vitro release kinetics.

  2. Estabilidad en el almacenamiento congelado de rebanadas de lomo de atún rojo (Thunnus sp. empacadas en atmósfera modificada con CO2

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    Myrna Luisa Medina Bracamonte

    2014-12-01

    Full Text Available La disponibilidad atún rojo fresco, entero y rebanado, como todo producto pesquero fresco está restringida para los consumidores en zonas distantes a los centros de producción por su estabilidad limitada en el almacenamiento. Por ello la industria pesquera en general, en la época de mayor producción, recurre a la congelación para conservar el excedente de producción, y al empacado para protegerlo del ambiente frío y seco del congelador, evitar su deshidratación y “quemaduras por frío”. El surgimiento del Empacado en Atmósfera Modificada como alternativa para incrementar la vida útil de productos alimenticios despertó la inquietud de evaluar la estabilidad de rebanadas de lomo de atún rojo (Thunnus sp. fresco, congeladas y empacadas con 100 % de CO2 durante su almacenamiento a las temperaturas convencionales para su distribución y venta, -10 y -18 ºC, evaluando la estabilidad química, física, microbiológica y sensorial de las rebanadas de lomo de atún rojo durante ≈ 4 meses de almacenamiento congelado. El 50 % de las rebanadas se congeló a -10 ºC (Tratamiento 1 y el 50 % restante a -18 ºC (Tratamiento 2. Las rebanadas congeladas se empacaron individualmente, el 50 % en atmósfera de 100 % de CO2 conservando la proporción 1:2 (rebanada:gas y el 50 % restante en atmósfera de aire. Se almacenaron a la temperatura correspondiente: Tratamiento 1 a -10 ºC y Tratamiento 2 a -18 ºC durante 111 días. Al final del almacenamiento el tratamiento P2 (100 % CO2 ofreció mejor barrera a la pérdida de humedad, favoreció la estabilidad de la fracción de proteínas solubles en solución salina. Las muestras P2 tuvieron mayor aceptación sensorial, fueron las más oscuras y rojas, con menor recuento microbiológico, coincidiendo con el menor contenido en bases volátiles totales. A -10 ºC la atmósfera de 100 % de CO2 no evitó la “quemadura por frío” y los panelistas percibieron el “olor a pescado”.

  3. Atmosfera modificada e refrigeração para conservação pós-colheita de camu-camu

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    Jacqueline de Oliveirai

    2014-06-01

    Full Text Available O presente trabalho tem por objetivo avaliar a conservação pós-colheita de camu-camu, utilizando a refrigeração e a atmosfera modificada propiciada pelos filmes de policloreto de vinila (PVC e polipropileno biaxialmente orientado de 50µm espessura (BOPP50 e assim avaliar a durabilidade em relação ao controle (sem embalagem. Os frutos foram mantidos a 5±1°C e 90±2% de umidade relativa, durante 25 dias e avaliados a cada quatro dias de armazenamento quanto à firmeza, pH, sólidos solúveis, acidez titulável, ácido ascórbico, antocianinas, perda de massa e concentração de CO2 da atmosfera no interior da embalagem. O filme de BOPP50 mostrou não ser a melhor alternativa para a conservação de camu-camu, pois a sua baixa permeabilidade aos gases ocasionou o acúmulo de CO2 no interior da embalagem, propiciando o processo fermentativo dos frutos após 13 dias de armazenamento. Os atributos pH, sólidos solúveis, acidez titulável, ácido ascórbico e antocianinas não foram afetados pelos tipos de filmes utilizados, mas sim pelos dias de armazenamento. Os resultados mostraram que a utilização do filme de PVC, juntamente com refrigeração, para conservação pós-colheita de camu-camu, foi eficaz na manutenção da firmeza do fruto e na redução de perda de massa, mantendo os frutos comercialmente viáveis por 21 dias, enquanto o controle e os revestidos por BOPP50 se apresentaram inviáveis após 13 dias de armazenamento.

  4. Avaliação do uso da Escala Modificada de Borg na crise asmática Evaluación del uso de la Escala Modificada de Borg en la crisis de asma Evaluation of the use of the Modified Scale of Borg in the asthmatic crisis

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    Tatiane G. de Liz Cavallazzi

    2005-03-01

    Full Text Available A dispnéia é a maior causa de incapacidade e redução da qualidade de vida para pacientes com doenças respiratórias como é o caso da asma. Os objetivos deste estudo foram verificar o grau de dispnéia dos pacientes em crise asmática pela Escala Modificada de Borg e a correlação da melhora do grau de dispnéia com a melhora da função pulmonar verificada pelo Pico de Fluxo Expiratório (PFE. Foram incluídos 40 pacientes asmáticos em crise aguda, atendidos no serviço de Pronto Atendimento em Pneumologia do Hospital São Paulo, no período de setembro à dezembro de 2003. Antes e após o tratamento, os seguintes dados foram coletados: freqüência cardíaca (FC, freqüência respiratória (FR, PFE e saturação periférica de oxigênio (SpO2. O paciente era questionado sobre sua percepção da dispnéia pela Escala Modificada de Borg. No pré-tratamento ocorreu uma tendência dos valores altos da escala de Borg estarem relacionados aos valores baixos do PFE, invertendo esta relação no pós-tratamento. Esta escala é rápida, barata e de fácil aplicabilidade na avaliação de pacientes asmáticos. Pode ser utilizada por profissionais de saúde para a avaliação inicial dos pacientes em crise, bem como sua resposta ao tratamento.La disnea es probablemente, el factor aislado más importante en la limitación de la capacidad de pacientes con asma para el desempeño de las funciones básicas del dia a dia. En consecuencia da esse sintoma, esos pacientes procuran con frecuencia, los servicios de atención de salud. Considerando la necesidad de uma evaluación acurada de ese síntoma, este estudio tuvo como objetivos: evaluar el grado de dísnea de pacientes en crisis de asma, utilizando la escala modificada de Borg y verificar la correlación entre la majoria del grado de dísnea y la mejoria de la función pulmonar, verificada por el Pico de Flujo Expiratorio (PFE y la saturación de oxígeno (SpO2 . Participaron del estudio 40

  5. Estudio de libertad de operación para una línea genéticamente modificada de papa (Solanum tuberosum L.

    Directory of Open Access Journals (Sweden)

    Alejandro Chaparro-Giraldo

    2014-01-01

    Full Text Available Título en ingles: Study of freedom to operate for a genetically modified potato (Solanum tuberosum L. line Título corto: Libertad de operación para papa GM Resumen: Durante el desarrollo de los productos biotecnológicos son utilizados materiales y procesos, que pueden estar protegidos por derechos de propiedad intelectual. Para evitar problemas legales en su comercialización, se deben realizar estudios de libertad de operación. Este estudio se realizó sobre una línea genéticamente modificada (GM de papa (Solanum tuberosum L. derivada de la variedad Pastusa Suprema, que expresa el gene Cry1Ac de Bacillus thuringiensis, desarrollada por la Corporación de Ciencias Biológicas y la Universidad Nacional de Colombia, Sede Medellín. El punto de partida, fue la deconstrucción del producto, cuyo resultado fue la lista de materiales y procesos usados en el desarrollo del producto. Se buscaron en bases de datos nacionales e internacionales de acceso público, las solicitudes de patentes y patentes relacionadas. En el nivel internacional, se encontraron cuatro solicitudes de patentes y dieciocho patentes relacionadas, la mayoría de las cuales, no han sido solicitadas en Colombia. En el nivel nacional, se encontraron 13 solicitudes de patentes, que han caducado, han sido negadas, abandonadas, desistidas, o están en requerimiento. Se encontró que la variedad tiene registro comercial, pero no título de obtentor. También se examinaron documentos de las instituciones participantes, que contuvieran cláusulas sobre propiedad intelectual, y otros documentos de interés, como los acuerdos de transferencia de materiales (ATM. Se concluye que la libertad de operación puede estar afectada más por problemas detectados en los ATM y en la complejidad de los acuerdos interinstitucionales suscritos, que por los derechos de propiedad intelectual. Palabras clave: Derechos de propiedad intelectual, biotecnología, cultivos transgénicos. Abstract:

  6. Estabilidade de emulsões de d-limoneno em quitosana modificada Stability of d-limonene emulsions in modified chitosan

    Directory of Open Access Journals (Sweden)

    Camila Figueiredo Borgognoni

    2006-09-01

    Full Text Available A quitosana é um biopolímero produzido a partir da quitina, presente na casca de crustáceos. Atualmente, o estudo de suas propriedades se deve às suas diversas utilizações nas áreas farmacêutica e alimentícia. A quitosana utilizada neste estudo foi quimicamente modificada para tornar-se solúvel em água (quitosana succinilada. Estudou-se a estabilidade de emulsões com d-limoneno para que estes dados sejam úteis na sua posterior utilização como agente de encapsulação de d-limoneno por liofilização. Sua estabilidade foi analisada por espectrofotometria, em diferentes temperaturas, e por cromatografia gasosa associada à técnica da análise do espaço livre, à temperatura ambiente. Sua caracterização foi feita por microscopia óptica. Emulsões de maltodextrina com d-limoneno foram utilizadas para comparação já que maltodextrinas são muito usadas como agentes de encapsulação de aromas. Observou-se boa estabilidade de emulsões de quitosana succinilada com d-limoneno ao longo do tempo e características muito distintas em relação às observadas em emulsões de maltodextrina com d-limoneno. Pode-se concluir neste estudo que emulsões de quitosana succinilada com d-limoneno apresentaram características favoráveis à encapsulação de aromas.Chitosan is a biopolymer derived from chitin, a component of the shells of crustaceans. Recently, special attention has been given to the study of chitosan properties as a consequence of their wide application in pharmaceutical and food areas. In this study, the chitosan used was chemically modified in order to become water soluble (succinyl chitosan. The stability of succinyl chitosan emulsion with d-limonene was studied so that these results could be useful in a subsequent use of succinyl chitosan as a d-limonene encapsulating agent by lyophilization. The stability of the emulsion was analyzed using a spectrophotometer in different temperatures and by the headspace

  7. Deformidade de Sprengel: tratamento cirúrgico pela técnica de green modificada Sprengel's deformity: surgical correction by a modified green procedure

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    Sandro da Silva Reginaldo

    2009-06-01

    Full Text Available OBJETIVO: Demonstrar os resultados estéticos e funcionais de pacientes submetidos à correção cirúrgica de escápula alta congênita - deformidade de Sprengel - por uma modificação da técnica de Green, bem como avaliar o grau de satisfação dos pacientes e as complicações da técnica utilizada. MÉTODOS: Foram avaliados nove pacientes operados pela técnica de Green modificada, no período de setembro de 1993 a abril de 2008. Como modificação da técnica original foram realizados descolamento muscular subperiosteal, ressecção apenas da porção súpero-medial da escápula e, em vez da utilização de tração esquelética, optou-se pela fixação com fio de aço subcutâneo da porção medial da espinha da escápula à crista ilíaca posterior contralateral. A idade média dos pacientes foi de sete anos e três meses. O seguimento pós-operatório médio foi de três anos e sete meses. RESULTADOS: Houve incremento médio na elevação de cerca de 39º (variando de 0º a 80º . Segundo a classificação de Cavendish, obteve-se a melhora estética de dois graus em oito casos e de três graus em um. Todos os pacientes ficaram satisfeitos com o resultado. CONCLUSÕES: Os pacientes com deformidade de Sprengel submetidos a tratamento cirúrgico por meio de uma modificação da técnica de Green, com fixação da escápula na crista ilíaca posterior contralateral em vez de se utilizar tração esquelética, apresentaram melhora tanto funcional como estética; todos os pacientes e/ou familiares ficaram satisfeitos e as complicações relacionadas com a técnica cirúrgica não interferiram no resultado final.OBJECTIVE: To evaluate the cosmetic and functional results of patients submitted to surgical correction of Congenital High Scapula (Sprengel's Deformity using modified Green's Procedure, as well as patients' satisfaction and complications. METHODS: Nine patients submitted to surgical treatment from September 1993 to April 2008 have

  8. A musculatura epaxial e a fibrose epidural na compressão medular em cães submetidos à laminectomia dorsal modificada

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    Diego V. Beckmann

    2010-02-01

    Full Text Available O objetivo deste experimento foi isolar a musculatura epaxial da medula espinhal de cães submetidos à laminectomia dorsal modificada (LDM e averiguar se os músculos influenciaram na formação da fibrose epidural, na compressão medular e no aparecimento dos sinais neurológicos. Para isso, dez cães hígidos foram submetidos à LDM entre as vértebras T13 e L1 e distribuídos aleatoriamente em dois grupos denominados controle (I onde a medula espinhal permaneceu exposta sem a presença de implante, e tratado (IIonde foi colocado um im-plante a base de alumínio entre a musculatura epaxial adjacente e a medula espinhal exposta pela LDM. As avaliações constaram de exames neurológicos diários até 180 dias de pós-operatório (PO; mielografia, decorridos 15, 30 e 60 dias de PO; e avaliação macroscópica mediante a reintervenção cirúrgica. Não houve diferença durante as avaliações neurológicas. Aos 15 dias de PO, foi verificado na mielografia, que o grau de compressão da linha de contraste foi maior no grupo tratado (PThe purpose of this study was to isolate the adjacent epaxial musculature from exposed spinal cord by modified dorsal laminectomy in dogs with aluminum implant and to verify whether the muscles contribute to form epidural fibrosis, spinal cord compression, and development of neurological signs. Ten dogs were submitted to modified dorsal laminectomy between T13 and L1 and then distributed along two groups. Dogs in the group 1 remained with the spinal cord exposed without the implant; dogs in the group 2 had an aluminum implant inserted between the epaxial muscles and the exposed spinal cord. Neurological examination was daily performed until 180 days post surgery. Additionally, myelography at 15, 30, and 60 days post surgery and macroscopic evaluation of the implant at six months post surgery were done. There was no difference between groups in the neurological examination. A statistical difference in the degree of

  9. Envasado de Carne de Vacuno con Hueso y Grasa en Atmósfera Modificada con CO2 y CO Packaging of Bone and Fat Containing Beef Meat under a Modified Atmosphere Containing CO2 and CO

    OpenAIRE

    Estrella R Aspé; Marlene D Roeckel; Cristina Martí; Romel Jiménez

    2008-01-01

    Se evaluó el efecto de envasado en atmósfera modificada (MAP) con bajo contenido de CO (0.1% y 0.4%) y presencia de CO2 sobre el color rojo y la vida útil de carne de vacuno. Se determinaron características microbiológicas, fisicoquímicas, organolépticas-sensoriales y de color del músculo y se compararon los resultados con el MAP de 70%O2+30%CO2. La vida útil de las muestras con O2 fue de 30 días mientras que para las muestras en MAP la vida útil fue de 40 a 45 días y no dependió de la concen...

  10. Desenvolvimento de eletrodos de pasta de carbono modificada com 2-aminotiazol sílica gel para a determinação de metais em etanol combustível

    OpenAIRE

    Takeuchi, Regina Massako [UNESP

    2007-01-01

    Neste trabalho foram desenvolvidos métodos eletroanalíticos para a determinação de íons metálicos em etanol combustível, empregando-se eletrodos de pasta de carbono modificada com uma sílica organofuncionalizada com grupos 2-aminotiazol (CPE-SiAt). Foi realizado um estudo comparativo entre dois aglutinantes: Nujol® e parafina; sendo observado que este último foi mais apropriado para aplicações em amostras comerciais de etanol combustível. Além da utilização dos CPE-SiAt, empregou-se também um...

  11. Implementación de la filosofía hooponopónica modificada en el programa terapéutico para pacientes que funcionan a nivel neurótico

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    Roberto Anselmo Ramos Valverde

    2014-09-01

    Full Text Available Se fundamenta la implementación de la filosofía hooponopónica, modificada en el programa terapéutico de los pacientes que funcionan a nivel neurótico en el Hospital de Día de Las Tunas, lo cual responde a una de las líneas de investigación del proyecto institucional FiloArtMed. La filosofía hooponopónica de fundamento idealista, exotérico y negador de la realidad, de orígenes milenarios en Hawái, fue modificada teniendo en cuenta el significado de sus palabras claves: perdóname, gracias, lo siento, te amo, de acuerdo a los preceptos dialécticos materialistas de la Medicina y la Psicología cubanas, insertándola en el programa terapéutico integral del hospital de día para pacientes neuróticos como técnica cognitiva conductual reguladora del comportamiento, rectorizando las terapias a manera de núcleo terapéutico. Se desecharon sus preceptos acientíficos tradicionales y se incluyó, además, el ejercicio de meditación, derivado de esta filosofía, basado en el principio de la neuroplasticidad cerebral, como técnica de relajación y de limpieza mental, fungiendo como la entrada B de la psicoterapia grupal sistémica de regulación emocional

  12. Tratamento da espondilólise sintomática com reparo direto pela técnica de Buck modificada Tratamiento de la espondilolisis sintomática con preparo directo por la técnica de Buck modificada Modified Buck's direct repair to simptomatic spondylolysis treatment

    Directory of Open Access Journals (Sweden)

    Bruno Pinto Coelho Fontes

    2009-03-01

    Full Text Available OBJETIVO: justificar a reconstrução da pars interarticularis pela técnica modificada de Buck como método efetivo no tratamento de lombalgia por espondilólise ou espondilolistese tipo 1, refratárias ao tratamento conservador. MÉTODOS: avaliação retrospectiva de oito pacientes com idade entre 11 e 34 anos, operados e acompanhados no período de outubro de 2004 a maio de 2008 com a técnica de Buck utilizando-se parafusos canulados de titânio. Nenhum paciente foi imobilizado no pós-operatório. Os pacientes foram selecionados após serem submetidos a estudos por imagem utilizando radiografias e ressonância magnética. Também foram avaliados no pós-operatório, segundo os critérios de Henderson e quanto à satisfação com o tratamento, assim como o índice de consolidação. RESULTADOS: sete pacientes foram classificados como excelentes, retornando ao nível de prática esportiva e laboral prévia. Dentre eles, um evoluiu com parestesia transitória, com recuperação completa. A oitava paciente apresentou uma pseudartrose bilateral, mas com bom resultado do ponto de vista clínico. Todos os pacientes ficaram satisfeitos com o resultado. CONCLUSÃO: a reconstrução ístmica com parafusos de titânio atingiu excelentes resultados ao aliar biomecânica estável, dissecção mínima da musculatura, com preservação da anatomia e mobilidade do segmento.OBJETIVO: justificar la reconstrucción de la pars interarticularis por la técnica modificada de Buck como método efectivo en el tratamiento de la lumbalgia por espondilosis o espondilolistesis tipo 1, refractarias al tratamiento conservador. MÉTODOS: evaluación retrospectiva de ocho pacientes con edad entre 11 a 34 años, operados y acompañados en el periodo de Octubre de 2004 hasta Mayo de 2008 con la técnica de Buck usando tornillos canulados de titanio. Ningún paciente fue inmovilizado en el postoperatorio. Los pacientes fueron seleccionados después de ser sometidos a

  13. Estudo transversal de ansiedade pré-operatória em crianças: utilização da escala de Yale modificada Estudio transversal de ansiedad preoperatoria en niños: utilización de la escala de Yale modificada A transversal study on preoperative anxiety in children: use of the modified Yale scale

    Directory of Open Access Journals (Sweden)

    Álvaro Antônio Guaratini

    2006-12-01

    Full Text Available JUSTIFICATIVA E OBJETIVOS: O emprego de escalas pode ser útil no reconhecimento dos estados de ansiedade, direcionando medidas que previnam complicações decorrentes de níveis elevados de ansiedade. A escala de ansiedade pré-operatória de Yale modificada (EAPY-m foi desenvolvida para avaliação da ansiedade em crianças na idade pré-escolar no momento da indução da anestesia. Essa escala possui caráter observacional e é rápida de ser completada. Os estudos sobre ansiedade em crianças no período pré-operatório não fazem menção à ansiedade no momento da avaliação pré-anestésica ambulatorial (APA. Este estudo transversal procurou avaliar o nível e a prevalência de ansiedade no momento da APA e da consulta clínica utilizando a escala EAPY-m, em crianças em idade pré-escolar. MÉTODO: Foram selecionadas 100 crianças, estado físico ASA I e IIi: G PED = 50 crianças a serem submetidas à avaliação clínica; G APA = 50 crianças a serem submetidas à apa para programação cirúrgica. O estudo se desenvolveu na sala de espera dos ambulatórios de pediatria e de apa enquanto as crianças aguardavam as consultas. Dois observadores aplicaram a escala EAPY-m de forma independente. Os parâmetros analisados foram dados sociodemográficos; mediana e porcentagem de pacientes com ansiedade (EAPY-m > 30. Foi realizada a análise estatística, sendo considerado significativo p JUSTIFICATIVA Y OBJETIVOS: La utilización de escalas puede ser útil en el reconocimiento de los estados de ansiedad, dirigido a medidas que prevengan complicaciones provenientes de niveles elevados de ansiedad. La Escala de Ansiedad Preoperatoria de Yale modificada (EAPY-m fue desarrollada para la evaluación de la ansiedad en niños en la edad preescolar al momento de la inducción de la anestesia. Esa escala posee un carácter de observación y es muy fácil para ser completada. Los estudios sobre ansiedad en niños en el período preoperatorio no

  14. Ethylbenzene Disproportionation on HZSM-5 Zeolite : The Effect of Aluminum Content and Crystal Size on the Selectivity for p-Diethylbenzene

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    Velasco N.D.

    1998-01-01

    Full Text Available The aim of this work was to verify the effect of MFI aluminum content and crystal size on the selectivity for para-diethylbenzene during ethylbenzene disproportionation. It was observed that the para-diethylbenzene selectivity increased as MFI crystal size increased. The increase in aluminum content caused a decrease in the selectivity for para-diethylbenzene. However, for crystals larger than 8 m m, the decrease in aluminum content had little influence on the selectivity for para-diethylbenzene. The results can be explained by the number of active aluminum sites on the external surface of the crystals.

  15. Selective catalytic reduction of NO by ammonia using mesoporous Fe-containing HZSM-5 and HZSM-12 zeolite catalysts: An option for automotive applications

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Hansen, T. W.; Kustova, Marina

    2007-01-01

    , the activity of the mesoporous samples in NO SCR with NH3 is significantly higher than for conventional samples. Such a difference in the activity is probably related with the better diffusion of reactants and products in the mesopores and better dispersion of the iron particles in the mesoporous zeolite...... as was confirmed by SEM analysis. Moreover, the maximum activity for the mesoporous zeolites is found at higher Fe concentrations than for the conventional zeolites. This also illustrates that the mesoporous zeolites allow a better dispersion of the metal component than the conventional zeolites. Finally...

  16. Quantitative 3D Fluorescence Imaging of Single Catalytic Turnovers Reveals Spatiotemporal Gradients in Reactivity of Zeolite H-ZSM-5 Crystals upon Steaming

    NARCIS (Netherlands)

    Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Hofmann, Jan P.|info:eu-repo/dai/nl/355351110; De Cremer, Gert; Kubarev, Alexey V.; Rohnke, Marcus; Meirer, Florian; Hofkens, Johan; Roeffaers, Maarten B. J.; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2015-01-01

    Optimizing the number, distribution, and accessibility of Bronsted acid sites in zeolite-based catalysts is of a paramount importance to further improve their catalytic performance. However, it remains challenging to measure real-time changes in reactivity of single zeolite catalyst particles by

  17. Fas2-ELISA y la técnica de sedimentación rápida modificada por lumbreras en el diagnóstico de la infección por Fasciola hepática

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    Vicente Maco Flores

    2002-04-01

    Full Text Available La fasciolosis humana es un problema de salud pública debido a la mayor incidencia de casos reportados en los últimos años alrededor del mundo. La necesidad de contar con técnicas o métodos de diagnóstico para Fasciola hepatica de mayor sensibilidad y especificidad es importante tanto para la práctica clínica como para determinar zonas endémicas. Objetivo: Evaluar las técnicas coprológicas y serológicas para el diagnóstico de la infección por Fasciola hepatica en humanos. Material y métodos: La población de estudio comprendió a niños en edad escolar entre 1-16 años de edad, pertenecientes a una zona de alta endemicidad (Junin, Perú. Se obtuvieron un total de 194 muestras de heces y 158 muestras de suero. Se evaluaron tres métodos coproparasitológicos: Método de Concentración éter-formol (MCEF, Técnica de Sedimentación Espontánea (TSE y la Técnica de Sedimentación Rápida (TSR modificada por Lumbreras, y tres métodos serológicos: Arco 2, Western blot para F. hepatica y Fas2-ELISA. Resultados: La TSR modificada por Lumbreras fue la de mayor rendimiento (20.61% en comparación con la TSE (13.40% y MCEF (7.72%. La sensibilidad de Fas2-ELISA fue de 96.77% superior a la del Western blot y Arco 2, con sensibilidades de 71.87% y 35.48%, respectivamente. Conclusiones: La TSR es superior a TSE y MCEF para el diagnóstico de la fasciolosis humana en la fase crónica. Fas2-ELISA, es una prueba de inmunodiagnóstico altamente sensible y que se propone debe ser usada como la prueba de diagnóstico de fasciolosis humana y de tamizaje de la infección en poblaciones humanas que habitan en regiones de alta endemicidad para esta parasitosis.

  18. Armazenamento de pitanga sob atmosfera modificada e refrigeração: I-transformações químicas em pós-colheita Storage of Suriname cherry under modified atmosphere and refrigeration: I - postharvest chemical changes

    Directory of Open Access Journals (Sweden)

    Adriana Ferreira dos Santos

    2006-04-01

    Full Text Available Este experimento teve como objetivo avaliar as transformações pós-colheita em pitangas colhidas nos estádios de maturação vermelho-alaranjado (VA e vermelho predominante (VP e mantidas sob atmosfera modificada (AM por filme de cloreto de polivinila (PVC, a 10 ± 0,5 ºC, 14 ± 0,5ºC e (90 ± 1%UR e a temperatura ambiente (23 ± 2°C e 85 ± 2%UR. O uso de AM associada à refrigeração permitiu manutenção dos sólidos solúveis, acidez titulável, dos açúcares solúveis totais e vitamina C, e também resultou em menor taxa de aumento nos carotenóides totais para frutos do estádio de maturação VA mantido a 10 e 14ºC. Em conjunto, pitangas colhidas no estádio vermelho-alaranjado foram as que apresentaram melhor manutenção das características intrínsecas durante oito dias de armazenamento sob atmosfera modificada a 10ºC.The aim of this experiment was to evaluate postharvest changes in Suriname Cherry harvested in the maturity stages red-orangish (RO and predominant red (PR, kept under modified atmosphere (MA by polyvinyl chloride film (PVC, at 10± 0.5 ºC, 14± 0.5 ºC, 90 ± 1% RH and room temperature (23 ± 2°C. The use of MA associated with refrigeration allowed the maintenance of total soluble solids, titratable acidity, soluble sugars, and vitamin C, and also resulted in lower increase rate in total carotenoids for fruits in the RO maturity stages kept at 10 e 14ºC. All together, Suriname Cherries harvested in red-orangish skin color were those that presented better maintenance of the intrinsic characteristics during 8 days storage under modified atmosphere at 10ºC.

  19. Resistance of genetically modified potatoes to Potato virus Y under field conditions Resistência de plantas de batata geneticamente modificadas ao Potato virus Y em condições de campo

    Directory of Open Access Journals (Sweden)

    André Nepomuceno Dusi

    2009-09-01

    Full Text Available The objective of this work was to evaluate the resistance of genetically modified clones of potato to Potato virus Y (PVY under field conditions. Genetically modified plants were compared with nontransformed plants of the same cultivar. The plots were flanked with potato plants infected with both PVYº and PVY N strains (spread lines, in order to provide the experimental area with the source of virus, which was naturally spread by the native aphid population. The experiment was weekly monitored by visual inspections and by DAS-Elisa in the plants produced from the harvested tubers, in order to evaluate the resistance of transgenic plants throughout the plant growth cycle. By the end of the third year, no infection symptoms were observed in the 1P clone; clone 63P showed 1% of infection, in contrast to about 90% of nontransformed plants infected. The stable expression of resistance to PVY provided by the coat protein gene was obtained in genetically modified clones of potato plants cultivar Achat under field conditions, during three consecutive years.O objetivo deste trabalho foi avaliar a resistência de clones geneticamente modificados de batata ao Potato virus Y (PVY em condições de campo. As plantas geneticamente modificadas foram comparadas com plantas não modificadas da mesma cultivar. As parcelas foram delimitadas com plantas infectadas com as estirpes PVYº e PVY N (linhas disseminadoras, para tornar disponível, na área experimental, a fonte de inóculo de vírus, que foi naturalmente disseminada pela população nativa de afídeos. O experimento foi monitorado semanalmente por inspeção visual e por DAS-Elisa nas plantas produzidas a partir dos tubérculos colhidos, para avaliar a resistência de plantas transgênicas ao longo do ciclo de crescimento. Ao final do terceiro ano, nenhum sintoma de infecção foi observado no clone 1P; o clone 63P apresentou 1% de infecção, em contraste com cerca de 90% de plantas-controle infectadas

  20. Armazenamento de pitangas sob atmosfera modificada e refrigeração: II - qualidade e conservação pós-colheita Storage of Suriname cherry under modified atmosphere and refrigeration: quality and postharvest conservation

    Directory of Open Access Journals (Sweden)

    Adriana Ferreira dos Santos

    2006-04-01

    Full Text Available Este trabalho teve como objetivo avaliar o efeito de atmosfera modificada (AM na conservação pós-colheita de pitangas colhidas nos estádios de maturação e início da pigmentação (IP, vermelho-alaranjado (VA e vermelho predominante (VP e armazenadas a 10 e a 14 ºC (90 ± 1%UR e condições ambientes (23± 2 ºC e 85 ± 2%UR. O uso de AM associada à refrigeração resultou em menores perdas de massa, incidência de fungo e enrugamento. A AM também permitiu um aumento de quatro dias na vida útil pós-colheita, mantendo a qualidade acima do limite de aceitação durante oito dias, para pitangas do estádio VA mantidas sob refrigeração. Em conjunto, pitangas colhidas no estádio de maturação vermelho-alaranjado apresentaram melhor potencial de armazenamento, quando mantidas sob atmosfera modificada a 10 ºC.The aim of this work was to evaluate the effect of modified atmosphere (MA on postharvest conservation of Suriname cherry harvested in the maturity stages: pigment initiation (PI, red-orangish (RO and predominant red (PR, and stored at 10, 14 ºC (90 ± 1% RH, and room temperature (23± 2 ºC and 85 ± 2% RH. The use of MA associated with refrigeration resulted in lower mass loss, fungi incidence, and fruit shrinkage. The MA also allowed a four-day increase in postharvest life, maintaining the general quality above acceptance limit during eight days, for Suriname cherries of RO maturity stage, kept under refrigeration. Collectively, Suriname cherries harvested at the maturity stage red-orangish presented the best storage potential, when kept under modified atmosphere at 10 ºC.

  1. Preparação de fibras de polipropileno modificadas com grupos mercaptan e sua utilização em compósitos com resina epoxídica

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    Dutra Rita C. L.

    1999-01-01

    Full Text Available Fibras de polipropileno modificadas com grupos mercaptan foram desenvolvidas através de processo de extrusão/fiação de misturas contendo PP e EVA modificado com grupos mercaptan (EVASH. A superfície destas fibras foi analisada por espectroscopia foto-eletrônica de raios-X (XPS, espectroscopia no infravermelho com transformada de Fourier, utilizando-se a técnica de refletância difusa (DRIFTS, tensão superficial e microscopia eletrônica de varredura. A partir destas técnicas, chegou-se à conclusão que o componente polar (EVASH se situa próximo à superfície da fibra. A utilização destas fibras em compósitos com resina epoxídica resultou em aumento considerável da resistência ao impacto e da temperatura de transição vítrea do material, indicando boa adesão interfacial matriz-fibra. Estas interações foram comprovadas por análise dinâmico-mecânicas.

  2. Produção de três espécies de cogumelos Pleurotus e avaliação da qualidade em atmosfera modificada Production of three species of Pleurotus mushrooms and quality evaluation in modified atmosphere

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    Cristina Ramos

    2011-01-01

    Full Text Available A utilização de substratos vegetais à base de palha tem vindo a assumir uma importância crescente na cultura de cogumelos sapróbios, principalmente do género Pleurotus. Estes cogumelos são considerados muito interessantes do ponto de vista comercial, não só pelas suas características organolépticas e nutricionais, mas também pela sua fácil adaptação e manutenção, crescimento rápido e relativo baixo custo de cultura. No entanto, por se tratar de alimentos perecíveis, devido sobretudo à sua composição e elevada taxa respiratória, podem apresentar reduzido valor comercial, caso a conservação não seja efectuada nas melhores condições. No sentido de minimizar estas alterações, os cogumelos frescos devem ser submetidos a um processamento mínimo com utilização combinada de embalagem em atmosfera modificada, de forma a manter a qualidade e estabilidade no período de conservação. Neste trabalho foram efectuados ensaios de produção de três espécies do género Pleurotus, cultivadas em palha de trigo, com a finalidade de determinar a espécie mais produtiva e avaliar a qualidade dos mesmos durante a conservação quando processados e embalados em atmosfera modificada. Os resultados permitem concluir que a espécie mais produtiva foi a P. ostreatus, seguida da P. sajor-caju e P. eryngii, tendo sido a P. eryngii a que mostrou maior resistência à degradação no período de conservação estabelecido.The use of substrates straw has been increasing importance in mushroom saprophytic species grown, especially of Pleurotus genus. They are considered very interesting from the commercial point of view, not only for its nutritional and organoleptic characteristics, but also for its easy adaptation, rapid growth and relatively low culture cost. Mushrooms have a short shelf life when compared to most vegetables at ambient temperatures mainly due to its composition and high respiration rate. After yield and to reduce losses and

  3. Avaliação da utilização de embalagem em atmosfera modificada sobre a conservação de sardinhas (Sardinella brasiliensis Evaluation of the use of modied atmosphere packaging in sardine (Sardinella brasiliensis preservation

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    Anderson Junger Teodoro

    2007-03-01

    Full Text Available A vida útil dos alimentos perecíveis conservados em atmosfera normal é limitada principalmente pelo efeito do oxigênio atmosférico e o crescimento de microorganismos aeróbios produtores de alterações, que promovem mudanças de odor, sabor, cor e textura, conduzindo à perda da qualidade. A modificação da atmosfera prolonga significativamente a vida útil dos alimentos, quando comparados à refrigeração, podendo chegar a um aumento de três a quatro vezes. O trabalho teve como objetivo avaliar o efeito da embalagem de sardinhas (Sardinella brasiliensis em atmosfera modificada. As amostras foram divididas em 8 lotes, embaladas com aproximadamente 1,5 L de ar (100%, CO2 (100%, 50/50 CO2/O2 e vácuo e termo-seladas, sendo armazenadas por um período de 22 dias. A cada 2 dias as amostras foram avaliadas quanto ao pH, bases voláteis totais (BVT e contagens totais de microrganismos heterotróficos aeróbios mesófilos. Os valores de pH aumentaram durante o tempo de estocagem, com exceção das amostras armazenadas em 100 e 50% CO2. A evolução de BVT foi compatível com outros parâmetros, como pH e contagem de bactérias totais, sendo sua evolução mais lenta nas amostras em que ocorreu o uso de atmosfera modificada. Os microrganismos mesófilos, nas atmosferas enriquecidas com CO2, apresentaram fases de latência e tempos de duplicação maiores, quando comparados com os das amostras em que não foi aplicado o método. Sob o ponto de vista microbiológico, as embalagens enriquecidas com CO2 demonstraram ser o melhor método de conservação, como também os resultados de BVT se encontraram dentro dos limites de 30 mg.100 g -1 de acordo com o estabelecido pela RIISPOA8. Recomenda-se o uso da atmosfera de 100% de CO2 como forma de conservação da sardinha por apresentar melhores parâmetros de vida útil.The objective of the work was to evaluate the effect of sardines (Sardinella brasiliensis packaged in a modified atmosphere. The

  4. A operação de Norwood modificada para tratamento da síndrome de hipoplasia do coração esquerdo Modified Norwood procedure for hypoplastic left heart syndrome

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    Fernando A. Fantini

    2004-03-01

    Full Text Available OBJETIVO: Apresentar os resultados do tratamento da síndrome de hipoplasia do coração esquerdo (SHCE com técnica de Norwood modificada, na qual somente são usados tecidos autólogos para a reconstrução do arco aórtico. MÉTODO: De janeiro a dezembro de 2002, cinco recém-nascidos com idade variando de dois a nove dias (média 5,0 dias foram submetidos a operação de Norwood modificada. O diâmetro da aorta ascendente variou de 5 a 8 mm (média 6,2 mm. Foi empregada técnica na qual o arco aórtico e seus ramos foram amplamente dissecados, permitindo a reconstrução de um novo arco aórtico tendo a artéria pulmonar como via de saída, e com a utilização exclusiva de tecidos do próprio paciente. Anastomose sistêmico-pulmonar com politetrafluoretileno expandido de 3,0 mm foi utilizada em três pacientes e de 3,5 mm em dois pacientes. Todos foram operados com parada cardiocirculatória total. RESULTADOS: O tempo de parada cardiocirculatória variou de 41 a 60 minutos (média 52,8 minutos. Todas as crianças sobreviveram ao ato operatório e foram encaminhadas para a unidade de terapia intensiva com o esterno aberto. Ocorreu um óbito no 9: dia de pós-operatório por sepse, o que resultou numa taxa de sobrevivência imediata de 80%. Ocorreu um óbito tardio por pneumonia de aspiração aos dois meses. Uma criança foi submetida ao segundo estágio da operação (cavo pulmonar e encontra-se bem. Duas crianças estão em acompanhamento aguardando o próximo estágio. Em nenhuma delas existem evidências de obstrução do novo arco aórtico. CONCLUSÃO: A técnica de Norwood modificada mostrou-se eficaz e com risco cirúrgico aceitável para o tratamento da SHCE, sem evidências de obstrução do arco aórtico reconstruído.OBJECTIVE: To show current results of a modified Norwood procedure, where only autologous tissues are used in the reconstruction of the new aortic arch. METHOD: Between January and December of 2002, five neonates with

  5. Efecto de la adición mineral cal- zeolita sobre la resistencia a la compresión y la durabilidad de un hormigón Effect of lime- zeolite binder on compression strength and durability properties of a concrete

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    Juan José Dopico Montes de Oca

    2009-08-01

    Full Text Available La práctica internacional reporta una creciente utilización de los hormigones de altas resistencias, con excelentes resultados en la durabilidad, relacionado con la obtención de una matriz cementicia muy densa, a partir del empleo de altos volúmenes de adiciones minerales muy finas, tales como las cenizas volantes, la microsílice, el metacaolín y otros materiales. Para los países emergentes, entre los cuales se ubica Cuba, el uso de estas adiciones puzolánicas resultan una solución relativamente costosa, dado los altos precios de importación de estos materiales puzolánicos, de ahí la utilidad de usar las fuentes nacionales de puzolanas disponibles de probada reactividad, como sustituías parciales de los contenidos de Cemento Portland Ordinario (CPO en las mezclas de hormigón, sin que se vean afectadas significativamente sus propiedades. El presente trabajo muestra la influencia del nivel de sustitución de los contenidos de Cemento Portland por adición mineral cal- puzolana, en combinación con superplastificante, en el comportamiento de la resistencia a la compresión y la durabilidad de un hormigón. Varios niveles de sustitución de CPO son evaluados, utilizando toba zeolítica como puzolana. Los resultados obtenidos corroboran la posibilidad del reemplazo de altos volúmenes de CPO por aglomerante cal-zeolita, sin que se afecten la resistencia a compresión requerida y su comportamiento ante la acción del ingreso del ion cloruro y la carbonatación.The international construction practice reports a remarkable use and development of high performance concretes, with excellent results in the durability properties, associated with a very dense cement matrix, defined from the use of high volumes of very fine minerals additions, such as, fly ash, silica fume, metakaolin and other fine powders. For the developing countries, among others Cuba, the use of these pozzolanic additions are relatively expensive, given for the high import

  6. Árvores geneticamente modificadas: técnicas, aplicações, riscos e os potenciais impactos associados a sua utilização Genetically modified trees: techniques, applications, risk and potential impacts associated with their use

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    Erlon Barbosa Valdetaro

    2011-03-01

    Full Text Available

    As espécies florestais possuem grande importância, oferecendo diversos produtos madeireiros e não madeireiros fundamentais para a sociedade. Neste contexto, a busca de novas tecnologias capazes de promover incremento na produtividade das florestas comerciais tem merecido grande atenção, sendo que a biotecnologia tem contribuído substancialmente para isso. Este ramo da ciência pode promover a modificação direta do genoma de um organismo alvo, por meio da análise e manipulação do DNA ou pela inserção de fragmentos do mesmo com função conhecida e, deste modo, alcançar características previamente desejadas, tais como resistência a doenças e ataques de pragas, redução do teor de lignina na madeira e geração de plantas tolerantes a diferentes tipos de estresse. Esta revisão objetiva relatar técnicas para a geração de árvores geneticamente modificadas, aplicações da transformação genética em essências florestais, riscos do uso desta tecnologia e seus potenciais impactos ambientais.

    doi: 10.4336/2011.pfb.31.65.51

    Forest species have great economic and social importance, offering various products as wood and non-timber fundamental to society. In this context, the search for new technologies that promote increase in productivity of commercial forests has received special attention and biotechnology has contributed substantially to this. This branch of science can promote direct modification of the genome of a target organism, through the analysis and manipulation of DNA genome or by insertion of fragments of the same with known function and thus to achieve desired characteristics, such as resistance to diseases and pests, lignin reduction in wood and generation of plants tolerant to different kinds of stresses. This review aims at reporting techniques for the generation of genetically modified trees, applications of genetic transformation in forest species, risks of using this technology and its potential

  7. Estudo retrospectivo de 11 casos de aerofagia em equinos operados pela técnica de miectomia de Forssell modificada Modified Forssell's myectomy operation in windsucking horses: a retrospective study of 11 cases

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    José Luiz de Mello Nicoletti

    1996-12-01

    Full Text Available No presente trabalho foi feita unta revisão do resultado pós-operatório com a técnica de miectomia de Forssell modificada aplicada em 11 equinos portadores de aerofagia, atendidos no Hospital Veterinário da FMVZ-UNESP, Botucatu, no período entre julho de 1992 e abril de 1995. A técnica consiste basicamente na ressecção dos músculos omohioídeo, esternohioídeo e esternotirohioídeo associado à neurectomia do ramo ventral do nervo acessório, que inerva o músculo esternomandibular. As informações sobre a evolução pós-operatória. que variou entre 4 e 36 meses, foram obtidas por contacto telefônico ou carta questionário. As raças acometidas foram: Quarto de Milha (5 animais. Apaloosa (4 animais, Mangalarga (1 animal e Brasileira de Hipismo (1 animal, sendo 7 fêmeas e 4 machos, e as idades variaram entre 1,5 e 11 anos. O resultado pós-operatório mostrou que 7 animais (63.3% estavam totalmente recuperados; 2 animais (18.1% recuperaram-se parcialmente pois o problema recidivou embora em menor intensidade entre 30 e 90 dias após a cirurgia e 2 animais (18,1% não tiveram nenhuma melhora.The objective of this study was to observe the long-term results of the modifica Forssell's operation to correct windsucking in 11 horses. The post-operative results was obtained by telephone and written reports, 4 to 36 months after operation. Seven animals (63.3% became free of the vice. while two horses (18.1% were recorded as having partial improvement. The other two horses (18.1%, retumed to windsucking as the same as before surgery. Cosmetic results were considered excellent in the owners opinion.

  8. Operação de Blalock-Taussig modificada para o tratamento paliativo de cardiopatias congênitas com hipofluxo pulmonar Blalock-Taussig operation for palliative treatment of congenital heart disease with low pulmonary flow

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    Miguel A Maluf

    1995-09-01

    Full Text Available De janeiro de 1990 a novembro de 1994, 72 pacientes portadores de cardiopatias congênitas com hipofluxo pulmonar foram submetidos à operação de Blalock-Taussig. A idade variou entre 2 dias e 11 anos (M:9,0 meses; 44 (61,1% eram do sexo masculino e 28 (38,8% do feminino; 38 (52,8% casos portadores de tétrade de Fallot; 7 (9,7% atresia pulmonar com septo interventricular íntegro (AP c/ SIVI; 6 (8,4% transposição das grandes artérias (TGA + estenose pulmonar (EP; 6 (8,4% atresia tricúspide (AT + EP; 6 (8,4% dupla via de entrada (DVE do ventrículo direito (VD ou ventrículo esquerdo (VE + (EP; 3 (4,2% transposição corrigida das grandes artérias (TCGA + comunicação interventricular (CIV + EP; 2 (2,7% dupla via de saída (DVS de VD ou VE + EP; 2 (2,7% defeito septal atrioventricular (DSAV + EP; 2 (2,7% isomerismo direito (D ou (E + EP. Os critérios de indicação foram: a neonatos com cardiopatias "dueto dependente"; b lactentes com piora de cianose ou crise de hipoxia; c crianças durante a infância com cardiopatias sem chance de uma correção biventricular. A técnica empregada foi a operação de Blalock-Taussig modificada, interpondo prótese entre artéria subclávia e artéria pulmonar. A prótese de Polytetrafluoroethylene (PTFE foi usada em 69 (94,5% casos, veia umbilical em 3 (4,1% casos e artéria mamária bovina em 1 (1,4% caso. Durante o ato operatório foi administrada dose única de heparina (1mg x kg peso, não sendo neutralizada no pós-operatório (PO e no seguimento tardio, dispensado o uso de anticoagulantes ou antiagregantes plaquetários. Houve 8 (11,1% óbitos no PO imediato: 5 (6,9% casos por obstrução da prótese (3 foram reoperados, 2 (2,7% casos por morte súbita (AP c/ SIVI e 1 (1,3% devido a processo infeccioso pulmonar. A obstrução da prótese como principal causa de óbito esteve diretamente relacionada à anatomia dos vasos (calibre da artéria subclávia e pulmonar e ou problemas de técnica cir

  9. Evaluación de las propiedades mecánicas de una mezcla densa en caliente modificada con un desecho de polietileno de baja densidad (PEBD Mechanical properties evaluation of a dense hot asphalt mixture modified with a residue of low density polyethylene (LDPE

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    Hugo Rondón Quintana

    2010-04-01

    Full Text Available El artículo presenta los resultados experimentales de ensayar una mezcla asfáltica densa en caliente tipo MDC-2 (acorde con las especificaciones del Instituto Nacional de Vías - INVIAS, 2007 modificada con un desecho de polietileno de baja densidad (PEBD. Para la evaluación del comportamiento de las mezclas asfálticas convencionales (sin aditivo y modificadas se realizaron ensayos Marshall, módulo dinámico, deformación permanente y resistencia a fatiga. Las mezclas fueron elaboradas con un cemento asfáltico (CA producido en Colombia tipo CA 80-100. Al CA con y sin aditivo se realizaron ensayos de caracterización de asfaltos como penetración y punto de ablandamiento. La modificación de las mezclas se realizó por vía húmeda. Las mezclas modificadas con desecho de PEBD experimentan mayor rigidez (bajo carga monotónica y cíclica y resistencia a la deformación permanente en comparación con las convencionales. Sin embargo la resistencia a fatiga de las mezclas convencionales disminuye cuando se adiciona PEBD al CA. Adicionalmente el CA modificado presenta mayor resistencia a la penetración, mayor punto de ablandamiento y menor susceptibilidad térmica a fluir que el convencional.Laboratory tests were used to evaluate the effect on the mechanical properties of a hot asphalt mix (MDC-2 as per INVIAS, 2007 specifications due to the addition by wet way of a residue of low density polyethylene (LDPE. The strength under monotonic load, resilient modulus, rutting and fatigue strength were evaluated. Asphalt cement (AC AC 80-100 was used from Colombia. The results show that the monotonic and cyclic mechanical strength evaluated were higher for the mixes modified with LDPE compared with mixtures with asphalts without additives. However, the mixes modified with LDPE undergo less fatigue strength. Additionally, characterization tests were conducted on asphalt cement with and without additive. The LDPE produces higher penetration resistance

  10. Performance of natural and modified smectite: kinetic and thermodynamics involving arsenic (V adsorption Desempenho de esmectita natural e modificada: cinética e termodinâmica envolvendo adsorção de arsênio (V

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    D. L Guerra

    2010-03-01

    Full Text Available A natural smectite sample has been modified by organofunctionalization process using synthetic route involved the reaction of 2-mercaptopyrimidine with 3-chloropropyltriethoxysilane. The resulting material (S MPY was characterized by SEM, FTIR, textural analysis and 29Si MAS-NMR. The ability of this material to removed As (V from aqueous solution was followed by series of adsorption isotherms adjusted to the Langmuir equation at room temperature and pH 2.0. The kinetic parameters analyzed by Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k2 in the 4.9 to 14.0 mmol-1 min-1 range for S MPY. The adsorption process was exothermic (ΔintH = -4.09 to -5.79 kJ.mol-1 accompanied by increase in entropy (ΔintS = 41.29 to 61.80 JK-1.mol-1 and Gibbs energy (ΔintG = -22.34 to -24.19 kJmol-1. The energetic effect caused by arsenic cation adsorption was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.Uma amostra de esmectita natural foi modificada por processo de organofuncionalização usando rota sintética, envolvendo a reação de 2-mercaptopirimidina com 3-cloropropiltrietoxisilano. O material resultante (S MPY foi caracterizado por microscopia eletrônica de varredura, espectroscopia de infravermelho com transformada de Fourier, análise textural e 29Si MAS-NMR. A habilidade deste material para remover As (V a partir de solução aquosa foi investigada por series de isotermas ajustadas pela equação de Langmuir em temperatura ambiente e pH 2,0. Os parâmetros cinéticos foram analisados por modelos de Lagergren e Elovich, em que um bom ajuste foi obtido para o modelo de reação de pseudo-segunda ordem com k2 em 4,9 para 14,0 mmol-1 min-1 para S MPY. O processo de adsorção foi exotérmico (ΔintH = -4,09 to -5,79 kJmol-1 acompanhado por aumento de entropia (ΔintS = 41,29 to 61

  11. Atmosfera modificada e controle de etileno para bananas 'Prata-Anã' cultivadas na Amazônia Setentrional Brasileira Atmospheric modification and ethylene's control in posthaverst, for 'Prata-Anã' bananas cultivated in the Setentrional Brazilian Amazon

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    Marcos André de Souza Prill

    2012-12-01

    Full Text Available O presente trabalho teve por objetivo avaliar o efeito da atmosfera modificada (AM pelo uso de embalagem plástica de polietileno de baixa densidade (PEBD, do vácuo e da adsorção de etileno, visando à manutenção da qualidade das bananas 'Prata-Anã' produzidas em Roraima. As análises foram realizadas em intervalos de 5 dias após a colheita, até 35 dias de armazenamento refrigerado (AR. Verificou-se que os frutos submetidos a embalagem de PEBD apresentaram as menores perdas de massa fresca quando comparados aos demais. Da mesma forma, os frutos embalados na presença do adsorvedor de etileno obtiveram a melhor manutenção na coloração da casca, atraso temporal, do pico climatérico, assim como o retardamento na degradação do amido, os menores incrementos de sólidos solúveis e acidez titulável, as menores concentrações de etileno nos interiores das embalagens e atraso temporal e a diminuição da atividade enzimática. Isso, possivelmente, proporcionou os maiores teores de pectina total e solúvel ao final do período experimental. A combinação do uso da embalagem de PEBD com o sachê de permanganato de potássio (KMnO4 resultou no retardamento do processo de maturação dos frutos de banana 'Prata-Anã', quando armazenada a 12 ºC. Pode-se atribuir esse efeito benéfico à presença do sachê na adsorção de etileno e, consequentemente, na ação do etileno no amadurecimento dos frutos, retardando a senescência das bananas 'Prata-Anã'.This present study aimed to evaluate the effect of modified atmosphere (MA by the use of plastic packaging for low density polyethylene (LDPE, the vacuum and the adsorption of ethylene, aiming the maintenance of the quality of bananas 'Prata Anã' cultived in Roraima.. Analyses were performed each 5 days after harvest, up to 35 days. It was verified that the fruit under LDPE bags showed the lowest losses of fresh weight when compared to the others. Likewise, as the fruits packed in the

  12. Atmosfera modificada e refrigeração para conservação pós-colheita de uva 'Niagara Rosada' Modified atmosphere and cold storage for postharvest conservation of 'Niagara Rosada' table grape

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    Patrícia Cia

    2010-10-01

    Full Text Available O objetivo deste trabalho foi avaliar os efeitos da atmosfera modificada na conservação pós-colheita da uva 'Niagara Rosada' armazenada sob refrigeração, em dois experimentos. No primeiro experimento avaliou-se o acondicionamento de cachos nas seguintes embalagens: papelão ondulado (testemunha; tereftalato de polietileno (PET; cloreto de polivinila (PVC 17 μm; polietileno linear de baixa densidade (PELBD 25 μm; e PELBD 50 μm. Em outro experimento, avaliaram-se os sistemas de acondicionamento: sacolas de plástico abertas (testemunha; polietileno de baixa densidade (PEBD 25 μm; PEBD 25 μm, com injeção de mistura gasosa (21% O2/5% CO2; PEBD 25 μm (21% O2/10% CO2; PEBD 25 μm (21% O2/20% CO2. Os cachos foram armazenados a 1±1°C e 90±5% de umidade relativa (UR por 28 dias, seguido de armazenamento em condições do ambiente (25±2°C e 80±5% UR. Os cachos foram avaliados quanto à perda de massa de matéria fresca, firmeza, cor das bagas, esbagoamento, sólidos solúveis totais (SST, acidez titulável (AT, relação SST/AT e incidência de podridões. O filme PELBD 50 μm, a partir do 14º dia a 1°C, seguido por mais três dias a 25°C, causou a fermentação dos cachos. As embalagens PELBD 25 μm, com ou sem injeção de mistura gasosa, e PVC 17 μm reduzem a perda de massa de matéria fresca dos cachos, mas não reduzem o esbagoamento e a incidência de podridões.The objective of this work was to evaluate the effect of the modified atmosphere, on the storage life of 'Niagara Rosada' Table grape kept under refrigeration in two experiments. In the first one, grape clusters stored in different package materials were evaluated: corrugated cardboard boxes, polyethylene tereftalate (PET; 17-μm polyvinyl chloride (PVC; 25-μm low density linear polyethylene film (PELDB; and 50-μm PELDB. On a second assay, different packaging systems were evaluated: opened plastic bags; 25-μm low density polyethylene film (PEBD; 25-μm PEBD, with

  13. Atmosfera modificada e 1-metilciclopropeno na conservação pós-colheita de kiwis cv. Bruno Modified atmosphere and 1-methylciclopropene on postharvest conservation of kiwis cv. Bruno

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    Leandro Camargo Neves

    2003-12-01

    Full Text Available Neste trabalho avaliou-se, em kiwis da cv Bruno, a ação do 1-Metilciclopropeno (1-MCP, na concentração de 625 ppb, associado ou não à atmosfera modificada gerada com o emprego de embalagem de polietileno de baixa densidade (PEBD, de 22µm. Os tratamentos testados foram: T1, controle (sem embalagem e 1-MCP; T2, sem embalagem com 1-MCP; T3, com embalagem de PEBD sem 1-MCP; T4, embalagem de PEBD mais o 1-MCP, sendo após armazenados em câmara fria a - 0,5 ± 0,5 ºC e 95 ± 5% de umidade relativa (U.R.. As avaliações foram realizadas após o pré-resfriamento, aos 45 dias, 45 + 5 dias (22 ± 3ºC e 75 ± 5% de U.R., 90 dias e 90 + 5 dias (22 ± 3ºC e 75 ± 5% de U.R.. As variáveis analisadas foram: firmeza de polpa (FP, sólidos totais (ST, acidez titulável (AT, concentração de etileno e de CO2 e análise sensorial (somente ao final do experimento. A maior firmeza de polpa e acidez titulável, o menor conteúdo de sólidos totais, as menores concentrações de etileno e CO2 e a melhor aceitabilidade pelos julgadores foi obtida com os frutos acondicionadas em PEBD de 22 µm e tratadas com 1-MCP.In this work was evaluated, for kiwis cv. Bruno, the Methylcyclopropene action (1-MCP, in concentration of 625 ppb, associated or not with modified atmosphere (MA using low density polyethylene bags (LDPE of 22µm. The following treatments were tested: T1: control (no bags and 1-MCP; T2 no bags with 1-MCP; T3 LDPE bags no 1-MCP; T4 LDPE bags and 1-MCP, then they were stored in cold chamber at - 0,5 ± 0,5 ºC and 95 ± 5% of RH for 45 or 90 days. The fruits were evaluated after pre-cooling, 45 days, 45 + 5 days (22 ± 3ºC and 75 ± 5% of RH., 90 days and 90 + 5 days (22 ± 3ºC and 75 ± 5% of RH.. The parameters analyzed were: pulp firmness (PF, total solids (TS, titritable acidity (TA, ethylene and CO2 concentration, and sensorial analyzes (only in the end of the experiment. The largest pulp firmness and titritable acidity, the smaller

  14. Conservação pós-colheita de melão Charentais tratado com 1-MCP e armazenado sob refrigeração e atmosfera modificada Postharvest conservation of charentais melons treated with 1-MCP and stored under refrigeration and modified atmosphere

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    Pahlevi A de Souza

    2008-12-01

    Full Text Available Objetivando avaliar a vida útil pós-colheita de melão tipo Charentais (Cucumis melo L. sob refrigeração, tratados com 1-MCP e associado ou não a atmosfera modificada (AM, foram conduzidos dois experimentos em laboratório da Embrapa Agroindústria Tropical, Fortaleza-CE. Os frutos foram provenientes da Agroindústria Nolem Comercial Importadora e Exportadora Ltda, localizada no Agropólo Mossoró Açu-RN. Os frutos foram tratados com 300 e 600 ppb de 1-MCP, em seguida, metade desses frutos foram embalados em filmes plásticos, mantendo-se frutos embalados sem aplicação de 1-MCP nas mesmas condições de armazenamento dos demais. Os melões foram armazenados por 21 dias sendo 14 dias (9±1ºC e 87±5% UR + 7 dias (22±2ºC e 70±5% UR. Em função da aparência externa, a vida útil pós-colheita dos frutos armazenados sob atmosfera modificada, com ou sem tratamento inicial de 1-MCP foi de 21 dias, enquanto que dos frutos tratados inicialmente apenas com 1-MCP foi de 19 dias. A aplicação do 1-MCP proporcionou redução na atividade respiratória e na produção de etileno, e maior retenção da firmeza da polpa, menor perda de massa e melhor aparência externa quando associado a atmosfera modificada. A atmosfera modificada, isoladamente, foi eficiente em reduzir a perda de massa e manter melhor aparência externa.Aiming to evaluate the postharvest shelf life of Charentais melon (Cucumis melo L. stored under refrigeration, the fruits were treated with 1-MCP, associated or not with modified atmosphere (MAP. Two experiments were carried out at the laboratory of Embrapa Agroindústria Tropical in Fortaleza, Brazil, analyzing the chemical and physic quality characteristics. The fruits were obtained at the Agroindústria Nolem Comercial Importadora e Exportadora Ltda, located in Mossoró Açu, Brazil. The fruits were treated with 300 and 600 nL L-1 of 1-MCP, half of those were wrapped in plastic films, which were wrapped without the use of 1

  15. Efecto de una película plástica modificada en algunos aspectos bioquímicos de un cultivo de tomate (Solanum lycopersicum L. / Effect of a modified plastic film on some biochemical aspects of a tomato (Solanum lycopersicum L. crop

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    Ema Laura García-Enciso

    2014-04-01

    Full Text Available El objetivo del presente estudio fue conocer el efecto de una cubierta para invernadero modificada con nanopartículas y pigmentos fluorescentes, la cual se nombró CIQA, sobre el rendimiento, y algunas variables bioquímicas y la calidad de frutos de tomate. El trabajo se realizó en el Centro de Investigación en Química Aplicada ubicado en Saltillo, Coahuila. Se instalaron dos invernaderos, en uno se usó la cubierta convencional y en el otro la película modificada. Se midió la Radiación Fotosintéticamente Activa (PAR y la temperatura al interior y exterior de los invernaderos. Se estableció un cultivo de tomate en los invernaderos, se determinó el contenido de clorofilas y carotenoides en las plantas y en los frutos se evaluó el contenido de Vitamina C y licopeno. Las lecturas máximas de PAR fueron mayores en el exterior, luego en el invernadero convencional y por último en el invernadero CIQA. En cuanto a temperatura, las lecturas más altas se presentaron en el invernadero de plástico convencional, seguido por el invernadero con la película CIQA y el exterior. Se encontraron diferencias durante algunos muestreos para el contenido de carotenoides, Vitamina C y licopeno. Lo anterior permite concluir que la película plástica CIQA disminuye la radiación y la temperatura al interior del invernadero, sin afectar los estándares de calidad de los frutos y el rendimiento del cultivo.

  16. Preparação de argila modificada com cloreto de cetilpiridíneo e avaliação da interação desta com o PVC Preparation of modified clay with cetylpyridinium chloride and evaluation of their interaction with PVC

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    Daniel K. Resende

    2010-09-01

    Full Text Available Foi preparada uma argila modificada com cloreto de cetilpiridíneo a partir da argila sódica por troca de cátions em solução. Foi avaliada a quantidade de agente de modificação em relação à argila sódica e o tempo reacional. Os materiais obtidos foram caracterizados por difração de raio X (XRD, análise termogravimétrica (TGA e ressonância magnética nuclear (RMN de baixo campo. Após a caracterização foi confirmada a modificação da argila e, também, foi verificado que o produto obtido pode ser empregado na preparação de nanocompósitos de PVC, considerando que o início da degradação do material preparado ocorreu em temperatura superior às comumente utilizadas no processamento do polímero. A adição da argila modificada apresentou uma dispersão adequada no PVC e manteve o início da degradação do material em temperatura compatível com o processamento do polímero, gerando um nanocompósito com parte esfoliada e intercalada.A modified silicate with cetylpyridinium was prepared from sodium clay with cation exchange in solution. The amount of modification agent for clay and the reaction time were evaluated. The materials produced were characterized using X ray diffraction (XRD, termogravimetric analysis (TGA and low field nuclear magnetic resonance (NMR. The formation of new organic clay was confirmed, which was introduced in PVC for the formation of nanocomposites. The beginning of degradation of the new clay occurred at temperatures higher than commonly used in the processing of PVC. The nanocomposites were partially exfoliated and partially intercalated.

  17. Influência da embalagem de atmosfera modificada e do tratamento com cálcio na cinética de degradação de ácido ascórbico e perda de massa em goiabas (Psidium guajava L.

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    YAMASHITA Fábio

    2000-01-01

    Full Text Available Goiabas de mesa (var. Pedro Sato no estádio verde maturo foram armazenadas a 8°C (85-95% UR por 49 dias. Uma parte das amostras foi tratada com solução de cloreto de cálcio 2% (p/v e o restante permaneceu sem tratamento. Posteriormente, foram embaladas individualmente em dois tipos de embalagem de atmosfera modificada (CryovacÒ PD-900 e CryovacÒ PD-961. Goiabas sem embalagem e não tratadas com cálcio, mantidas à mesma temperatura de 8°C serviram como controle. Foram realizadas análises de perda de massa, acidez titulável, teores de sólidos solúveis totais e ácido ascórbico. Os frutos embalados apresentaram taxas de perda de massa menores que os sem embalagem (p<0,05. Os frutos tratados com cálcio não apresentaram diferença na taxa de degradação de ácido ascórbico em relação aos não tratados e os frutos embalados com PD-900 apresentaram retenção de ácido ascórbico maior. Após 4 semanas, as goiabas sem embalagem apresentaram-se impróprias para consumo, devido ao murchamento e ataque de fungos, enquanto que as embaladas estavam em bom estado. Após a sexta semana, apenas os frutos embalados com PD-900 sem tratamento com cálcio estavam próprios para consumo. A embalagem de atmosfera modificada reduziu a perda de massa e ácido ascórbico e prolongou a vida-de-prateleira do produto. O emprego de cálcio não afetou as características analisadas.

  18. Structural simulation of natural zeolites; Simulacion estructural de zeolitas naturales

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez P, E.; Carrera G, L.M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The application of X-ray diffraction (XRD) in the study of crystalline structures of the natural and modified zeolites allows the identification, lattice parameter determination and the crystallinity grade of the sample of interest. Until two decades ago, simulation methods of X-ray diffraction patterns were developed with which was possible to do reliable determinations of their crystalline structure. In this work it is presented the first stage of the crystalline structure simulation of zeolitic material from Etla, Oaxaca which has been studied for using it in the steam production industry and purification of industrial water. So that the natural material was modified for increasing its sodium contents and this material in its turn was put in contact with aqueous solutions of Na, Mg and Ca carbonates. All the simulations were done with the Lazy-Pulverix method. The considered phase was clinoptilolite. It was done the comparison with three clinoptilolite reported in the literature. (Author)

  19. Conservação da qualidade de caqui 'Fuyu' em ambiente refrigerado pela combinação de 1-MCP e atmosfera modificada Quality maintenance of 'Fuyu' persimmon in cold storage by combining 1-MCP and modified atmosphere

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    Luiz Carlos Argenta

    2009-06-01

    Full Text Available O presente estudo analisou os efeitos do inibidor da ação do etileno 1-MCP (1-metilciclopropeno, da AM (atmosfera modificada e do oxidante de etileno KMnO4 (permanganato de potássio sobre a qualidade de caqui 'Fuyu' após a armazenagem refrigerada. Os fatores 1-MCP, AM e KMnO4 foram combinados de quatro maneiras, correspondendo aos seguintes tratamentos: T1 Controle + AM + KMnO4;T2 1-MCP + AM + KMnO4; T3 1-MCP + AM, e T4 1-MCP + AA (AA=atmosfera do ar. Frutos maduro-firmes com coloração da casca predominantemente amarela foram colhidos em sete pomares comerciais no nordeste do Estado do Rio Grande do Sul. Parte dos frutos foi exposta a 0.3 µL L-1 de 1-MCP por 12 h em 24 h após a colheita. A seguir, os frutos foram armazenados sob AA ou sob AM induzida por bolsas de polietileno (0,04 mm de espessura, por 20; 40; 60 ou 80 dias a -0,1±0,8ºC. Dois sachês contendo 8,5 g de Alumina-KMnO4foram adicionados em cada uma das bolsas de polietileno dos tratamentos um e dois, antes de elas serem vedadas. Os frutos de cada período de armazenagem refrigerada foram analisados após 0; 3; 6 ou 9 dias de prateleira sob AA a 22±1ºC. O tratamento 1-MCP retardou o amolecimento da polpa, mas não afetou consistentemente o desenvolvimento de 'estrias' e manchas pretas na superfície dos frutos armazenados sob AM contendo KMnO4. A incidência de 'estrias' e manchas pretas em frutos tratados com 1-MCP e armazenados sob AM foi significativamente menor que a de frutos tratados com 1-MCP e armazenados sob AA. Houve efeitos aditivos do 1-MCP e AM na conservação da firmeza e na redução de danos por frio manifestados pela formação de textura gel-firme e manchas translúcidas na casca. O uso de KMnO4 não aumentou a conservação da qualidade dos frutos quando tratados com 1-MCP e armazenados sob AM. O desenvolvimento dos distúrbios da epiderme dependeu do pomar e de períodos de armazenagem e prateleira. No entanto, os benefícios da combinação de 1-MCP e

  20. Avaliação de diferentes tipos de atmosferas modificadas na vida útil de carambolas minimamente processadas Evaluation of different types of modified atmosphere in cold storage of star fruits minimally processed

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    Leandro Camargo Neves

    2006-12-01

    Full Text Available Este trabalho teve por objetivo a avaliação da vida útil potencial de carambolas cv. Golden Star, minimamente processadas, armazenadas em diferentes tipos de embalagens plásticas, para a concepção da atmosfera modificada. Os frutos colhidos fisiologicamente maturos apresentaram coloração verde-amarelada, sólidos solúveis (SS médios de 6,8 ºBrix e massa média de 185 g. Antes da aplicação dos tratamentos, os frutos foram selecionados, higienizados em solução de hipoclorito de sódio (NaOCl a 100 mg. L-1, resfriados por 12 horas a 15 ± 0,5 °C, seccionados transversalmente, sendo então novamente higienizados em solução de NaOCl a 10 mg.L-1, por 3 minutos. Em seguida, os pedaços em forma de estrelas foram acondicionados em bandejas rígidas de poliestireno, com capacidade para 250 g, e revestidas com os seguintes materiais: T1: filme plástico perfurado de polietileno de baixa densidade (PEBD, de 0,006 mm; T2: filme plástico poliolefínico com antiembassamento da Dupont® (AGF, de 0,015 mm; T3: filme plástico poliolefínico da Dupont® (HF, de 0,015 mm; T4: filme plástico de PEBD, de 60 µm; T5: filme plástico de PEBD, de 80 µm; T6: filme plástico de polipropileno (PP, de 22 µm, e T7: bandeja rígida de polietileno tereftalato (PET, com capacidade para 500 mL, com tampa do mesmo material. As embalagens foram então armazenadas em câmara frigorífica a 12 ± 0,5 °C e 90 ± 3% de U.R, por 18 dias. Observou-se que não houve diferença significativa quanto aos sólidos solúveis (SS e acidez titulável (AT. O maior número de microrganismos e valor de pH foram observados nos frutos embalados nos filmes plásticos de PEBD de 0,006 mm, AGF e HF de 0,015 mm da Dupont®. Entretanto, os frutos acondicionados nas embalagens PET apresentaram o maior teor de ácido ascórbico. Da mesma forma, somente nas embalagens PET é que se conseguiu modificação atmosférica eficiente do ponto de vista da manutenção dos atributos de

  1. Armazenamento refrigerado sob atmosfera modificada de pedúnculos de cajueiro-anão-precoce dos clones CCP-76, end-157, end-183 e end-189 Storage of cashew apples from dwarf clones CCP-76, end-157, end-183 and end-189 under refrigeration and modified atmosphere

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    Auricélia de Souza Morais

    2002-12-01

    Full Text Available Pedúnculos de clones de cajueiro-anão-precoce, dos clones CCP-76, END-157, END-183 e END-189, foram armazenados durante 25 dias, sob refrigeração associada a atmosfera modificada, com o objetivo de avaliar o efeito das condições atualmente utilizadas (5ºC e 85-90% de UR para conservação, transporte e comercialização de cajus in natura. Os pedúnculos foram avaliados a cada 5 dias quanto às seguintes características: perda de peso, firmeza, cor (antocianinas, sólidos e açúcares solúveis, acidez, pH, vitamina C e compostos fenólicos. O uso da refrigeração (5ºC e 85% U.R, associada a atmosfera modificada, proporcionou uma vida útil pós-colheita de 10 dias para o clone END 189, de até 15 dias para o clone END 157 e de até 25 dias para os clones CCP 76 e END 183. A temperatura de 5ºC não se mostrou adequada para armazenamento de pedúnculos de coloração mais intensa (END 157 e END 189 que a testemunha (CCP 76, provocando perda de cor (antocianinas a partir do 10º dia de armazenamento. A atmosfera modificada reduziu significativamente a perda de peso, favorecendo a aparência do produto para comercialização, independentemente do clone estudado.Apples or false fruits from early dwarf cashew clones CCP-76, END-157, END-183 and END-189 were stored for 25 days under refrigeration associated to modified atmosphere with the aim of evaluating the effect of the conditions presently adopted (5ºC and 85-90% RH for conservation, storage and commercialization of fresh cashew apples. The cashew apples were evaluated every 5 days for the following characteristics: weight loss, pulp firmness, color (anthocyannins, acidity, pH, soluble solids, vitamin C and phenolic contents. With the use of refrigeration and modified atmosphere it was possible to attain postharvest storage life of 10 days for clone END 189, 15 days for clone END 157 and up to 25 days for clones CCP 76 and END 183. It was found that 5ºC was not an adequate

  2. Modified technique to increase nostril cross-sectional area after using rib and septal cartilage graft over alar nasal cartilages Técnica modificada para aumentar a área seccional externa da narina após o uso de enxerto cartilaginoso de costela e septo sob as cartilagens alares nasais

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    Marcelo Wulkan

    2012-10-01

    Full Text Available PURPOSE: Describe a modified technique to increase nostril cross-sectional area using rib and septal cartilage graft over alar nasal cartilages. METHODS: A modified surgical technique was used to obtain, carve and insert cartilage grafts over alar nasal cartilages. This study used standardized pictures and measured 90 cadaveric nostril cross-sectional area using Autocad®; 30 were taken before any procedure and 60 were taken after grafts over lateral crura (30 using costal cartilage and 30 using septal cartilage. Statistical analysis were assessed using a model for repeated measures and ANOVA (Analysis of Variance for the variable "area". RESULTS: There's statistical evidence that rib cartilage graft is more effective than septal cartilage graft. The mean area after the insertion of septal cartilage graft is smaller than the mean area under rib graft treatment (no confidence interval for mean difference contains the zero value and all P-values are below the significance level of 5%. CONCLUSIONS: The technique presented is applicable to increase nostril cross section area in cadavers. This modified technique revealed to enhance more nostril cross section area with costal cartilage graft over lateral crura rather than by septal graft.OBJETIVO: Descrever uma técnica modificada para se aumentar a área seccional externa da narina com cartilagem septal e costal acima das cartilagens alares nasais. MÉTODOS: Utilizou-se uma técnica cirúrgica modificada para obter, esculpir e inserir enxertos de cartilagem sobre as cartilagens alares. Realizou-se fotos padronizadas e mensuração de 90 áreas seccionais externas de narina em cadáveres com Autocad®; 30 antes sem procedimento; 60 após a inclusão de enxertos sob a cruz lateral (30 usando cartilagem costal e 30 usando cartilagem septal. A análise estatística foi feita com um modelo de medidas repetidas e ANOVA para a variável "área" RESULTADOS: Existe evidência estatística de que o enxerto de

  3. Comparação de parâmetros periodontais após utilização de contenção convencional 3x3 plana e contenção modificada Comparison of periodontal indexes after the use of conventional 3X3 plain retainer and modified retainer

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    Bianca Keiko Shirasu

    2007-02-01

    Full Text Available OBJETIVO: o presente estudo teve como propósito comparar os parâmetros periodontais após a utilização de dois tipos de contenções ortodônticas fixas: contenção convencional 3x3 plana (fio ortodôntico 0,8mm retilíneo fixado apenas nos caninos contralaterais e a contenção modificada (fio ortodôntico 0,6mm com dobras permitindo o livre acesso do fio dental e fixado em todos os dentes do segmento anterior. METODOLOGIA: quinze voluntários primeiramente utilizaram a contenção convencional por seis meses. Após um intervalo de quinze dias, foi instalada a contenção modificada, utilizada pelo mesmo período de tempo. Antes de cada fase os voluntários passaram por raspagem e alisamento radicular dos dentes e orientação de higiene bucal. Ao final de cada fase os seguintes parâmetros foram avaliados: índice de placa dentária, índice gengival e índice de cálculo dentário. Além disso, foi realizada a mensuração do cálculo no fio da contenção e todos os voluntários responderam a um questionário sobre a utilização, aceitação e conforto dos dois tipos de contenções. RESULTADOS E CONCLUSÕES: foi observado que o índice de placa e o índice gengival foram maiores para a contenção modificada (pAIM: the purpose of the present study was to compare periodontal indexes after the use of two types of bonded fixed retainers: conventional 3x3 plain retainer (orthodontic wire 0.8mm, bonded to the canine teeth only and the modified retainer (0.6mm multi strand wire, allowing free access to dental floss and bonded to all anterior teeth. METHODS: a test group of fifteen patients used the conventional retainer for 6 months. After a two week interval, the modified retainer was used for another 6 months. Previous to each phase, the patients went through tooth scaling, root planing and oral hygiene orientation. At the end of each phase the dental plaque index, gingival index and dental calculus index were evaluated. Furthermore, the

  4. Condições de secagem de uma pasta de anchoita modificada enzimaticamente na oxidação lipídica, lisina disponível e atividade antioxidante do produto Drying conditions of an enzymatic modified paste of anchovy in the lipid oxidation, available lisina and antioxidant activity of the product

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    Kelly de Moraes

    2013-03-01

    Full Text Available O objetivo do trabalho foi analisar as condições da secagem convectiva de uma pasta de anchoita (Engraulis anchoita modificada enzimaticamente, através da metodologia de superfícies de resposta, sendo as respostas consideradas: a oxidação lipídica (TBA, a redução da lisina disponível e a perda da atividade antioxidante específica. A pasta de anchoita modificada foi obtida por hidrólise enzimática da fração muscular (filés do pescado por Neutrase®. Foram avaliadas na operação de secagem, a temperatura do ar (60, 70 e 80°C e a espessura das amostras (1,5; 2,5 e 3,5mm. A análise estatística da secagem mostrou efeitos significativos da temperatura do ar e da espessura das amostras (PThe aim of the work was to analyze the conditions of the convective drying of an enzymatic modified paste of anchovy (Engraulis anchoita through the response surfaces methodology, and the responses were the lipid oxidation (TBA, reduction of the available lisina and loss of the specific antioxidant activity. The modified paste of anchovy was obtained through enzymatic hydrolysis of the fish muscular fraction (fillets by Neutrase®. In drying operation the air temperature (60, 70 and 80°C and the samples thickness (1.5, 2.5 and 3.5mm were studied. The statistical analysis of the drying showed significant effects of the air temperature and samples thickness (P<0.05. The best drying condition was obtained in the air temperature of 60°C and samples thickness of 2.5mm. In this condition the TBA index was of 0.93mgMDA kg-1, available lisina reduction of 16% and loss of the specific antioxidant activity of 20.2%.

  5. Comparação de parâmetros periodontais após utilização de contenção ortodôntica com fio trançado e contenção modificada Comparison of periodontal parameters after the use of orthodontic multi-stranded wire retainers and modified retainers

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    Marlice Azoia Lukiantchuki

    2011-08-01

    Full Text Available OBJETIVO: o presente estudo teve como objetivo comparar dois tipos de contenções ortodônticas fixas, em relação a parâmetros periodontais estabelecidos. A contenção com fio trançado é a mais comumente utilizada e a contenção modificada apresenta dobras que têm a finalidade de permitir o livre acesso do fio dental às áreas interproximais. MÉTODOS: para esse estudo cruzado, foram selecionados 12 voluntários que utilizaram, por 6 meses, A Contenção com fio trançado e B Contenção modificada - sendo essas fixadas em todos os dentes do segmento anterior. Após esse período experimental, foram feitas as seguintes avaliações: Índice de Placa Dentária, Índice Gengival, Índice de Cálculo Dentário e Índice de Cálculo ao longo do fio de contenção. Os voluntários também responderam a um questionário com relação à utilização, conforto e higienização das contenções. RESULTADOS: foi observado que o índice de placa e o índice gengival foram maiores nas faces linguais (pOBJECTIVE: The objective of the present study was to compare two types of fixed orthodontic retainers (a multi-stranded wire retainer and a modified retainer in relation to established periodontal parameters. The multi-stranded wire retainer is commonly used, and the modified retainer has bends to enable free access of dental floss to interproximal areas. METHODS: For this crossover study, 12 volunteers were selected and used the following retainers for six months: (A a multi-stranded wire retainer and (B a modified retainer. Both retainers were fixed to all anterior lower teeth.After this experimental period, the following evaluations were made: Dental Plaque Index, Gingival Index, Dental Calculus Index and Retainer Wire Calculus Index. The volunteers also responded to a questionnaire about the use, comfort and hygiene of the retainers. RESULTS: It was observed that the plaque index and the gingival index were higher on the lingual surface (p<0

  6. Estudo da validade e confiabilidade intra e interobservador da versão modificada do teste de Schöber modificado em indivíduos com lombalgia Study of validity and intra and inter-observer reliability of modified-modified Schöber test in subjects with low-back pain

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    Christiane de Souza Guerino Macedo

    2009-09-01

    Full Text Available Em pacientes com lombalgia, mensura-se a amplitude de movimento (ADM da coluna lombar por meio da versão modificada do teste de Schöber modificado (MTSM, mas suas propriedades psicométricas não são comprovadas para uso clínico. Este estudo verificou a validade e confiabilidade intra e interobservador do MTSM em indivíduos com lombalgia, comparando as medidas da ADM com as obtidas por meio de radiografia, método considerado padrão-ouro. Participaram 20 voluntários com lombalgia, de ambos os sexos, funcionários de um Hospital Universitário. O MTSM foi aplicado duas vezes por dois avaliadores. As medidas obtidas pelo teste e por radiografia foram comparadas usando o coeficiente de correlação de Pearson, obtendo-se r=0,14, ou seja, correlação fraca. O coeficiente de correlação intraclasse (CCI dos MTSM intra-observador foi 0,96 (IC 95% 0,91;0,98 e interobservador 0,93 (IC 95% 0,84;0,97, indicando alta confiabilidade; o teste de Bland & Altman mostrou alta concordância intra e interobservador, com valores de -0,21 e -0,28, respectivamente. Embora tenha sido encontrada alta confiabilidade intra e interobservador na aplicação da versão modificada do teste de Schöber modificado, este apresentou baixa validade para medir a ADM da coluna lombar, quando comparado ao padrão-ouro.In patients with low-back pain the lumbar spine range of motion (ROM is often measured by the modified version of the modified Schöber test (MMST, but its psychometric properties have not been ascertained for clinical use. The purpose here was to verify intra and inter-observer validity and reliability of the MMST in subjects with low-back pain, and to compare obtained ROM measures to those obtained by radiography, taken as gold standard. The study involved 20 subjects with chronic low-back pain, of both sexes, employees at a university hospital. The MMST was applied twice by two examiners each. The Pearson correlation coefficient found when comparing

  7. Influência do armazenamento refrigerado em associação com atmosfera modificada por filmes plásticos na qualidade de mangas 'Tommy Atkins Influence of refrigerated storage associated with plastic film-modified atmosphere in quality of 'Tommy Atkins' mangoes

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    Joaci Pereira de Sousa

    2002-12-01

    Full Text Available Avaliou-se a qualidade de mangas Tommy Atkins, embaladas em filmes plásticos e armazenadas sob condição refrigerada. Utilizaram-se frutos da safra 2000 obtidos na Fazenda Paulicéia Empreendimentos Ltda., situada no Pólo Agrícola Mossoró-Assu. Os frutos foram colhidos no estádio 2 (Brix 7 º e 75% verde e 25% vermelha e selecionados de acordo com o tipo 12 (12 frutos/caixa e tratados com fungicida para evitar podridões. No laboratório, os frutos foram submetidos aos seguintes tratamentos: 1 - frutos não embalados; 2 - frutos embalados individualmente em cloreto de polivinila (PVC; 3 - frutos embalados em sacola de polietileno de alta densidade (PEAD; 4 - frutos embalados em sacola de polietileno de baixa densidade (PEBD. Os frutos foram armazenados por 42 dias em condição controlada (11 ± 1°C; 85-90% UR. O armazenamento dos frutos sob condição controlada, associada à atmosfera modificada pelos filmes plásticos, reduziu-lhes a perda de matéria fresca e proporcionou-lhes a manutenção dos teores de sólidos solúveis totais, açúcares solúveis totais e acidez total titulável. A atmosfera modificada pelos filmes plásticos manteve mais regular as perdas na firmeza da polpa, possibilitando uma vida útil pós-colheita de 42 dias em ralação à testemunha. Até o final do armazenamento, o uso de PEAD promoveu o desenvolvimento da coloração da casca e da polpa dos frutos, porém o uso de PVC e PEBD reteve a coloração da casca.The quality of mangoes cv Tommy Atkins enclosed in plastic films and stored under refrigerated conditions were evaluated. Mangoes from the 2000 crop harvested at the Fazenda Paulicéia Empreendimentos Ltda., located in the Mossoró-Assu Agropole were used as experimental unity. The fruits were harvested in stage 2 ( 7º brix and 75% green, 25% red and selected for the type 12 (12 fruits/box, then treated with fungicide to prevent rots. The fruits were submited to the following treatments in the

  8. Tratamento cirúrgico videolaparoscópico da doença do refluxo gastroesofagiano: técnica de Nissen modificada - resultados clínicos e funcionais Videolaparoscopic surgical treatment of gastroesophageal reflux disease: modified Nissen technique - clinical and functional results

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    L. R. LOPES

    2001-06-01

    Full Text Available A doença do refluxo gastroesofagiano é muito freqüente na população e o tratamento cirúrgico é indicado em um número respeitável de pacientes. A escolha da via de acesso é a laparoscopia. Várias técnicas anti-refluxo podem ser empregadas e preferimos a técnica de Nissen modificada. OBJETIVO: Analisar os parâmetros clínicos e funcionais pré-operatórios comparados com os mesmos parâmetros pós-operatórios com a técnica empregada. MÉTODOS: Um grupo de 59 pacientes foi submetido a tratamento cirúrgico pela técnica de Nissen modificada videolaparoscópica. O diagnóstico pré-operatório foi feito por exame radiográfico contrastado e endoscopia digestiva alta em todos os pacientes. A manometria do esôfago realizada em 35 e a cintilografia em 15. Esofagite complicada ocorreu em 54,2% sendo 21 pacientes (35,6% com epitélio de Barrett. A técnica cirúrgica laparoscópica foi concluída em todos os pacientes. O tempo médio de cirurgia foi de 123,9 minutos. RESULTADOS: Não ocorreram complicações intra-operatórias. A alta se deu em média com 47,6 horas. Sintomas de disfagia, dor, epigastralgia, regurgitação e flatulência até o 30° dia ocorreram em 48,1% dos pacientes. Ocorreu uma reoperação por recurrência da doença e um óbito por necrose do fundo gástrico. O seguimento médio foi de 20,8 meses. Os exames pós-operatórios radiográficos, endoscópicos, manométricos e de cintilografia mostraram melhora significativa, bem como a avaliação clínica, que mostrou excelentes e bom resultados em 93,1% dos pacientes. CONCLUSÃO: A cirurgia de Nissen modificada videolaparoscópica corrigiu a doença do refluxo gastroesofagiano na maioria dos doentes acompanhados, associada à baixa morbimortalidade.BACKGROUND: Gastroesophageal reflux disease is highly common worldwide and surgical treatment is being indicated more frequently. Currently, laparoscopic is the access of choice and several antireflux techniques may be used

  9. Utilização de Placas de polipropileno e fios de náilon na técnica de fixação espinhal segmentar modificada em uma jibóia Polypropylene plates and nylon suture in a modified technique of segmental spinal fixation in a redtail boa

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    Simone Borges Salgueiro De Simone

    2011-05-01

    Full Text Available Um exemplar adulto de Boa constrictor com histórico de atropelamento foi atendido no Hospital Veterinário. Exames clínico e radiográfico identificaram a presença de uma luxação no terço médio da coluna vertebral. O paciente foi submetido à estabilização cirúrgica da lesão, em que se avaliou a eficácia de uma variação da técnica de fixação espinhal segmentar modificada. O segmento foi estabilizado através da fixação e placas plásticas sob forma de hemicerclagem nos corpos vertebrais, com auxílio de fio de náilon n. 0 e a síntese tecidual finalizou o procedimento. No pós-operatório, instituiu-se a antibioticoterapia, curativos locais diários e restrição de espaço até a cicatrização total do ferimento. A variação da técnica mostrou ser eficaz no realinhamento e estabilização anatômica da luxação do segmento vertebral para a serpente em questão.An adult exemplar of Boa constrictor with a history of overthrowing was send to the Veterinary Hospital. Clinical and radiographic examinations identified the presence of a dislocation in the third middle of the spine. The patient was submitted to a surgical correction of the lesion, which evaluated the effectiveness of a variation of the modified technique of segmental spinal fixation. The segment was stabilized by fixing plastic plates in the form of hemicerclage in the vertebral bodies, with nylon n.0, and tissue synthesis completed the procedure. Postoperatively, it was instituted antibiotic therapy, daily curatives and space restrictions until the complete healing of the wound. The variation of the technique has proved to be safe and effective for the snake of this study, promoting the realignment and stabilization of the anatomical vertebral segment.

  10. Comportamiento de la corrosión de aleaciones de magnesio AZ31-B en ambiente marino, modificadas por el proceso de fricción-agitación Corrosion behavior in marine environment of magnesium alloy AZ31-B welded by friction-agitation process

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    Willian Aperador Chaparro

    2012-04-01

    Full Text Available En el presente artículo se estudia el comportamiento de la corrosión de la aleación de magnesio AZ31-B en ambiente marino simulado, modificada mediante el proceso de fricción-agitación (PFA, con el fin de determinar el efecto de las variables del proceso, velocidad de rotación y velocidad de avance. Se llevaron a cabo análisis mediante espectroscopia de impedancia electroquímica y curvas de polarización potencio-dinámicas (Tafel. Adicionalmente, se determinó la microestructura en las zonas del cordón de soldadura a través de metalografía óptica. Finalmente, se analizaron los productos de corrosión formados en la superficie de las muestras por medio del microscopio electrónico de barrido (SEM equipado con el analizador químico por EDS. Se observó que una relación de velocidad de avance/velocidad de rotación mayor produce menor velocidad de corrosión y con ello mayor resistencia a la corrosión en medios salinos, al parecer relacionados con el gran tamaño de grano en la zona agitada, que corresponde a más entrada de calor.The corrosion behavior of AZ31B magnesium alloy modified by friction stir processing (FSP was studied in simulated marine environment, in order to determine the effect of process variables rotation speed and travel speed. The corrosion analysis was carried upon by means of electrochemical impedance spectroscopy and potentiodynamic polarization curves (Tafel, metallographic analysis of the welded zones was done by optical microscopy and the chemical analysis of the corrosion products were done by using scanning electron microscope (SEM, equipped with EDS analyzer. It was observed that the increase of the rate rotation speed/travel speed of the process produces a decrease in the corrosion rate and the corresponding increase of the corrosion resistance in marine environment, apparently related to the higher grain size found in the stir zone, corresponding to a higher heat input.

  11. Avaliação clínica de uma resina composta modificada por poliácido, utilizada como selante oclusal, quando aplicada por dentista, THD e graduando Clinical evaluation of a polyacid-modified resin composite, used as an occlusal sealant, when applied by dentist, dental hygienist and undergraduate

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    Roberta Tarkany BASTING

    1999-04-01

    Full Text Available O presente trabalho tem por finalidade comparar as diferenças de retenção de uma resina composta modificada por poliácido (Variglass V.L.C., utilizada como selante oclusal, quando aplicada por dentista, THD e graduando em Odontologia. Foram seladas as superfícies oclusais de 370 primeiros molares permanentes superiores de crianças entre 6 e 8 anos de idade provenientes de escolas públicas do município de Piracicaba. As avaliações clínicas foram realizadas após seis e oito meses da aplicação do selante. Aos seis meses, verificou-se que 78,42% dos selantes clinicamente aceitáveis permaneceram retidos sobre a superfície oclusal. O índice de perdas totais corresponderam a 10,20% do total de selantes aplicados. O melhor índice de retenção total foi obtido quando aplicado por graduando. Aos 12 meses, houve um aumento do número de selantes perdidos (43,79% e conseqüente decréscimo do número de selantes totalmente retidos (18,96%, não havendo diferenças significativas de retenção do selante quando aplicado por dentista, THD e graduando. Nos casos de perdas totais do selante, não se constatou presença de lesão cariosa.The aim of this work is to evaluate the differences of clinical retention of a polyacid-modified resin composite (Variglass V.L.C., used as an occlusal sealant, when applied by dentist, dental hygienist and undergraduate in Dentistry. The occlusal surfaces of 370 superior first molars of children ageing from 6 to 8 years from public schools in Piracicaba, were sealed. The presented data are related to the final evaluation after 6 and 12 months. It was observed that after 6 months, 78.42% of the sealants clinically acceptable, remained on the occlusal surfaces and that the completely lost sealants reached 10.20%. The best results of the sealants retention were obtained when the sealants were applied by an undergraduate. After 12 months, there was an increase of completely lost sealants (43.79% and a decrease of

  12. Aplicaciones tecnológicas de las arcillas modificadas

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    Zavala Huaytán, Candy Natalie; Zavala Huaytán, Candy Natalie; Zavala Huaytán, Candy Natalie

    2009-01-01

    Las arcillas de la familia de las esmectitas representan un grupo de minerales constituidos por filosilicatos, cuyas propiedades físico-químicas dependen de su estructura y del tamaño de grano, muy fino (menor a 2 pm). Una propiedad peculiar de estas estructuras es que presentan sustituciones isomórficas que permiten sustituir al átomo de silicio (Si), situado en el centro de los tetraedros, por otro de menor carga, como el aluminio (Al3+); igualmente, se puede reemplazar el aluminio de las c...

  13. Aplicaciones tecnológicas de las arcillas modificadas

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    Picasso, Gino; Sun Kou, María del Rosario

    2008-01-01

    Las arcillas de la familia de las esmectitas representan un grupo de minerales constituidos por filosilicatos, cuyas propiedades físico-químicas dependen de su estructura y del tamaño de grano, muy fino (menor a 2 µm). Una propiedad peculiar de estas estructuras es que presentan sustituciones isomórficas que permiten sustituir al átomo de silicio (Si), situado en el centro de los tetraedros, por otro de menor carga, como el aluminio (A1(3+)); igualmente, se puede reemplazar el aluminio de las...

  14. As sementes geneticamente modificadas e o direito ao desenvolvimento

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    Milena Barbosa Melo

    2017-12-01

    Full Text Available O presente artigo apresenta como objeto de investigação a ligação entre os direitos da propriedade intelectual no contexto dos organismos geneticamente modificados (OGM´S. Objetivou-se, especificamente, responder inquietações acerca dos danos reais para os consumidores, bem como o lucro para as empresas multinacionais, sem desconsiderar, ainda, os efetivos danos ao meio ambiente e à saúde. Utilizou metodologia pautada em pesquisa bibliográfica e documental a partir do método hermenêutico fazendo uso da interpretação judicial-histórica. Conclui pela relevância da temática para efetivação do direito ao desenvolvimento, bem como pela urgência de uma regulamentação da biossegurança, de forma a permitir melhor sustentação aos OGM´s.

  15. Controle do amadurecimento de banana 'Prata-Anã' armazenada sob refrigeração e atmosfera modificada passiva com o uso do 1-metilciclopropeno Control of the ripening of banana 'Prata Anã' stored under refrigeration and passive modified atmosphere with use of 1-methylcyclopropene

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    Luciana Costa Lima

    2005-04-01

    Full Text Available O 1- Metilciclopropeno (1-MCP é um produto inovador que inibe a ação do etileno em vegetais, retardando o início do amadurecimento de pomáceas, frutas de caroço e frutas tropicais. Com este trabalho objetivou-se avaliar a eficiência de diferentes concentrações do 1-MCP no controle do amadurecimento de bananas 'Prata-Anã' produzidas no Norte de Minas Gerais, armazenadas a 12°C e 95% de UR sob atmosfera modificada passiva. Os cachos foram colhidos no grau 1 de coloração da casca, que corresponde ao estádio verde de maturação. Foram utilizadas somente as segundas pencas dos cachos selecionados e estas foram separadas em buquês de 4 frutos. Cada parcela constou de 4 repetições e cada repetição 1 buquê. As concentrações do 1-MCP aplicadas foram: 0, 30, 60 e 90 ppb. Os frutos foram acondicionados em bandejas de isopor e embalados em filme de PVC de 15 micras, armazenados a 12°C e 95% de UR, sendo avaliados aos 10, 15, 20, e 25 dias. As avaliações realizadas constaram de diâmetro, grau de coloração da casca, firmeza, sólidos solúveis, acidez titulável e pH. A aplicação do 1-MCP foi eficaz em retardar o amadurecimento de bananas 'Prata-Anã' cultivadas na região Norte de Minas Gerais. As concentrações de 30, 60 e 90 ppb não apresentaram efeito diferenciado quanto às características avaliadas, podendo ser utilizada a concentração de 30 ppb, com economia do produto, obtendo-se os mesmos benefícios das concentrações de 60 e 90 ppb.Methylcyclopropene (1-MCP is an innovating chemical which inhibits the action of ethylene in plants, delaying the onset of the ripening of pomaceous fruits, stone fruits and tropical fruits. The present work intended to evaluate the efficiency of different concentrations of 1-MCP upon the control of ripening of bananas 'Prata Anã' produced in Northern Minas Gerais State (Brazil, stored at 12°C and 95% of RH under passive modified atmosphere. The clusters were harvested at degree 1

  16. Marginal leakage of polyacid-modified composite resin restorations in primary molars: an in vitro study Infiltração marginal em restaurações de resinas compostas modificadas por poliácidos, em molares decíduos: estudo in vitro

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    Cleide Cristina R. Martinhon

    2005-06-01

    Full Text Available The purpose of this in vitro study was to compare the marginal leakage in primary molars restored with 2 polyacid-modified composite resins (Dyract AP - Dentsply and F2000 - 3M and a composite resin (Filtek Z250 - 3M as control. First and second primary molars were used for preparation of cavities on the proximal surfaces, with extension of the gingival margin to the cementoenamel junction. Restorations were accomplished after total etching and application of the respective adhesive system, and were divided into groups according to the restorative system and the number of adhesive layers used. The teeth were stored in distilled water for 7 days, followed by thermocycling with 500 cycles at 5ºC - 55ºC, with one minute in each bath. Thereafter, teeth were prepared for immersion in 0.5% methylene blue solution for four hours. The teeth were sectioned in mesiodistal direction for assessment of dye penetration. According to the results of the Kruskal-Wallis test, the three restorative materials employed did not completely avoid marginal leakage at the gingival margin of primary molars. The marginal leakage of PMCR F2000 (4.06 and 3.95 displayed to be higher than the marginal leakage observed for the materials Dyract AP (2.7 and 2.55 and Filtek Z250 (2.25 and 2.43. The number of adhesive layers did not influence the degree of leakage of the three materials.O estudo in vitro avaliou a infiltração marginal em molares decíduos restaurados com três materiais resinosos: as resinas compostas modificadas por poliácidos (Dyract AP - Dentsply e F2000 - 3M e uma resina composta (Filtek Z 250 como grupo controle. Foram utilizados primeiros e segundos molares decíduos hígidos e as cavidades foram confeccionadas nas faces proximais, estendendo-se até a junção amelo-cementária. As restaurações foram realizadas após o condicionamento ácido total e a aplicação dos sistemas adesivos divididas em grupos de acordo com o sistema restaurador e o n

  17. Resfriamento rápido e armazenamento de caquis (Diospyrus kaki, L., cv. Fuyu, em condições de atmosfera refrigerada e modificada Fast cooling and storage of kakis (Diospyrus kaki, L., cv. Fuyu, in conditions of refrigerated atmosphere and modified

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    Valdecir Carlos Ferri

    2004-04-01

    Full Text Available Para aumentar o período de conservação após a colheita de caquis, da cultivar Fuyu, dois sistemas de armazenamento foram estudados: atmosfera refrigerada (AR e atmosfera modificada (AM. As frutas foram separadas em dois lotes: 1º resfriamento rápido a 0ºC até que a polpa atingisse 10ºC e, então, armazenadas em AR a 10±0,5ºC e 90±5% UR; 2º resfriamento rápido a 0ºC até que a polpa atingisse 0,5ºC, para serem armazenadas em condições de AR a 0±0,5ºC e 90±5% de UR e em AM com filme PEBD 80mim a 0±0,5ºC e 90±5% UR. Neste sistema (AM, também se testou o uso de sachet contendo 1g de permanganato de potássio. Através dos resultados obtidos, observou-se que, para o armazenamento de caquis 'Fuyu', por períodos de até 30 dias, a temperatura de 10ºC é eficiente e, para períodos superiores, o emprego de filmes de polietileno de baixa densidade de 80mim, associado com a absorção do etileno, é o mais aficaz. O armazenamento em AR a 0±0,5ºC e 90±5% UR não foi eficiente na conservação dos caquis.In order to increase the conservation period of kakis cultivar Fuyu after harvest, two storage systems were studied: refrigerated atmosphere (RA and modified atmosphere (MA. The fruits were separated in two groups: 1 rapid cooling at 0 ºC until the pulp reached 10ºC and, then stored in RA to 10±5 ºC and 90±5% RH; 2 rapid cooling at 0 ºC until the pulp reached 0,5 ºC and, then stored in RA to 0±0,5 ºC and 90±5% RH; and in MA with LDPE film 80mum 0±0.5ºC and 90±5% RH. In the systems (MA, also the sachet containing 1 g of potassium permanganate were tested. Through the obtained results it was observed that for the storage of kakis 'Fuyu', for periods until 30 days, the temperature of 10 ºC is efficient and, for longer periods the use of films of polyethylene of low density (LPDE of 80mum, associated with the absorption of the ethylene is also efficient. The storage in RA at 0±0,5 ºC and 90±5% RH was not efficient

  18. Escala Razões para Fumar Modificada: tradução e adaptação cultural para o português para uso no Brasil e avaliação da confiabilidade teste-reteste Modified Reasons for Smoking Scale: translation to Portuguese, cross-cultural adaptation for use in Brazil and evaluation of test-retest reliability

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    Elisa Sebba Tosta de Souza

    2009-07-01

    Full Text Available OBJETIVO: Traduzir, fazer a adaptação cultural e testar a confiabilidade teste-reteste de uma versão em língua portuguesa da Escala Razões Para Fumar Modificada (ERPFM para uso no Brasil. MÉTODOS: Uma versão em língua inglesa da ERPFM foi traduzida por médicos brasileiros com profundo conhecimento sobre a língua inglesa. Uma versão de consenso foi obtida por grupo multidisciplinar composto por dois pneumologistas, um psiquiatra e um psicólogo. Essa versão foi traduzida de volta ao inglês por um tradutor americano. A avaliação da adaptação cultural da versão final foi efetuada em uma amostra de 20 fumantes saudáveis. A avaliação da confiabilidade teste-reteste foi feita pela aplicação da versão traduzida da escala em 54 fumantes saudáveis em duas ocasiões separadas por 15 dias. RESULTADOS: Essa versão traduzida da ERPFM exibiu excelente identidade cultural, sendo bem compreendida por 95% dos fumantes. Os graus de concordância das respostas em duas ocasiões distintas foram quase perfeito para duas questões, substancial para dez questões, moderado para oito questões e discreto para uma questão. Os valores dos coeficientes de correlação intraclasse dos fatores motivacionais em duas ocasiões, empregando-se modelos teóricos previamente publicados, foram superiores a 0,7 em seis dos sete domínios. CONCLUSÕES: A presente versão da ERPFM exibe identidade cultural e confiabilidade teste-reteste satisfatórias, podendo ser de utilidade no tratamento e na avaliação de tabagistas em nosso meio.OBJECTIVE: To translate the Modified Reasons for Smoking Scale (MRSS to Portuguese, to submit it to cross-cultural adaptation for use in Brazil and to evaluate the test-retest reliability of the translated version. METHODS: An English-language version of the MRSS was translated to Portuguese by Brazilian doctors who have thorough knowledge of the English language. A consensus version was produced by a multidisciplinary group

  19. Fungos micorrízicos nativos e Glomus clarun no rendimento de trevo vesiculoso cultivado em condições naturais e modificadas pela calagem e aplicação de fósforo Glomus clarun and native mycorrhizal fungi on yield of Trifolium spp. cultivated under natural and modified soil contitions with addition by phosphorus and liming

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    Antonio Carlos dos Santos Pessoa

    1997-03-01

    Full Text Available Em experimento desenvolvido na casa de vegetação na UFSM-RS, avaliou-se o efeito da introdução de fungos micorrizicos arbusculares (fMA Glomus clarum e nativos no rendimento de massa seca (MS e absorção de P pelo trevo vesiculoso (Trifolium spp. e verificou-se a compatibilidade entre a espécie introduzida e os fMA nativos ocorrentes no solo estudado. Os tratamentos/oram constituídos defatorial 4x2x2 com quatro níveis de fMA: G. clarum, fungos nativos, mistura de ambas as populações e controle sem inoculação de fMA: com dois valores de pH: 4,4 e 5,4 e com dois níveis de fósforo disponível (Mehlich l: 6 e ISmg/kg de solo. A introdução de G. clarum isoladamente ou em conjunto com fMA nativos, na condição de pH 4,4, e em baixa disponibilidade de P, aumentou o rendimento de MS e absorção de P. Em disponibilidade intermediária de P (l5mg/kg de solo e pH 5,4 não ocorreu diferença entre os tratamentos inoculados com fMA, mas destes ocorreu diferença para o tratamento sem inoculação, evidenciando a dependência do trevo pela micorrizaçâo. Tratamentos inoculados com G. clarum apresentaram maiores rendimentos de MS, absorção de P, colonização micorrizica e esporulação, mostrando que a introdução dessa espécie pode ser viável quando espécies nativas não são eficientes para a cultura ou tornam-se ineficientes quando a fertilidade do solo é modificada por aplicação de P e/ou calagem.The experiment v/as conducted under greenhouse condition at the University of Santa Maria, RS, Brazil. The objectives were to evaluate the introduction of arbuscular mycorrhizalfúngi (AMF Glomus clarum and natives fungi on the phosphorus uptake and dry matter (DM production from Trifolium spp. and Io verify lhe compatibilily between introduced specie and lhe nativo AMF occurence in lhe studied soil. The treatments was constituled of 4x2x2 factorial withfour AMF leveis: G. clarum, AMf native, mixture of both populations of AMF

  20. Qualitative and quantitative assessment of genetically modified soy in enteral nutrition formulas by polymerase chain reaction based methods Avaliação qualitativa e quantitativa de soja geneticamente modificada em fórmulas de nutrição enteral

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    Natália Eudes Fagundes de Barros

    2010-02-01

    ível extrair ácido desoxirribonucléico amplificável a partir de todas as amostras, demonstrado pela amplificação do gene endógeno (lectina. Adicionalmente, o fragmento relativo à modificação genética da soja transgênica foi detectado em uma das nove amostras avaliadas, bem como na amostra relativa ao material de referência contendo 1,0% de organismo geneticamente modificado. As análises quantitativas realizadas a partir da reação em cadeia da polimerase em tempo real revelaram a presença de aproximadamente 0,3% de ácido desoxirribonucléico recombinante derivado de organismo geneticamente modificado na amostra de fórmula que apresentou resultado positivo. CONCLUSÃO: Os resultados demonstram que uma das fórmulas analisadas apresentava ingredientes derivados de soja geneticamente modificada, apontando para a necessidade de regulamentar a utilização de transgênicos, e de rotulagem específica nessa categoria de produtos.

  1. Cenouras minimamente processadas em embalagens com atmosferas modificadas e tratadas com radiação gama: avaliação microbiológica, físico-química e química Minimally processed carrots in modified atmosphere packaging and gama irradiation treatment: microbiological, fisical-chemistry and chemistry evaluation

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    Keila S. Cople Lima

    2003-08-01

    Full Text Available As cenouras são as principais fontes de origem vegetal em carotenóides provitamínicos A (a e o b-caroteno e podem ser transformados em vitamina A dentro do organismo animal. Segundo a Pesquisa de Orçamento Familiar realizada na região Sudeste do Brasil, no grupo de raízes e tubérculos, a cenoura é amplamente consumida. As cenouras minimamente processadas foram acondicionadas em embalagens com atmosferas modificadas de 5% O2/10% CO2 e 21% O2 (ar sintético, e tratadas com radiação ionizante gama, fonte de césio, nas doses de 0,25, 0,50, 0,75 e 1,00kGy. Os produtos após o emprego da radiação foram armazenados em refrigeração de 5°C durante 24 dias. Os diferentes tratamentos da cenoura e o grupo controle foram avaliados através das análises de pH, sólidos solúveis totais (SST, acidez total titulável (ATT e microbiologia. Os resultados de microbiologia evidenciaram que os produtos tratados com as doses de 0,50, 0,75 e 1,0kGy apresentaram redução de 3 a 4 ciclos logarítmicos na contagem total de mesófilos (CTM logo após a irradiação e uma vida-útil de 20 dias. Não foram detectados coliformes totais e E. coli até o 24º dia. Os patógenos B. cereus, Salmonella e Estafilococos coagulase positivos em 0,1g do produto, também não foram detectados. As contagens de bactérias láticas mantiveram-se menores que 100UFC/g. O processo de irradiação em baixas doses mostra-se promissor na manutenção da qualidade e apresenta-se como uma medida alternativa na redução de perdas pós-colheita.Carrots are the mains vegetable sources of carotenoids provitamin A (a and b-carotene which might be transformed into vitamin A in animal organism. According to the Family Budget Survey (FBS, 1991 carried out in the Brazilian Southeast, within the roots and tubers group, carrots are widely consumed. The minimally processed carrots were packaging with 5% O2/10% CO2 and 21% O2 (sintetic air, and g ionizing radiation treatments was carried

  2. Fresh cut yellow melon (CAC submitted to different type cuts and concentrations of calcion chloride stored under modified passive atmosphereMelão amarelo (CAC minimamente processado submetido a diferentes cortes e concentrações de cloreto de cálcio armazenado em atmosfera modificada passiva

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    Rogério Lopes Vieites

    2012-04-01

    de açúcares redutores e o ratio foram superiores nas fatias em relação aos cubos. As fatias de melão mantiveram maiores valores de firmeza comparadas aos cubos e de modo geral houve redução nos valores deste parâmetro ao longo do período de armazenamento para todos os tratamentos. Concentrações de 1,0 e 1,5% de CaCl2, propiciaram maiores valores de firmeza. A temperatura de armazenamento e atmosfera modificada passiva contribuíram para manutenção da qualidade do melão MP. Concentrações de até 1,0% de CaCl2 poderiam ser recomendada para manter a qualidade de melão MP melão amarelo inodorus (CAC.

  3. Avaliação do uso de glyphosate em soja geneticamente modificada e sua relação com o ácido chiquímico Evaluation of glyphosate application on transgenic soybean and its relationship with shikimic acid

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    D.A.S. Franco

    2012-09-01

    Full Text Available Com o aumento da comercialização de culturas geneticamente modificadas (GM resistentes ao glyphosate, é importante investigar a relação entre o uso desse herbicida e seus efeitos no crescimento e desenvolvimento de plantas de soja GM, assim como sua relação com o ácido chiquímico. Nesse sentido, foi conduzido um ensaio de campo e outro em casa de vegetação, com o objetivo de verificar a influência do glyphosate no crescimento, no desenvolvimento e na qualidade dos grãos da soja GM, bem como sua exsudação radicular e posterior absorção por plântulas de soja convencional cultivada sob condições hidropônicas. O ensaio de campo foi realizado em Eng. Coelho-SP, em 2007/08, sob delineamento de blocos ao acaso com quatro repetições, com aplicações isoladas (720 e 960 g e.a. ha-1 equivalente ácido e sequenciais de glyphosate, com intervalo de 15 dias (720/720, 960/720 e 960/720/720 g e.a. ha-1 . Transcorridos 42 dias da última aplicação de glyphosate, foram avaliados os efeitos sobre a densidade, altura de plantas e produtividade do cv. BRS Valiosa RR. Avaliou-se também o teor de ácido chiquímico sete dias após a última aplicação de glyphosate e o conteúdo de óleo e proteína dos grãos. No ensaio em casa de vegetação, conduzido sob o delineamento inteiramente casualizado com três repetições, soja GM cv. M8045RR e soja convencional cv. Conquista foram mantidas crescendo conjuntamente em solução hidropônica após aplicação de 2.400 g e.a. ha-1 de glyphosate no cultivar transgênico. O acúmulo de ácido chiquímico foi medido por HPLC a 0, 1, 3, 7 e 10 dias após aplicação do glyphosate, determinando-se também sua concentração e de seu metabólito, ácido aminometilfosfônico (AMPA, na solução nutritiva, por GC-MS. Os resultados mostraram que nenhum parâmetro fitométrico nem a qualidade nutricional dos grãos foram alterados pelas aplicações de glyphosate. Houve acúmulo de ácido chiquímico nas

  4. Proteção fetal frente a desafio com o vírus da Diarréia Viral Bovina (BVDV em ovelhas imunizadas com duas amostras de vírus modificadas experimentalmente Fetal protection against challenge with bovine viral diarrhea virus (BVDV in pregnant ewes immunized with two strains experimentally attenuated

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    Mário C.S. Brum

    2002-04-01

    Full Text Available Duas amostras do vírus da Diarréia Viral Bovina (BVDV submetidas a múltiplas passagens em cultivo celular e exposição à radiação ultravioleta (UV a cada passagem foram avaliadas como candidatos a vírus vacinais. As amostras foram testadas quanto à sua atenuação para bezerros e fetos ovinos, reatividade antigênica contra isolados de campo, e capacidade de induzir proteção fetal em ovelhas prenhes. Inoculação intramuscular (IM dos vírus modificados em quatro bezerros produziu apenas uma elevação discreta e passageira da temperatura corporal, seguida de produção de altos títulos de anticorpos neutralizantes. O vírus não foi detectado em secreções nasais ou sangue nos dias seguintes à inoculação. Porém, a inoculação IM desses vírus em quatro ovelhas prenhes foi seguida de transmissão transplacentária e infecção em todos os fetos. Para os testes de proteção fetal, ovelhas prenhes previamente imunizadas com duas doses vacinais, foram inoculadas por via intranasal com amostras de BVDV-1 (SV-126.8, n=6 ou BVDV-2 (SV-260, n=5. No dia do desafio (134 dias após a segunda dose, todos os animais apresentavam altos títulos de anticorpos neutralizantes (256 a >4096 contra os vírus vacinais; além de títulos variados (8 a >4096 contra várias isolados brasileiros de BVDV-1 e BVDV-2. Quinze dias após o desafio, as ovelhas foram sacrificadas e os tecidos fetais foram examinados para a presença de vírus. Todos os fetos das ovelhas controle não-vacinadas apresentaram-se (n=4 positivos para os vírus utilizados no desafio. Em contraste, nenhum feto das ovelhas imunizadas (n=11 foi positivo para vírus, indicando que a resposta imunológica induzida pela vacinação com os vírus modificados foi capaz de prevenir a infecção fetal. Estes resultados indicam que é possível obter-se forte resposta imunológica e proteção fetal contra o BVDV com o uso de vacinas vivas modificadas.Two isolates of bovine viral diarrhea

  5. Estudo comparativo da ultrafiltração convencional e associação de ultrafiltração convencional e modificada na correção de cardiopatias congênitas com alto risco cirúrgico Comparative study of standard ultrafiltration and its association with modification for the correction of high surgical risk congenital heart diseases

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    Miguel Angel MALUF

    1999-07-01

    Full Text Available A necessidade de correção cirúrgica de má-formações cardíacas complexas, que requerem tempos prolongados de circulação extracorpórea (CEC aumentou a morbimortalidade devido a retenção hídrica e reação inflamatória sistêmica. O objetivo deste estudo é comparar a evolução pós-operatória imediata de pacientes submetidos a ultrafiltração convencional (UFC durante a CEC e ultrafiltração modificada (UFM após CEC. Quarenta e um pacientes submetidos a correção cirúrgica de cardiopatias congênitas foram divididos em 2 grupos: G1: 21 pacientes com idade de 15 dias a 36 meses (mediana: 11 meses e peso de 3,6 a 13,5 kg (M: 7,27 ± 3,07, operados entre 1996 e 1997, foram submetidos a UFC. G2: 20 pacientes com idade de 9 dias a 36 meses (mediana: 5,5 meses e peso entre 2,2 e 12 kg (M: 5,7 ± 2,5, operados entre 1997 e 1998, foram submetidos a UFC+UFM. Dentre as operações mais freqüentes temos: ventriculosseptoplastia, 15 (36,5% casos; operação de Jatene, 10 (24,3% casos; correção de defeito septal A-V total, 7 (17,0% casos etc. A análise estatística de idade, peso e complexidade cirúrgica mostrou semelhança entre os grupos. Houve 6 (28,5% óbitos no G1 e 4 (20% no G2, (p=0,71. O volume médio ultrafiltrado no G1 (UFC foi 143,3 ml e no G2 (UFC+UFM foi 227,0 ml, (pSurgical correction of complex cardiac malformations that require extended extracorporeal circulation (ECC increase morbidity/mortality due to water retention and systemic inflammatory reaction. The purpose of this study is to compare the immediate postoperative evolution of patients submitted to conventional ultrafiltration (CUF during ECC and modified ultrafiltration (MUF after ECC. Forty-one patients submitted to surgical correction of congenital cardiac disease were divided into 2 groups: G1 - 21 patients with ages from 15 days to 36 months (median 11 months and weighing from 3.6 kg (M: 7.27 ± 3.07, operated on between 1996 and 1997 were submitted to CUF

  6. Treatment of effluent containing uranium with magnetic zeolite; Tratamento de efluente contendo uranio com zeolita magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Craesmeyer, Gabriel Ramos

    2013-07-01

    Within this work, a magnetic-zeolite composite was successfully synthesized using ferrous sulfate as raw material for the magnetic part of the composite, magnetite, and coal fly ash as raw material for the zeolitic phase. The synthesis of the zeolitic phase was made by alkali hydrothermal treatment and the magnetite nanoparticles were obtained through Fe{sup 2+} precipitation on alkali medium. The synthetic process was repeated many times and showed good reproducibility comparing the zeolitic nanocomposite from different batches. The final product was characterized using infrared spectroscopy, powder X-ray diffraction, X-ray fluorescence, scanning electron microscopy with coupled EDS. Specific mass, specific surface area and other physicochemical proprieties. The main crystalline phases found in the final product were magnetite, zeolites types NaP1 and hydroxysodalite, quartz and mullite, those last two remaining from the raw materials. Uranium removal capacity of the magnetic zeolite composite was tested using batch techniques. The effects of contact time and initial concentration of the adsorbate over the adsorption process were evaluated. Equilibrium time was resolved and the following kinetics and diffusion models were evaluated: pseudo-first order kinetic model, pseudo-second order kinetic model and interparticle diffusion model. A contact time of 120 min turned out to be enough to reach equilibrium of the adsorption process. The rate of adsorption followed the pseudo-second order model and the intra particle diffusion did not turn out to be a speed determinant step. Two adsorption isotherms models, the Langmuir model and the Freundlich model, were also evaluated. The Langmuir model was the best fit for the obtained experimental data. Using the best fitted adsorption isotherm and kinetic model, the theoretical maximum adsorption capacity of uranium over the composite was determined for both models. The maximum removal capacity calculated was 20.7 mg.g{sup -1} for the Langmuir isotherm and 23.4 mg.g{sup -1} for the pseudo-second order model. The experimental value attained was 23,3 mg.g{sup -1}. (author)

  7. UKURAN PARTIKEL DAN KONFORMASI KRISTAL ZEOLIT-A HASIL SINTESIS DENGAN PENAMBAHAN TETRAPROPILAMMONIUM HIDROKSIDA (TPAOH

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    Nurul - Widiastuti

    2014-12-01

    Full Text Available Abstract PARTICLE SIZE AND CRYSTAL CONFORMATION OF SYNTHESIZED ZEOLITE-A WITH TETRAPROPYLAMMONIUM HYDROXIDE (TPAOH ADDITION. The aims of this research is to study the effect of tetrapropylammonium hydroxide (TPAOH concentration in the synthesis of zeolite A to its physical characteristics such as crystallinity, crystal conformation and average crystal size. The zeolite A was synthesized with composition 3.165 Na2O : 1.000 Al2O3 : 1.926 SiO2 : 128 H2O : x TPAOH where x was 0; 0.0385; 0.0577; 0.0770; 0.1540 and 4.1602. The zeolite was crystalized under hydrothermal condition in a stainless steel autoclave at 100°C for 5 hours. The resulting crystal was washed with distilled water until pH 8 and then dried in an oven at 80oC for 24 hours. FT-IR and XRD analysis results show that the synthesized zeolite A at x = 4.1602 has the lowest crystallinity. It is estimated due to the mass of TPAOH was four times higger than the mass of zeolite framework components (Si and Al. SEM and PSD (Particle Size Distribution analysis results show that TPAOH concentration affected the crystal conformation and the average size of zeolite A particles. The formation of chained crystal conformation was caused by the electrostatic interactions between TPA+ and negatively charge of zeolite framework. In addition, the particel size of the synthesized zeolite A at x = 0.1540 was 2.024 µm which was smaller than the particel size of the synthesized zeolite A without TPAOH, which was 3.534 µm. Keywords: average size of particles; crystal conformation; TPAOH; zeolite A Abstrak Penelitian ini bertujuan untuk mempelajari pengaruh konsentrasi TPAOH (Tetrapropilamonium hidroksida dalam sintesis zeolit A terhadap sifat fisikanya yang meliputi kekristalan, konformasi kristal dan ukuran rata-rata kristal yang terbentuk. Pada penelitian   ini   zeolit A   disintesis    dengan komposisi 3,165 Na2O : 1 Al2O3 : 1,926 SiO2 :128 H2O: x TPAOH. Konsentrasi TPAOH divariasikan dengan nilai x adalah 0; 0,0385; 0,0577; 0,0770; 0,1540 dan 4,1602. Metode hidrotermal digunakan dalam penelitian ini dengan kondisi suhu  hidrotermal 100°C dan waktu kristalisasi selama 5 jam dengan pH pencucian 8. Hasil karakterisasi menggunakan FT-IR (Fourier Transform – Infrared Spectroscopy dan XRD (X-Ray Diffraction  menunjukkan bahwa zeolit A yang disintesis dengan x = 4,1602 memiliki kekristalan terendah. Hal ini diperkirakan terjadi karena masa TPAOH yang digunakan empat kali lebih besar daripada masa penyusun zeolit (Si dan Al. Berdasarkan hasil karakterisasi menggunakan SEM (Scanning Electron Microscopy dan PSD (Particle Size Distribution, dapat diketahui bahwa TPAOH berpengaruh terhadap konformasi kristal dan rata-rata ukuran kristalnya.  Terbentuknya konformasi kristal seperti rantai disebabkan oleh adanya interaksi elektrostatik antara muatan positif pada TPA+ dan muatan negatif dari kerangka zeolit. Zeolit A yang disintesis dengan x = 0,1540 memiliki ukuran partikel rata-rata 2,024 µm yang lebih kecil dari daripada zeolit A tanpa TPAOH yaitu sebesar 3,534 µm. Kata kunci : ukuran partakel rata-rata; konformasi kristal; TPAOH; zeolite A 

  8. Clinical, manometric and profilometric evaluation after surgery for Hirschsprung's disease: comparison between the modified Duhamel and the transanal rectosigmoidectomy techniques Avaliação clínica, manométrica e profilométrica após correção cirúrgica para doença de Hirschsprung: comparação entre as técnicas de Duhamel modificado e a retossigmoidectomia transanal modificada

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    Elaine Cristina Soares Martins

    2009-10-01

    Full Text Available PURPOSE: To evaluate fecal continence, anorectal manometry (AM and profilometry (P, in patients operated for congenital megacolon, using either the modified Duhamel technique (MDT or the modified transanal rectosigmoidectomy (MTR technique. METHODS: 42 patients were evaluated clinically and via AM and P, for postoperative control. The resting, coughing, voluntary contraction, maintained voluntary contraction and perianal stimulation pressures were investigated. The rectosphincteric reflex was tested and the simple and enhanced pressure curves were evaluated. The three-dimensional profilometric outline was produced. Student's t, chi-squared and Fisher's exact tests were used for statistical analysis (pOBJETIVO: Avaliar a continência fecal, a manometria anorretal (MAR e a profilometria (PFM, em pacientes submetidos a tratamento cirúrgico do megacolo congênito pelas técnicas de Duhamel modificado (DM ou de retossigmoidectomia transanal modificada (RTM. MÉTODOS: 42 pacientes foram clinicamente avaliados e submetidos à MAR e PFM para controle pós-operatório. Foram pesquisadas as pressões no repouso (PR, à tosse (T, à contração voluntária (CV, à contração voluntária mantida (CVM e à estimulação perianal (EPA. O reflexo reto-esficteriano (RRE foi testado e as curvas pressóricas simples e potencializada foram avaliadas. Foi elaborado traçado tridimensional de PFM. Utilizamos os testes t de Student, Qui-Quadrado e exato de Fisher para análise estatística (p<0,05. RESULTADOS: A MAR mostrou médias de PR=53,44 mmHg para DM e 60,67 mmHg para RTM; CV média = 94,50 mmHg para o grupo DM e 95,47 mmHg para o grupo RTM. Não houve diferença estatística entre os grupos. A forma das CPS e CPP não apresentou diferença estatística, independentemente da técnica cirúrgica utilizada CONCLUSÃO: As duas técnicas operatórias foram manometricamente equivalentes. DM determinou maior incidência de constipação pós-operatória que RTM. A

  9. Vineberg Procedure by "Vineberg technique modified by Lobo Filho": morbidity and mortality in the imediate post operative period, angiography results and flow analyze of the left internal thoracic artery implanted Procedimento de Vineberg pela técnica de "Vineberg modificada por Lobo Filho": morbi-mortalidade imediata, resultados angiográficos e análise do fluxo na artéria torácica interna esquerda implantada

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    José Glauco Lobo Filho

    2003-10-01

    êmica do ventrículo esquerdo. O principal questionamento acerca desse procedimento é a capacidade de fornecimento de fluxo sanguíneo adequado para o miocárdio isquêmico. OBJETIVOS: Avaliar os resultados angiográficos do procedimento de Vineberg pela técnica de Vineberg modificada por Lobo Filho e a morbi-mortalidade no pós-operatório imediato (POI, bem como analisar o fluxo na artéria torácica interna esquerda (ATIE implantada, em repouso e estresse. MÉTODO: De setembro de 1999 a abril 2002, em nosso serviço, oito pacientes foram operados pela técnica supracitada, na qual a introdução da artéria torácica interna na intimidade da musculatura do ventrículo esquerdo foi realizada com auxílio de um "kit" destinado à introdução de marcapassos cardíacos endocárdicos definitivos por punção da veia subclávia. Após seis meses, os pacientes foram estudados angiograficamente e submetidos ao ecodoppler da ATIE implantada. Para estudo do fluxo da ATIE pelo ecodoppler, constituímos dois grupos: "Grupo Vineberg", composto pelos oito pacientes citados; e o "Grupo Controle", composto por vinte pacientes, nos quais a ATIE foi utilizada para revascularizar diretamente a artéria interventricular anterior. O estudo angiográfico demonstrou perviabilidade de todos os enxertos em ambos os grupos. No estudo pelo ecodoppler, foram realizadas medidas de débito e velocidade de fluxo no enxerto. A análise dos dados obtidos foi feita pelo teste-T para amostras pareadas e não pareadas. RESULTADOS: Não houve óbitos ou complicações no POI. O estudo angiográfico demonstrou perviabilidade em 100% dos casos. O débito total observado foi cerca de 55% daquele encontrado no Grupo Controle. Em ambos os grupos, o débito total aumentou do repouso para o estresse. CONCLUSÃO: A técnica de Vineberg modificada por Lobo Filho pode ser utilizada com baixas taxas de morbi-mortalidade, alto índice de perviabilidade, oferecendo fluxo sanguíneo significativo em repouso e sob

  10. Modified constraint-induced movement therapy and modified forced-use therapy for stroke patients are both effective to promote balance and gait improvements Terapia de constrição com indução do movimento e terapia de uso forçado modificadas em pacientes pós-acidente vascular encefálico são eficientes em promover melhora do equilíbrio e da marcha

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    Amanda C. Fuzaro

    2012-04-01

    ção com indução do movimento (CIMT foram desenvolvidas objetivando a reversão do desuso aprendido do membro superior parético. Não se encontrou na literatura quais seriam os possíveis efeitos dessas técnicas na reabilitação da marcha e do equilíbrio. OBJETIVOS: Avaliar o efeito da FUT e da CIMT modificadas (mFUT e mCIMT na marcha e no equilíbrio durante quatro semanas de tratamento e três meses de seguimento. MÉTODOS: Este estudo incluiu 37 sujeitos hemiparéticos pós-AVE, divididos em dois grupos com base no protocolo de tratamento. A imobilização do membro superior não-parético foi feita por 23 horas ao dia, cinco dias por semana. Os sujeitos foram avaliados no início, durante quatro semanas de tratamento e três meses de acompanhamento. Para a avaliação, utilizou-se a Escala de Impacto do AVE (SIS, Berg Balance Scale (BBS e Fugl-Meyer Motor Assesment (FM. Para a marcha, utilizou-se o teste de caminhada de 10 metros (T10 e Timed Up & Go test (TUG. RESULTADOS: Ambos os grupos revelaram um melhor estado de saúde (SIS, melhor equilíbrio, com melhor utilização dos membros inferiores (BBS e FM e maior velocidade na marcha (T10 e TUG durante tratamento e seguimento em comparação com o início. CONCLUSÃO: Os resultados mostram que a mFUT e a mCIMT são eficazes para a reabilitação do equilíbrio e da marcha.

  11. Regeneration of clinoptilolite zeolite used for the ammonium removal; Regeneracion de zeolita clinoptilolita empleada para la remocion de amonio

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, M C

    2002-07-01

    The use of zeolites has been increased in the last years with different applications and with a great boom in the environmental area, but a little had been make about the regeneration of such zeolites. The presence of nitrogen-ammonia in water may cause serious pollution problems since it results to be toxic for fishes and other aquatic life forms, also it provokes the algae growing. The natural clinoptilolite contains interchangeable ions such as the sodium (Na{sup +}), potassium (K{sup +}), magnesium (Mg{sup 2+}) and calcium (Ca{sup 2+}) in different proportions depending on the mineral origin When the zeolite is upgraded to its sodium form, the cation exchange capacity and the preference by the nitrogen-ammonia are increased, allowing the reversible process of sorption. In this work it was proposed the regeneration to its sodium form about the ammonia clinoptilolite zeolite. The natural mineral was characterized using the methods such as: X-ray diffraction, Infrared spectroscopy, Thermal gravimetric analysis and surface area. The results show that the ammonium sorption was between 95% and 98.7% such an ambient temperature as a flow back. the zeolite was regenerated approximately from 60% in the first cycle up to 97% in the last cycle at flow back temperature and of 59.2% up to 96.9% at ambient temperature, it was not presented any significant effect which could be attributed to the temperature. During the exchange process, the cations present in the natural zeolite were exchanged with the ammonium ions, this process was not completed due to that retained ammonium quantity was major that of the desorpted ions, what shows that in addition of ion exchange, another type of sorption process exists. (Author)

  12. Generación de mesoporosidad en zeolitas ZSM-5 sintetizadas en medio inorgánico

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    Carmen M. López

    2011-10-01

    Full Text Available In this work we presented a study over the generation of mesoporosity in ZSM-5 zeolites with ratio Si/Al of 10 and 35 synthesized in inorganic medium. A mesoporous phase with hexagonal arrangement that coexists with the zeolite ZSM-5 remnant, was obtained after alkaline treatment of zeolite followed by hydrothermal treatment in the presence of CTAB surfactant micelles. The acidity and catalytic activity of the zeolite ZSM-5 with higher relation Si/Al were kept after the treatment, whereas a notable decrease of these properties was obtained for the zeolite with minor relation Si/Al

  13. Evaluación de procedimientos de extracción de cinc presente en una zeolita activada

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    Mercedes Machúa Veitía

    1999-08-01

    Full Text Available Los productos activos zeolíticos (PAZ están enriquecidos con un catión que en nuestro caso determina su acción antimicrobiana. Se establecieron las condiciones para la extracción de este elemento, considerando las características intrínsecas de esta materia prima y sus formas terminadas tabletas y cremas. Se realizan diferentes tratamientos a las muestras optimizando las condiciones de trabajo. La determinación del contenido de cinc se realiza por fluorescencia de rayos X y espectrofotometría de absorción atómica. Se estableció el ataque triácido con H2SO4 HNO3 (2:3 y HCl como óptimo para el tratamiento de cremas y tabletas, mientras que el principio activo (PAZ se trató con intercambio iónico.Active zeolite products (AZP are enriched with a cathion that determines their animicrobial effects. The extraction conditions were set taking inherent features of the raw material and its forms - tablets and creams - into account. Different treatment were applied to samples under optimized working conditions. Zinc conten was estimated by X - ray fluorescence and atomic absorption spectrophotometry. There - acid effect treatment with H2DO4 HNO (2:3 and HCL as an optimal method for treatting tablets and creams was shown whereas the active principla (AZ was treated with ion - exchange.

  14. Preparación y caracterización de la zeolita MCM-22 y de su precursor laminar

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    Pergher Sibele B. C.

    2003-01-01

    Full Text Available The layered precursor of MCM-22 was prepared with different Si/Al ratios: 15, 25, 50, 100 and ¥. Upon heat treatment these precursors form MCM-22 zeolite. Both layered precursor and MCM-22 zeolite were characterized by several techniques: Chemical Analysis by Atomic Absorption Spectroscopy (AAS, X-Ray Diffraction (XRD, Thermo-gravimetric Analysis (TGA, Pore Analysis by N2 and Ar adsorption, Scanning Electron Microscopy (SEM, Infrared Spectroscopy (IR and Temperature Programmed Desorption of ammonium (TPD.

  15. Sorption of Cs-137 and Co-60 in Natural Zeolites; Sorcion de Cs-137 y Co-60 en zeolitas naturales

    Energy Technology Data Exchange (ETDEWEB)

    Chales Suarez, G; Moreno Alvarez, D; Coutin Correa, D [Agencia de Energia Nuclear, La Habana (Cuba)

    1996-07-01

    The sorption of Cs-137 and Co-60 in natural zeolites under different conditions was studied. The behaviour of samples of mineral and rock from different deposit of the country was obtained and the decontamination of radioactive waters containing both radionuclides was performed; as part of the research to determine its application in the treatment of radioactive wastes in the country.

  16. On two alternative mechanisms of ethane activation over ZSM-5 zeolite modified by Zn2+ and Ga1+ cations

    NARCIS (Netherlands)

    Kazansky, V.B.; Subbotina, I.R.; Rane, N.J.; Santen, van R.A.; Hensen, E.J.M.

    2005-01-01

    The activation of ethane over zinc- and gallium-modified HZSM-5 dehydrogenation catalysts was studied by diffuse reflectance infrared spectroscopy. Hydrocarbon activation on HZSM-5 modified by bivalent Zn and univalent Ga cations proceeds via two distinctly different mechanisms. The stronger

  17. Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts

    NARCIS (Netherlands)

    Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.

    2016-01-01

    Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved

  18. Structural aspects of crotoxin modified by ionizing radiation; Aspectos estruturais da crotoxina modificada pela radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Karina Corleto de; Albero, Felipe Guimaraes; Zezell, Denise Maria; Spencer, Patrick Jack; Nascimento, Nanci do, E-mail: kcorleto@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-03-15

    Ionizing radiation has proven to be an excellent tool for reducing the toxicity of venoms and isolated toxins, resulting in better immunogens for serum production, the only effective treatment in case of snake bites, and contributing to the welfare of serum-producing animals. Since the action of gamma radiation of venoms and toxins has not been yet fully clarified from the structural point of view, we proposed in this paper, to characterize the crotoxin, a venom protein of the species Crotalus durissus terrificus by Circular Dichroism (CD) and Infrared Spectroscopy (FTIR) techniques. After chromatographic techniques, crotoxin was irradiated with 2.0 kGy ({sup 60}Co source). The CD spectra obtained of native and irradiated crotoxin solutions showed changes between the samples in characteristic regions of -sheet and-helix . The Infrared analyse showed expressive changes in the spectra of the native and irradiated crotoxin (amide I band region). These tests showed that crotoxin when subjected to gamma radiation, showed changes in their structural conformation compared with the samples in the native state. Such changes probably occur in the secondary structure and may explain its neurotoxic activity loss. (author)

  19. Fluxo gênico recíproco entre cultivares de soja convencional e geneticamente modificada

    Directory of Open Access Journals (Sweden)

    Welison Andrade Pereira

    2012-02-01

    Full Text Available O objetivo deste trabalho foi determinar o fluxo gênico recíproco entre duas cultivares de soja, uma tolerante e outra sensível ao glifosato, além de aplicar estimadores para determinar a taxa de fecundação cruzada na população e o número de sementes híbridas na progênie. O experimento compôs-se de quatro blocos com 40 fileiras de soja, com 20 fileiras de cada cultivar (CD217 e CD219RR. No estádio R8, cinco fileiras, distantes 0, 5, 1, 2, 4 e 8 m da cultivar adjacente, foram colhidas, trilhadas e analisadas quanto à ocorrência de fluxo gênico. Como características marcadoras, foram utilizadas as cores da flor, hipocótilo e pubescência, e a tolerância ao glifosato. As cultivares contrastam quanto às características analisadas, cada uma condicionada por um gene com dois alelos, em interação de dominância completa. Na progênie da cultivar tolerante, a maior taxa de híbridos encontrada foi 0, 27% e, na progênie da cultivar sensível, identificou-se 0, 83%; pela hipótese do efeito diluição, as taxas de hibridação natural populacional seriam 0, 104 e 0, 388%, respectivamente. O fluxo gênico recíproco entre as cultivares CD217 e CD219RR não é o mesmo em ambas as direções. Os estimadores propostos são úteis para determinar a taxa de híbridos em amostras de sementes.

  20. Qualidade de melão minimamente processado armazenado em atmosfera modificada passiva

    Directory of Open Access Journals (Sweden)

    Arruda Maria Cecília de

    2003-01-01

    Full Text Available Frutos de melão do tipo, rendilhado cv. Bônus II, foram minimamente processados na forma de cubos e acondicionados em embalagens de diversos materiais sendo, em seguida, armazenados a 3ºC. Nas embalagens foram utilizados os materiais: AFG: filme poliolefínico da DuPont 15µm, HP: filme poliolefínico da DuPont 15µm, PD-900: filme poliolefínico da Cryovac 58µm, PEBD: filme de polietileno de baixa densidade 87µm, PP: filme de polipropileno 52µm, BB-200: filme multicamada da Cryovac 65µm, PET: embalagem rígida de polietereftalato de etileno. Foram determinadas as taxas de permeabilidade ao O2 e ao CO2 de cada uma das embalagens. As composições gasosas do espaço livre das embalagens foram determinadas diariamente durante 8 dias e no 9º dia as características físico-químicas e sensoriais foram avaliadas. A taxa respiratória foi determinada nos melões inteiros e nos melões minimamente processados. Os filmes utilizados não promoveram modificação efetiva da atmosfera, mas a embalagem rígida de PET proporcionou, a partir do 6º dia, uma atmosfera de equilíbrio com 12% O2 e 7% CO2. As características físico-químicas dos melões foram mantidas em todos os tratamentos, enquanto as características sensoriais foram mantidas apenas nos melões acondicionados na embalagem rígida de PET. A modificação passiva da atmosfera, para melão minimamente processado armazenado a 3ºC, não foi verificada na extensão desejada com as embalagens estudadas, provavelmente devido à baixa taxa respiratória observada nesta temperatura, associada à alta relação entre área de permeação da embalagem e massa de melão.

  1. Synthesis and application of different phthalocyanine molecular sieve catalyst for oxidative desulfurization

    Science.gov (United States)

    Zhao, Na; Li, Siwen; Wang, Jinyi; Zhang, Ronglan; Gao, Ruimin; Zhao, Jianshe; Wang, Junlong

    2015-05-01

    M2(PcAN)2 (M=Fe, Co, Ni, Cu, Zn and Mn) anchored onto W-HZSM-5 (M2(PcAN)2-W-HZSM-5) or the M2(PcTN)2 doping W-HZSM-5 (M2(PcTN)2/W-HZSM-5) were prepared and their catalytic performances were tested for oxidative desulfurization in the presence of oxygen. Thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) were considered as sulfur compounds. Among zeolite-based catalysts, the Cu2(PcAN)2-W-HZSM-5 and Cu2(PcTN)2/W-HZSM-5 showed superior desulfurization performance and the activity of selectivity followed the order: T>BT>DBT. The effects of phthalocyanine concentration were studied by UV-Vis and calcination temperature was obtained by TG-DSC for Cu2(PcTN)2/W-HZSM-5. Catalysts were characterized by EA, IR, XRD, SEM, TEM, ICP, and N2 adsorption. Reaction time, temperature and the amount of catalyst were investigated as the important parameters for optimization of the reaction. Furthermore, a possible process of oxidative desulfurization and the reaction products were proposed. The reaction process of ultra-deep desulfurization.

  2. The mild liquid-phase synthesis of 3-picoline from acrolein diethyl acetal and ammonia over heterogeneous catalysts

    Science.gov (United States)

    Luo, Cai-Wu; Chao, Zi-Sheng; Lei, Bo; Wang, Hong; Zhang, Jun; Wang, Zheng-Hao

    2017-11-01

    The liquid-phase synthesis of 3-picoline from the reaction of acrolein diethyl acetal and ammonia over ion-exchanged resins (D402 and D002) and HZSM-5 (Si/Al = 25) was carried out in a batch reactor. Various influencing parameters, including by the addition of water, ion-exchanged resins, reaction temperature and HZSM-5, were systematically investigated. The results showed that the reaction could be directly conducted, and organic acid wasn’t utilized. The highest yield of 3-picoline reached up to 24% using HZSM-5 as catalyst at 110 °C.

  3. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Administrator

    reaction on medium pore HZSM-5 zeolites differing in crystal size and ... effect of various parameters on the yield and cy- ... toluene. (DIPT) + water (cymene isopropylation) .... tain the stability of the mordenite catalysts. .... From the slope of the.

  4. D2-H2 equilibration over γ-irradiated zeolites

    International Nuclear Information System (INIS)

    Novakova, J.; Wichterlova, B.

    1987-01-01

    D 2 -H 2 equilibration was studied at 77 and 298 K over HY, AlHY, HZSM-5 and Alsub(x)Osub(y)HZSM-5 zeolites which had been γ-irradiated at 77 and/or 298 K. The exchange rate was found to be higher at the lower temperature regardless of the temperature of irradiation. Moreover, at 77 K the exchange rates were similar and more stable over the individual zeolites than at 298 K, thus indicating a common reaction path at 77 K. The exchange rate at 298 K depended on the zeolite type: it was more stable and higher over HZSM-5 than over HY, and extra-lattice Al increased both these properties on HY as well as on HZSM-5. The reaction mechanism is discussed in connection with the nature of defects generated by γ-irradiation. (author)

  5. In-situ catalytic upgrading of biomass pyrolysis vapor: Using a cascade system of various catalysts in a multi-zone fixed bed reactor

    International Nuclear Information System (INIS)

    Asadieraghi, Masoud; Wan Daud, Wan Mohd Ashri

    2015-01-01

    Highlights: • A cascade system of different catalysts exhibited the best performance to produce high quality bio-oil. • Meso-HZSM-5, Ga (1 wt.%)/meso-HZSM-5 and Cu (5 wt.%)/SiO 2 were employed in a cascade system. • The incorporation of the appropriate gallium amount to meso-HZSM-5 enhanced the aromatics selectivity. • Meso-HZSM-5 indicated a very good activity in bio-oil upgrading. - Abstract: The in-situ catalytic upgrading of palm kernel shell (PKS) fast pyrolysis vapors was performed over each individual meso-H-ZSM-5, Ga/meso-HZSM-5 and Cu/SiO 2 catalyst or a cascade system of them in a multi-zone fixed bed reactor. The effects of mesoporosity creation into the parent H-ZSM-5 catalyst and also gallium incorporation into mesoporous H-ZSM-5 on the produced bio-oil chemical composition and distribution were studied. Key upgrading reactions for different oxygenated compounds in pyrolysis oil (small oxygenates, lignin derived and sugar derived components), including aldol condensation, alkylation, hydrogenation, aromatization, and deoxygenation were discussed. The catalysts were characterized using SEM, XRF, XRD, N 2 adsorption and NH 3 -TPD methods. Furthermore, the produced bio-oils (catalytic and non-catalytic) were analyzed using GC–MS, FTIR, CHNS/O elemental analyzer and Karl Fischer titration. Production of the upgraded bio-oil with lower content of oxygenated compound was the main objective of this investigation. Among different catalysts, meso-H-ZSM-5 zeolite demonstrated a very good activity in aromatization and deoxygenation during the upgrading of pyrolytic vapors, although it decreased the bio-oil yield (32.6 wt.%). The gallium incorporation into the meso-HZSM-5 zeolite increased the bio-oil yield from 32.6 wt.% (meso-HZSM-5) to 35.8 wt.% (using 1.0 wt.% Ga). Furthermore, the aromatics selectivity was enhanced when the appropriate amount of gallium (1.0 wt.%) was introduced. A cascade system of various catalysts comprising meso-HZSM-5, Ga (1

  6. Heterogeneously Catalyzed Endothermic Fuel Cracking

    Science.gov (United States)

    2016-08-28

    reactor was circumferentially delivered from a 4.2 kW array consisting of 4 independently PID controlled fiber insulated heaters (Zircar ceramics, FIH...the H-ZSM- 5 lattice and Brønsted acid site characteristics” Micropor . Mesopor. Mater., 222 (2016) 256−270. DISTRIBUTION A: Distribution...distribution on the H-ZSM-5 lattice and Brønsted acid site characteristics" Micropor . Mesopor. Mater., 222 (2016) 256-270. S. M. Opalka, H. Huang

  7. Synthesis and application of different phthalocyanine molecular sieve catalyst for oxidative desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Na; Li, Siwen; Wang, Jinyi; Zhang, Ronglan [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Material Science, Northwest University, Xi’an 710069, Shaanxi (China); Composites Research Institute, Weinan Normal University, Weinan 714000 (China); Gao, Ruimin [Research Institute of Shaanxi Yanchang Petroleum Group Corp. Ltd., Xi’an 710075 (China); Composites Research Institute, Weinan Normal University, Weinan 714000 (China); Zhao, Jianshe, E-mail: jszhao@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry & Material Science, Northwest University, Xi’an 710069, Shaanxi (China); Composites Research Institute, Weinan Normal University, Weinan 714000 (China); Wang, Junlong [Research Institute of Shaanxi Yanchang Petroleum Group Corp. Ltd., Xi’an 710075 (China); Composites Research Institute, Weinan Normal University, Weinan 714000 (China)

    2015-05-15

    M{sub 2}(PcAN){sub 2} (M=Fe, Co, Ni, Cu, Zn and Mn) anchored onto W-HZSM-5 (M{sub 2}(PcAN){sub 2}–W-HZSM-5) or the M{sub 2}(PcTN){sub 2} doping W-HZSM-5 (M{sub 2}(PcTN){sub 2}/W-HZSM-5) were prepared and their catalytic performances were tested for oxidative desulfurization in the presence of oxygen. Thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) were considered as sulfur compounds. Among zeolite-based catalysts, the Cu{sub 2}(PcAN){sub 2}–W-HZSM-5 and Cu{sub 2}(PcTN){sub 2}/W-HZSM-5 showed superior desulfurization performance and the activity of selectivity followed the order: T>BT>DBT. The effects of phthalocyanine concentration were studied by UV–Vis and calcination temperature was obtained by TG-DSC for Cu{sub 2}(PcTN){sub 2}/W-HZSM-5. Catalysts were characterized by EA, IR, XRD, SEM, TEM, ICP, and N{sub 2} adsorption. Reaction time, temperature and the amount of catalyst were investigated as the important parameters for optimization of the reaction. Furthermore, a possible process of oxidative desulfurization and the reaction products were proposed. - Graphical abstract: The ODS reaction schematic shows the reaction mechanism of ultra-deep desulfurization. The sulfur compounds are oxidized to their corresponding sulfoxides or sulfones through the use of oxygen and catalysts. The reaction process of ultra-deep desulfurization. - Highlights: • A kind of novel catalyst for deep desulfurization was synthesized. • Cu{sub 2}(PcAN){sub 2}–W-HZSM-5 exhibits excellent catalytic performance for desulfurization. • The reaction conditions that affect desulfurization efficiency are investigated. • The reaction process of model sulfur compounds is proposed.

  8. Synthesis and application of different phthalocyanine molecular sieve catalyst for oxidative desulfurization

    International Nuclear Information System (INIS)

    Zhao, Na; Li, Siwen; Wang, Jinyi; Zhang, Ronglan; Gao, Ruimin; Zhao, Jianshe; Wang, Junlong

    2015-01-01

    M 2 (PcAN) 2 (M=Fe, Co, Ni, Cu, Zn and Mn) anchored onto W-HZSM-5 (M 2 (PcAN) 2 –W-HZSM-5) or the M 2 (PcTN) 2 doping W-HZSM-5 (M 2 (PcTN) 2 /W-HZSM-5) were prepared and their catalytic performances were tested for oxidative desulfurization in the presence of oxygen. Thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) were considered as sulfur compounds. Among zeolite-based catalysts, the Cu 2 (PcAN) 2 –W-HZSM-5 and Cu 2 (PcTN) 2 /W-HZSM-5 showed superior desulfurization performance and the activity of selectivity followed the order: T>BT>DBT. The effects of phthalocyanine concentration were studied by UV–Vis and calcination temperature was obtained by TG-DSC for Cu 2 (PcTN) 2 /W-HZSM-5. Catalysts were characterized by EA, IR, XRD, SEM, TEM, ICP, and N 2 adsorption. Reaction time, temperature and the amount of catalyst were investigated as the important parameters for optimization of the reaction. Furthermore, a possible process of oxidative desulfurization and the reaction products were proposed. - Graphical abstract: The ODS reaction schematic shows the reaction mechanism of ultra-deep desulfurization. The sulfur compounds are oxidized to their corresponding sulfoxides or sulfones through the use of oxygen and catalysts. The reaction process of ultra-deep desulfurization. - Highlights: • A kind of novel catalyst for deep desulfurization was synthesized. • Cu 2 (PcAN) 2 –W-HZSM-5 exhibits excellent catalytic performance for desulfurization. • The reaction conditions that affect desulfurization efficiency are investigated. • The reaction process of model sulfur compounds is proposed

  9. Role of Brønsted acid in selective production of furfural in biomass pyrolysis.

    Science.gov (United States)

    Zhang, Haiyan; Liu, Xuejun; Lu, Meizhen; Hu, Xinyue; Lu, Leigang; Tian, Xiaoning; Ji, Jianbing

    2014-10-01

    In this work, the role of Brønsted acid for furfural production in biomass pyrolysis on supported sulfates catalysts was investigated. The introduction of Brønsted acid was shown to improve the degradation of polysaccharides to intermediates for furfural, which did not work well when only Lewis acids were used in the process. Experimental results showed that CuSO4/HZSM-5 catalyst exhibited the best performance for furfural (28% yield), which was much higher than individual HZSM-5 (5%) and CuSO4 (6%). The optimum reaction conditions called for the mass ratio of CuSO4/HZSM-5 to be 0.4 and the catalyst/biomass mass ratio to be 0.5. The recycled catalyst exhibited low productivity (9%). Analysis of the catalysts by Py-IR revealed that the CuSO4/HZSM-5 owned a stronger Brønsted acid intensity than HZSM-5 or the recycled CuSO4/HZSM-5. Therefore, the existence of Brønsted acid is necessary to achieve a more productive degradation of biomass for furfural. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Optimizing anti-coking abilities of zeolites by ethylene diamine tetraacetie acid modification on catalytic fast pyrolysis of corn stalk

    Science.gov (United States)

    Zhang, Bo; Zhong, Zhaoping; Song, Zuwei; Ding, Kuan; Chen, Paul; Ruan, Roger

    2015-12-01

    In order to minimize coke yield during biomass catalytic fast pyrolysis (CFP) process, ethylene diamine tetraacetie acid (EDTA) chemical modification method is carried out to selectively remove the external framework aluminum of HZSM-5 catalyst. X-ray diffraction (XRD), nitrogen (N2)-adsorption and ammonia-temperature programmed desorption (NH3-TPD) techniques are employed to investigate the porosity and acidity characteristics of original and modified HZSM-5 samples. Py-GC/MS and thermo-gravimetric analyzer (TGA) experiments are further conducted to explore the catalytic effect of modified HZSM-5 samples on biomass CFP and to verify the positive effect on coke reduction. Results show that EDTA treatment does not damage the crystal structure of HZSM-5 zeolites, but leads to a slight increase of pore volume and pore size. Meanwhile, the elimination of the strong acid peak indicates the dealumination of outer surface of HZSM-5 zeolites. Treatment time of 2 h (labeled EDTA-2H) is optimal for acid removal and hydrocarbon formation. Among all modified catalysts, EDTA-2H performs the best for deacidification and can obviously increase the yields of positive chemical compositions in pyrolysis products. Besides, EDTA modification can improve the anti-coking properties of HZSM-5 zeolites, and EDTA-2H gives rise to the lowest coke yield.

  11. Niobium (V) doped bioceramics: evaluation of the hydrothermal route modified with citric acid and urea to obtain modified hydroxyapatite; Bioceramicas aditivadas com niobio (V): avaliacao da rota hidrotermica modificada com acido citrico e ureia para obtencao de hidroxiapatitas modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Simomukay, E.; Souza, E.C.F. de; Antunes, S.R.M.; Borges, C.P.F.; Michel, M.D.; Antunes, A.C. [Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, PR (Brazil)

    2016-01-15

    Synthetic hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HA) has become a widely used ceramic material for bone reconstruction due to its biocompatibility with the bone tissue. This biocompatibility as well as other physical and chemical properties of the hydroxyapatite can be modified by the addition of different ions to its structure. Niobium (V) ion has not been commonly used in the hydroxyapatite synthesis. The objective of this study was to evaluate the use of hydrothermal route in the niobium (V) doped hydroxyapatite synthesis. The route used the niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO(C{sub 2}O{sub 4}){sub 3}].3H{sub 2}O) complex as a niobium (V) ion precursor. The addition of citric acid and urea in the hydrothermal route is used for the control of synthesis pH and precipitation rate. Pure sample and sample added with 5.3 ppm of niobium (V) ion were prepared. The coexistence of other phases besides the hydroxyapatite was not observed in any of the samples through the use of X-ray diffraction and infrared spectroscopy (FTIR) techniques. The FTIR technique revealed the presence of hydroxyapatite characteristic functional groups. The scanning electron microscopy analysis showed the formation of agglomerates composed of round particles, confirmed by the transmission electron microscopy technique. The X-ray fluorescence spectroscopic analysis detected the presence of niobium in the doped sample. The results showed that niobium (V) doped hydroxyapatite can be synthesized by means of hydrothermal route, which may be considered as huge potential for future application in bioceramics. (author)

  12. Zeolite and wollastonite synthesis from rice hull ash; Sintese de zeolitas e wolastonita a partir da cinza da casca de arroz

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Alberto de Andrade

    2006-07-01

    Rice hull ash (RHA) is a industry scrap rich in amorphous silica. A simple and low-energy cost method for the extraction of this silica was researched. A low level of impurity and high reactivity material was produced, which is appropriate for the synthesis of zeolites and wollastonite (CaSiO{sub 3}). The synthetic zeolites has not similar structures in nature, and they have been more and more valued in the market due to their purity and efficiency in specific applications like ion exchange, molecular sieve and catalysis areas. High purity wollastonite has many applications in manufacturing and agriculture. The mineral wollastonite can be formed in nature in different ways; it is generally accepted two forming processes, both encompassing limestone metamorphism (heat and pressure). In this work, a new process for the synthesis of zeolites and wollastonite from RHA colloidal silica was developed. Moreover, the process is aimed at lower energy costs, fewer stages and fewer reactants consume. In this work, zeolite A used in detergent and zeolite ZSM-5, employed in the petrochemical industry due to its high selectivity in catalytic reactions and its high thermo and acid stability, were synthesized. The first step of the wollastonite synthesis was studied, with the purpose of obtaining calcium hydrosilicate. Eleven different hydrosilicates occur in the system Ca(OH){sub 2}-SiO{sub 2}-H{sub 2}O, in the second step it was annealed to form the wollastonite phase. (author)

  13. Síntesis de zeolitas a partir de cenizas volantes de centrales termoeléctricas de carbón

    OpenAIRE

    Umaña Peña, Juan Carlos

    2002-01-01

    Los sub-productos de combustión del carbón producidos en centrales térmicas, están compuestos generalmente por más de un 70% de material vítreo aluminosilicatado. Esta composición los hace potencialmente utilizables en obras de ingeniería civil o alternativamente como rellenos inertes en minería, así como adsorbentes, inmovilizadores, fuente alternativa en la extracción de Al, Fe, Si, Ge, Ga, V y Ni, y aditivos en suelos.Las cenizas volantes se caracterizan por una distribución granulométrica...

  14. Arsenic adsorption in pre-treatment natural zeolite with magnesium oxides; Adsorcion de arsenico en zeolita natural pretratada con oxidos de magnesio

    Energy Technology Data Exchange (ETDEWEB)

    Mejia Z, F. [Universidad Autonoma de Baja California, Instituto de Ingenieria, Blvd. Benito Juarez s/n, 21900 Mexicali, Baja California (Mexico); Valenzuela G, J. L.; Aguayo S, S.; Meza F, D., E-mail: fleridam@iq.uson.m [Universidad de Sonora, Departamentos de Geologia e Ingenieria Quimica y Metalurgia, Blvd. Luis Encinas y Rosales s/n, Col. Centro, 83000 Hermosillo, Sonora (Mexico)

    2009-07-01

    A methodology was developed to modify a natural zeolite (chabazite) with magnesium oxide in order to remove arsenic (As{sup +5}) from water for human consumption. It is proposed a magnesium oxide while regarded as an efficient adsorbent for removing metals in water. X-ray diffraction analyses show significant changes in the chabazite due to the presence of oxides and amorphous hydroxides incorporated during the pre-treatment. Experimental design results show an efficiency greater than 90% of As{sup +5} adsorbed in five minutes. The results indicate that the most significant variables affecting the adsorption of As{sup +5} are the initial concentration of As and the solid/liquid ratio. Experimental data fitted better to Freundlich isotherm with a 20.17 mg/g adsorption capability. (Author)

  15. Combined used of natural zeolites and microalgaes for the denitrification of wastewater from fertilizer plants; Uso combinado de zeolitas naturales y microalgas en la denitrificacion de aguas residuales

    Energy Technology Data Exchange (ETDEWEB)

    Soca Olazabal, N.; Blanco Toledo, F.; Pizarro Camacho, D.

    1997-06-01

    In our work we investigated the process of denitrification of waster-water with high percentage of nitrate and ammonia using natural zeolites that can be used later in agricultures fertilizer, because of the nitrogen load received. This effluents was used for micro algae growth reducing the nitrate concentration, the micro algae was Chlorella Vulgaris. The zeolite reduced the NH``+{sub 4} concentration up to 5 mg/l. and the NH``+{sub 4} concentration in the zeolite, it si very important in the agriculture. The chlorella Vulgaris reduces 30 mg/l of nitrate in six hours in the steady state. (Author) 9 refs.

  16. Ammonia removal from high salt waste water using natural zeolite; Remocao de amonia de efluentes de alta salinidade utilizando zeolita natural

    Energy Technology Data Exchange (ETDEWEB)

    Geraldo, Lucia M.L. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Arroyo, Pedro A. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Barros, Maria Angelica S.D.; Pazin, Elenice [Universidade Estadual de Maringa (UEM), PR (Brazil). Dept. de Quimica; Zola, Andreia S.; Zschornack, Marlon A. [Universidade Estadual de Maringa (UEM), PR (Brazil). Dept. de Quimica. Pos-Graduacao em Engenharia Quimica

    2008-07-01

    The present work aimed to study ammonium ion exchange using a fixed bed of natural zeolite clinoptilolite. First of all, it was carried out a bi component ion exchange of ammonium (150 mg/L) in the presence of K{sup +}, Ba{sup 2+}, Ca{sup 2+}, Sr{sup 2+} e Mg{sup 2+}. Thus, clinoptilolite showed a preference for strontium, barium and potassium cations, while there is a higher preference for Nh{sub 4}{sup +} cations instead calcium and magnesium. Secondly, it was studied the multicomponent ion exchange of ammonium (solution containing all cations). It was observed that the presence of competing cations decreases the content of ammonium retained in the bed until breakthrough point. Furthermore, it was also verified that multicomponent exchange in the presence of high salinity solution (60.000 mg/L of Na{sup +}), sodium influences the ion exchange mechanism, decreasing the up take capacity of ammonium for zeolitic bed. On the other hand, ammonium capture increases in the presence of natural effluent that possesses lower salinity (30.000 mg/L). Therefore, the results obtained evidence the application potentiality of clinoptilolite for ammonia up takes from industrial effluents, in what competition conditions by others cations are too severe and for that the zeolite natural presented good performance. (author)

  17. Zeolitas para la obtención y redistribución de aromáticos en la fracción BTX

    OpenAIRE

    Portilla Ovejero, Mª Teresa

    2016-01-01

    [EN] This thesis focusses on reactive processes catalysed by zeolites to obtain and convert BTX aromatics. These compounds, together with light olefins, are the pillars of the petrochemical and organic chemical industry, as they are the raw materials to produce basic intermediates, such as polyester monomers, polyamides, engineering plastics and intermediate products for the manufacture of detergents, pharmaceuticals, fertilizers, and explosives. Currently, the aromatics and light olefins...

  18. Sorption of cobalt in zeolites and natural clays of the clinoptilolite and kaolinite type; Sorcion de cobalto en zeolitas y arcillas naturales del tipo clinoptilolita y caolinita

    Energy Technology Data Exchange (ETDEWEB)

    Davila R, J.I.; Solache R, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2006-07-01

    In this work the sorption of cobalt of aqueous solutions in two natural zeolites (clinoptilolite) and a clay (kaolinite) of origin in the center-north region of Mexico is evaluated. The effect of the pH and the time of contact in the process of sorption were evaluated. The cobalt retained in the aluminosilicates was determined by neutron activation analysis. The cobalt sorption in the materials in a range of pH from 4 to 7 does not present significant variations. The studies of reaction kinetics show a very fast sorption in the first 5 hours of contact, reaching the equilibrium in approximately 24 hours. The kinetics of sorption of the cobalt ions was represented better by the Ritchie reaction model modified of second order. The experimental data for the zeolites obtained at ambient temperature and varying the concentration were adjusted to the models of Freundlich, Langmuir and Freundlich-Langmuir isotherms and it was observed that the cobalt sorption it behaves according to the Freundlich isotherm model. (Author)

  19. Zeolite A synthesized from wastes of kaolin improvement process; Zeolita A sintetizada a partir de rejeitos do processo de beneficiamento de caulim

    Energy Technology Data Exchange (ETDEWEB)

    Santana, D.L.; Neves, R.F.; Silva, D.L., E-mail: danielaliraeq@yahoo.com.br, E-mail: dasilva@ufpa.br [Programa de Pos-Graduacao em Engenharia Quimica, Universidade Federal do Para - UFPA, Belem, PA (Brazil); Saraiva, A.C.F. [Centro de Tecnologia da Eletronorte, Belem, PA (Brazil)

    2012-04-15

    Raw materials were used to synthesize zeolite A as an alternative and more economical source of silica and aluminum, using waste from the kaolin of the paper industry. Zeolites are crystalline substances with a structure characterized by a framework of linked tetrahedra, each one consisting of four oxygen atoms surrounding a cation. The development of processes for the synthesis of zeolites is of great interest for use in the areas of purification, adsorption and catalysis. The starting materials for the synthesis of zeolite A consisted of wastes from kaolin beneficiation of paper companies of Para state, Brazil. The zeolite was obtained after calcination at 85 and 110 deg C during 24 h. The characterization of the starting material was performed by X-ray diffraction, chemical analysis, thermogravimetric and differential thermal analysis, and scanning electron microscopy. The characterization of zeolite A was done by X-ray diffraction and scanning electron microscopy. The kaolin waste used as starting material showed to be essentially kaolinite mineral. For the temperatures and time used in the synthesis it was possible to form the crystalline phase of zeolite A for the two starting materials. (author)

  20. Obtaining of iron particles of nanometer size in a natural zeolite; Obtencion de particulas de hierro de tamano nanometrico en una zeolita natural

    Energy Technology Data Exchange (ETDEWEB)

    Xingu C, E. G.

    2013-07-01

    The zeolites are aluminosilicates with cavities that can act as molecular sieve. Their crystalline structure is formed by tetrahedrons that get together giving place to a three-dimensional net, in which each oxygen is shared by two silicon atoms, being this way part of the tecto silicate minerals, its external and internal areas reach the hundred square meters for gram, they are located in a natural way in a large part of earth crust and also exist in a synthetic way. In Mexico there are different locations of zeolitic material whose important component is the clinoptilolite. In this work the results of three zeolitic materials coming from San Luis Potosi are shown, the samples were milled and sieved for its initial characterization, to know its chemical composition, crystalline phases, morphology, topology and thermal behavior before and after its homo-ionization with sodium chloride, its use as support of iron particles of nanometer size. The description of the synthesis of iron particles of nanometer size is also presented, as well as the comparison with the particles of nanometer size synthesized without support after its characterization. The characterization techniques used during the experimental work were: Scanning electron microscopy, X-ray diffraction, Infrared spectroscopy, specific area by means of BET and thermogravimetry analysis. (Author)

  1. Comparative study of cerium (IV) sorptive properties in zeolite Y and clinoptilolite; Estudio comparativo de la fijacion de cerio (IV) en zeolitas, faujasita-Y y clinoptilolita

    Energy Technology Data Exchange (ETDEWEB)

    Garcia D, O C

    1994-12-31

    Among the problems of protecting the environment from radioactive contamination, the reduction of radioactive releases by improving monitoring, decontamination, and burial methods is one of the most important. Natural sorbents are gaining increased significance for solving this problem. Among these, zeolites deserve special attention since they have sufficient sorptive capacity, are highly radiation resistant, are widely distributed exhibit selectivity and are inexpensive. In the present work we determine experimentally the sorptive characteristics of clinoptilolite as a function of various factors and demonstrate that clinoptilolite is capable of sorbing Ce(IV) over a wide pH range. (Author).

  2. Synthesis of zeolites from boiler fly ash: physical, chemical and mineralogical characterization; Sintese de zeolitas a partir de cinza volante de caldeiras: caracterizacao fisica, quimica e mineralogica

    Energy Technology Data Exchange (ETDEWEB)

    Rocha Junior, C.A.F.; Santos, S.C.A.; Souza, C.A.G., E-mail: augustorocha2@gmail.com [Programa de Pos Graduacao em Engenharia Quimica (PPEQ-UFPA), Belem, PA (Brazil); Angelica, R.S.; Neves, R.F. [Programa de Pos-Graduacao em Geologia e Geoquimica, Instituto de Geociencias (PPGG-IG-UFPA), Ananindeua, PA (Brazil)

    2012-01-15

    Along the years, worldwide industrial development has causing a growing generation of residues, bringing potentials environmental problems. A study of the characteristics of these wastes, as well as the development of techniques for their use in new processes becomes indispensable for the environment preservation. The main purpose of this work is to evaluate the possible use of two important industrial residues from the Amazon region for zeolite synthesis: (a) the fly ash (particle size < 100 {mu}m) that comes from burning of mineral coal in boiler; and (b) the micro silica, a by-product of the reaction between quartz and coal in the production of metallic silicon and alloys iron-silicon.The following chemical, physical and mineralogical characterization methods were carried out: X-ray diffractometry, X-ray fluorescence, scanning electron microscopy, granulometric analysis, differential thermal and thermogravimetric analysis (DTA-TG). The analyses were carried out at the following conditions: 60, 100, 150 and 190 deg C, Na{sub 2}O/Al{sub 2}O{sub 3} molar ratio of 5 and Si/Al molar ratio ranging from 2.12 to 15, and reaction time of 24 h. The results of the fly characterization demonstrate its enormous potential as raw material for the zeolite synthesis. SiO{sub 2} and Al{sub 2}O{sub 3} represent more than 50% of its composition, mineralogical phases defined, low humidity content, low particle size (d{sub 90} < 10 {mu}m), among others. Mineralogical analyses of the synthesized products showed the formation of some zeolite types, as follow: analcime, phillipsite, sodalite, zeolite P and tobermorite. The results show that the mixture fly ash-micro silica in these reaction conditions point to a promising material for zeolite synthesis (author)

  3. Removal of cadmium in urban wastewater with systems based on zeolite type clinoptilolite; Remocion de cadmio en aguas residuales urbanas con sistemas a base de zeolita tipo clinoptilolita

    Energy Technology Data Exchange (ETDEWEB)

    Barragan P, P.

    2016-07-01

    From an environmental issue detected in wastewater samples taken in a municipal wastewater collector in Nogales, Sonora, which is related to cadmium pollution, a research project came out where the principal aim was to implement a system to remove metallic ions of cadmium in wastewater, based on modified and unmodified natural zeolites. The zeolitic material used was natural clinoptilolite modified with NaCl and thiourea, sourced in El Cajon and Guaymas, Sonora. The materials were characterized with X-ray diffraction, Sem, Ft-IR spectra, and Bet analysis. The kinetics of four modified zeolites was investigated at ph=5 and initial concentration of 30 mgL{sup -1} of Cd{sup 2+}. The pseudo-first, the pseudo-second order, and Elovich models were applied to the experimental results. The results best fitted to pseudo-second order model. The maximum sorption capacity of modified zeolites was investigated through isotherms, The Langmuir model, Freundlich, and the combined Langmuir-Freundlich models were applied to the experimental results afterwards. ZGuayThio showed the highest sorption capacity, 11.60 mgg{sup -1}, with R{sup 2}=0.978 according to Langmuir-Freundlich model. Fixed-bed column adsorption experiments were carried out with ZGuayNa and ZGuayThio with three bed heights with 30 mgL{sup -1} solution of Cd{sup 2+}. influent at a flow rate of 1 mLmin{sup -1}, at ph=5. The Thomas, mass balance, and Bed Depth Service Time models were applied to the results. The dynamic adsorption capacity (No) and the constant of sorption velocity (K a) were determined, 28.67 gL{sup -1} and 0.072 Lg{sup -1}min{sup -1} respectively for ZGuayNa with R{sup 2}= 0.9954. Column experiments with municipal wastewater from Colinas del Yaqui sub-collector, previously characterized, were conducted using ZGuayNa and ZGuayThio. A mass transference model was applied to the results which accounted for K{sub p}= 0.815 m{sup 3}Kg{sup -}1 with R{sup 2}= 0.9789 for ZGuayNa, and K{sub p}= 3.1 m{sup 3}Kg{sup -}1 for ZGuayThio with R{sup 2}= 0.78. Finally, the capacity of the column system was investigated with ZGuayThio and municipal wastewater that had experienced biological oxidation. The results showed a Cd{sup 2+} uptake of 34.17 % for an influent concentration of 31.04 mgL{sup -1} de Cd{sup 2+}. (Author)

  4. Study of the ortho-positron annihilation process in zeolite Y; Estudio del proceso de aniquilacion de ortopositronio en zeolita Y

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado D, M E

    2010-07-01

    For several years a great interest has existed for the study of the natural and synthetic zeolites due to its properties. The porosity, one of their main characteristics allows that these materials are used as molecular sieves, catalysts, gases drying, etc. In order to investigating the porosity and other zeolite properties one carries out the study of the process of positron annihilation lifetime spectroscopy (Pals). This is a technique that provides information about the size and the pores form since is highly sensitive to the free volume and the superficial area of those porous materials as the zeolites. The study began with the elaboration of zeolite Y tablets in a hydraulic press where different pressures (from 0 to 1.26 GPa) and masses (70, 80 and 100 mg) were proven to obtain the estimate porosity of each tablet. A graph was elaborated and the effect of the mass and pressure with regard to the zeolite porosity was analyzed. Later on, the powder and tablets of 70 mg were characterized by means of X-ray diffraction (the glass size, interplanar distance, length and the volume of the unitary cell); scanning electron microscopy (the particles size and morphology); thermo gravimetric analysis (dehydration temperature and the stability up to 700 C) and the Brunauer Emmett Teller method (specific area). After the zeolite Y tablets characterization was carried out the positron annihilation process by means of Pals where its free volume of zeolite Y was analyzed, which includes to the structural cavities and the interparticle volume. The powdered zeolite was analyzed to different experimental conditions (preparation of the sample and the Pals equipment) to obtain the optimal conditions (a window with a time of 400 ns and a enlarged energy window) of analysis. On the other hand, the tablets were analyzed under optimal conditions to obtain the four components of time and intensity ({tau}, {Iota}), result of the different ways of positrons annihilation in the zeolite. These values were related with the free volume in the zeolite, with the size of the pores radii using a model of spherical pores and with the specific area. Finally, the best correlation was obtained between the parameters of Pals and the estimate porosity to define an equation that models the interparticle volume change in the zeolite for smaller or similar pressures to 1.26 GPa. (Author)

  5. Removal of the blue 1 dye of aqueous solutions using ferric zeolite; Remocion del colorante azul 1 de soluciones acuosas utilizando zeolita ferrica

    Energy Technology Data Exchange (ETDEWEB)

    Pinedo H, S. Y.

    2010-07-01

    Water is essential to all life forms, including humans. In recent years water use has increased substantially, also has been altered in its capacity as a result of various human activities, such as domestic, industrial and agricultural, also by natural activity. Undoubtedly one of the main pollutants today are the waste generated by the food industry, due to the use of dyes for the production of their products. So it is necessary to restore water quality through treatment systems to remove contaminants, and thus prevent disease and imbalance of ecosystems. Due to the above, it is important to conduct research directed towards finding new ways to remove dyes such as blue 1 used in the food industry, using low cost materials and abundant in nature as zeolites. To accomplish the above, the present study has the purpose to evaluate the adsorption capacity of the blue dye 1 in aqueous solutions. To accomplish that objective, the zeolite material was reconditioned to improve its sorption properties of the material and provide the ability to adsorb pollutants such as this dye. The zeolite material was characterized by scanning electron microscopy and elemental analysis, X-ray diffraction and infrared spectroscopy. To evaluate the ability of blue 1 dye sorption the kinetics and sorption isotherms were determined; the experimental results were adjusted to mathematical models such as pseudo-first order, pseudo second order and Elovich to describe the kinetic process, and the Langmuir, Freundlich and Langmuir-Freundlich to describe sorption isotherms. The results showed that ferric zeolite surface is a heterogeneous material and has a considerable adsorption capacity, which makes it a potential adsorbent for removing color from aqueous streams. Also the sorption of the dye was evaluated at different ph values; the most sorption was carried out at ph values 1, 3 and 11. We also evaluated the change in mass where the sorption capacities for the blue 1 increase by increasing amount of adsorbent from 10 to 200 mg of adsorbent and 10 ml of solution. Finally there was a column sorption test, obtaining the curve os load vs time of contact, and important design parameters such as the rupture time, it was at 100 minutes, with an initial concentration of 5 mg/L taking final concentration breakpoint of 0.4 mg/L, the results were evaluated with the Thomas model. The results of this work can conclude that it is possible to extend the scope of natural zeolites as adsorbents for the removal of organic pollutants in wastewater, by changing its outer surface with ferric chloride, without a significant effect on their ion exchange properties. (Author)

  6. Susceptibilidad del almidón presente en harinas crudas y modificadas al ataque enzimático con amilasa

    Directory of Open Access Journals (Sweden)

    A. Lozano

    2009-05-01

    Full Text Available Se determinaron las ratas de hidrólisis de almidones, para algunas harinas de alimentos (yuca, maíz y plátano y la influencia de ciertos procedimientos industriales y caseros, de dichos productos, sobre las constantes anterioraiente mencionadas.

  7. Characterization of montmorillonite-Ca to use polymer nanocomposites; Caracterizacao de argila esmectitica modificada visando seu uso em nanocompositos polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Neto, Joao E.; Neto, Jose C.M.; Campo, Eduardo R.B. del, E-mail: joao_evengelista_neto@yahoo.com [Universidade do Estado do Amazonas (UEAM), Manaus, AM (Brazil). Coordenacao de Engenharia de Materiais; Nascimento, Nayra R. do [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Departamento de Engenharia de Materiais e Bioprocessos; Diaz, Francisco Rolando Valenzuela [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Metalurgica e Materiais

    2015-07-01

    Bentonite is an important type of industrial clays due to its rheological properties or accession that are dependent on its high hydrophilicity. This clay has the capability of being modified with organic compounds by treatment with ammonium quaternary salts. After the clay treatment with these salts it presents a high degree of swelling property in organic liquids. Due to this swelling characteristics, the bentonite can be used in dispersions of organic liquids viscous and thixotropic. Another focus of interest this clay is in industry and academia because of its potential use in the adsorption of toxic substances and as fillers in nanocomposites clay / polymer. The objective of this study is to characterize a Cuban calcium bentonite modified with sodium dodecyl sulfate. The clay was characterized by X-ray diffraction, particle size analysis by laser diffraction and scanning electron microscopy. (author)

  8. Removal of remazol yellow with modified clays with iron; Remocion de amarillo remazol con arcillas modificadas con hierro

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Gomez T, A. P.

    2012-07-01

    Clays have the ability to absorb water and to retain in its structure both hydrophilic and hydrophobic substances, therefore, it is possible to use them in the sorption of dyes from waste water, in order to avoid affecting water bodies or storm drains when they are discharged. In this paper the montmorillonite KSF and a sodium bentonite from the Morelos State, Mexico were studied for the sorption of an azo dye used in textiles knows as remazol yellow. These clays were modified with iron, the dye sorption behaviors and their regeneration processes for their reuse were determined. It was difficult to separate the sodium bentonite after being in contact with aqueous solutions; therefore it was nor a candidate dor the removal of remazol yellow from aqueous solutions. The montmorillonite KSF was characterized before and after the iron modification, and after its regeneration by scanning electron microscopy (elemental analysis), infrared spectrometry, X-ray diffraction, and the specific areas of the materials were determined by Bet analysis. The adsorption equilibrium time and the adsorption rate for remazol yellow were determined from the fitting of the experimental results to mathematical models for the unmodified and iron modified montmorillonite KSF. The adsorption capacity was determined from the adsorption isotherms and mathematical models. The influence of the ph in the sorption processes was determined as well, and it was found that, ph values between 2 and 12 do not have any influence on the adsorption processes for iron modified montmorillonite KSF. The montmorillonite KSF and the iron modified montmorillonite KSF are adequate adsorbents for the removal of remazol yellow from aqueous solutions. Although, the sorption capacity for the unmodified montmorillonite KSF is higher (about 10%) than the capacity for the iron modified montmorillonite KSF and the stability of the last one increased. The saturated clays with remazol yellow were treated with Fenton reactive, hydrogen peroxide and distilled water to determine their regeneration behaviors. Any desorption process was not observed when the clays were treated with distilled water. The regeneration was best accomplished with Fenton reactive, the sorption increased in about 300% in comparison with the original capacity. The iron modified montmorillonite shows a better sorption behavior after regeneration than the unmodified montmorillonite KSF. (Author)

  9. Temperature and modified atmosphere affect the quality of okra Temperatura e atmosfera modificada influenciam a qualidade do quiabo

    Directory of Open Access Journals (Sweden)

    Fernando Luiz Finger

    2008-01-01

    Full Text Available Little information is available on the influence of temperature on plastic films wrapped okra (Albelmoschus esculentus for their postharvested conservation. This works investigated the influence of the temperature and PVC film on the development of chilling injury and storability from one of the most popular Brazilian cultivar of okra cv. Amarelinho in fruits stored at 5, 10ºC and at 25ºC. Fruits were harvest at commercial maturity stage with length ranging from 8 to 12 cm, and immediately wrapped in PVC over a polystyrene tray and than stored until visible deterioration or wilting symptoms. Lowering the temperature of storage room from 25 to 10 or 5ºC decreased the weight loss in both PVC wrapped and control fruits, with a lower rate at 5ºC. By reducing the temperature to 5 or 10ºC and wrapping the fruits in PVC film, the relative water content of the fruit pericarp was maintained throughout the storage, while at 25ºC the high weight loss was associated with significant reduction of the water content. The development of chilling symptoms was delayed by the presence of PVC film in fruits stored at 5ºC. However, at 10ºC symptoms of pitting were not developed in PVC wrapped or control fruits up to tenth day of storage. The rate of chlorophyll degradation was diminished by reducing the temperature and by wrapping the fruits with PVC film. The appearance of severe chilling symptoms at 5ºC was associated to less chlorophyll in the fruit pericarp on the control as compared to their content in the PVC wrapped fruits.Para o armazenamento do quiabo (Albelmoschus esculentus há poucas informações disponíveis sobre a influência da temperatura e filmes plásticos na conservação pós-colheita desta hortaliça. Para investigar a influência da temperatura e do filme de PVC na qualidade e desenvolvimento de sintomas de injúria por frio de uma das mais populares cultivares brasileira de quiabo cv. Amarelinho, os frutos foram armazenados a 5, 10 e 25ºC. Os frutos foram colhidos no estádio de maturação comercial, com comprimento entre 8 e 12 cm, sendo então envoltos por uma camada de filme de PVC em bandeja de poliestireno expandido, seguido do armazenamento até o aparecimento de sintomas de deterioração ou murcha. A redução da temperatura de armazenamento de 25 para 10 ou 5ºC diminuiu a perda de massa nos frutos envoltos com PVC e dos frutos controle, com menor taxa a 5ºC. Ao reduzir a temperatura para 5 ou 10ºC e cobrir com filme de PVC, o conteúdo relativo de água foi mantido durante o armazenamento, porém a 25ºC a elevada perda de massa esteve associada a significante redução do conteúdo de água do pericarpo do fruto. O aparecimento de sintomas de injúria por frio foi retardado pela presença de filme de PVC nos frutos armazenados a 5ºC. No entanto a 10ºC, não foram detectados sintomas de degeneração associados à injúria por frio nos frutos envoltos com PVC ou controle até o décimo dia de armazenamento. A taxa de degradação de clorofila durante o armazenamento foi menor nos frutos mantidos nas temperaturas mais baixas e com filme PVC. O aparecimento de sintomas severos de injúria por frio a 5ºC relacionou-se com o menor conteúdo de clorofila dos frutos controle, quando comparado àqueles envoltos em filme de PVC.

  10. Catalytic pyrolysis of LDPE using modified vermiculite as a catalyst; Pirolise catalitica do PEBD usando como catalisador a vermiculita modificada

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Franciel Aureliano [Universidade Federal de Uberlandia (UFU), MG (Brazil); Figueiredo, Aneliese Lunguinho; Araujo, Antonio Souza de; Guedes, Ana Paula de Melo Alves, E-mail: anachemistry@hotmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal (Brazil)

    2016-07-01

    Low density polyethylene (LDPE) is one of the most commonly-used polymers currently, and the great quantity of this polymer produced results in tons of waste that must be treated. We studied the thermocatalytic pyrolysis of LDPE with a modified clay vermiculite catalyst as an alternative for treatment of waste. The clay was treated with a solution of nitric acid at different concentrations and calcined at 400 °C. The materials were characterized by X-ray diffraction, thermogravimetry, nitrogen adsorption, and energy dispersive spectroscopy. Thermal and thermocatalytic pyrolysis were carried out in a microreactor coupled with GC/MS at 500 °C. The aim of the polymeric waste pyrolysis is the obtainment of light hydrocarbons (C<16), which can be used in the chemical and petrochemical industry, through breaks in the polymer chain. The results were satisfactory, with an increase in yield for light hydrocarbons by using catalysts reaching up to 71.4% of products with C<16, whereas thermal pyrolysis resulted in only 25.8%. (author)

  11. Conservação de pinha com uso de atmosfera modificada e refrigeração

    Directory of Open Access Journals (Sweden)

    Gisele Polete Mizobutsi

    2012-12-01

    Full Text Available Os frutos da pinheira possuem limitações para sua distribuição a mercados distantes, por causa do rápido amadurecimento, que os torna muito macios, de difícil manuseio sem a ocorrência de danos e de conservação extremamente reduzida. O objetivo deste trabalho foi avaliar a influência do filme de policloreto de vinila (PVC, associado às temperaturas de refrigeração, na conservação pós-colheita da pinha. Os frutos foram selecionados, lavados, sanitizados e acondicionados em bandejas de isopor, com, ou sem, envolvimento de película de policloreto de vinila, e conservados a 12 e 25 ºC. Foram avaliados: cor da casca, firmeza, perda de matéria fresca, sólidos solúveis, acidez titulável, açúcares totais e amido. Os frutos conservados a 12 ºC, com policloreto de vinila, mantiveram a coloração verde da casca até o 18º dia, apresentaram menor perda de massa de matéria fresca e firmeza da casca e menor teor de sólidos solúveis e acidez titulável, em relação aos frutos armazenados a 25 ºC. A utilização da embalagem, associada à temperatura de 12 ºC, permite um período seguro de 18 dias de conservação, com adequada manutenção dos atributos físicos e químicos. Os frutos armazenados a 25 ºC conservaram-se por seis dias. A película de PVC, associada ao armazenamento de 12 ºC, pode ser utilizada para atrasar o amadurecimento dos frutos por 18 dias, mantendo sua qualidade. Os frutos que permaneceram armazenados, por seis dias, a 25 ºC com, ou sem, PVC, não apresentaram características físicas e químicas desejáveis.

  12. Invarianza de las ecuaciones de movimiento bajo transformaciones de escala espacio-temporales en la dinamica de Newton modificada (MOND)

    Science.gov (United States)

    Acosta, R.; Tuiran, E.; Molina Redondo, U.

    2015-02-01

    The basic principles that originated the Modified Newtonian Dynamics MOND, are shown, as well as a description of the fundamentals aspects of the theory: modification of gravity and modification of inertia. Also, it is considered the behaviour of the movement equations under space-temporal scale transformations of the movement equations, that is, transformations that have the form (t, r) --> (lambda*t, r). It was observed in this way that the MOND regime comes from the requirement of the invariance of the movement equations with respect to this transformations.

  13. Estudo eletroquímico do azul de metileno adsorvido sobre sílica gel quimicamente modificada com óxido de nióbio

    Directory of Open Access Journals (Sweden)

    Schiavo Débora de Almeida

    2000-01-01

    Full Text Available Methylene blue (AM was immobilised on surface of the silica gel modified with niobium oxide. This material was incorporated in a carbon paste electrode, which showed a redox couple in a potential of E= -113 mV vs SCE in KCl solution at pH 7.0. The formal potential, in 0.5 mol L-1 KCl at pH 7.0, shifted about 290 mV towards more positive values compared to those observed for AM solubilized in aqueous solution. The dependence on the formal potential with solution pH between 2 and 7 was much lower than those observed for AM solubilized in aqueous solution.

  14. Optimization of fuel cells for BWR based in Tabu modified search; Optimizacion de celdas de combustible para BWR basada en busqueda Tabu modificada

    Energy Technology Data Exchange (ETDEWEB)

    Martin del Campo M, C.; Francois L, J.L. [Facultad de Ingenieria, UNAM, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, 62550 Jiutepec, Morelos (Mexico); Palomera P, M.A. [Facultad de Ingenieria, UNAM, Posgrado en Ingenieria en Computacion, Circuito exterior s/n, Ciudad Universitaria, Mexico, D.F. (Mexico)]. e-mail: cmcm@fi-b.unam.mx

    2004-07-01

    The advances in the development of a computational system for the design and optimization of cells for assemble of fuel of Boiling Water Reactors (BWR) are presented. The method of optimization is based on the technique of Tabu Search (Tabu Search, TS) implemented in progressive stages designed to accelerate the search and to reduce the time used in the process of optimization. It was programed an algorithm to create the first solution. Also for to diversify the generation of random numbers, required by the technical TS, it was used the Makoto Matsumoto function obtaining excellent results. The objective function has been coded in such a way that can adapt to optimize different parameters like they can be the enrichment average or the peak factor of radial power. The neutronic evaluation of the cells is carried out in a fine way by means of the HELIOS simulator. In the work the main characteristics of the system are described and an application example is presented to the design of a cell of 10x10 bars of fuel with 10 different enrichment compositions and gadolinium content. (Author)

  15. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    OpenAIRE

    Carboneras, M.; Pérez-Maceda, B. T.; Valle, Jorge del; García-Alonso, M. C.; Alobera, M. A.; Clemente, Carmen; Rubio, J. C.; Escudero Rincón, María Lorenza; Lozano, R.M.

    2011-01-01

    [ES] En el presente trabajo se ha estudiado el comportamiento frente a la corrosión y la biocompatibilidad in vitro/in vivo de la aleación de magnesio AZ31, cuyas propiedades mecánicas son superiores a los requisitos mecánicos del hueso. La aleación en estado de recepción ha mostrado una cinética de corrosión no compatible con el crecimiento celular. Para mejorar su comportamiento, el material ha sido modificado superficialmente mediante tratamiento de conversión química en ácido fluorhídr...

  16. Técnicas FT-IR (PAS, UATR e Objetiva ATR Aplicadas à Caracterização de EPDM Modificada com Plasma

    Directory of Open Access Journals (Sweden)

    Renata Patrícia dos Santos

    2014-06-01

    Full Text Available Técnicas FT-IR (UATR, PAS e MIC, com objetiva ATR foram escolhidas para a caracterização da superfície da borracha de EPDM vulcanizada, após tratamento em plasma de Ar/O2 e N2/H2/Ar gerado em micro-ondas. Após tratamento, grupos oxigenados foram detectados por UATR e MIC/FT-IR, com objetiva ATR para as duas misturas gasosas, e possíveis grupos nitrogenados foram inseridos na superfície das amostras tratadas com plasma de N2/H2/Ar. A análise MIC/FT-IR sugeriu a formação de grupos em uma camada mais externa, para as amostras tratadas com plasma de N2/H2/Ar, sendo possível observar a redução na intensidade das bandas da absorção do CH2 e CH3, o que pode estar relacionado ao fato de o nitrogênio ser um gás menos permeável que o oxigênio. Diferentes velocidades, 0,05 cm.s-1 e 0,2 cm.s-1, foram utilizadas na análise PAS para avaliar a superfície após tratamento, e apenas para a velocidade 0,05 cm.s-1 com plasma de Ar/O2 alterações espectroscópicas foram detectadas. A redução na medida de ângulo de contato e o aumento na resistência ao descascamento da colagem indicaram melhoras nas propriedades adesivas da superfície. Falhas de adesão foram observadas entre a interface do filme de adesivo de PU e da borracha de EPDM, e confirmados por UATR/FT-IR.

  17. Valoración ambiental preliminar del riesgo-beneficio de la liberación de una semilla de arroz genéticamente modificada

    Directory of Open Access Journals (Sweden)

    Sergio Bermúdez Muñoz

    2010-10-01

    Full Text Available La Evaluación de Impacto Ambiental (EIA es una herramienta de gestión que permite, de forma holística, determinar las potenciales alteraciones que una puede tener sobre el ambiente, pues considera los impactos positivos y negativos que podrían presentarse. La aplicación de esta herramienta cuando se libera un OGM, con la ayuda de información de campo y secundaria, se convierte en un esfuerzo pionero, pues permite a quienes toman decisiones y a la opinión pública analizar los pro y contra que la actividad podría tener. Mediante el empleo de un software para valorar impactos como RIAM, se logra una visión integral del riesgo y el beneficio gracias a la información obtenida, y se elabora un pronóstico de lo que podría ocurrir a partir de los supuestos planteados. Aunque el flujo de genes (-B es un riesgo, también se observan beneficios como la recuperación de campos infestados de arroz rojo y una menor persistencia de herbicidas en el ambiente (E.

  18. Structural aspects of crotalic venom proteins modified by ionizing radiation; Aspectos estruturais de proteinas do veneno crotalico modificadas por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Karina Corleto de

    2010-07-01

    Snake bites are a serious public health problem, especially in subtropical countries. In Brazil, the Ministry of Health notified around 26 000 accidents in 2008. The genus Crotalus (rattlesnakes) accounts for approximately 7% of the total, with a high mortality rate of 72% when untreated with the specific serum, the only effective treatment in case of snake bites. In Brazil, the serum is produced in horses which, despite the large size, have a reduced lifespan due to the high toxicity of the antigen. Ionizing radiation has proven to be an excellent tool for reducing the toxicity of venoms and isolated toxins, resulting in better immunogens for serum production, and contributing to the welfare of serum producing animals. Since the action of gamma radiation on venoms and toxins has not been yet fully clarified from the structural point of view, we proposed in this paper, to characterize two toxins of the species Crotalus durissus terrificus: crotoxin and crotamine. After isolation of the toxins of interest by chromatographic techniques, they were subjected to structural analysis with the application of the following methods: Fluorescence, Circular Dichroism, Differential Calorimetry and Infrared Spectroscopy. These tests showed that both crotamine as crotoxin when subjected to gamma radiation, showed changes in their structural conformation compared with the samples in the native state. Such changes probably occur in the secondary and tertiary structure and may explain the changes on the biological activity of these toxins. (author)

  19. Modified gum Arabic hydrogels as matrices for controlled release of curcumin supramolecular complexes; Hidrogeis de goma arabica modificada como matrizes para libertacao controlada de complexos supramoleculares de curcumina

    Energy Technology Data Exchange (ETDEWEB)

    Gerola, Adriana P.; Silva, Danielle C., E-mail: avalente@ci.uc.pt [Department of Chemistry, University of Coimbra, Coimbra (Portugal); Rubira, Adley F.; Muniz, Edvani C. [Universidade Estadual de Maringa (GMPC/UEM), PR (Brazil). Grupo de Materiais Polimericos e Compositos; Jesus, Sandra; Borges, Olga [Faculty of Pharmacy, University of Coimbra, Coimbra (Portugal)

    2015-07-01

    Modified gum Arabic (GA) hydrogels show a pH-responsive behavior making them excellent matrices to be used for oral administration of drugs. Our goal is to study the behavior of those matrices in simulated gastric and intestinal fluids. In this work we will present how the methacrylation degree of GA, by using glycidyl methacrylate, can affect the properties of these hydrogels for controlled release. The drug used in this work is the curcumin (Cur). Cur is associated with numerous pharmacological activities, but their application is limited by the low water solubility. We will present some studies involving the formation of host-guest complexes between Cur and natural cyclodextrins. Both modified GA and hydrogels were characterized by different techniques. The kinetics release of Cur complex-containing modified GA hydrogels was studied to have an insight on the release mechanism and rate constants. Toxicity studies on undifferentiated and differentiated Caco-2 were also carried out. (author)

  20. Use of Fricke solution modified with dyes for dosimetry in phototherapeutic treatments; Uso da solucao Fricke modificada com corantes para futura dosimetria em tratamentos fototerapeuticos

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Mayara Gabriella Oliveira de; Nascimento, Rizia Keila; Vieira, Rafaela Etelvina de Amorim; Souza, Vivianne Lucia Bormann, E-mail: mayaradqf@hotmail.com, E-mail: riziakeila@hotmail.com, E-mail: rafaelarodriguesss@hotmail.com, E-mail: vlsouza@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife (Brazil)

    2014-07-01

    Dyes and pigments (photosensitizers) are characterized by their ability to absorb visible light, and to participate in photochemical reactions. These colors are used in medicine in the dose recommended for use in photodynamic therapy (PDT). There are lasers that can meet most of the phototherapeutic agents and are capable of providing light of considerable power with precision on the injured tissue. The use of light emitting diodes (LEDs) have become feasible, thus reducing the cost of the procedures. The Dosimetry Laboratory Chemistry of the CRCN-NE/Brazilian CNEN has worked with some likely dye use in phototherapy treatments, including: methylene blue, malachite green and toluidine blue. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique.

  1. Validación Estructural de la Escala Básica de Empatía (Basic Empathy Scale Modificada en Adolescentes: un Estudio Preliminar

    Directory of Open Access Journals (Sweden)

    César Merino-Soto

    2015-10-01

    Full Text Available Se hizo un estudio preliminar para verificar la estructura de una versión de 9 ítems de la Escala Básica de Empatía (EBE, un instrumento que evalúa la empatía afectiva y cognitiva. Los participantes fueron 135 adolescentes entre 11 y 18 años (M=14, DE=1.4 de educación regular, en una región urbana de Lima Metropolitana. Se usó metodología de ecuaciones estructurales para confirmar la estructura, y la transformación Schmid-Leiman para evaluar el modelo bi-dimensional. Los resultados indican que un modelo oblicuo de dos factores es satisfactorio para los datos, la confiabilidad es superior a .70, y no se justifica la interpretación de un solo puntaje tal como anteriormente se hacía. Se discuten las diferencias en la interpretación de los modelos y la valoración de la metodología factorial.

  2. Changes in suspension properties of structural modified montmorillonites Mudanças em propriedades de suspensões de montmorilonitas modificadas estruturalmente

    Directory of Open Access Journals (Sweden)

    C. Volzone

    2001-03-01

    Full Text Available Rheological changes were found in smectite (Wyoming- and Cheto-type montmorillonites suspensions after structural modifications. The effect of the particle size and Na+ exchange on the flow curves of 6% wt/wt suspensions of smectites with and without Na2CO3 were examined. Mineralogical, structural and physicochemical characteristics were studied by X-ray diffraction (XRD, infrared spectroscopy (IR, cationic exchange capacity (CEC, Mg2+, Al3+ determinations, particle size distribution and swelling index (SI. Grinding in an oscillating mill modified the particle sizes. The montmorillonite grain size and the structural disorder increased after larger grinding times. The grinding treatment modified the apparent viscosity and the yield stress of the montmorillonite suspensions. The homoionic Na Cheto-type montmorillonite with fine particle size (obtained by grinding increased the flow properties. Nevertheless, rheological properties were lower than those of suspensions of the Wyoming-type montmorillonite. Montmorillonite-types reacted differently with Na2CO3 additions and this behavior may be related to their structural composition. The Na2CO3 activation improved the flow properties of the original Wyoming-type montmorillonite and after 30 s grinding.Foram encontradas mudanças reológicas em suspensões de esmectitas (montmorillonitas tipos Wyoming e Cheto após modificações estruturais. Foi examinado o efeito do tamanho de partícula e troca de Na+ nas curvas de escoamento de suspensões de esmectitas 6% peso com e sem Na2CO3. As características mineralógicas, estructurais e físico-químicas foram estudadas por difração de raios X (DRX, espectroscopia no infravermelho (IV, capacidade de troca catiônica (CTC, determinações de Mg2+ e Al3+, de distribuição de tamanho de partículas e de índice de expansão (swelling index - SI. Moagem em moinho oscilatório modificou o tamanho das partículas. O tamanho de grão da montmorillonita e a desordem estrutural aumentaram após maiores tempos de moagem. O tratamento por moagem modificou a viscosidade aparente e o limite de escoamento das suspensões de montmorillonita. A montmorillonita homoiônica de Na do tipo Cheto com pequeno tamanho de partícula (obtido por moagem melhorou as propriedades de escoamento. Entretanto, as propriedades reológicas foram piores que as de suspensões de montmorillonita do tipo Wyoming. Os diferentes tipos de montmorillonitas reagiram de modo diferente com adições de Na2CO3 e este comportamento pode estar relacionado com suas composições estruturais. A ativação por Na2CO3 melhorou as propriedades de escoamento da montmorillonita tipo Wyoming original após moagem por 30 s.

  3. SINTESIS Y CARACTERIZACIÓN DE BENTONITA MODIFICADA CON ESPECIES DE TiO2 y Fe-TiO2 OBTENIDAS DEL MINERAL ILMENITA

    Directory of Open Access Journals (Sweden)

    Juan Torres

    2014-07-01

    Full Text Available Se sintetizó una serie de sólidos nanoestructurados, obtenidos por la intercalación de nanopartículas de TiO2 y Fe-TiO2 en los espacios interlaminares de un mineral de arcilla esmectítico. Los nuevos materiales se prepararon mediante la modificación simultánea de dos minerales naturales: una bentonita y una ilmenita. Los materiales obtenidos se caracterizaron por fluorescencia de rayos X (FRX, espectroscopía infrarroja (IR, difracción de rayos X (DRX, microscopía electrónica de barrido (SEM y sortometría de nitrógeno. Los resultados del análisis químico (FRX confirmaron claramente la incorporación de titanio y de hierro en los materiales sintetizados. Los análisis por DRX, SEM y sortometría de nitrógeno verificaron la modificación del mineral de arcilla por incorporación de especies de dióxido de titanio, demostrando la generación de estructuras mesoporosas delaminadas o exfoliadas con incremento en los valores de área superficial y porosidad controlada.

  4. Utilização de atmosfera modificada na conservação de morangos em pós-colheita

    Directory of Open Access Journals (Sweden)

    Calegaro Júlio Marques

    2002-01-01

    Full Text Available Foram realizados dois experimentos com o objetivo de testar a utilização de três composições iniciais de atmosferas (3 kPa O2 + 10 kPa CO2, 5 kPa O2 + 15 kPa CO2 e do ar ambiente com dois tempos de armazenagem (7 e 14 dias a 0ºC, para a conservação de morangos (Fragaria x ananassa Duch. cv. Oso Grande. Os frutos eram provenientes de uma lavoura comercial do Município de Farroupilha, RS. No primeiro experimento, utilizaram-se vidros de 1.700 mL de capacidade para a armazenagem, e no segundo, empregaramse sacos de polietileno, de 53 cm x 90 cm e 90 mim de espessura. As atmosferas com 3 kPa O2 + 10 kPa CO2 ou 5 kPa O2 + 15 kPa CO2 apresentaram bom potencial para a conservação dos frutos por até 7 dias. A modificação da atmosfera em embalagens de polietileno empregando concentrações iniciais de ar ambiente aumentou o período de conservação e manteve a qualidade dos frutos por até 7 dias. Os benefícios decorrentes da utilização dessas atmosferas foram a manutenção da firmeza da polpa, da coloração dos frutos, dos teores de açúcares totais, e de ácido ascórbico.

  5. EFICIÊNCIA DE MÉTODOS ALTERNATIVOS UTILIZANDO ATMOSFERA MODIFICADA PASSIVA, NO CONTROLE DA PODRIDÃO DE MELÃO CANTALOUPE

    Directory of Open Access Journals (Sweden)

    Cynthia Renata Lima Sá

    2008-01-01

    Full Text Available This research avollue the efficiency of Potassium permanganate (KMnO4 plus other alternatives to control rot of melons. The trials were carried out at Embrapa Agroindústria Tropical located in Fortaleza, Ceara state, Brazil. Cantaloupe melons, hybrid 'Vera Cruz', were harvested from Dinamarca Indústria Agricola farm, located in the 304 BR km 38 - Nova Betânia - Mossoró, Rio Grande do Norte State. Fruits were sorted for uniformity, rinsed with alcohol 70%, inoculated with Fusarium pallidoroseum, and assembled for treatments with 600ppb of 1-methyiciclopropene (1- MCP; 1, 2 or 3g of Potassium permanganate; Carnauba wax; and Funginat (a blend essential oil. Five fruits were placed per box, and each box taken as a repetition. Fruits were also divided into two lots: not packed and packed in Xtend. Vermiculite sachets impregnated with potassium permanganate (KMnO4 were distributed according to the weight of the fruits in each box. Upon treatments, fruits were stored under low temperature, 3 ± 2°C, and relative humidity of 85 ± 2% for 14 days. After that period, fruit packages and boxes were removed from storage, low temperature and room temperature (23 ± 2°C and 90 ± 2% RH, respectively. Evaluations were loss of mass and grading from 15th to 18th day of storage. The experimental design was completely randomized in a factorial system 5x2, being five treatments (1- MCP, KMnO4, Carnaúba wax, Funginat, and control fruits, and two modified atmospheres (with and without X-tend. Results on disease incidence were written in percentage per box, transformed into arc sine and degrees of quadrant. The analysis of variance was performed with the aid of the ESTAT - System for Statistics Analysis, version 1.0, UNESP. Results showed significant difference principally regarding the use of packaging, suggesting that the use of modified atmosphere affects the quality of melons by increasing fruit shelf life. It has been also concluded that association of modified atmosphere with other postharvest technologies may increase modified atmosphere efficiency.

  6. Dupla filtração modificada utilizando filtro de pressão a montante de filtro ascendente no tratamento de águas eutrofizadas

    OpenAIRE

    José Airton Pereira Lima; José Capelo-Neto

    2015-01-01

    A implantação de uma unidade de pré-tratamento a montante de um filtro ascendente (FA) existente objetiva condicionar a água bruta eutrofizada à capacidade de tratamento do FA. Essa solução esbarra na necessidade de se instalar essa unidade de pré-tratamento com cota mais elevada que o filtro a jusante. Nesta pesquisa, a instalação de um filtro de pressão de fluxo descendente possibilitou a eliminação do problema do desnível geométrico e a adequação da água bruta com elevada presença de fitop...

  7. Rat pinealectomy: a modified direct visual approach Pinealectomia em ratos: técnica modificada com visualização direta

    Directory of Open Access Journals (Sweden)

    Carla Cristina Maganhin

    2009-08-01

    Full Text Available PURPOSE: To report a new, direct visual approach for rat pinealectomy. METHODS: Eighty adult female rats (Rattus norvegicus albinus EPM-1 strain were weighted and anesthetized intraperitoneally with 15 mg/kg xylazine and 30 mg/kg ketamine. The animal was fastened to a dissection table, an incision was made in the skin and the subcutaneous tissue, bringing the lambda into view. The skullcap was opened with a dental drill, bringing the cerebral hemispheres and the superior sagittal sinus into view. The pineal gland, located under the venous sinus, was removed in a single piece using tweezers. Next, the bone fragment was returned to its place and the surgical layers were sutured. RESULTS: This new technique is easy to be done, avoids bleedings and removes only the pineal gland without damage to the remaining encephalon. In addition it makes possible the achievement of a sham surgery, allowing the pineal gland to remain intact. CONCLUSION: The proposed technique intends to facilitate studies aiming to better understanding the complexity and importance of the pineal gland on reproductive and other body systems.OBJETIVO: Apresentar nova técnica para pinealectomia em ratos. MÉTODOS: 80 ratos adultos fêmeas (Rattus norvegicus albinus foram pesados e em seguida anestesiados por via intraperitoneal com xilazina e cetamina. Em seguida os animais foram fixados em uma prancha de cortiça e feita uma incisão na pele e no tecido subcutâneo, na região superior da cabeça, evidenciando a junção dos ossos parietais e occipital. Na região do lambda, realizou-se uma perfuração circular, na calota craniana, com o auxilio de uma broca (4 mm acoplada a um micromotor. Nesse orifício, após a dissecação da dura-mater visibiliza-se a confluência dos seios venosos longitudinal e transverso. Com o auxilio de uma pinça curva esses seios são deslocados, ligados e identificada a glândula pineal, que pode ser removida em peça única. Em seguida, o fragmento ósseo é devolvido ao seu lugar e as camadas cirúrgicas suturadas. RESULTADOS: Esta nova técnica é fácil de ser feita, evita hemorragias e só remove a glândula pineal, sem prejuízos para o restante do encéfalo. Além disso, possibilita a realização de uma cirurgia sham, visto que a glândula pineal permanece sem alterações. CONCLUSÃO: Espera-se que a técnica proposta facilite estudos visando a uma melhor compreensão da complexidade e importância da glândula pineal sobre a reprodução e outros sistemas do organismo.

  8. Use of nuclear magnetic resonance in the characterization of modified clays; Uso da ressonancia magnetica nuclear na caracterizacao de argilas modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Sidnei Q.M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Menezes, Sonia M.C. de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Gil, Rosane A.S. San [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Quimica

    1992-12-31

    This work uses NMR spectroscopy with rotation in the {sup 29} Si, {sup 27} Al and {sup 23} Na magic angles for characterization of clays with Si/Al ratio in the range 3.0 - 16,5, obtained by chemical treatment of commercial samples, under different conditions of leaching with mineral acid 5 refs., 2 figs., 2 tabs.

  9. Determinação de mercúrio em águas por CVAAS empregando sílica modificada por 2-aminotiazol

    OpenAIRE

    Silva, F. A. [UNESP; Alcântara, I. L. de [UNESP; Roldan, P. S. [UNESP; Padilha, C. C. F. [UNESP; Araújo, A. B. de [UNESP; Valente, J. P. S. [UNESP; Florentino, A. O. [UNESP; Padilha, P. M. [UNESP

    2005-01-01

    This paper discusses a rapid and sensitive method developed to determine trace levels of mercury in natural water samples by cold vapor atomic absorption spectrometry using a preconcentration system composed by mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT) coupled on-line with the spectrometer's cold vapor generator system. The optimum preconcentration conditions are also described here. The preconcentrated Hg(II) ions were eluted directly from the column to the ...

  10. Deslignificación de pasta kraft de Pinus radiata con una levadura genéticamente modificada para producir lacasa

    OpenAIRE

    Arana-Cuenca, A.; Yagüe, Susana; Fermiñán, Encarnación

    2010-01-01

    Una posible aplicación biotecnológica de las lacasas fúngicas es el blanqueo de pasta de papel mediante la degradación de la lignina en la pasta cruda. Para ello es necesaria su producción a bajo coste y a concentraciones superiores a las secretadas por los hongos de forma natural. La expresión heteróloga en levaduras es una alternativa para su producción a mayor escala. En el presente trabajo se ha realizado la expresión heteróloga del gen cglcc1, responsable de la producción de lacasa en el...

  11. Cinética de adsorción de Cr (VI usando biomasas residuales modificadas químicamente en sistemas por lotes y continuo

    Directory of Open Access Journals (Sweden)

    Candelaria Tejada Tovar

    2015-06-01

    Full Text Available Se estudia la adsorción de Cr (VI a partir de biomasa residual: bagazo de palma y cáscaras de ñame, además se estudia la modificación con ácido cítrico de las biomasas. La determinación del metal en solución fue llevada a cabo usando el método de la 1,5-difenilcarbazida. Del análisis FTIR se encontró que los grupos hidroxilo y carbonilo presentes en los adsorbentes son los de mayor contribución al proceso de remoción. Además, la modificación mejora la eficiencia del metal de acuerdo con la isoterma de Langmuir de 13 a 4mg/g para el bagazo de palma, y de 22 a 26mg/g para las cáscaras de ñame. Se establece además una mejora en el proceso al trabajar las biomasas en sistema continuo. De las condiciones óptimas de adsorción se determinó que el pH de 2 y el tamaño de partícula de 1mm son las que más favorecen el proceso, y el modelo de Elovich el que mejor lo describe.

  12. 194. Tratamiento quirúrgico de la miocardiopatía hipertrófica obstructiva mediante la técnica de Konno modificada

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    G. Candela Navarro

    2010-01-01

    Conclusiones: Esta técnica supone una alternativa a la cirugía convencional de la MHO, cambiando la resección muscular (Morrow por la ampliación del tracto de salida de ventrículo izquierdo (VI en la zona hipertrofiada. En nuestro caso se ha mostrado eficaz y segura, y ha proporcionado resultados estables en el tiempo.

  13. Respuesta metalúrgica de fracciones finas de minerales sulfurados de cobre en un proceso combinado de flotación modificada y biolixiviación agitada

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    Ibáñez, J. P.

    2007-04-01

    Full Text Available The metallurgical behavior of fine fractions of copper sulfide minerals of Compañía Minera Quebrada Blanca S.A. was studied by concentration through flotation in aqueous media modified by alcohol followed by bioleaching of the concentrates. By using a 1 % v/v of methanol, the metallurgical recovery of copper reaches 88 %, while the iron recovery was 43 %, the weight recovery was 18%, which indicates a high selectivity. These concentrates were then bioleached with and without nutrient medium, reaching 80 % of copper recovery after 10 and 17 days, respectively. Then, it is possible to conclude that this concentration-bioleaching metallurgical process is a promising route for copper recovery from the fine fraction of sulfide minerals.

    Se estudió la respuesta metalúrgica de la fracción fina, 100 % -100 # ASTM, de un mineral sulfurado de cobre de la Compañía Minera Quebrada Blanca S.A., sometido a una etapa de concentración mediante flotación en medio acuoso modificado (FEMAM® con metanol y la posterior biolixiviación agitada de este concentrado. Al emplear un 1 % v/v de metanol se logran los mejores resultados: una recuperación metalúrgica de cobre y hierro de 88 y 43 %, respectivamente, y una recuperación en peso del 18 %. Lo cual indica una alta selectividad de este tipo de flotación para especies sulfuradas de cobre. El concentrado FEMAM® fue posteriormente sometido a una etapa de biolixiviación agitada en ausencia y presencia del medio nutriente 9 K, lográndose el 80 % de extracción de cobre a los 17 y 10 días, respectivamente. Esto permite concluir que una ruta de concentración-biolixiviación es una alternativa tecnológica apropiada para procesar la fracción fina de minerales sulfurados de cobre.

  14. Método da árvore temporal modificada aplicado à análise de impactos ambientais: um estudo de caso

    OpenAIRE

    Moscardi, Jean Prost [UNESP

    2009-01-01

    O Relatório de Impacto Ambiental (RIMA), por muitas vezes sub-estimados em seu valor, apresenta-se apenas como um capítulo no Estudo de Impacto Ambiental (EIA) sem o devido reconhecimento e grau de relevância. O objetivo do presente estudo foi à proposição de um novo método de avaliação de impactos ambientais, no qual, a caracterização e formatação apresentaram-se direcionadas ao público leigo e distinto dos profissionais que realizam os trabalhos ambientais, porém, de grande relevância em pr...

  15. Conservação de pinha com uso de atmosfera modificada e refrigeração Conservation of Sweetsop using modified atmosphere and refrigeration

    Directory of Open Access Journals (Sweden)

    Gisele Polete Mizobutsi

    2012-12-01

    Full Text Available Os frutos da pinheira possuem limitações para sua distribuição a mercados distantes, por causa do rápido amadurecimento, que os torna muito macios, de difícil manuseio sem a ocorrência de danos e de conservação extremamente reduzida. O objetivo deste trabalho foi avaliar a influência do filme de policloreto de vinila (PVC, associado às temperaturas de refrigeração, na conservação pós-colheita da pinha. Os frutos foram selecionados, lavados, sanitizados e acondicionados em bandejas de isopor, com, ou sem, envolvimento de película de policloreto de vinila, e conservados a 12 e 25 ºC. Foram avaliados: cor da casca, firmeza, perda de matéria fresca, sólidos solúveis, acidez titulável, açúcares totais e amido. Os frutos conservados a 12 ºC, com policloreto de vinila, mantiveram a coloração verde da casca até o 18º dia, apresentaram menor perda de massa de matéria fresca e firmeza da casca e menor teor de sólidos solúveis e acidez titulável, em relação aos frutos armazenados a 25 ºC. A utilização da embalagem, associada à temperatura de 12 ºC, permite um período seguro de 18 dias de conservação, com adequada manutenção dos atributos físicos e químicos. Os frutos armazenados a 25 ºC conservaram-se por seis dias. A película de PVC, associada ao armazenamento de 12 ºC, pode ser utilizada para atrasar o amadurecimento dos frutos por 18 dias, mantendo sua qualidade. Os frutos que permaneceram armazenados, por seis dias, a 25 ºC com, ou sem, PVC, não apresentaram características físicas e químicas desejáveis.Sweetsop fruits show limitations to the distribution to distant markets due to their fast ripening, which turns them very soft and difficult to handle without the occurrence of damage, with their conservation extremely reduced. This study was carried out to evaluate the influence of the polyvinyl chloride associated to cooling temperatures in the post-harvest conservation of the sweetsop. The fruits were selected, washed, sanitized and stored in polystyrene trays with or without polyvinyl chloride and stored at 12 ºC and 25 ºC. The following characteristics were evaluated: color rind, firmness, fresh matter loss, soluble solids, titrable acidity, total sugars and starch. The fruits stored at 12 ºC with polyvinyl chloride kept the green coloration of the rind up to the 18th day, showing lower loss of fresh matter and rind firmness as well as lower content of the soluble solids and titrable acidity in relation to the fruits stored at 25 ºC. The use of the package associated to the temperature of 12 ºC allowed a safe period of 18 days under storage with appropriate maintenance of the physiochemical attributes. The fruits stored for 6 days at 25 ºC, with or without PVC, did not show desirable physicochemical characteristics.

  16. Seletividade de herbicidas pós-emergentes aplicados na soja geneticamente modificada Selectivity of post-emergence herbicides applied on genetically modified soybeans

    Directory of Open Access Journals (Sweden)

    M.E.F. Neto

    2009-06-01

    Full Text Available O experimento foi instalado em área de plantio comercial de soja Roundup Ready®, na região do Pontal do Paranapanema, no município de Euclides da Cunha Paulista-SP, localizada a 20º 43' 11'' S e 50º 10' 20'' W, com uma altitude de 270 m. A fase experimental foi conduzida de dezembro de 2006 a abril de 2007, sob sistema plantio direto, com uma temperatura média de 25 ºC e índice pluviométrico de 800 mm. O solo da área experimental apresenta classe textural franco-argilo arenosa. Objetivou-se com este trabalho avaliar a eficácia e seletividade de glyphosate na formulação Roundup Transorb®, associado aos herbicidas diclosulam, cloransulam-methyl, flumioxazina e S-metolachlor em duas modalidades de aplicação: única, com associação do glyphosate aos herbicidas; e uma sequencial apenas com glyphosate aos 15 DAA, no manejo das plantas daninhas trapoeraba (Commelina benghalensis e corda-de-viola (Ipomoea triloba durante o cultivo da soja. O experimento foi instalado no delineamento de blocos ao acaso, com 12 tratamentos e quatro repetições. Os tratamentos foram distribuídos em arranjo fatorial acrescido de duas testemunhas: sem capina manual e com capina manual. O arranjo fatorial 2 x 5 contemplou duas condições de aplicação dos herbicidas (única e sequencial e cinco herbicidas (glyphosate, glyphosate + diclosulam, glyphosate + cloransulam-methyl, glyphosate + flumioxazin e glyphosate + S-metolachlor. Nas condições de produtos, épocas de aplicação e doses, os resultados mostraram que o herbicida glyphosate aplicado em dose única ou sequencial e suas combinações com diclosulam e cloransulam-methyl na primeira aplicação não promovem fitointoxicação nas plantas de soja. A combinação com flumioxazin e S-metolachlor promoveu atraso no crescimento das plantas e no fechamento da cultura, em razão do efeito na altura dos indivíduos e comprimento dos ramos. No tratamento com o S-metolachlor, isso pode ser explicado pelo fato de o herbicida ser registrado para controle em pré-emergência e ter sido aplicado em pós-emergência. Nenhum dos tratamentos influenciou significativamente a produção de grãos da cultura da soja. A aplicação única ou a complementação com aplicação sequencial de glyphosate promoveram excelente controle de Commelina benghalensis e Ipomoea triloba.The experiment was carried out in a Roundup Ready® commercial soybean field in the Pontal do Paranapanema region in Euclides da Cunha Paulista-SP, located 20º 43' 11'' S and 50º 10' 20'' W, 270 m altitude. The experimental phase was carried out from December 2006 to April 2007, under no-tillage system. The soil classification is sandy clay loam Argisol. This work aimed to evaluate the efficiency of Roundup Transorb® glyphosate formulation selectivity associated with the herbicides diclosulam, cloransulam-methyl, flumioxazina and S-metolachlor under two spray modalities (single, with glyphosate associated to the herbicides and sequential, with only glyphosate in tropical Spiderwort (Commelina benghalensis and little bell (Ipomoea triloba management during soybean cultivation. The experiment was arranged in a randomized block design, with 12 treatments and 4 replications. Treatments were distributed in a factorial scheme + 2 controls (no control and clean field. The factorial scheme 2 x 5 comprises two herbicide sprays (single and sequential and five herbicides (glyphosate, glyphosate + diclosulam, glyphosate + cloransulam-methyl, glyphosate + flumioxazin and glyphosate + S-metolachlor. Under the conditions and time the herbicides were used as well as spray dosage, the results showed that glyphosate sprayed in a single dose or sequentially, in combination with diclosulan and cloransulam-methyl in the first spray did not cause phyto-intoxication in the soybean plants. The flumioxazin and S-metolachlor combination promoted delay in the growing plants as well as in the complete formation of the culture due to the effect on plant height and branch length. Neither the herbicides tested nor the sequential spray influenced significantly soybean grain production. All treatments using single application or combined with sequential glyphosate spray promoted an excellent control of Commelina benghalensis and Ipomoea triloba.

  17. Conservação de melão rendilhado minimamente processado sob atmosfera modificada ativa Conservation of minimally processed net melon under active modified atmosphere

    Directory of Open Access Journals (Sweden)

    Maria Cecília de Arruda

    2004-03-01

    Full Text Available Melões rendilhados cv. Bônus II foram minimamente processados manualmente na forma de cubos, acondicionados em diversos materiais de embalagem com injeção da mistura gasosa (5% O2 + 20% CO2 + 75% N2 e armazenados a 3ºC durante 12 dias. Os materiais de embalagem foram: BB-200: filme multicamada da Cryovac 65µm; PBC:filme poliolefínico Probag Conservax 64µm; PP: filme de polipropileno 52µm. Como controle, utilizou-se bandeja de polietileno com tampa perfurada. Realizou-se monitoramento da composição gasosa, análises microbiológicas, sensoriais e físico-químicas a cada 3 dias. Foram determinadas as taxas de permeabilidade ao O2 e CO2 de cada filme. A embalagem BB-200 promoveu acúmulo de CO2 até níveis de 24% e redução de O2 até níveis de 0,4%. Na embalagem PBC a concentração de O2 estabilizou-se ao redor de 8% e a de CO2 ao redor de 4%, enquanto na embalagem de PP os níveis de gases estabilizaram-se ao redor de 13% O2 e 6% CO2. De maneira geral, as características físico-químicas e sensoriais foram pouco influenciadas pelos tratamentos. A alteração da composição gasosa foi eficiente no controle de microrganismos. A partir do 9º dia de armazenamento, os melões controle apresentaram níveis de bactérias mesófilas acima de 10(5 NMP/g, com riscos de apresentarem microrganismos patogênicos e/ou deterioradores.Net melons cv. Bonus II were minimally processed as cubes, wrapped in several packaging materials with injection of the gaseous mixture (5% O2 + 20% CO2 + 75% N2 and stored at 3ºC for 12 days. The packaging materials were: BB-200: Cryovac multlayer film 65mm; PBC: Probag Conservax polyolephinic film 64µm; PP: polypropylene film 52µm. Polystyrene trays were used as control with perforated cover. Gaseous composition inside of the packaging, microbiological, sensorial and physical-chemical characteristics were determined each 3 days. The gas permeability was determined for each film. BB-200 packaging promoted CO2 accumulation until 24% and O2 reduction until 0,4%. Inside PBC packaging the O2 concentration stabilized at 8% and CO2 about 4%, while inside PP packaging the gaseous concentration stabilized near 13% for O2 and 6% for CO2. In a general sense, physical-chemical and sensorial characteristics were not influenced by the treatments. The modified atmosphere packaging was efficient for the microorganism control. The melon without modified atmosphere packaging showed levels over 10(5 NMP/g, of mesophilics bacteria, wich pathogenic microorganisms risks and/or deteriorative microorganisms, after 9th storage day.

  18. Armazenagem em atmosfera modificada passiva de carambola azeda (Averrhoa carambola L. cv. 'Golden Star' Storage in passive modified atmosphere of 'Golden Star' starfruit (Averrhoa carambola L.

    Directory of Open Access Journals (Sweden)

    Leandro Camargo Neves

    2004-04-01

    Full Text Available Este trabalho avaliou o efeito das embalagens de polietileno de baixa densidade (PEBD, em diferentes espessuras, no prolongamento da vida útil pós-colheita de carambolas cv. 'Golden Star'. Os frutos foram colhidos fisiologicamente maturos, sendo selecionados pela ausência de defeitos e acondicionados nas embalagens de PEBD, constituindo os seguintes tratamentos: T1 - controle (sem embalagem; T2 - PEBD de 6 mim; T3 - PEBD de 10 mim; T4 - PEBD de 15 mim. Os frutos foram armazenados a 12 +/- 0,5 ºC e 95 +/- 5% de UR, por 45 dias, e mais 5 dias a 22 +/- 3ºC e 72 +/- 5% de UR. Vinte e quatro horas após a colheita e a cada nove dias, amostras eram retiradas do armazenamento refrigerado (AR, mantidas por 12 horas em condições ambiente (22 +/- 3ºC e 72 +/- 5% UR e analisadas quanto à firmeza de polpa (FP, à perda de massa fresca, à coloração da epiderme, aos sólidos solúveis totais (SST, à acidez total titulável (ATT e à ocorrência de distúrbios fisiológicos. Realizou-se também uma análise sensorial ao final do experimento. A maior firmeza de polpa e acidez total titulável, o melhor padrão de coloração, o menor conteúdo de sólidos solúveis totais, a ausência de manchas e podridões, e a melhor aceitabilidade pelos julgadores foram obtidos com os frutos acondicionados em embalagens de 10 mim.This work was carried out to evaluate the effects of low density polyethylene bags (LDPB with different thickness on Golden Star starfruit shelf life. The fruits were harvested at mature-green ripening stage, selected from lack of defects and placed in LDPB bags, constituting the following treatments: T1 - control (no bags; T2 - 6 mum thickness LDPB; T3 - 10 mum thickness LDPB; T4 - 15 mum thickness LDPB. Fruits were stored for 45 days in refrigerated air at 12 +/- 0,5ºC and 95 +/- 3% RH and then left at 22 +/- 3ºC and 72 +/- 5% RH for 5 days. Twenty-four hours after harvest and every nine days, samples were removed from cold storage, kept for 12 hours in ambient air (22 +/- 3ºC and 72 +/- 5% RH and then analyzed for flesh firmness, weight loss, epidermal color, total soluble solids, total titratable acidity, and occurrence of physiological disorders. Fruits were also evaluated by a trained taste panel. Highest values of flesh firmness and titratable acidity, the best color standard, the lowest soluble content as well as decay incidence and the best acceptance scores by the taste panelists were achieved in fruits stored in 10 mum thickness LDPB.

  19. Ensayo de arcillas modificadas con materia orgánica soluble para la eliminación de Cu y Zn

    OpenAIRE

    Durán, Esperanza; Gámiz, B.; Cox, L.; Hermosín, M.C.

    2015-01-01

    La contaminación por metales pesados es un tema de gran preocupación. Entre las diversas actividades que contribuyen a aumentar la presencia de metales pesados en el medio ambiente, se encuentra la agricultura. Por ejemplo, el uso de fertilizantes de tipo fosforados y algunos fungicidas incrementan la aparición Cu y Zn en aguas de zonas agrícolas e incluso residuales de la industria agroalimentaria. La eliminación de metales pesados mediante el uso de minerales de la arcilla tipo montmorillon...

  20. Evaluación de la degradación de una membrana de polipropileno modificada con monómeros naturales

    OpenAIRE

    HERNANDEZ AGUIRRE, OMAR ALBERTO

    2016-01-01

    Las membranas poliméricas tienen una gran variedad de aplicaciones principalmente en el tratamiento de aguas residuales, sin embargo debido a las características propias de algunos de los polímeros, las aplicaciones de este tipo de membranas se ven limitadas, además de que en cuanto termina su tiempo de vida útil como membrana favorece la generación de residuos plásticos los cuales debido a su estabilidad tienen un largo tiempo de degradación. Es por ello que, es de suma importancia el bri...

  1. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    Directory of Open Access Journals (Sweden)

    Escudero, M. L.

    2011-06-01

    Full Text Available The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair.En el presente trabajo se ha estudiado el comportamiento frente a la corrosión y la biocompatibilidad in vitro/in vivo de la aleación de magnesio AZ31, cuyas propiedades mecánicas son superiores a los requisitos mecánicos del hueso. La aleación en estado de recepción ha mostrado una cinética de corrosión no compatible con el crecimiento celular. Para mejorar su comportamiento, el material ha sido modificado superficialmente mediante tratamiento de conversión química en ácido fluorhídrico. La capa de fluoruro de magnesio generada tras este tratamiento mejora el comportamiento del material frente a la corrosión, permitiendo el crecimiento in vitro de células osteoblásticas sobre su superficie y la formación in vivo de una capa de nuevo tejido óseo muy compacta. Estos resultados permiten concluir que el recubrimiento de fluoruro de magnesio es necesario para que el material AZ31 pueda ser potencialmente aplicado como implante biodegradable y reabsorbible en reparaciones óseas.

  2. Classificação de sombra em imagens orbitais e aéreas utilizando uma matriz de co-ocorrência modificada

    Directory of Open Access Journals (Sweden)

    Jorge Antonio Silva Centeno

    Full Text Available Embora seja considerada útil para a identificação de objetos mais elevados, a presença de sombras pode ser um elemento prejudicial na extração de informações quando esconde objetos de menor altura. Neste trabalho é descrito o desenvolvimento conceitual e exemplos de aplicação de um método para a segmentação de sombras em imagens de satélite e fotografias aéreas baseado na análise da matriz de co-ocorrência. A matriz de co-ocorrência traduz a relação entre o pixel e sua vizinhança, o que permite identificar áreas uniformes e escuras, que correspondem a sombras. Com esta premissa, foi proposto um método que analisa a diagonal principal da matriz de co-ocorrência e identifica nela os agrupamentos associados a sombras. Para delimitar as sombras, é usada uma função contextual derivada da melhor reta perpendicular à diagonal principal da matriz de co-ocorrência que separa áreas escuras e uniformes. Testes com imagens aéreas e de satélite são apresentados para ilustrar o método. O método proposto é do tipo adaptativo e pode ser usado tanto em imagens de 8 bits como também estendido à maiores resoluções radiométricas, além disso seu funcionamento não é afetado pela eventual contribuição atmosférica, que afeta principalmente as bandas do visível.

  3. Valoración ambiental preliminar del riesgo-beneficio de la liberación de una semilla de arroz genéticamente modificada

    OpenAIRE

    Bermúdez-Muñoz, Sergio; Víquez-Camacho, Miguel

    2011-01-01

    La Evaluación de Impacto Ambiental (EIA) es una herramienta de gestión que permite, de forma holística, determinar las potenciales alteraciones que una puede tener sobre el ambiente, pues considera los impactos positivos y negativos que podrían presentarse. La aplicación de esta herramienta cuando se libera un OGM, con la ayuda de información de campo y secundaria, se convierte en un esfuerzo pionero, pues permite a quienes toman decisiones y a la opinión pública analizar los pro y contra que...

  4. Interferência de plantas concorrentes em arroz irrigado modificada por métodos culturais Interference of concurrent plants in flooded rice modified by cultural methods

    Directory of Open Access Journals (Sweden)

    N.G. Fleck

    2004-03-01

    Full Text Available A otimização de um programa de controle de plantas daninhas depende da previsão precoce e confiável do impacto destas sobre o rendimento da cultura. Este trabalho teve por objetivos avaliar os efeitos de cultivares e de arranjos de plantas na perda de rendimento de grãos em arroz irrigado e identificar a variável explicativa que proporcione melhor ajuste ao modelo testado. Foram conduzidos dois experimentos em campo, na estação estival de crescimento 2000/01. Os tratamentos constaram de três cultivares de arroz (BRS-38 Ligeirinho, IRGA 417 e BR-IRGA 409, dois espaçamentos entre linhas (15 e 25 cm e populações (dez e seis níveis para o primeiro e segundo experimentos, respectivamente do cultivar de arroz EEA 406, simulando infestação de arroz-vermelho. Os dados foram analisados utilizando-se o modelo de regressão não-linear da hipérbole retangular, ajustado de modo independente para os três fatores estudados. Os resultados do primeiro experimento foram utilizados para avaliar o ajuste dos dados ao modelo e os do segundo para validar o modelo obtido no primeiro experimento. O cultivar IRGA 417 apresentou maior habilidade competitiva com o cultivar simulador de arroz-vermelho do que os outros dois. A redução no espaçamento entre linhas aumentou a habilidade competitiva dos cultivares de arroz em relação ao cultivar concorrente. O modelo da hipérbole retangular foi apropriado para estimar perdas de rendimento de grãos de arroz irrigado por interferência de plantas concorrentes. A variável explicativa área foliar do cultivar EEA 406, em geral, apresentou equivalência à população de plantas como variável independente no modelo matemático testado.The optimization of a weed control program depends on early and reliable prediction of the impact of weeds on crop yield. This research aimed to evaluate the effects of rice cultivars and plant arrangements on flooded rice grain yield loss and to identify the explicative variable that provides the best adjustment to the model tested. Two field experiments were carried out during the 2000/2001 growing season. Treatments consisted of three rice cultivars (BRS-38 Ligeirinho, IRGA 417, and BR-IRGA 409, two row widths (15 and 25 cm, and plant populations (ten and six levels for the first and second experiments, respectively of the rice cultivar EEA 406, mimicking red rice infestation.. Data were analyzed using the non - linear regression model of rectangular hyperbole, adjusted independently for the three studied factors. Results of the first experiment were used to evaluate data adjustment to the model and results of the second to validate the model generated in the first. IRGA 417 cultivar presented greater competitive ability than the other two. Reduction of row width increased the ability of rice cultivars to compete with the concurrent genotype. The rectangular hyperbolic model was suitable to estimate flooded rice grain yield loss due to interference of concurrent plants. The explicative variable leaf area of EEA 406 cultivar, in general, was equivalent to plant population as an independent variable in the mathematical model tested.

  5. Preparatory of X zeolite (faujasite) with surfactant hexa decyl trimethyl ammonium bromide (HMDTA) for adsorption of organic compounds; Acondicionamiento de zeolita X (faujasita) con surfactante bromuro de hexa decil trimetil amonio (HDTMA) para adsorcion de compuestos organicos

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez R, V

    2003-07-01

    The water represents one of the most valuable natural resources for the alive beings, since it is the essential component of the alive matter. Also, it is fundamental part of our planet, since is an indispensable element for the integral development of the same one. The demographic growth, the human being's activities and the industrial growth, he/she brings as consequence an increase in the use of the water and the generation of residual waters that successively contaminate the hydrological basins, becoming an environmental problem urgent. The contamination of the water with compound such as phenol and benzene, it is a problem that it requires the search of solutions, since it is of compound not very biodegradable, able to accumulate through the food chains and very toxic to the alive beings that they enter in contact with them (Tolgyessy, 1993). In the human beings it can take place damages in liver and kidney, the Agency of Protection to the Atmosphere of the United States (EPA) it considers that the exhibition for benzene is related with the leukemia, it is also considered as a carcinogen substance. Of the methods that are used for the treatment of polluted waters, it highlights the use of adsorber and one of them is the zeolites, since they are broadly used in those separation processes. The zeolites is crystalline aluminosilicates, they are characterized for to have a big superficial area and for their great capacity of exchange cationic, due to it the process of adsorption depends on these two characteristics, since to the modified being superficially for surfactants cationic it originates an enriched layer of carbon organic, which has the capacity to remove pollutants of the water. The present work outlines as objective to carry out the superficial modification of zeolite X using hexa decyl trimethyl ammonium bromide (HMDTA-Br) to different concentrations, with the purpose of making it useful in the removal of pollutants organic, present in watery solution. The results of this investigation work indicate that the superficial modification of the zeolite X with HMDTA-Br to the four used concentrations 29, 58, 116 and 174 mmol L was possible, and it is demonstrated by the results of electronic microscopy of sweeping and for the decrease of the content of sodium carried out by Neutron activation analysis. In relation to the removal tests, it was found that the zeolite modified X with the biggest surfactant concentration it presents the highest phenol percentage removed, being this of 38% for a time of contact of 3 hours. In accordance with the results of removal of benzene is observed that the zeolite X removes 56%, but the modified zeolite removes a bigger quantity of until 90%, said percentage varies with regard to the time of contact. Therefore the modification of the zeolite X is favorable for the removal of the benzene. (Author)

  6. Effect of the modification of a natural mexican zeolite in the sorption of cadmium and 4-chloro phenol; Efecto de la modificacion de una zeolita natural mexicana en la sorcion de cadmio y 4-clorofenol

    Energy Technology Data Exchange (ETDEWEB)

    Cortes M, R [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    Clinoptilolite type zeolite is a material of relative abundance in Mexico, which possess ion exchange properties and it can be used in the removal of metal ions from polluted waters. The external surface of zeolites can be modified with cationic surfactants. This modification could have a negative effect on the removal of metal ions and provides to the material the capacity to adsorb phenolic compounds. For this reason, it is important to know the capability of the modified material on the sorption of metal ions and phenolic compounds, simultaneously. The aim of this work was to evaluate the effect of the external surface modification with surfactant of a Mexican zeolite over its sorption capacity of cadmium and 4-chloro phenol, in batch and column systems. To accomplish that, a clinoptilolite type zeolitic rock from a deposit located in the state of Sonora, Mexico, was used. It was ground, sieved and characterized with different techniques; and its external surface area was modified with hexadecyltrimethylammonium bromide (HDTMA-Br). A grain size fraction was selected to carry out sorption kinetics and equilibrium experiments, as well as packed column tests with zeolitic material and solutions of cadmium and 4-chloro phenol. There are different models proposed in literature that are used to describe sorption kinetics and equilibrium. In this work, the sorption experimental results were adjusted to some of these models to identify controlling mechanisms on the kinetics and equilibrium of the studied systems. The results showed that the cadmium adsorption on natural and modified zeolite was similar in batch systems. For the case of 4-chloro phenol sorption, it was observed that natural zeolite does not retain this compound, while in modified zeolite the sorption is better than other comparable materials. The results also showed that for the case of cadmium sorption, the mechanism involved was ion exchange; while for sorption of 4-chloro phenol, a partition mechanism was implicated. Basic design parameters for the sorption of cadmium on natural and modified zeolites were calculated from breakthrough curves obtained from column experiments, by using simplified models. Column adsorption capacities for these two systems were good compared with other adsorbents and column efficiencies achieved were acceptable according to maximum adsorption capacities obtained for batch systems. For 4-chloro phenol, the same models were applied to calculate design parameters and column adsorption capacity and reasonable results were obtained. In this work was demonstrated that the field for application of natural zeolites as adsorbents can be amplified for the removal or organic pollutants from wastewaters, by the modification of their external surfaces with cationic surfactants, without having a significant effect on their ion exchange properties used for the uptake of heavy metals from polluted waters. (Author)

  7. Evaluación de un electrodo de carbón vítreo modificado con Zeolita tipo “A” en la adsorción de 2-clorofenol

    Directory of Open Access Journals (Sweden)

    Aurora Molina

    2009-10-01

    Full Text Available Glassy carbon electrodes modified with Zeolite “A” were studied in order to evidence the adsorption of 2-chlorophenol. Synthesis of zeolite was undertaken by a hydrothermal method using calcined kaolin as raw material. The zeolite was first exchanged with calcium ions. Then, it was modified with the cationic surfactant CTAB (cetyl trimethyl ammonium bromide or the non-ionic surfactant Triton X-100 (t-octylphenoxy-polyethoxyethanol. Adsorption of 2-chlorophenol was evaluated by cyclic voltammetry, once it was adsorbed onto the modified electrode. Electrochemical results indicated that the films surfactant-zeolites were able to adsorb the 2-chlorophenol from an aqueous alkaline medium. The best results were achieved when the cationic surfactant CTAB was used. The importance of electrode surface cleaning to guarantee the complete adherence between the vitreous carbon and the modified surfactant zeolite was determinated. Polishing and cleaning processes depend on the type of surfactant used.

  8. Influence of zeolite treated with sulphuric acid and sodium hydroxide on the coagulation-flocculation process of drainage. Influencia de la zeolita tratada con acido sulfurico y con hidroxido de sodio en el proceso de coagulacion floculacion en aguas superficiales

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez Duque, M.; Herrera Vasconcelos, T.; Laria Piedra, N.

    1994-01-01

    The present paper has had as objective the treatment of natural zeolite from Tasajera with sulfuric acid and sodium hydroxide (residuals acid and basic from the regeneration of cationic and anionic resins of the ''Otto Parallada'' thermoelectric plant) at different times and concentrations, with a further comparison and testing of the effectiveness of the obtained zeolite in respect to the natural one as a coadyuvant of the coagulation-flocculation process in the treatment of superficial water. (Author)

  9. Synthesis of LTA zeolite on corundum supports: Preliminary assessment for heavy metal removal from waste water; Sintesis de zeolita LTA sobre soportes de corindon: Evaluacion preliminar para la eliminacion de metales pesados de efluentes acuosos

    Energy Technology Data Exchange (ETDEWEB)

    Jacas, A.; Ortega, P.; Velasco, M. J.; Camblor, M. A.; Rodriguez, M. A.

    2012-11-01

    The effectiveness of materials based on LTA Zeolite as active phase, for their incorporation into systems aimed at the removal of heavy metals on waste water is evaluated in a preliminary way. This type of Zeolite with the main channel of a minimum free diameter of 0,41 nm and a low SiO{sub 2}/Al{sub 2}O{sub 3} ratio is an interesting molecular sieve, which in turn display a high ion exchange capacity. From this point of view, LTA Zeolite crystals were obtained in situ by hydrothermal synthesis and characterized by x ray diffraction (XRD) and scanning electron microscopy (SEM). We have studied the effect of hydrothermal synthesis time at 378 K. Likewise, the removal capacity of heavy metal from the active phase was evaluated in as a first step on diluted solutions of cooper salts at slightly acidic pH ({approx} 4,7). (Author) 28 refs.

  10. Preparatory of X zeolite (faujasite) with surfactant hexa decyl trimethyl ammonium bromide (HMDTA) for adsorption of organic compounds; Acondicionamiento de zeolita X (faujasita) con surfactante bromuro de hexa decil trimetil amonio (HDTMA) para adsorcion de compuestos organicos

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez R, V

    2003-07-01

    The water represents one of the most valuable natural resources for the alive beings, since it is the essential component of the alive matter. Also, it is fundamental part of our planet, since is an indispensable element for the integral development of the same one. The demographic growth, the human being's activities and the industrial growth, he/she brings as consequence an increase in the use of the water and the generation of residual waters that successively contaminate the hydrological basins, becoming an environmental problem urgent. The contamination of the water with compound such as phenol and benzene, it is a problem that it requires the search of solutions, since it is of compound not very biodegradable, able to accumulate through the food chains and very toxic to the alive beings that they enter in contact with them (Tolgyessy, 1993). In the human beings it can take place damages in liver and kidney, the Agency of Protection to the Atmosphere of the United States (EPA) it considers that the exhibition for benzene is related with the leukemia, it is also considered as a carcinogen substance. Of the methods that are used for the treatment of polluted waters, it highlights the use of adsorber and one of them is the zeolites, since they are broadly used in those separation processes. The zeolites is crystalline aluminosilicates, they are characterized for to have a big superficial area and for their great capacity of exchange cationic, due to it the process of adsorption depends on these two characteristics, since to the modified being superficially for surfactants cationic it originates an enriched layer of carbon organic, which has the capacity to remove pollutants of the water. The present work outlines as objective to carry out the superficial modification of zeolite X using hexa decyl trimethyl ammonium bromide (HMDTA-Br) to different concentrations, with the purpose of making it useful in the removal of pollutants organic, present in watery solution. The results of this investigation work indicate that the superficial modification of the zeolite X with HMDTA-Br to the four used concentrations 29, 58, 116 and 174 mmol L was possible, and it is demonstrated by the results of electronic microscopy of sweeping and for the decrease of the content of sodium carried out by Neutron activation analysis. In relation to the removal tests, it was found that the zeolite modified X with the biggest surfactant concentration it presents the highest phenol percentage removed, being this of 38% for a time of contact of 3 hours. In accordance with the results of removal of benzene is observed that the zeolite X removes 56%, but the modified zeolite removes a bigger quantity of until 90%, said percentage varies with regard to the time of contact. Therefore the modification of the zeolite X is favorable for the removal of the benzene. (Author)

  11. Effect of the humic acids in the adsorption of U (Vi) in a Mexican natural zeolite; Efecto de los acidos humicos en la adsorcion de U (VI) en una zeolita natural mexicana

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval G, H. A.; Lopez del R, H.; Davila R, J. I.; Mireles G, F., E-mail: hlopezdelrio@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2012-10-15

    The uranium adsorption was studied in a Mexican natural zeolite of the clinoptilolite type in presence and absence of humic acids (Ha). The adsorption kinetics of the binary U-zeolite and ternary U-Ha-zeolite systems were compared, and the effect of the humic matter impregnated in the zeolite in the uranium removal in function of the solution ph was studied. The experiments were made to environmental conditions and lightly acid ph, with fixed concentrations of uranium and Ha of 1 x 10{sup -5} M and 20 ppm, respectively, and a reason m/V of 5 mg/ml. The uranium adsorption in absence of Ha was of 96% and decreased to 45% in the ternary system U-Ha-zeolite. The data of the binary system U-zeolite were analyzed with three kinetic models of adsorption (pseudo-first order, pseudo-second order and Elovich). By means of non lineal regression was found that the uranium adsorption obeys a kinetic of pseudo-second order. It was observed that the uranium adsorption in the zeolite impregnated with Ha is favored to more ph at 5. (Author)

  12. Study of the influences of the zeolites physical and chemical characteristics in the soya oil cracking; Estudo das influencias das caracteristicas fisico-quimicas de zeolitas no craqueamento do oleo de soja

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Frances Regiane dos

    1995-10-01

    Vegetable oils have been studied as raw materials to yield fuel hydrocarbons. The catalytic and thermal transformations of these oils have been presented as being able to generate hydrocarbons from which diesel oil and vegetable gasoline may be obtained. (author)

  13. Sorption of Fe{sup 3+} , Co{sup 2+} , Ce{sup 3+} , Cs{sup +} and Ba{sup 2+} in zeolite X.; Sorcion de Hierro (III), Cobalto (II), Cerio (III), Cesio (I), Bario (II) en Zeolita X.

    Energy Technology Data Exchange (ETDEWEB)

    Martinez M, V

    1994-12-31

    The sorption behavior of Fe{sup 3+} , Co{sup 2+} , Ce{sup 3+} , Cs{sup +} , and Ba{sup 2+} in aqueous solutions, was studied in presence of zeolite X. Solutions of Fe(NO{sub 3}){sub 3} . 9 H{sub 2} O, Co(NO{sub 3}){sub 2} . 6 H{sub 2} O, Ce(NO{sub 3}){sub 3} . 6 H{sub 2} O, Cs NO{sub 3} and Ba(NO{sub 3}){sub 2} were labelled with the respectively radioactive isotopes Fe{sup 59} , Co{sup 60}, Cs{sup 134}, Ba{sup 139} and Ce{sup 141}. 20 ml. of each solution was left in contact with 200 mg. of zeolite for different periods. Later the zeolites were separated by centrifugation from the aqueous solutions and the radioactivity of the aqueous phases was measured with a NaI(Tl) solid-state well detector coupled to a single-channel Picker analyzer or with a Gel hyper pure solid-state detector coupled to a 2048 channel pulse height analyzer. When Cs{sup +} in the aqueous solutions was left in contact with zeolite X it was found that it does not occupy all cationic sites in the zeolite due to the ionic radium effect. A similar behavior was found for the divalent ions. In all cases, when the pH was not controlled, the zeolite lost part of its crystallinity and when the divalent ions were exchanged again by Na{sup +}, the zeolite recovered completely its crystallinity. During the sorption, the ionic radius, and the charge are important parameters as well as the pH. When the pH of the solution was adjusted between 6.5 - 7.0 the crystallinity was maintained in some cases. For Fe{sup 3+} the crystallinity after the ion exchange was 94 % and when the pH was not adjusted the crystallinity was completely lost. It was found as well that the zeolite X induces the formation of H{sub 3} O{sup +} which competes with the cations for the sites in the zeolite. (Author).

  14. Influence of zeolite treated with sulphuric acid and sodium hydroxide on the coagulation-flocculation process of drainage. Influencia de la zeolita tratada con acido sulfurico y con hidroxido de sodio en el proceso de coagulacion floculacion en aguas superficiales

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez Duque, M; Herrera Vasconcelos, T; Laria Piedra, N

    1994-01-01

    The present paper has had as objective the treatment of natural zeolite from Tasajera with sulfuric acid and sodium hydroxide (residuals acid and basic from the regeneration of cationic and anionic resins of the ''Otto Parallada'' thermoelectric plant) at different times and concentrations, with a further comparison and testing of the effectiveness of the obtained zeolite in respect to the natural one as a coadyuvant of the coagulation-flocculation process in the treatment of superficial water. (Author)

  15. Synthesis of zeolites 'type A' for adsorption of CO{sub 2}; Sintese de zeolitas 'tipo A' para adsorcao de CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, L.O.; Madeira, A.C.; Merlini, A.; Melo, C.R.; Mendes, E.; Santos, M.G.S.; Angioletto, E., E-mail: elidio@unesc.net [Universidade do Extremo Sul Catarinense (IPARQUE/UNESC), Criciuma, SC (Brazil). Parque Cientifico e Tecnologico

    2012-07-01

    The separation of gases is a very expensive step in the chemical industry and unquestionable relevance. In this work it was found the effectiveness of using zeolites of type A in the separation of CO{sub 2} in a gas mixture containing 25% CO{sub 2}, 4% O{sub 2} and 71% N{sub 2} concentrations similar to exhaust gases from combustion processes. To this end, was synthesized using zeolites type A commercial kaolin and mounted to an adsorption column to test the efficiency of zeolites in the adsorption of CO{sub 2}. The synthesized zeolites showed surface area of 66.22m{sup 2}/g. The CO{sub 2} concentration was determined by gas chromatography with TCD detector. Adjusting the data to the Langmuir model, there was obtained the kinetics of adsorption. From these, we found the ability of zeolite to adsorb CO{sub 2} used in the column of 0.461285mg/g. The results of adsorption proved promising and showed maximum adsorption of 78.4% at a time of 10 seconds. (author)

  16. Immobilization of Co{sup 2+} and Cs{sup +} in zeolites by thermal treatment and by combustion; Inmovilizacion de Co{sup 2+} y Cs{sup +} en zeolitas por tratamiento termico y por combustion

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez T, R.; Bulbulian G, S. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: rosarodtre@yahoo.com

    2005-07-01

    The radioactive waste, either those that take place in the {sup 235}U fission or those that are used in the radiochemical laboratories, are dangerous for the human being and for the one environment. The liquid radioactive wastes are of those that present bigger problem. It has intended to retain by the ion exchange method the radioactive ions of the liquids using, for example, zeolites. In this work so much synthetic zeolites was used (A and X) like a natural zeolite (clinoptilolite). Its were put in contact with cobalt or cesium solutions to simulate radioactive solutions. A part of the zeolite cations were exchanged with cobalt or cesium cations, eliminating them by this way of the solution. However, in extreme conditions these cations can be leached of the solids. To immobilize the cobalt or cesium cations in the zeolites net its are usually carried out thermal treatments to such temperatures that the structure is destroyed and that the contaminating ions are trapped in a solid often vitreous. The exchanged zeolites with cobalt or cesium, on one hand, its were thermally treated to different temperatures during three hours and by the other one, according to the treatment method by combustion, to different temperatures during five minutes in presence of urea, later its were put in contact with a solution of NaCl to measure the leaching of the interest cations. These solutions were analyzed by neutron activation. In general it was found that as the treatment temperature increases (in both methods) the so much immobility of the cesium like of the cobalt it increases. The grade of crystallinity of the samples before and after the treatments it was determined by X-ray diffraction. (Author)

  17. STUDY OF EPOXIDE DECYCLISATION OF CARYOPHYLENE OXIDE WITH SYNTHETIC ZEOLITE AS CATALYSTS

    Directory of Open Access Journals (Sweden)

    Winarto Haryadi

    2010-06-01

    Full Text Available The reaction of epoxide ring opening of caryophillene oxide has been done using zeolite H-Y, H-sodalit, and H-ZSM-5 as catalysts. The reactions were done in two types, there were in dioxane solvent at temperature of 110 oC and without solvent at temperature of 175 oC. The catalyst weight was 10 % from caryophillene oxide weight, and the time of reaction was four hours. The product of reaction was analyzed using GC, FTIR, and GC-MS. The reactions of caryophillene oxide in dioxane solvent with the three kinds of zeolites did not give any targeted product. Whereas, the reactions without solvent gave three main products, there was one compound with one group of secondary hidroxyl (secondary alcohol, and two compounds of ketone from caryophillene. The reaction product of caryophillene oxide obtained without using solvent with the three type of catalysts were then compared. Conversion of three main products produced by H-ZSM-5 catalyst, H-sodalit catalyst and H-Y catalyst were 82.11 %, 54.92 % and 38.53 % respectively. For that reason, the transformation of caryophillene oxide using H-ZSM-5 catalyst was considered to be the best selective product. The alcohol product was resulted from reaction between caryophillene oxide and Bronsted acid, and  the ketone products was resulted from the reaction with Lewis acid in zeolite.   Keywords: Epoxide ring opening, HY, H-sodalit and HZSM-5

  18. Effect of high-temperature treatment on Fe/ZSM-5 prepared by chemical vapor deposition of FeCl3. II. Nitrous oxide decomposition, selective oxidation of benzene to phenol, and selective reduction of nitric oxide by isobutane

    NARCIS (Netherlands)

    Zhu, Q.; Teeffelen, van R.M.; Santen, van R.A.; Hensen, E.J.M.

    2004-01-01

    The catalytic performance (nitrous oxide decomposition, hydroxylation of benzene to phenol with nitrous oxide, and selective reduction of nitric oxide by i-butane) was evaluated for a set of HZSM-5 and sublimed Fe/ZSM-5 catalysts, which have been extensively characterized in an earlier contribution

  19. Value addition to lignocellulosics and biomass-derived sugars: An ...

    Indian Academy of Sciences (India)

    .59 HMF is mainly produced from fructose ... Sn–W oxide catalyst was evaluated in this reaction and it yielded 48% of ... Catalytic cracking of bio-oils is also known over. HZSM-5 ≥ 340 ...... Kim S B and Lee Y Y 1985 Biotechnol. Bioeng. Symp.

  20. Dehydrogenation of light alkanes over rhenium catalysts on conventional and mesoporous MFI supports

    DEFF Research Database (Denmark)

    Rovik, Anne Krogh; Hagen, Anke; Schmidt, I.

    2006-01-01

    Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time...

  1. Alkali resistivity of Cu based selective catalytic reduction catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Jensen, Anker Degn; Riisager, Anders

    2012-01-01

    The deactivation of V2O5–WO3–TiO2, Cu–HZSM5 and Cu–HMOR plate type monolithic catalysts was investigated when exposed to KCl aerosols in a bench-scale reactor. Fresh and exposed catalysts were characterized by selective catalytic reduction (SCR) activity measurements, scanning electron microscope......–energy dispersive X-ray spectroscopy (SEM–EDX) and NH3-temperature programmed desorption (NH3-TPD). 95% deactivation was observed for the V2O5–WO3–TiO2 catalyst, while the Cu–HZSM5 and Cu–HMOR catalysts deactivated only 58% and 48%, respectively, after 1200 h KCl exposure. SEM analysis of the KCl aerosol exposed...... catalysts revealed that the potassium salt not only deposited on the catalyst surface, but also penetrated into the catalyst wall. Thus, the K/M ratio (M = V or Cu) was high on V2O5–WO3–TiO2 catalyst and comparatively less on Cu–HZSM5 and Cu–HMOR catalysts. NH3-TPD revealed that the KCl exposed Cu–HZSM5...

  2. Liquid Phase Isomerisation of Dichlorobenzenes over H-Zeolites

    Czech Academy of Sciences Publication Activity Database

    Kaucký, Dalibor; Fajula, F.; Moreau, P.; Finiels, A.

    2003-01-01

    Roč. 243, - (2003), s. 301-307 ISSN 0926-860X Institutional research plan: CEZ:AV0Z4040901 Keywords : dichlorobenzenes * isomerisation * H-ZSM-5 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.825, year: 2003

  3. Highly selective oxidation of styrene to benzaldehyde over a tailor-made cobalt oxide encapsulated zeolite catalyst.

    Science.gov (United States)

    Liu, Jiangyong; Wang, Zihao; Jian, Panming; Jian, Ruiqi

    2018-05-01

    A tailor-made catalyst with cobalt oxide particles encapsulated into ZSM-5 zeolites (Co 3 O 4 @HZSM-5) was prepared via a hydrothermal method with the conventional impregnated Co 3 O 4 /SiO 2 catalyst as the precursor and Si source. Various characterization results show that the Co 3 O 4 @HZSM-5 catalyst has well-organized structure with Co 3 O 4 particles compatibly encapsulated in the zeolite crystals. The Co 3 O 4 @HZSM-5 catalyst was employed as an efficient catalyst for the selective oxidation of styrene to benzaldehyde with hydrogen peroxide as a green and economic oxidant. The effect of various reaction conditions including reaction time, reaction temperature, different kinds of solvents, styrene/H 2 O 2 molar ratio and catalyst dosage on the catalytic performance were systematically investigated. Under the optimized reaction condition, the yield of benzaldehyde can achieve 78.9% with 96.8% styrene conversion and 81.5% benzaldehyde selectivity. Such an excellent catalytic performance can be attributed to the synergistic effect between the confined reaction environment and the proper acidic property. In addition, the reaction mechanism with Co 3 O 4 @HZSM-5 as the catalyst for the selective oxidation of styrene to benzaldehyde was reasonably proposed. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Elucidation of the mechanism of conversion of methanol and ethanol to hydrocarbons on a new type of synthetic zeolite

    NARCIS (Netherlands)

    Derouane, E.G.; Nagy, J.B.; Dejaifve, P.; Hooff, van J.H.C.; Spekman, B.P.A.; Védrine, J.C.; Naccache, C.

    1978-01-01

    13C nuclear magnetic resonance and vapor-phase chromatography have been used to investigate the conversions of methanol and ethanol to hydrocarbons on a synthetic zeolite of the type H-ZSM-5 as described by Mobil. Methanol is first dehydrated to dimethyl ether and ethylene. Then the reaction

  5. Catalytic Performance of Zeolite-Supported Vanadia in the Aerobic Oxidation of 5-hydroxymethylfurfural to 2,5- diformylfuran

    DEFF Research Database (Denmark)

    Sádaba, Irantzu; Gorbanev, Yury; Kegnæs, Søren

    2013-01-01

    on the four different zeolite supports H-beta, H-Y, H-mordenite, and H-ZSM-5 with 1–10 wt% vanadia loading were prepared and characterized by nitrogen physisorption, X-ray powder diffraction, scanning electron  microscopy, ammonia temperature-programmed desorption, Raman spectroscopy and UV...

  6. The conversion of dimethyl ether over Pt/H-ZSM5. A bifunctional catalyzed reaction

    NARCIS (Netherlands)

    Engelen, C.W.R.; Wolthuizen, J.P.; Hooff, van J.H.C.; Imelik, B.; Naccache, C.; Coudurier, G.

    1985-01-01

    At low temperatures dimethylether mixed with hydrogen reacts over a platinum loaded H-ZSM5 catalyst selectivity to methane. Two successive steps can be distinguished; first the acid-catalyzed formation of a trimethyloxoniumion, followed by a metal-catalyzed hydrogenation to methane. Experiments with

  7. Aromatic hydrocarbon production via eucalyptus urophylla pyrolysis over several metal modified ZSM-5 catalysts – an analysis by py-GC/MS

    Science.gov (United States)

    Metal modified HZSM-5 catalysts were prepared by ion exchange of NH4ZSM-5 (SIO2/Al2O3 = 23) using gallium, molybdenum, nickel and zinc, and their combinations thereof. The prepared catalysts were used to evaluate catalytic pyrolysis for the conversion of Eucalyptus urophylla to fuels and chemicals, ...

  8. Liquid phase in situ hydrodeoxygenation of biomass-derived phenolic compounds to hydrocarbons over bifunctional catalysts

    Science.gov (United States)

    Junfeng Feng; Chung-yun Hse; Zhongzhi Yang; Kui Wang; Jianchun Jiang; Junming Xu

    2017-01-01

    The objective of this study was to find an effective method for converting renewable biomass-derived phenolic compounds into hydrocarbons bio-fuel via in situ catalytic hydrodeoxygenation. The in situ hydrodeoxygenation of biomass-derived phenolic compounds was carried out in methanol-water solvent over bifunctional catalysts of Raney Ni and HZSM-5 or H-Beta. In the in...

  9. Nafion®/H-ZSM-5 composite membranes with superior performance for direct methanol fuel cells

    NARCIS (Netherlands)

    Yildirim, M.H.; Curos, Anna Roca; Motuzas, Julius; Motuzas, J.; Julbe, Anne; Stamatialis, Dimitrios; Wessling, Matthias

    2009-01-01

    Solution cast composite direct methanol fuel cell membranes (DEZ) based on DE2020 Nafion® dispersion and in-house prepared H-ZSM-5 zeolites with different Si/Al ratios were prepared and thoroughly characterized for direct methanol fuel cell (DMFC) applications. All composite membranes have indeed

  10. Aromatization of propane over MFI-gallosilicates

    NARCIS (Netherlands)

    Bayense, C.R.; vd Pol, A.J.H.P.; Hooff, van J.H.C.

    1991-01-01

    The results of propane aromatization over gallium containing HZSM-5 zeolites are described. Highly dispersed gallium in the zeolite (framework or extra-framework) was found to possess dehydrogenation activity, especially in the presence of strong Brønsted acid sites. The extra-framework gallium was

  11. Styrene oligomerization as a molecular probe reaction for zeolite acidity: a UV-Vis spectroscopy and DFT study

    NARCIS (Netherlands)

    Buurmans, I.L.C.; Pidko, E.A.; Groot, de J.M.; Stavitski, E.; Santen, van R.A.; Weckhuysen, B.M.

    2010-01-01

    A series of H-ZSM-5 crystallites with different framework Si/Al ratios was studied by analyzing the kinetics and reaction mechanism of the oligomerization of 4-fluorostyrene as molecular probe reaction for Brønsted acidity. The formation of carbocationic species was followed by UV-Vis spectroscopy.

  12. Catalytic copyrolysis of cork oak and bio-oil distillation residue

    Science.gov (United States)

    Lee, Yejin; Oh, Daejun; Kim, Young-Min; Jae, Jungho; Jung, Sang-Chul; Jeon, Jong-Ki; Kim, Sang Chai; Park, Young-Kwon

    2018-01-01

    The atmospheric distillation residue (ADR) of cork oak (CO) pyrolysis oil was used as the co-feeding material for the catalytic pyrolysis of CO over HZSM-5 catalysts to improve the formation of aromatic hydrocarbons. Although the non-catalytic copyrolysis of CO and ADR did not improve the formation of aromatic hydrocarbons, the catalytic copyrolysis of CO and ADR promoted the synergistic formation of aromatic hydrocarbons. HZSM-5(30), having a lower SiO2/Al2O3(30), showed better performance for the formation of aromatic hydrocarbons than HZSM-5(80) because of its higher acidity. The catalytic copyrolysis of CO and ADR also decreased the formation of coke. The largest quantity of aromatic hydrocarbons was obtained from the catalytic copyrolysis of CO and ADR over HZSM-5 (30) at 600 °C, whereas the lowest coke yield was achieved at 700 °C. When the catalyst to sample ratio was increased from 2:1 to 5:1, the synergistic formation of aromatic hydrocarbons was limited, resulting in a lower experimental yield of aromatic hydrocarbons than the theoretical yield. A lower coke yield was also achieved at a high catalyst to sample ratio (5:1).

  13. Production of alkyl-aromatics from light oxygenates over zeolite catalysts for bio-oil refining

    Science.gov (United States)

    Hoang, Trung Q.

    Upgrading of light oxygenates derived from biomass conversion, such as propanal and glycerol, to more valuable aromatics for biofuels has been demonstrated on zeolite catalysts. Aromatics with a high ratio of C 9/(C8+C7) and little benzene are produced at much higher yield from oxygenates than from olefins at mild conditions over HZSM-5. It is proposed that C9 aromatics are predominantly produced via acid-catalyzed aldol condensation. This reaction pathway is different from the pathway of propylene and other hydrocarbon aromatization that occurs via a hydrocarbon pool at more severe conditions with major aromatic products C6 and C7. In fact, investigation on the effect of crystallite size HZSM-5 has shown a higher ratio of C9/(C8+C 7) aromatics on small crystallite. This is due to faster removal of products from the shorter diffusion path length. As a result, a longer catalyst lifetime, less isomerization, and less cracking were observed on small crystallites. Beside crystallite size, pore geometry of zeolites was also found to significantly affect aromatic production for both conversion of propanal and glycerol. It is shown that the structure of the HZSM-22, with a one-dimensional and narrower channel system, restricts the formation of aromatics. In contrast, a higher yield of aromatic products is observed over HZSM-5 with its three-dimensional channel system. By increasing channel dimension and connectivity of the channels, increasing catalyst activity was also observed due to more accessible acid sites. It was also found that glycerol is highly active for dehydration on zeolites to produce high yields of acrolein (propenal), a high value chemical. To maximize aromatics from glycerol conversion, HZSM-5 and HY were found to be effective. A two-bed reactor of Pd/ZnO and HZSM-5 was used to first deoxygenate/hydrogenate glycerol over Pd/ZnO to intermediate oxygenates that can further aromatize on HZSM-5. The end results are very promising with significant improvement

  14. Towards a methanol economy: Zeolite catalyzed production of synthetic fuels

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie

    The main focus of this thesis is zeolite catalyzed conversion of oxygenates to hydrocarbon fuels and chemicals. Furthermore, conversion of ethane to higher hydrocarbons has also been studied. After a brief introduction to the concept of “the methanol economy” in the first chapter, the second...... a commercial H-ZSM-5 zeolite impregnated with gallium and/or molybdenum is described. The object was to investigate if the presence of methanol in the feed could enhance the conversion of ethane, but in all cases the opposite is observed; the presence of methanol actually suppresses the conversion of ethane...... various zeolite catalysts is studied in Chapter 4. When 2-propanol or 1-butanol is converted over H-ZSM-5, the total conversion capacities of the catalyst are more than 25 times higher than for conversion of methanol and ethanol. Furthermore, for conversion of C3+ alcohols, the selectivity shifts during...

  15. Decomposição catalítica de óleo de soja em presença de diferentes zeólitas

    Directory of Open Access Journals (Sweden)

    Santos Frances R.

    1998-01-01

    Full Text Available The catalytic decomposition of soybean oil was studied in a fix bed reactor at 673 and 773 K and using amorphous silica-alumina and the zeolites USY, H-Mordenite and H-ZSM-5 as catalysts. Both the selectivity and the catalytic activity were determined by studying the product composition resulting from the chemical reactions. Physicochemical characteristics of the catalysts were obtained by X-ray fluorescence, Fourier Transform infrared spectroscopy, 29Si and 27Al Nuclear Magnetic Ressonance and textural analysis. The zeolites USY and H-ZSM-5, showing higher Brönsted acidity, yielded products with higher concentration in aromatic hydrocarbons, whereas with both H-Mordenite and amorphous silica-alumina the main products were paraffins.

  16. Hydrodeoxygenation of Guaiacol Over Pt/Al-SBA-15 Catalysts.

    Science.gov (United States)

    Yu, Mi Jin; Park, Sung Hoon; Jeon, Jong-Ki; Ryu, Changkook; Sohn, Jung Min; Kim, Sang Chai; Park, Young-Kwon

    2015-01-01

    Upgrading of bio-oil through catalytic hydrodeoxygenation (HDO) reaction was investigated for guaiacol as a model compound. A batch reactor was used for the reaction condition of 40 bar and 250 degrees C. The target product was cyclohexane. Pt/Al-SBA-15 with the Si/Al ratios of 20, 40, and 80 and Pt/HZSM-5 were used as the catalyst. The SBA-15 catalysts were characterized by N2 adsorption-desorption, X-ray diffraction analysis, and temperature programmed desorption of ammonia. The order of cyclohexane yield was Pt/Al-SBA-15 (Si/Al = 20) > Pt/Al-SBA-15(40) > Pt/Al-SBA-15 (80), indicating that the quantity of acid sites plays an important role in the HDO reaction. On the other hand, Pt/HZSM-5 led to a very low cyclohexane yield, in spite of its abundant strong acid sites, due to its small pore size.

  17. Directional synthesis of ethylbenzene through catalytic transformation of lignin.

    Science.gov (United States)

    Fan, Minghui; Jiang, Peiwen; Bi, Peiyan; Deng, Shumei; Yan, Lifeng; Zhai, Qi; Wang, Tiejun; Li, Quanxin

    2013-09-01

    Transformation of lignin to ethylbenzene can provide an important bulk raw material for the petrochemical industry. This work explored the production of ethylbenzene from lignin through the directional catalytic depolymerization of lignin into the aromatic monomers followed by the selective alkylation of the aromatic monomers. For the first step, the aromatics selectivity of benzene derived from the catalytic depolymerization of lignin reached about 90.2 C-mol% over the composite catalyst of Re-Y/HZSM-5 (25). For the alkylation of the aromatic monomers in the second step, the highest selectivity of ethylbenzene was about 72.3 C-mol% over the HZSM-5 (25) catalyst. The reaction pathway for the transformation of lignin to ethylbenzene was also addressed. Present transformation potentially provides a useful approach for the production of the basic petrochemical material and development of high-end chemicals utilizing lignin as the abundant natural aromatic resource. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Analysis of coke precursor on catalyst and study on regeneration of catalyst in upgrading of bio-oil

    International Nuclear Information System (INIS)

    Guo, Xiaoya; Zheng, Yong; Zhang, Baohua; Chen, Jinyang

    2009-01-01

    Catalyst HZSM-5 was used in bio-oil catalytic cracking upgrading. The precursor of coke on the catalyst was analyzed by means of TGA, FTIR and C13 NMR. Precursors of coke deposited in the pore of the molecular sieve were mainly aromatic hydrocarbon with the boiling point range from 350 o C to 650 o C. Those on the outer surface of the pellet precursor were identified as saturated aliphatic hydrocarbons with the boiling point below 200 o C. The activity of HZSM-5 was studied after regeneration. In terms of yield of organic distillate and formation rate of coke, results showed that catalytic activity change moderately during the first three times of regeneration.

  19. “Aplicaciones farmacéuticas de los materiales zeolíticos"

    OpenAIRE

    Regragui, Salwa

    2016-01-01

    Las zeolitas son aluminosilicatos de estructura cristalina y microporosa. Pueden ser de origen natural u obtenido por síntesis química en el laboratorio. Incorporan en su estructura tridimensional moléculas de agua y cationes que ocupan los microporos. Estas características les confieren muchas ventajas como un gran poder de adsorción y una importante capacidad de intercambio catiónico. Además, la presencia de microporos de tamaño variable dependiendo del tipo de zeolita permite su uso como t...

  20. Effect of aluminium distribution in the framework of ZSM-5 on hydrocarbon transformation. Cracking of 1-butene

    Czech Academy of Sciences Publication Activity Database

    Sazama, Petr; Dědeček, Jiří; Gábová, Vendula; Wichterlová, Blanka; Spoto, G.; Bordiga, S.

    2008-01-01

    Roč. 254, č. 2 (2008), s. 180-189 ISSN 0021-9517 R&D Projects: GA AV ČR IAA4040308; GA AV ČR KAN100400702 Institutional research plan: CEZ:AV0Z40400503 Keywords : H-ZSM-5 * Al destribution * catalytic cracking * zeolite acidity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.167, year: 2008

  1. Co-Aromatization of Methane with Olefins: The Role of Inner Pore and External Surface Catalytic Sites

    Energy Technology Data Exchange (ETDEWEB)

    Yung, Matthew M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); He, Peng [University of Calgary; Jarvis, Jack [University of Calgary; Meng, Shijun [University of Calgary; Wang, Aiguo [University of Calgary; Kou, Shiyu [University of Calgary; Gatip, Richard [University of Calgary; Liu, Lijia [Soochow University; Song, Hua [University of Calgary

    2018-04-22

    The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 degrees C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, which might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ring formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.

  2. Moessbauer investigations of the Fe-Cu-Mn catalysts for Fischer-Tropsch synthesis

    International Nuclear Information System (INIS)

    Spanu, V.; Filoti, G.; Ilie, I.; Zamfirescu, E.

    1990-01-01

    In the selective process of the syngas conversion to synthetic gasoline a bifunctional catalytic system has to be used. It was obtained by combination a Fischer-Tropsch catalyst with the HZSM-5 zeolite. The phase compositions of the precursor and the fresh catalyst were established as well as the optimum thermal treatment. The catalyst was reduced in pure H 2 or in a H 2 +CO mixture. The influence of the reduction and reaction conditions on the catalyst structure was investigated. (orig.)

  3. Preparation of silico-alumino-phosphates by the rapid crystallization method and their catalytic performance in the conversion of methanol to light olefins

    Energy Technology Data Exchange (ETDEWEB)

    Inui, T.; Matsuda, H.; Okaniwa, H.; Miyamoto, A. (Kyoto Univ. (Japan))

    1990-02-19

    Shape-selective silico-alumino-phosphates, SAPO-34 and SAPO-17, having the chabazite and erionite structure, respectively, were prepared within 4 h of hydrothermal treatment by the rapid crystallization method. They are highly effective for the selective conversion of methanol to light olefins, such as ethene, propene and butenes. It is shown that these SAPOs are more weakly acidic than typical H-ZSM-5 but more strongly acidic than H-Fe-silicates. 7 figs., 24 refs.

  4. Use of Zeolite ZSM-5 for Loading and Release of 5-Fluorouracil

    Directory of Open Access Journals (Sweden)

    Ruba A. Al-Thawabeia

    2015-01-01

    Full Text Available Samples of zeolite ZSM-5 have been synthesized in both the sodium form (ZSM-5 and the acid activated form (H-ZSM-5. In addition, each of these two forms was prepared in the two molar SiO2/Al2O3 ratios of 169 and 15. All samples of these ZSM-5 derivatives were characterized by X-ray diffraction (XRD, nitrogen adsorption-desorption isotherms, thermal gravimetric analysis (TGA, X-ray fluorescence (XRF, and scanning electron microscopy (SEM. The samples were successfully loaded with the anticancer drug 5-fluorouracil (5-FU with loading capacities varying from 22% (for the sodium form having the lower molar SiO2/Al2O3 ratio of 15, ZSM-5-(15 to 43% (for the corresponding acid form, H-ZSM-5-(15. Percent release of the drug-loaded ZSM-5 samples into simulated body fluid (SBF was measured at pH 7.4 and 37°C. The results showed a slight variation in the % release within the range 84–93%, while the first-order rate constant (k varied from 2.2 h−1 for ZSM-5-(15 to 3.9 h−1 for H-ZSM-5-(15. It was interesting to note that at the higher molar SiO2/Al2O3 ratios of 169, both the sodium form, ZSM-5-(169, and the acid form, H-ZSM-5-(169, exhibit an intermediate efficiency in either % loading (38% or first-order kinetic release constant (k = 2.9 h−1.

  5. Catalytic Cracking of Palm Oil Over Zeolite Catalysts: Statistical Approach

    Directory of Open Access Journals (Sweden)

    F. A. A. Twaiq and S. Bhatia

    2012-08-01

    Full Text Available The catalytic cracking of palm oil was conducted in a fixed bed micro-reactor over HZSM-5, zeolite ? and ultrastable Y (USY zeolite catalysts. The objective of the present investigation was to study the effect of cracking reaction variables such as temperature, weight hourly space velocity, catalyst pore size and type of palm oil feed of different molecular weight on the conversion, yield of hydrocarbons in gasoline boiling range and BTX aromatics in the organic liquid product.  Statistical Design of Experiment (DOE with 24 full factorial design was used in experimentation at the first stage.  The nonlinear model and Response Surface Methodology (RSM were utilized in the second stage of experimentation to obtain the optimum values of the variables for maximum yields of hydrocarbons in gasoline boiling range and aromatics.  The HZSM-5 showed the best performance amongst the three catalysts tested.  At 623 K and WHSV of 1 h-1, the highest experimental yields of gasoline and aromatics were 28.3 wt.% and 27 wt.%, respectively over the HZSM-5 catalyst.  For the same catalyst, the statistical model predicted that the optimum yield of gasoline was 28.1 wt.% at WHSV of 1.75 h-1 and 623 K.  The predicted optimum yield of gasoline was 25.5 wt.% at 623 K and WHSV of 1 h-1.KEY WORDS: Catalytic Cracking, Palm Oil, Zeolite, Design Of Experiment, Response Surface Methodology.

  6. Thermal decomposition of dimethoxymethane and dimethyl carbonate catalyzed by solid acids and bases

    International Nuclear Information System (INIS)

    Fu Yuchuan; Zhu Haiyan; Shen Jianyi

    2005-01-01

    The thermal decomposition of dimethoxymethane (DMM) and dimethyl carbonate (DMC) on MgO, H-ZSM-5, SiO 2 , γ-Al 2 O 3 and ZnO was studied using a fixed bed isothermal reactor equipped with an online gas chromatograph. It was found that DMM was stable on MgO at temperatures up to 623 K, while it was decomposed over the acidic H-ZSM-5 with 99% conversion at 423 K. On the other hand, DMC was easily decomposed on the strong solid base and acid. The conversion of DMC was 76% on MgO at 473 K, and 98% on H-ZSM-5 at 423 K. It was even easier decomposed on the amphoteric γ-Al 2 O 3 . Both DMM and DMC were relatively stable on SiO 2 possessing little surface acidity and basicity. They were even more stable on ZnO with the conversion of DMM and DMC of about 1.5% at 573 K. Thus, metal oxides with either strong acidity or basicity are not suitable for the selective oxidation of DMM to DMC, while ZnO may be used as a component for the reaction

  7. Thermo-Catalytic Pyrolysis of Waste Plastics from End of Life Vehicle

    Directory of Open Access Journals (Sweden)

    Miskolczi Norbert

    2016-01-01

    Full Text Available Pyrolysis of waste plastics is widely used recycling method. Owing to the end-of-life vehicles regulations, 95% of passenger cars and vehicles must reused/recovered after the dismantling. Pyrolysis of waste polyethylene and polypropylene obtained from end-of-life vehicles was investigated in a continuously stirred batch reactor using 500 and 600°C temperatures. To ensure the pyrolysis reactions the tested catalysts (5% of ZSM-5, HZSM-5, Ni-ZSM-5 and Fe-ZSM-5 were added directly to the mixtures of raw materials. Products of pyrolysis were separated into gases, pyrolysis oil and heavy oil, which was further analyzed by gas-chromatography, Fourier transformed infrared spectroscopy and other standardized methods. Based on the results it was concluded, that the catalysts significantly increase the yields of volatile products, and modify their composition. Especially the alkane/alkene ratio, the methane concentration and the concentration of branched hydrocarbon could be affected by the applied catalysts. Ni-ZSM-5 catalyst had the highest activity in methane production, while HZSM-5 catalyst proved effective in isomerization reactions. Using H-ZSM-5, Ni-ZSM-5, and Fe-ZSM-5 catalyst notably decreased average molecular weight of pyrolysis oils and significantly higher aromatic content was observed.

  8. Removal of toluene by sequential adsorption-plasma oxidation: Mixed support and catalyst deactivation.

    Science.gov (United States)

    Qin, Caihong; Huang, Xuemin; Zhao, Junjie; Huang, Jiayu; Kang, Zhongli; Dang, Xiaoqing

    2017-07-15

    A sequential adsorption-plasma oxidation system was used to remove toluene from simulated dry air using γ-Al 2 O 3 , HZSM-5, a mixture of the two materials or their supported Mn-Ag catalyst as adsorbents under atmospheric pressure and room temperature. After 120min of plasma oxidation, γ-Al 2 O 3 had a better carbon balance (∼75%) than HZSM-5, but the CO 2 yield of γ-Al 2 O 3 was only ∼50%; and there was some desorption of toluene when γ-Al 2 O 3 was used. When a mixture of HZSM-5 and γ-Al 2 O 3 with a mass ratio of 1/2 was used, the carbon balance was up to 90% and 82% of this was CO 2 . The adsorption performance and electric discharge characteristics of the mixed supports were tested in order to rationalize this high CO x yield. After seven cycles of sequential adsorption-plasma oxidation, support and Mn-Ag catalyst deactivation occurred. The support and catalyst were characterized before and after deactivation by SEM, a BET method, XRD, XPS and GC-MS in order to probe the mechanism of their deactivation. 97.6% of the deactivated supports and 76% of the deactivated catalysts could be recovered by O 2 temperature-programmed oxidation. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Understanding the Performance and Stability of Supported Ni-Co-Based Catalysts in Phenol HDO

    Directory of Open Access Journals (Sweden)

    Thuan M. Huynh

    2016-11-01

    Full Text Available Performances of bimetallic catalysts (Ni-Co supported on different acidic carriers (HZSM-5, HBeta, HY, ZrO2 and corresponding monometallic Ni catalysts in aqueous phase hydrodeoxygenation of phenol were compared in batch and continuous flow modes. The results revealed that the support acidity plays an important role in deoxygenation as it mainly controls the oxygen-removing steps in the reaction network. At the same time, sufficient hydrothermal stability of a solid catalyst is essential. Batch experiments revealed 10Ni10Co/HZSM-5 to be the best-performing catalyst in terms of conversion and cyclohexane yield. Complementary continuous runs provided more insights into the relationship between catalyst structure, efficiency and stability. After 24 h on-stream, the catalyst still reveals 100% conversion and a slight loss (from 100% to 90% in liquid hydrocarbon selectivity. The observed alloy of Co with Ni increased dispersion and stability of Ni-active sites, and combination with HZSM-5 resulted in a well-balanced ratio of metal and acid sites which promoted all necessary steps in preferred pathways. This was proved by studies of fresh and spent catalysts using various characterization techniques (N2 physisorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM and infrared spectroscopy of adsorbed pyridine (pyr-IR.

  10. Mechanisms of catalytic cleavage of benzyl phenyl ether in aqueous and apolar phases

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiayue; Lu, Lu; Zhao, Chen; Mei, Donghai; Lercher, Johannes A.

    2014-03-01

    Catalytic pathways for the cleavage of ether bonds in benzyl phenyl ether (BPE) in liquid phase using Ni- and zeolite-based catalysts are explored. In the absence of catalysts, the C-O bond is selectively cleaved in water by hydrolysis, forming phenol and benzyl alcohol as intermediates, followed by alkylation. The hydronium ions catalyzing the reactions are provided by the dissociation of water at 523 K. Upon addition of HZSM-5, rates of hydrolysis and alkylation are markedly increased in relation to proton concentrations. In the presence of Ni/SiO2, the selective hydrogenolysis dominates for cleaving the Caliphatic-O bond. Catalyzed by the dual-functional Ni/HZSM-5, hydrogenolysis occurs as the major route rather than hydrolysis (minor route). In apolar undecane, the non-catalytic thermal pyrolysis route dominates. Hydrogenolysis of BPE appears to be the major reaction pathway in undecane in the presence of Ni/SiO2 or Ni/HZSM-5, almost completely suppressing radical reactions. Density functional theory (DFT) calculations strongly support the proposed C-O bond cleavage mechanisms on BPE in aqueous and apolar phases. These calculations show that BPE is initially protonated and subsequently hydrolyzed in the aqueous phase. Finally, DFT calculations suggest that the radical reactions in non-polar solvents lead to primary benzyl and phenoxy radicals in undecane, which leads to heavier condensation products as long as metals are absent for providing dissociated hydrogen.

  11. High-efficiency plasma catalytic removal of dilute benzene from air

    International Nuclear Information System (INIS)

    Fan, Hong-Yu; Shi, Chuan; Li, Xiao-Song; Zhao, De-Zhi; Xu, Yong; Zhu, Ai-Min

    2009-01-01

    Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min -1 flow rate, the energy cost was as low as 3.7 x 10 -3 kWh m -3 air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

  12. Characterization of gallium-containing zeolites for catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Sanchez, M.

    2003-12-08

    The present study considers the synthesis, characterization, and catalytic evaluation of extra-framework gallium-containing zeolites. We focus on modification of zeolites by chemical vapor deposition of trimethylgallium on HZSM-5 and Mordenite zeolites. Chapter 2 is dedicated to the chemisorption and stability of TMG on HZSM-5 and HMOR zeolites. The effect of silylation is also addressed. Some theoretical calculations are also shown in this study to support part of the experimental results. In Chapter 3, the effect of oxidation and reduction treatments on these catalysts is investigated by FTIR, ICP and multinuclei NMR. In Chapter 4, the oxidation state and Ga coordination obtained during and after thermal treatment with H2 and O2 is analysed by X-ray adsorption spectroscopy (XANES and EXAFS) and IR analysis of CO adsorption. These results allow a better understanding of the catalytic behaviour of Ga-containing zeolites catalyst. Chapter 5 consists of two parts: one discusses the H2 activation over Ga/HZSM5 and Ga/MOR catalysts by H2/D2 isotopic exchange reaction, and the second part deals with the aromatization of n-heptane over the same catalysts.

  13. Evaluation of the adsorbent properties of a zeolite rock modified for the removal of the azo dyes as water pollutants; Evaluacion de las propiedades adsorbentes de una roca zeolitica modificada para la remocion de colorantes azoicos como contaminantes del agua

    Energy Technology Data Exchange (ETDEWEB)

    Torres P, J

    2005-07-01

    At the moment some investigations which make reference to the removal of dyes for diverse adsorbent materials; as well as the factors that influence in the sorption process, considering the type so much of dye as those characteristics of the adsorbent material. In this work were investigated those adsorbent properties of a zeolite rock coming from San Luis Potosi State for the removal of azo dyes, using as peculiar cases the Red 40 (Red Allura) and the Yellow 5 (Tartrazine); for it were determined kinetic parameters and the sorption isotherms, as well as the sorption mechanisms involved in each case, between the dyes and the zeolite rock. In this work also it was considered the characterization before and after to removal of color from the water, through advanced analytical techniques such as the scanning electron microscopy of high vacuum (SEM), elementary microanalysis (EDS) and X-ray diffraction (XRD). The experimental part of the work fundamentally consisted, in the conditioning with a NaCl solution and later on the modification with HDTMA-Br of the natural zeolite rock, for then to put it in contact with solutions of the dyes R-40 and A-5, varying so much the contact times as the concentrations; the quantification of sodium in the liquid phase after the modification of the zeolite rock to determine the capacity of external cation exchange (CICE) it was carried out by means of the atomic absorption spectroscopy technique (EAA), and the quantification of the surfactant and the dyes in the liquid phase, it was carried out by means of the UV-vis spectrophotometry technique. It was found that the kinetic model that better it describes the process of sorption of R-40 and A-5 for the modified zeolite rock with HDTMA-Br, leaving of monocomponent and bi component solutions, it is the pseudo- second order. Inside of the obtained results for the sorption isotherms, as much the dye R-40 as the dye A-5 its presented a better adjustment to the Langmuir model. In what refers to the sorption isotherm obtained for the mixture of both dyes, it was used the model of the Langmuir isotherm for multi components and with this it was determined the interference grade that exists among the two dyes; finding that the R-40 dye has a major interference in the sorption of the A-5 and therefore, it is retained in more quantity that the yellow dye when both are found in a bi component solution competing by the places of sorption of the modified zeolite. (Author)

  14. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    OpenAIRE

    Escudero, M. L.; Clemente, C.; Rubio, J. C.; Alobera, M. A.; García-Alonso, M. C.; del Valle, J. A.; Iglesias, C.; Pérez-Maceda, B. T.; Carboneras, M.; Lozano, R. M.

    2011-01-01

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, a...

  15. Anomalia de Ebstein em paciente adulto: valvuloplastia modificada para correção de insuficiência tricúspide Ebstein's anomaly in adult patients: modified repair technique for tricuspid insufficiency

    Directory of Open Access Journals (Sweden)

    Mauro Barbosa ARRUDA FILHO

    2002-06-01

    Full Text Available OBJETIVOS: Avaliar a correção cirúrgica em pacientes adultos portadores de anomalia de Ebstein, utilizando uma variação técnica para correção da insuficiência tricúspide. CASUÍSTICA E MÉTODOS: Entre janeiro de 1990 e março de 2001, seis pacientes adultos foram submetidos à correção cirúrgica com uma variação da técnica apresentada por Carpentier. A idade variou de 18 a 34 anos. Todos se apresentavam em classe funcional III ou IV (NYHA, com piora da cianose ou arritmias freqüentes. Em quatro pacientes a valva tricúspide era do tipo B e em dois do tipo A (Carpentier, quatro apresentavam comunicação interatrial (CIA associada. O hematócrito variou de 33% a 68%. O índice cardíaco variou de 0.47 a 0.88. A fração de ejeção do ventrículo esquerdo variou de 50% a 80%. RESULTADOS: Não se registrou óbitos no período hospitalar. Um paciente foi reoperado por sangramento no pós-operatório imediato. Em dois pacientes ocorreram derrames pericárdicos de repetição. Foi registrado um óbito no 14º mês de pós-operatório por morte súbita. Os pacientes foram seguidos por um período de 10 a 108 meses. Quatro encontram-se em classe funcional I e um encontra-se em classe funcional II (NYHA. O ecocardiograma no pós-operatório imediato e na última avaliação mostra insuficiência tricúspide discreta ou moderada em quatro e importante em um paciente. CONCLUSÃO: Apesar do pequeno número de pacientes nesta série, a modificação técnica cumpriu o seu papel, com a melhora clínica e funcional dos pacientes tratados em até nove anos de seguimento.PURPOSE: To value the surgical treatment of adult patients with Ebstein's anomaly, using a Carpentier's modified repair technique. MATERIAL AND METHODS: Between January 1990 and March 2001 six adult patients with Ebstein's anomaly were treated using a modification of Carpentier's repair technique, four were males and two were females, ages ranging from 18 to 34 years (Mean 23.3 years, all were in Functional Class III or IV (NYHA, with increased cyanoses and frequent rhythm disturbance. Four patients had an associated atrioventricular septal defect; in four patients the tricuspid valve was Carpentier's type B and two type A and all were able to benefit from this conservative technique. RESULTS: There were not hospital deaths and one patient died 14º months after surgery in this series. Actuarial survival was 83.3% in 9 years. Four patients are in Functional Class I and one in Functional Class II (NYHA. Echocardiography and Doppler studies demonstrated a normal shape of right ventricle and good tricuspid valve function in four patients and one has moderate tricuspid regurgitation but still in Functional Class II (NYHA. CONCLUSION: Although the small number of patients in this series, the modification of Carpentier's repair technique in adult patients was efficient, reproducible and improved the preoperative status with regard to functional class, tricuspid regurgitation cyanoses and rhythm disturbance.

  16. Atmosfera modificada e condições de armazenamento nas características físico-químicas de jabuticabas da cultivar 'paulista' Modified atmosphere and storage conditions in jaboticabas cv 'paulista' physicochemistry characteristics

    Directory of Open Access Journals (Sweden)

    Juliana da Silva Agostini

    2009-12-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de diferentes embalagens nas características físico-químicas de jabuticabas da cultivar 'paulista', sob condições de temperatura ambiente (25°C e refrigeração (8°C. Os frutos foram analisados no início do experimento (tempo 0 e no 2°, no 4°, no 6° e no 8° dia de armazenamento, em temperatura ambiente, e no 3°, no 6°, no 9° e no 12° dia, em câmara de refrigeração, sob diferentes condições de recobrimento (controle, filme PVC, plástico de polietileno e fécula de araruta a 2% gelatinizada. Estes foram avaliados quanto à perda de massa fresca, pH, acidez titulável, teor de sólidos solúveis (°Brix, teor de ácido ascórbico e teor de açúcares redutores. O experimento foi realizado em delineamento inteiramente casualizado, em fatorial 2 x 4 x 4, com três repetições. A embalagem de PVC e polietileno demonstraram ser eficientes em reduzir as perdas de massa em ambas as condições de temperatura. A refrigeração foi importante para a manutenção pós-colheita da jabuticaba, pois manteve a qualidade dos frutos armazenados até 12 dias, em comparação com os frutos armazenados em temperatura ambiente, por oito dias. A interação tempo e embalagem foi significativa para os parâmetros perda de massa, pH, teor de sólidos solúveis, vitamina C e açúcares redutores, exceto para acidez. No entanto, não se pode afirmar, com base nos resultados das análises químicas, qual dos tipos de embalagem proporcionou melhores condições de conservação.The aim of this study was to evaluate the effect of different kinds of packing in araruta and jaboticabas cv paulista' physicochemistry characteristics, stored at room temperature (25°C and at refrigeration (8°C. The fruits were analyzed at the beginning of experiment (time 0 and in the 2nd, 4th, 6th and 8th days of storage at room temperature, and in the 3rd, 6th, 9th and 12nd days in the refrigeration camera under different cover conditions (control, PVC film, polyethylene plastic and araruta starch to 2% jellied. They were evaluated by the loss of fresh mass, pH, titrable acidity, soluble solids content (°Bx, ascorbic acid content and reducing sugar content. The experiment was carried out by completely randomized design in factorial 2 x 4 x 4 with three repetitions. The PVC film and polyethylene proved to be efficient in reducing the mass losses in both temperature conditions. The refrigeration was important for the post-harvest maintenance of jabuticaba, because it maintained the superior quality of fruits stored up to 12 days compared to the stored at room temperature for 8 days. The interaction time and packing was significant for most of the evaluated parameters, except for the acidity one. However it cannot be affirmed through the results of the chemical analyses which of the different types of packing tested showed better conservation conditions.

  17. Caracterización, diseño y verificación de una mezcla asfáltica drenante en caliente modificada con grano de llanta triturado y fibra Kaltex

    OpenAIRE

    Yung Vargas, Yee Wan

    2014-01-01

    La resistencia, seguridad y comodidad son las características principales que se buscan en el comportamiento de los pavimentos durante la vida util de los mismos, los cuales se pueden conseguir en parte con el trabajo armónico del diseño, escogencia de materiales de calidad y sistemas constructivos convenientes. El trabajo del pavimento debe ir acompañado de obras que garanticen de una u otra forma la estabilidad de su estructura. Sin embargo en muchas ocasiones las funciones de esas obras ...

  18. Metallurgical behavior of fine fractions of copper sulfide minerals in a combined process of modified flotation and agitated bio leaching; Respuesta metalurgica de fracciones finas de minerales sulfurados de cobre en un proceso combinado de flotacion modificada y biolixiviacion agitada

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, J. P.; Ipinza, J.; Collao, N.; Ahlborn, G.

    2007-07-01

    The metallurgical behaviour of fine fraction of copper sulfide minerals of Compania Minera Quebrada Blanca S. A. was studied by concentration through flotation in aqueous media modified by alcohol followed by bio leaching of the concentrates. By using a 1% v/v of methanol, the metallurgical recovery of copper reaches 88%, while the iron recovery was 43%, the weight recovery was 18%, which indicates a high selectivity. these concentrates were then bio leached with and without nutrient medium, reaching 80% of copper recovery after 10 and 17 days, respectively. then, it is possible to conclude that this concentration-bio leaching metallurgical process is a promising route for copper recovery from the fine fraction of sulfide minerals. (Author) 24 refs.

  19. Predicción y análisis de emisiones de mezclas combustibles diésel/ biodiésel modificadas con nanopartículas de alúmina y ácido oleico

    Directory of Open Access Journals (Sweden)

    Andrés Peñaloza

    2017-06-01

    Full Text Available El software Diésel-RK fue utilizado para evaluar el efecto del uso de un aditivo basado en nanopartículas de alúmina y ácido oleico para la reducción de emisiones de gases contaminantes en mezclas diésel/biodiésel. Para esto, se estimaron las propiedades físico-químicas de las mezclas combustibles con ayuda de correlaciones para dispersiones coloidales y reglas de mezclado, fijando concentraciones de 10 y 20ppm del aditivo. Los resultados obtenidos mostraron reducciones del 11% y 25% en emisiones de SO2 y material particulado, respectivamente; mientras que las emisiones de CO2 no mostraron mejoras significativas, así como tampoco se presentaron mejoras en el consumo específico de combustible, los cuales permanecieron por debajo del 1,0%. En cuanto a las emisiones de NO2, se observó un incremento desde 2,1g/kWh a 3,1g/kWh con la adición de las diversas concentraciones de nanoaditivo; de esta forma se evidenciaron mejoras en la disminución en el retraso de los tiempos de ignición, lo cual es apropiado para el adecuado funcionamiento de los motores.

  20. Aplicación de sucralosa a cerezas orgánicas cv. Sweetheart® en atmósfera modificada y su aceptación sensorial

    Directory of Open Access Journals (Sweden)

    Nelson Loyola López

    2014-04-01

    Full Text Available Cerezas cv. Sweet Heart® de un cultivo orgánico en la comuna de Los Angeles, región del BíoBío, Chile, sometidas a los tratamientos:T0, control; T1, con 1.5% de sucralosa y T2, con 2.0% sucralosa. Se almacenaron en cajas de 5 kg con bolsas FreshView en A.M., conservadas por 20, 35 y 50 días a temperatura de 0 ± 0.5 °C y humedad relativa de 90 ± 0.5%. Después de 35 dias, las cerezas con el tratamiento (T1 exhibieron la menor pérdida de peso. Esta tendencia fue mantenida al día 50, al utilizar sucralosa (T1 y T2, con menor pérdida de peso respecto al tratamiento T0. La fruta con cobertura, mostró una leve disminución en la presión de pulpa, pero siempre sobre el valor límite menor recomendado en unidades Durofel. La sucralosa aplicada permitió incrementar levemente el brillo de cerezas tanto a 20 como a 50 días de almacenamiento. El tratamiento con 1.5% de sucralosa (T1 tuvo un efecto favorable en el sabor y color al día 35. La apariencia y aceptabilidad de las cerezas mostraron un cambio positivo y significativo durante los 35 días debido a la sucralosa a 1.5%(T1

  1. Characterization of n-TiO{sub 2} thin films modified with silver nanoparticles; Caracterizacion de peliculas delgadas de n-TiO{sub 2} modificadas con nanoparticulas de plata

    Energy Technology Data Exchange (ETDEWEB)

    Cueto, L.F. [Universidad Autonoma de Nuevo Leon, Monterrey, N.L. (Mexico). Dept. de Biotecnologia e Ingenieria de Alimentos; Sanchez-Cervantes, E.M. [Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, N.L. (Mexico). Facultad de Ciencias Quimicas. Lab. de Vidrio

    2010-07-01

    Carbon dioxide accumulation in the atmosphere has gained much attention and has reopened many research lines that initiated two or three decades ago. Electrochemical reduction represents one of the most discussed methods, especially where semiconductor and metal-semiconductor cathodes are used to achieve CO{sub 2} transformation into higher-energy products. In the present work, the influence of silver nanoparticles upon CO{sub 2} reduction on n-TiO{sub 2} cathodes in aqueous media is presented. Silver nanoparticles with an average diameter of 250nm were deposited on n-TiO{sub 2} surfaces by the electrochemical Double-Pulse Potential method. A Grazing-Incidence X-Ray Diffraction structural analysis is presented showing the presence of metallic silver, while Atomic Force Microscopy shows surface roughness and particle size before and after surface modification. These measurements were confirmed by Scanning-Electron Microscopy acquainting for the formation of metal particles on the n-TiO{sub 2} surface. Enhancement of CO{sub 2} reduction by the presence of silver on cathodes is shown by cyclic voltammetry. (author)

  2. Irradiation and passive modified atmosphere on the post-harvest quality of guavas ‘Pedro Sato’. = Irradiação e atmosfera modificada passiva na qualidade pós-colheita de goiabas ‘Pedro Sato’ .

    Directory of Open Access Journals (Sweden)

    André José de Campos

    2011-12-01

    Full Text Available The aim of this study was to evaluate the effect of gamma radiation associated with modified atmosphere on postharvest quality of guavas ‘Pedro Sato’. It was used guavas from the region of Vista Alegre do Alto/São Paulo/Brazil. After harvest, the fruits were immediately transported to the Fruit and Vegetables Laboratory from the Agroindustrial Management and Technology Department, Agronomic Sciences College - UNESP - Botucatu / SP, where they were kept at 10 ° C and 90-95% RH in cold storage, for 28 days. It was used the randomized design, with factorial scheme 5 x 5, three repetitions. The first factor consisted of the following effects: control 1 (without package or irradiation, control 2 (polystyrene package/PS + package low density polyethylene/LDPE and without irradiation, treatment 1 (PS + LDPE and 0.2 kGy , treatment 2 (PS + LDPE and 0.6 kGy and treatment 3 (PS + LDPE and 1.0 kGy. The second factor consisted of the evaluation periods: 0, 7, 14, 21 and 28 days. The analyses were: firmness, soluble solids (SS, titratable acidity (TA, maturity index, pH, respiration rate. Concluded that high doses of irradiation promoted a negative effect on physical-chemical characteristics of guava ‘Pedro Sato’, verifying that only the lowest dose associated with modified atmosphere provided fruits with higher quality and acceptability, due to higher maturation rate and soluble solids obtained. Regarding the days of analysis, there were no positive effect of the treatments during storage, where only the early days promoted better values for the variables studied.

  3. Preparação, caracterização e aplicação de fases estacionárias tipo C8 modificadas por óxidos metálicos para cromatografia líquida

    Directory of Open Access Journals (Sweden)

    Karen Goraieb

    2013-01-01

    Full Text Available This work describes three C8-stationary phases for high performance liquid chromatography based on silica metallized with ZrO2, TiO2 or Al2O3 layers, having poly(methyloctylsiloxane immobilized onto their surfaces. The stationary phases were characterized using XRF, XAS, FTIR, SEM and elemental analysis to determine the physical characteristics of the oxide and polysiloxane layers formed on the surfaces and chromatographically to evaluate the separation parameters. The results show the changes on the silica surface and allowed proposing a structure for the oxide layer, being observed tetrahedral and octahedral structures, what is completely new in the literature. The formation of a homogeneous layer of metallic oxide (TiO2 and ZrO2 was observed on the silica. The C8-titanized and C8-aluminized stationary phases presented good chromatographic performances, with good values of asymmetry and efficiency. All stationary phase presented few loss of the polymeric layer after the HPLC, indicating that this layer is well attached on the metalized support.

  4. Modified montmorillonite as a heterogeneous catalyst in (m)ethyl esterification reaction of lauric acid; Montmorilonita modificada como catalisador heterogeneo em reacoes de esterificacao (M)etilica de acido laurico

    Energy Technology Data Exchange (ETDEWEB)

    Zatta, Leandro; Nepel, Angelita; Barison, Andersson; Wypych, Fernando, E-mail: wypych@ufpr.br [Departamento de Quimica, Universidade Federal do Parana (UFPR), Curitiba , PR (Brazil)

    2012-07-01

    Montmorillonite was modified with zirconium polyoxycations in the presence of ammonium sulphate. The material was characterized and used as a catalyst in the esterification of lauric acid, the reactions being accompanied by 2{sup 3} factorial design. Conversions of up to 95.33 and 83.35% were observed for the methyl and ethyl esterification reactions respectively, proving superior to results obtained by thermal conversion. The material was submitted to three reaction cycles and similar conversions were observed, indicating the catalyst is not significantly deactivated after reuse. The catalyst was also tested under reflux conditions, yielding a maximum conversion of 36.86%. (author)

  5. Preparação e caracterização de organobentonita modificada com ionenos alifáticos Preparation and characterization of aliphatic ionene-modified organobentonite

    Directory of Open Access Journals (Sweden)

    Arão P. Costa Filho

    2005-07-01

    Full Text Available A preparação de complexos bentonita-ionenos a partir da adsorção de tetrametil-[x,y]-ionenos, onde x= 2 e y= 4,6,10 ou 12, e o 2-hidróxi-3-cloro-ioneno, EPI-DMA, foi realizada com a finalidade de observar o comportamento do tamanho do espaçador do ioneno na expansão basal (d001 das camadas de uma bentonita comercial do Brasil. Os complexos foram caracterizados por espectrometria de absorção na região do infravermelho, termogravimetria, fluorescência e difração de raios X. A partir das análises por fluorescência e difração de raios X dos complexos, foi observado que os poli-quaternários de amônio são adsorvidos nas superfícies internas e externas da argila delaminada, acima da capacidade de troca catiônica, CTC = 91 meq/100g de argila (calculada a partir de dados de fluorescência de raios X. A expansão basal das camadas da argila com os diferentes policátions revelou que o tamanho do espaçador é o fator mais importante, independentemente das massas molares dos ionenos, tal como foi observado principalmente entre os complexos Bt-2,10- e Bt-2,12-ioneno, com massas molares de 12000 e 5000 g/mol, respectivamente.The preparation of bentonite-ionene complexes based on the adsorption of 2y-ionenes, where y = 4, 6, 10 or 12 and an ionene of the epichloridrin-dimethylamine EPI-DMA kind, was carried out in order to observe the behavior of the ionene spacer size in the expansion of the basal space (d-spacing, d001 of a Brazilian commercial bentonite. The complexes were characterized by adsorption spectromety in the infrared region, thermogravimetry, fluorescence and X-Ray diffraction. Ionenes were synthesized and characterized by infrared and nuclear magnetic resonance, the latter technique being useful for determining the average number molecular weight values. Based on the clay-ionenes complexes it could be observed that the ammonium polyquaternaries are adsorbed on the inner and outer clay surfaces, above the ion exchange capacity, CEC = 91 meq/100 g clay (calculated based on X-Ray fluorescence data. The clay basal expansion with the several polycations revealed that the spacer size is the most important factor, independent of ionene molecular weight values. Among the bentonite-ionene complexes, mainly between Bt-2,10 and Bt-2,12-ionene complexes which differ in molar mass by more than 30,000 g/mol, it was observed that the spacer size has no dependence on the ionene molecular weights.

  6. Properties of polyester based powder coating containing Cloisite®30B modified with silane 3-aminopropyltriethoxysilane; Propriedades da tinta em po base poliester contendo Cloisite®30B modificada com 3-aminopropiltrietoxisilano

    Energy Technology Data Exchange (ETDEWEB)

    Bertuoli, P.T.; Frizzo, V.P.; Zattera, A.J., E-mail: paulabertuoli@hotmail.com [Universidade de Caxias do Sul (UCS), RS (Brazil). Programa de Pos-Graduacao em Engenharia de Processos e Tecnologias; Scienza, L.C. [Universidade Federal do Rio Grande do Sul (UFRGS), RS (Brazil). Departamento de Materiais

    2014-07-01

    The incorporation of clay into a polymer matrix results in nanocomposites with mechanical strength, thermal and barrier properties superior to the free filler matrix. With the aim to obtain a powder coating with better thermal properties than the coating free of filler, the organoclay Cloisite®30B was modified with 3-aminopropyltriethoxysilane (APS) and incorporated to a polyester based powder coating, on proportions of 2 to 8 wt% in the melt state. The powder coatings were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The powder coating containing clay showed no alteration in the basal spacing compared to that basal spacing of the clay. Compared to the powder coating free of the clay, powder coatings containing clay had lower thermal stability due to the presence of the organic modifier. The presence of clay reduced the crosslinking temperature and the incorporation of 2 wt% of the clay caused the increase in the energy released in the crosslinking process. (author)

  7. O emprego de quitosana quimicamente modificada com anidrido succínico na adsorção de azul de metileno The use of chemical modified chitosam with succinic anhydride in the methylene blue adsorption

    Directory of Open Access Journals (Sweden)

    Ilauro S. Lima

    2006-06-01

    Full Text Available The adsorption capacity of alpha-chitosan and its modified form with succinic anhydride was compared with the traditional adsorbent active carbon by using the dye methylene blue, employed in the textile industry. The isotherms for both biopolymers were classified as SSA systems in the Giles model, more specifically in L class and subgroup 3. The dye concentration in the supernatant in the adsorption assay was determined through electronic spectroscopy. By calorimetric titration thermodynamic data of the interaction between methyene blue and the chemically modified chitosan at the solid/liquid interface were obtained. The enthalpy of the dye/chitosan interaction gave 2.47 ± 0.02 kJ mol-1 with an equilibrium constant of 7350 ± 10 and for the carbon/dye interaction this constant gave 5951 ± 8. The spontaneity of these adsorptions are reflected by the free Gibbs energies of -22.1 ± 0.4 and -21.5 ± 0.2 kJ mol-1, respectively, found for these systems. This new adsorbent derived from a natural polysaccharide is as efficient as activated carbon. However 97% of the bonded dye can be eluted by sodium chloride solution, while this same operation elutes only 42% from carbon. Chitosan is efficient in dye removal with the additional advantage of being cheap, non-toxic, biocompatible and biodegradable.

  8. The use of chemical modified chitosan with succinic anhydride in the methylene blue adsorption; O emprego de quitosana quimicamente modificada com anidrido succinico na adsorcao de azul de metileno

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Ilauro S.; Ribeiro, Emerson S.; Airoldi, Claudio [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica]. E-mail: airoldi@iqm.unicamp.br

    2006-05-15

    The adsorption capacity of a-chitosan and its modified form with succinic anhydride was compared with the traditional adsorbent active carbon by using the dye methylene blue, employed in the textile industry. The isotherms for both biopolymers were classified as SSA systems in the Giles model, more specifically iclass and subgroup 3. The dye concentration in the supernatant in the adsorption assay was determined through electronic spectroscopy. By calorimetric titration thermodynamic data of the interaction between methylene blue and the chemically modified chitosan at the solid/liquid interface were obtained. The enthalpy of the dye/chitosan interaction gave 2.47 {+-} 0.02 kJ mol-1 with an equilibrium constant of 7350 {+-} 10 and for the carbon/dye interaction this constant gave 5951 {+-} 8. The spontaneity of these adsorptions are reflected by the free Gibbs energies of -22.1 {+-} 0.4 and -21.5 {+-} 0.2 kJ mol-1, respectively, found for these systems. This new adsorbent derived from a natural polysaccharide is as efficient as activated carbon. However 97% of the bonded dye can be eluted by sodium chloride solution, while this same operation elutes only 42% from carbon. Chitosan is efficient in dye removal with the additional advantage of being cheap, non-toxic, biocompatible and biodegradable. (author)

  9. Utilização de NBR modificada com grupos 2-oxazolina em misturas de NBR/EVA Utilization of 2-oxazoline modified NBR in NBR/EVA blends

    Directory of Open Access Journals (Sweden)

    Mauricio S. M. Almeida

    2003-06-01

    Full Text Available Misturas envolvendo borracha nitrílica e copolímeros de etileno-acetato de vinila na proporção 70:30 % em peso, foram preparadas na presença de borracha nitrílica funcionalizada com 2-oxazolina isoladamente ou combinada com EVA funcionalizado com grupos hidroxila, carboxila ou mercaptana. A reação entre os grupos funcionais foi verificada por análise de FTIR da fração insolúvel de amostras não vulcanizadas e pelo decréscimo nos valores de tan delta nos ensaios dinâmico-mecânicos. A utilização desses copolímeros funcionalizados não influenciou significativamente as propriedades mecânicas, provavelmente devido à proporção da mistura utilizada (rica em NBR o que facilita a localização da NBR funcionalizada no interior da fase elastomérica.Nitrile rubber/ethylene-vinyl acetate copolymer (NBR/EVA blends with ratio of 70/30 wt% were prepared in the presence of functionalized NBR with 2-oxazoline groups. This functionalized copolymer was employed alone or in combination with EVA copolymer functionalized with hydroxyl, carboxyl or mercaptan groups. The reaction between the functional groups was confirmed by FTIR analysis of the unvulcanized samples insoluble fraction, and by the decrease in the tan delta values. The mechanical properties were not substantially affected by the presence of these functionalized copolymers, probably due to the proportion of blend composition (with high amount of NBR, thus forcing the location of functionalized NBR inside the elastomer phase.

  10. Ecuación de capriste y lozano modificada para predecir la elevación en la temperatura de ebullición en soluciones de caña de azúcar

    Directory of Open Access Journals (Sweden)

    EVERALDO MONTES

    2007-01-01

    Full Text Available La elevación en la temperatura de ebullición del jugo de la caña de azúcar, utilizando soluciones modelos con cuatro componentes (sacarosa, glucosa, fructosa y dextrana, fue medida experimentalmente en un rango de concentraciones de sólidos solubles de 30 a 60 º Brix y a presiones entre 6.2 x 103 y 7.6 x 104 Pa (abs.. Se utilizó el modelo empírico de Capriste y Lozano para representar los datos experimentales. Los datos experimentales se ajustaron mejor a un modelo modificado de Capriste y Lozano, propuesto por los autores

  11. ECUACIÓN DE CAPRISTE Y LOZANO MODIFICADA PARA PREDECIR LA ELEVACIÓN EN LA TEMPERATURA DE EBULLICIÓN EN SOLUCIONES DE CAÑA DE AZÚCAR

    OpenAIRE

    MONTES, EVERALDO; TORRES, RAMIRO; ANDRADE, RICARDO

    2007-01-01

    La elevación en la temperatura de ebullición del jugo de la caña de azúcar, utilizando soluciones modelos con cuatro componentes (sacarosa, glucosa, fructosa y dextrana), fue medida experimentalmente en un rango de concentraciones de sólidos solubles de 30 a 60 º Brix y a presiones entre 6.2 x 10³ y 7.6 x 10(4) Pa (abs.). Se utilizó el modelo empírico de Capriste y Lozano para representar los datos experimentales. Los datos experimentales se ajustaron mejor a un modelo modificado de Capriste ...

  12. Ecuación de capriste y lozano modificada para predecir la elevación en la temperatura de ebullición en soluciones de caña de azúcar

    OpenAIRE

    MONTES, EVERALDO; TORRES, RAMIRO; ANDRADE, RICARDO

    2008-01-01

    La elevacion en la temperatura de ebullicion del jugo de la cana de azucar, utilizando soluciones modelos con cuatro componentes (sacarosa, glucosa, fructosa y dextrana), fue medida experimentalmente en un rango de concentraciones de solidos solubles de 30 a 60 o Brix y a presiones entre 6.2 x 103 y 7.6 x 104 Pa (abs.). Se utilizo el modelo empirico de Capriste y Lozano para representar los datos experimentales. Los datos experimentales se ajustaron mejor a un modelo modificado de Caprist...

  13. Nanopartículas com superfície modificada do tipo núcleo-coroa e novos copolímeros de dextrana-policaprolactona para conjugação de ligantes de reconhecimento

    OpenAIRE

    Rodrigues da Silva, Jaqueline

    2002-01-01

    A vetorização de fármacos para órgãos específicos é extremamente complexa devido a necessidade do carreador desempenhar simultaneamente diferentes funções. Primeiramente, as nanopartículas devem ser capazes de conduzir uma quantidade significativa de fármacos e promover a sua liberação com perfil cinético adequado. Numa segunda fase, após a administração o fármaco deve ser capaz de atingir o sítio alvo de uma maneira específica e subsequentemente liberar a droga. O Estado da Ar...

  14. Fluxo gênico em soja geneticamente modificada e método para sua detecção Gene flow in genetically modified soybean and method for its detection

    Directory of Open Access Journals (Sweden)

    Welison Andrade Pereira

    2007-07-01

    Full Text Available O objetivo deste trabalho foi avaliar métodos para detecção de sementes de soja tolerante ao glifosato e o fluxo gênico de uma cultivar transgênica para uma convencional, em Florestal e Viçosa, MG. Para adequar método de detecção, foi conduzido experimento comparativo entre cinco bioensaios, dos quais se destacou o teste de germinação em substrato umedecido com solução do glifosato. O experimento de fluxo gênico foi instalado em campo, no esquema de quadrados concêntricos. No centro, foi plantada a cultivar tolerante ao glifosato (fonte de pólen. À sua volta, foi semeada a cultivar sensível (receptora do pólen. No estádio R8, foram colhidas sementes das laterais dos quadrados, em distâncias variadas da fonte de pólen: 0,5, 1, 2, 4 e 8 m. Amostras de 900 sementes, por fileira, foram avaliadas pelo teste de germinação em substrato umedecido com solução de glifosato a 0,06%. Plântulas tolerantes ao glifosato indicaram fecundação cruzada. As maiores porcentagens de hibridação - 1,27% em Florestal e 0,25% em Viçosa - ocorreram a 0,5 m de distância, entre fonte e receptor de pólen, e essas taxas aproximaram-se de zero às distâncias de 2,26 e 1,16 m, para Florestal e Viçosa, respectivamente.The objective of this work was to assess the methods for detection of glyphosate tolerance soybean seeds and the gene flow from a genetically modified soybean cultivar to a conventional one, in Viçosa and Florestal, MG, Brazil. In order to assess the method for detection, a comparative experiment was conduct among five bioassays, from which the germination test in moistened substrate with glyphosate solution was outstanding. The experiment of gene flow was installed in field, in the concentric squares design. In the center, the glyphosate-tolerant cultivar (pollen source was planted. Around it, the sensitive cultivar (pollen receptor was sowed. In the stage R8, seeds of lateral of the squares were harvested, in various distances from the pollen source: 0.5, 1, 2, 4 and 8 m. Samples of 900 seeds by row were evaluated, using the germination test in moistened substrate with a solution of glyphosate at 0.06%. Glyphosate-tolerant seedlings indicated cross-pollination. The largest hybridization rates - 1.27% in Florestal, and 0.25% in Viçosa - ocurred at 0.5 m distance between source and pollen receiver, and these rates reached zero at 2.26 and 1.16 m distances, in Florestal and Viçosa, respectively.

  15. Independent dose calculation in IMRT for the Tps Iplan using the Clarkson modified integral; Calculo independiente de dosis en IMRT para el TPS Iplan usando la integral modificada de Clarkson

    Energy Technology Data Exchange (ETDEWEB)

    Adrada, A.; Tello, Z.; Garrigo, E.; Venencia, D., E-mail: jorge.alberto.adrada@gmail.com [Instituto Privado de Radioterapia, Obispo Oro 423, X5000BFI Cordoba (Argentina)

    2014-08-15

    Intensity-Modulated Radiation Therapy (IMRT) treatments require a quality assurance (Q A) specific patient before delivery. These controls include the experimental verification in dose phantom of the total plan as well as dose distributions. The use of independent dose calculation (IDC) is used in 3D-Crt treatments; however its application in IMRT requires the implementation of an algorithm that allows considering a non-uniform intensity beam. The purpose of this work was to develop IDC software in IMRT with MLC using the algorithm proposed by Kung (Kung et al. 2000). The software was done using Matlab programming. The Clarkson modified integral was implemented on each flowing, applying concentric rings for the dose determination. From the integral of each field was calculated the dose anywhere. One time finished a planning; all data are exported to a phantom where a Q A plan is generated. On this is calculated the half dose in a representative volume of the ionization chamber and the dose at the center of it. Until now 230 IMRT planning were analyzed carried out ??in the treatment planning system (Tps) Iplan. For each one of them Q A plan was generated, were calculated and compared calculated dose with the Tps, IDC system and measurement with ionization chamber. The average difference between measured and calculated dose with the IDC system was 0.4% ± 2.2% [-6.8%, 6.4%]. The difference between the measured and the calculated doses by the pencil-beam algorithm (Pb) of Tps was 2.6% ± 1.41% [-2.0%, 5.6%] and with the Monte Carlo algorithm was 0.4% ± 1.5% [-4.9%, 3.7%]. The differences of the carried out software are comparable to the obtained with the ionization chamber and Tps in Monte Carlo mode. (author)

  16. Synthesis and characterization of nanocomposites based on polyurethane in aqueous dispersions with non-modified hydrophilic clays; Sintese e caracterizacao de nanocompositos a base de poliuretanos em dispersoes aquosas com argilas hidrofilicas nao-modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, G.S.; Delpechi, M.C.; Santo, W.L.E., E-mail: mcd@uerj.b [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2010-07-01

    Several studies involving the formation of polyurethane nanocomposites employing clays of montmorillonite modified. This involves the presence of quaternary ammonium salts, the cation exchange needed to increase the interlayer space of clays that incorporate more than one step to the process, generates a higher cost. In this paper the synthesis of nanocomposite polyurethanes dispersed in water allowed not only the production of materials less harmful to the environment, but also the incorporation of hydrophilic clays, calcium and sodium in nature, without any modifications. Dispersions produced from 0.5, 1.0 and 2.5% clay (on the mass of prepolymer) were characterized in terms of total solids content, the films obtained by casting were evaluated for adhesiveness, diffraction X-rays, scanning electron microscopy. Most systems showed intercalated and partially exfoliated structures. (author)

  17. Clarification of Stevia rebaudiana (Bert. Bertoni extract by adsorption in modified zeolites Clarificação de extrato de Stevia rebaudiana (Bert. Bertoni por adsorção em zeólitas modificadas

    Directory of Open Access Journals (Sweden)

    Elida de Paula Moraes

    2001-05-01

    Full Text Available Selective adsorption on zeolites X and A was studied with Stevia rebaudiana (Bert. Bertoni (Asteraceae extract clarification. Ionic exchanges were made with calcium and barium ions in zeolites NaX and NaA and the effect of contact of aqueous extract of dry Stevia rebaudiana Bertoni leaves with CaX, BaX, CaA and BaA zeolites was evaluated. Stevia extract in contact with the zeolite CaX showed highest clarification and did not present alterations of initial characteristics in concentration, glycosides and flavor. In batch tests at room temperature, the contact of Stevia aqueous extract and CaX zeolite provided 70-80% clarification. Since zeolite may be reused, an approximate clarification of 65-70% is possible in regenerated zeolite.No presente trabalho, foi estudada a adsorção seletiva do extrato de Stevia rebaudiana (Bert. Bertoni (Asteraceae nas zeólitas X e A. Foram feitas trocas com íons de cálcio e bário nas zeólitas NaX e NaA. Foi avaliado o efeito do contato do extrato aquoso de Stevia com as zeólitas CaX, BaX, CaA and BaA. Os resultados mostraram que o extrato que ficou em contato com a zeólita CaX foi o que obteve maior descoloração e não teve as características iniciais alteradas, em termos de concentração, glicosídeos e sabor. Com testes feitos em batelada à temperatura ambiente, o contato entre o extrato aquoso de Stevia e a zeólita CaX, proporcionou uma descoloração entre 70-80%. Os testes mostraram ser possível a regeneração da zeólita, sendo possível a utilização da zeólita por mais de uma vez no processo, sendo alcançada uma descoloração entre 65-70%.

  18. Qualidade pós-colheita de nêsperas submetidas ao armazenamento sob baixa temperatura e atmosfera modificada Postharvest quality of loquat stored at a low temperature and modified atmosphere

    Directory of Open Access Journals (Sweden)

    Jacinta Tavares de Campos

    2007-06-01

    Full Text Available A curta vida-de-prateleira da nêspera (Eryobotria japonica Lindl. é um dos fatores que encarecem o preço final deste fruto constituindo um obstáculo para o aumento da sua produção e popularização de seu consumo. Neste contexto, o investimento em estratégias de armazenamento representa uma contribuição para a cadeia de produção da nêspera. Assim, o objetivo deste trabalho é apresentar uma alternativa de baixo custo para a extensão do tempo de armazenamento deste fruto. Nêsperas da cultivar Precoce de Itaquera, maduras, foram acondicionadas em bandejas de poliestireno teraftalato e embaladas com filme de polivinilcloreto de 14 µm de espessura. Os frutos foram armazenados em diferentes temperaturas (18 e 6 °C na presença e ausência de sachês de permanganato de potássio para remoção do etileno. Durante o armazenamento, os frutos foram periodicamente analisados quanto à produção de etileno e à respiração. Os frutos amostrados para análises posteriores foram descascados e a polpa congelada. Os frutos foram também monitorados quanto à perda de massa fresca e analisados os teores de glicose, frutose, sacarose e sorbitol por HPAEC-PAD. Os teores de etileno nos grupos armazenados na presença dos sachês foram significativamente menores em comparação aos demais grupos, independente da temperatura de armazenamento. A respiração mostrou dependência da temperatura, sendo menor nos frutos armazenados a 6 °C, independente da presença dos sachês. Os teores de açúcares solúveis apresentaram flutuações durante o armazenamento a baixa temperatura, mas sem alterações significativas em relação aos teores iniciais, com exceção do sorbitol que aumentou. Os efeitos do armazenamento à baixa temperatura, combinados com a presença de sachês absorvedores de etileno, sobre a respiração e os teores de etileno podem ser apontados como relevantes para o aumento na vida-de-prateleira das nêsperas, sem alterações nos níveis de açúcares solúveis, fundamentais para o desenvolvimento do sabor do fruto. A combinação da embalagem com baixas temperaturas e a presença de sachês absorvedores de etileno pode constituir uma estratégia viável para o armazenamento da nêspera, estendendo significativamente a pós-colheita.The short shelf-life of loquat (Eryobotria japonica Lindl. fruit is one of the factors that results in the final price of this fruit hindering the increase of its production and popularization. The investment in storage strategies represents a contribution for the loquat market. The aim of this work is to present a low cost alternative to extend the storage time for this fruit. Mature loquat fruit (Eryobotria japonica Lindl. cv Precoce de Itaquera were conditioned in trays of polystyrene terephthalate and wrapped with 14 µm polyvinyl chloride film. The fruits were stored at different temperatures (18 and 6 °C in the presence or absence of potassium permanganate sachets for ethylene removal. During the storage time, the fruit was periodically analyzed for ethylene production and respiration. Afterwards, it was peeled and the endocarp frozen after removing the seeds. The fruit was monitored for loss of fresh weight and the glucose, fructose, sucrose and sorbitol content were analyzed by HPAEC-PAD during the storage period. The ethylene production in the groups stored in the presence of sachets was significantly smaller in comparison to the other groups, regardless of the storage temperature. Respiration showed dependence of the temperature, and was smaller in the fruit stored at 6 °C, regardless of the presence of sachets. The soluble sugar levels presented fluctuations during the storage period at a low temperature, but without significant alterations in relation to the initial content, except for the sorbitol that presented an increase. The effects of storage at a low temperature combined with the presence of ethylene absorbing sachets on respiration and ethylene levels can be pointed out as relevant in terms of increasing the shelf life of the loquat fruit, without alterations in the levels of soluble sugars, fundamental for the development of the flavor of the fruit. The combination of packing, low temperature and sachets for ethylene removal is a viable strategy to keep the loquat, significantly extending its short postharvest life.

  19. Removal of blue 1 dye of aqueous solutions with a modified clay with iron chloride; Remocion de colorante azul 1 de soluciones acuosas con una arcilla modificada con cloruro de hierro

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez H, K. A.

    2012-07-01

    At the present time, several technologies have been proposed to remove dyes from water, adsorption is one of the most feasible methods and adsorbents with different properties, such as activated carbon, zeolites, clays and hydrogels among others. In this work, the sorption behavior of blue 1 dye by a natural clay from a site located in the Center-East of Mexico, and other modified with iron chloride were determined. The materials were characterized by X-ray diffraction to analyze its crystal structure, by scanning electron microscopy and elemental microanalysis of energy dispersive X-ray spectrometry to determine the composition and morphology, and the zero point charges were also determined to know the charge distribution on the surface of the clay. The ph effect, contact time, dye concentration and temperature were the parameters considered in this study. The results showed that clay does not suffer any important changes in its structure after the chemical treatments (modification with ferric chloride and contact with blue 1 solutions). The ph influences lightly the adsorption of the dye with natural clay, but the same effect is not observed in the ferric modified clay among the factor ph 6 and 8. The equilibrium time and the sorption capacity for natural clay were 48 hours and 6.16 mg/g, while for the ferric clay were 24 hours and 14.22 mg/g. Adsorption kinetics results were best adjusted to the pseudo first and pseudo second order models. Adsorption isotherms were best adjusted to the Langmuir model, indicating that both clays have a homogeneous surface. Thermodynamic parameters (E, {Delta}S and {Delta}G and {Delta}H) were calculated for the dye adsorption by the natural clay using data of the adsorption kinetics at temperatures between 20 and 50 C, indicating that the adsorption process is exothermic. For the case of ferric clay, it was not possible to calculate these thermodynamic parameters because the adsorption capacities were similar in the range of selected temperatures. (Author)

  20. Evaluation of the modified nanoclay effect on the vulcanization of SBR through rheometric curve and DSC;Avaliacao do efeito de nanoargila modificada na vulcanizacao de SBR atraves da curva reometrica e DSC

    Energy Technology Data Exchange (ETDEWEB)

    Forte, Maria Madalena C.; Brito, Karin J.S., E-mail: mmcforte@ufrgs.b [Universidade Federal do Rio Grande do Sul (PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Gheller Junior, Jordao [SENAI, Sao Leopoldo, RS (Brazil). Centro Tecnologico de Polimeros

    2009-07-01

    Rubber nanocomposites with nanoclays organically modified by quaternary ammonium salts may have the curing features modified significantly, since the salts may act on the rubber cure system. The aim of this work is to evaluate the influences of an organically modified montmorillonite (OMMT) on the curing reaction of an SBR (styrene butadiene rubber) with sulfur. The SBR/OMMT nanocomposites were prepared by co-coagulating SBR latex and Cloisite{sup R} 20A aqueous suspension at different nanoclay concentrations. The OMMT effect on the sulfur curing reaction was evaluated by the rheometric curve using a rheometer type RPA (Rubber Process Analyzer) and the heat of vulcanization (DELTAH{sub v}) using Differential Scanning Calorimetry (DSC). The evaluation of the clay nanolayers dispersion in the SBR matrix was accomplished by x-ray diffraction (XRD) analysis. (author)

  1. Selectivity of the adsorption process of modified zeolite rock with hexadecyl trimethylammonium bromide in front to chromates and dichromates; Selectividad del proceso de adsorcion de roca zeolitica modificada con bromuro de hexadeciltrimetilamonio frente a cromatos y dicromatos

    Energy Technology Data Exchange (ETDEWEB)

    Salgado G, N.

    2011-07-01

    In the present investigation natural zeolite (clinoptilolite) from the Chihuahua state, which was conditioned with sodium chloride solution and subsequently modified with a hexadecyl trimethylammonium bromide solution was used to evaluate the removal of Cr (Vi) from chromate or dichromate solutions. The zeolite materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, the influence of ph, contact time between phases were investigated and during the adsorption process was calculated the concentration of chromium ion present in aqueous solution (CrO{sub 4}{sup 2-}, Cr{sub 2}O{sub 7}{sup 2-}). The quantification of chromium removed from the aqueous solution by atomic absorption spectrometry technique was done. In order to understand the behaviour of the adsorption kinetics the pseudo first and pseudo second order models were applied, and to determine the adsorption capacity of the zeolite materials for Cr the Langmuir, Freundlich and Langmuir-Freundlich models were chosen. It was found that the removal efficiency of chromium ion is influenced by ph and the chemical species present: chromate or dichromate. The chromate and dichromate sorption kinetic data were best fitted to the pseudo-second and pseudo-first order models, respectively; and the Langmuir and Langmuir-Freundlich models described adequately the isotherms data considering a mono component system. In a mixture of Cr (Vi) ad CrO{sub 4}{sup 2-} and Cr{sub 2}O{sub 7}{sup 2-}, the surfactant modified zeolite has a greater selectivity for Cr{sub 2}O{sub 7}{sup 2-} ion than CrO{sub 4}{sup 2-}. In this case the Langmuir-Freundlich model described the adsorption isotherm behavior. (Author)

  2. Pontos marcados na superfície da pele representam os processos espinhosos quando a postura é modificada? Can skin markers represent spinous process when the posture is changed?

    Directory of Open Access Journals (Sweden)

    Tássia Silveira Furlanetto

    2011-06-01

    Full Text Available O objetivo do estudo foi verificar radiograficamente se a posição dos marcadores de superfície, identificados por palpação em ortostase, é alterada com a modificação da postura para o decúbito lateral. Dez indivíduos foram: palpados e marcados com adesivos de superfície, os processos espinhosos das vértebras C7, T2, T4, T6, T8, T10, T12, L2, L4 e S2; submetidos a um exame radiológico da coluna vertebral na posição ortostática e em decúbito lateral direito para verificar se o marcador de superfície colocado sobre o processo espinhoso estava condizente com o processo espinhoso da imagem radiográfica. Uma ANOVA two-way mostrou diferenças significativas para o deslocamento do marcador de superfície entre as posições para as vértebras C7, T2, T4, T6, T8, T10, L2 e S2 (pThe objective was to radiographically verify if the position of skin markers, identified by palpation in orthostasis posture, changes when the subject position shifts to lying posture. Ten subjects underwent two X-ray tests, first, in orthostasis and right lying posture. Ten subjects were palpated and marked with skin markers in the orthostasis posture, in the spinous process of the vertebrae C7, T2, T4, T6, T8, T10, T12, L2, L4 and S2 . After palpation, subjects underwent X-ray exams in orthostasis and lying postures to verify if the surface marker matched the spinous process shown on X-ray. A two-way ANOVA indicated significant differences for the displacement of the skin markers, for the C7, T2, T4, T6, T8, T10, L2 and S2 spinous processes (p<0.001. The T12 and L4 spinous processes did not indicate significant differences. The skin markers locations were not consistent with the spinous processes identified in X-rays for both positions. The skin movement may have displaced the skin markers when the subject changed from orthostasis to lying posture.

  3. Preparation and characterization of sugar cane bagasse fiber modified with nanoparticles of zirconium oxide; Preparacao e caracterizacao de fibras de bagaco de cana modificadas com nanoparticulas de oxido de zirconio

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, K.C.C. de; Mulinari, D.R.; Voorwald, H.C.J.; Cioffi, M.O.H., E-mail: kcccarvalho@hotmail.com.b [UNESP, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia(FEG)

    2010-07-01

    The sugar cane bagasse fiber are renewable materials and have great application potential when used as reinforcement in a polymer matrix to give rise to composite materials and as supports for adsorption of heavy metals. This paper therefore describes the preparation and characterization of bleached and hydrated zirconium oxide modified sugar cane bagasse fiber by conventional precipitation method. Through the technique of electron microscopy we observed the presence of oxide nanoparticles on the fiber surface, proving the efficiency of the conventional precipitation method. With the X-ray diffraction analysis it was determined a decrease of 6.2% in the crystallinity index of modified fibers when compared to the bleached fibers showing the deposition of amorphous zirconium oxide on the fiber surface. (author)

  4. Eliminación de etilmetilcetona en lecho fijo con óxidos mixtos equimolares de Fe-Mn y Cu-Mn másicos y soportados en arcillas modificadas

    OpenAIRE

    Picasso, Gino; Sun Kou, María del Rosario; Pina, María Pilar; Herguido, Javier; Irusta, Silvia; López, Rosario; Apolinario, Giovanna; Arzamendi, Gurutze; Gandía, Luis M.

    2007-01-01

    Los compuestos orgánicos volátiles (COV's) son un importante tipo de contaminantes atmosféricos responsables de la producción de oxidantes fotoquímicos, especialmente ozono troposférico, que causan daños en plantas y animales, irritación ocular y problemas respiratorios en los humanos. Por esta razón existe actualmente un fuerte interés por la reducción de las emisiones de COV's a la atmósfera. La combustión catalítica es una alternativa eficiente para el tratamiento de estos contaminantes. E...

  5. Evaluation of thermal properties of nanocomposites based on Ecobras matrix and vermiculite modified with alkyl phosphonium salt; Avaliacao das propriedades termicas dos nanocompositos de Ecobras e vermiculita modificada com sal alquil fosfonio

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Marcelo F.L. de; Leite, Marcia C.A.M., E-mail: marceloilha@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil); Braga, Fernanda C.F.; Oliveira, Marcia G. [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The use of biodegradable polymers for producing nanocomposites with mineral fillers fetch the production of new materials with low cost and reduced environmental impact, combined with improvements in the mechanical and thermal properties. Nanocomposites based on Ecobras and vermiculite (VMT) modified with hexadecyl tributyl phosphonium bromide (Ph-VMT) were prepared by melt intercalation. The intercalation of Ph-VMT in Ecobras was characterized by X-ray diffraction (XRD). The thermal properties of Ecobras and their compositions were characterized by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The addition of VMT and Ph- VMT in Ecobras increases the crystallization temperature (Tc) and crystalline melting (Tm), as observed by DSC analysis. The result of the thermogravimetric analysis showed that the addition of Ph-VMT in Ecobras improved thermal stability of the nanocomposite. (author)

  6. Obtenção e caracterização de tintas em pó base resina epóxi contendo montmorilonitas modificadas com cério

    OpenAIRE

    Diego Piazza

    2016-01-01

    Revestimentos orgânicos têm sido amplamente utilizados para a proteção à corrosão de substratos metálicos devido ao seu custo favorável e facilidade de aplicação. O uso de nanopartículas, mesmo que em baixas concentrações, apresenta-se como uma solução eficiente para aumentar as propriedades de barreira e resistência dos revestimentos orgânicos. A montmorilonita (MMT) é a fase inorgânica mais utilizada na obtenção de nanocompósitos poliméricos. O óxido de cério quando incorporado em revestime...

  7. Effect of the incorporation of modified purified clay with different content surfactants in the thermal and mechanical PET nanocomposites; Efeito da incorporacao de argila purificada modificada com diferentes teores de surfactantes nas propriedades termicas e mecanicas dos nanocompositos de PET

    Energy Technology Data Exchange (ETDEWEB)

    Leite, Itamara F. [Universidade Federal da Paraiba (DEMAT/UFPB), PB (Brazil); Soares, Anna P.S.; Silva, Suedina M.L., E-mail: suedina@yahoo.com.br [Universidade Federal de Campina Grande (UEAMa/CCT/UFCG), PB (Brazil); Malta, Oscar M.L. [Universidade Federal de Pernambuco (DQF/CCEN/UFPE), PE (Brazil)

    2011-07-01

    An organically modified bentonite purified with different amounts of alkyl ammonium salts and alkyl phosphonium was used as filler in the preparation of nanocomposites of poly(ethylene terephthalate) (PET). PET/organophilic bentonite masterbatch were prepared in a Haake torque rheometer at 260° C, 60 rpm for 10min. Then, the master batch obtained were mixed with PET in quantities necessary to obtain the nominal content of 1 wt% of bentonite, a twin screw extruder counter-rotating to 275°C in all heating zones and 60 rpm. Subsequently, the mixtures were injected (Arburg All Rounder), in the form of tensile specimens (ASTM D638). The effect of incorporating this type of filler on thermal and mechanical properties of nanocomposites of PET will be investigated. The incorporation of different types of organoclay to PET resulted in intercalated nanocomposites and partially exfoliated. The intercalated morphology showed higher thermal stability. (author)

  8. Corrosion behaviour and in vitro/in vivo biocompatibility of surface-modified AZ31 alloy; Comportamiento frente a la corrosion y biocompatibilidad in vitrolin vivo de la aleacion AZ31 modificada superficialmente

    Energy Technology Data Exchange (ETDEWEB)

    Carboneras, M.; Iglesias, C.; Perez-Maceda, B. T.; Valle, J. A. de; Garcia-Alonso, M. C.; Alobera, M. A.; Clemente, C.; Rubio, J. C.; Escudero, M. I.; Lozano, R. M.

    2011-07-01

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair. (Author) 18 refs.

  9. Morphological and structural evolution of the anatase phase of silicon modified titanium dioxide obtained by Sol-gel; Evolucao estrutural e morfologica da fase anatase de dioxido de titanio modificada com silicio obtido pelo Metodo Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, S.A.; Oliveira, C.T.; Ciola, R.A.; Cavalheiro, A.A., E-mail: silvanicelopes@gmail.com [Universidade Estadual de Mato Grosso do Sul (CPTREN/UEMS), Navirai, MS (Brazil). Centro de Pesquisas Tecnologicas em Recursos Naturais

    2011-07-01

    The photonic efficiency of the titanium dioxide photocatalyst is dependent on the crystalline structure and the anatase phase presents high efficiency in the border region between the UV-B and UV-A, with a redox potential sufficient to generate hydroxyl radicals and superoxide ion in order to oxidate organic compounds. In spite of the organic matter degradation effectiveness, the efficiency can be reduced substantially due to the presence of crystalline defects, which act as premature recombination centers of the electron-hole pair. The increasing of calcining temperature allows the elimination of most of these defects, but the structural ordering at temperatures around 600°C eventually leads to the phase transition toward rutile, which is not photoactive. In this work, it was demonstrated through FTIR and XRD that the silicon modifier presence stabilizes the anatase phase even at temperatures as high as 900°C. (author)

  10. Rumen dry matter degradability of fresh and ensiled sugarcane

    African Journals Online (AJOL)

    my mord

    2013-05-08

    May 8, 2013 ... Brasileira de Zootecnia, Viçosa-MG. pp. 977-985. Ferreira DA, Gonçalves L, Molina LR, Castro-Neto A, Tomich TR. (2007). Fermentation of sugarcane silage treated with urea, zeolita, bacteria inoculant and bacteria/enzymatic inoculants. Arq. Bras. Med. Vet. Zootec. 59:423-433. Garcia H, Abreu M, Soto JM ...

  11. Development a solid state sensor based on SnO{sub 2} nanoparticles for underground coal mine methane detection using zeolites as filter; Desenvolvimento de sensor de estado solido com nanoparticulas de SnO{sub 2} para metano de mina de carvao subterranea utilizando zeolitas como filtro

    Energy Technology Data Exchange (ETDEWEB)

    Abruzzi, R.C.; Dedavid, B.A.; Pires, M.J.R.; Luvizon, N.S., E-mail: rafael.abruzzi@acad.pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2016-07-01

    Aiming the monitoring of methane (CH{sub 4}) in underground coal mines, the tin oxide (SnO{sub 2}) was synthesis and applied to the development of a MOS sensor (metal oxide semiconductor). Zeolite have been tested as a filter of carbon dioxide (CO{sub 2}) to ensure the selectivity in the detection of CH{sub 4}. Analysis of Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) indicated a synthesis of nanoscaled structures. The energy band gap showed characteristic values for a potential application of SnO{sub 2} in CH{sub 4} sensors. Analysis of surface area by BET isotherms showed high values for the zeolite 13X and Y, while adsorption tests indicated that the zeolite 13X presents greater adsorption efficiency of CO{sub 2}. The sputtering technique for deposition of the electrodes, as well as the method of drop coating for deposition of SnO{sub 2}, proved effective in developing the sensor. (author)

  12. Adsorption of reactive Remazol Red RB dye of aqueous solution using zeolite of the coal ash and evaluation of acute toxicity with Daphnia similis; Adsorcao de corante reativo Remazol Vermelho RB de solucao aquosa usando zeolita de cinzas de carvao e avaliacao da toxicidade aguda com Daphnia similis

    Energy Technology Data Exchange (ETDEWEB)

    Magdalena, Carina Pitwak

    2010-07-01

    In this study, the capacity of zeolite synthesized from coal ash in the removal of Remazol Red dye aqueous solution was investigated by batch mode operation. The equilibrium was attained after 360 min of contact time. The adsorption rate followed the kinetic model of pseudo-second-order. The equilibrium data obtained fitted to Langmuir adsorption isotherm showing the adsorption capacity of up to 1.20mg g-1. The efficiency of adsorption was between 75 to 91% in the equilibrium time. In order to obtain the best conditions for removal of this dye, the influence of the following parameters was: initial concentration of the dye, pH of the aqueous solution, dose of adsorbent and temperature. The thermodynamic parameters were evaluated showing that the adsorption of Remazol red on the zeolite is of a spontaneous nature. Experiments by adding NaCl and Na{sub 2}SO{sub 4} were carried out to simulate the real conditions of the effluents from the dyeing bath and to evaluate the influence of these chemical compounds in the phenomenon of adsorption. The equilibrium data of adsorption of Remazol red on the zeolite was achieved in a shorter time in the presence of increasing concentrations of salts in solution and an increase in adsorption capacity. The efficiency of the study was evaluated as a treatment for acute toxicity using Daphnia similis microcrustacean. (author)

  13. Crystallization of mordenite zeolite with seed addition in reaction mixtures with different SiO{sub 2}/Al{sub 2}O{sub 3} ratios; Cristalizacao da zeolita mordenita com adicao de sementes em meio reacionais com diferentes razoes SiO{sub 2}/Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Cysneiros, O.M.S.; Silva, B.J.B.; Silva, A.O.S.; Alencar, S.L.; Santos, R.B.; Soares, P.F.M.; Mendonca, T.R.D.; Sousa Junior, L.V.; Santos, J.R., E-mail: brunojbarros@hotmail.com [Universidade Federal de Alagoas (UFAL), Maceio (Brazil). Departamento de Engenharia Quimica. Laboratorio de Sintese de Catalisadores

    2016-04-15

    The synthesis of samples of mordenite were performed using the hydrothermal method using two different types of crystallization seed (mordenite and ferrierite), where they were exploited to change some parameters of the synthesis, such as SiO{sub 2}/Al{sub 2}O{sub 3} = 20, 60 and 100 and the ratio OH/SiO{sub 2} = 0.2, 0.3 and 0.4, at different times of crystallization, at a temperature of 170 °C. The samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA/DTA), nitrogen adsorption at -196 °C (BET) and temperature programmed desorption of ammonia (NH{sub 3}-TPD). It was found that the use of the ratio OH/SiO{sub 2} = 0.4, together with the seeds of the most MOR and FER crystalline samples were obtained, demonstrating the critical role of mineralizing agent OH{sup -} in the middle. (author)

  14. Study of the Cd (II) removal in the presence of methyl orange with a natural zeolite conditioned with iron nanoparticles; Estudio de la remocion de Cd(II) en presencia de naranja de metilo con una zeolita natural acondicionada con nanoparticulas de hierro

    Energy Technology Data Exchange (ETDEWEB)

    Xingu C, E. G.

    2015-07-01

    This work presents a study on the removal of cadmium and/or methyl-orange dye in aqueous solution, using natural zeolite clinoptilolite, as sodium homo-ionized and impregnated with iron nanoparticles. Iron nanoparticles were synthesized in the presence of the zeolite by chemical reduction. The evaluation of the removal ability was performed in a monocomponent (cadmium or methyl-orange dye) system by varying the contact time and its initial concentration. Removal capacity in a bi-component (cadmium and methyl orange) system was also studied while varying their concentrations. The characterization of the zeolites, before and after the sorption process, was carried out using several analytical techniques. The characteristics of zeolite clinoptilolite and iron particles were observed by scanning electron microscopy. The iron particles showed diameter sizes between 60 and 200 nm, localized on the surface of the zeolite. By IR spectroscopy no structural changes were detected for any of the treatments made to the zeolitic materials. By X-ray diffraction the clinoptilolite crystalline phase was mainly identified, however, it failed to detect any phase of iron in the zeolite impregnated with iron nanoparticles. Moessbauer spectroscopy indeed detected the impregnated iron phase as iron borides. The homo-ionized and iron nanoparticles impregnated zeolite showed no change in the specific surface area, or the isoelectric point, their values were 22.3 m{sup 2}/g and ph 9.8, respectively. However, whereas the active site density for the homo-ionized zeolite was 2.87 sites/nm{sup 2}, for iron nanoparticles impregnated zeolite was 20.32 sites/nm{sup 2}. As a result of the analysis of the isotherms of cadmium, the maximum sorption capacity of the homo-ionized zeolite was 35.03 mg/g and for the iron nanoparticles impregnated zeolite was 36.43 mg/g. These maximum sorption capacities represent up to 85% of removed cadmium from concentrations of 50 to 600 mg/L. For the removal of methyl orange dye case, the homo-ionized zeolite did not remove any; however, the iron nanoparticles impregnated zeolite its maximum removal capacity was 79.8 mg/g. In the two-component system the removal capacity could not be assessed due to the presence precipitates formed between the methyl-orange dye and cadmium solutions. (Author)

  15. Ammonium ion interaction with conditioned natural zeolite with silver and its effect on the disinfection of polluted water in front of a consortium of gram (+) and gram (-) microorganisms; Interaccion del ion amonio con zeolita natural acondicionada con plata y su efecto sobre la desinfeccion de agua contaminada frente a un consorcio de microorganismos gram (+) y gram (-)

    Energy Technology Data Exchange (ETDEWEB)

    Gonzaga G, V. E.

    2013-07-01

    Clinoptilolite zeolite material is a relative abundance in Mexico, which has ion exchange properties, therefore, has the ability to retain metal ions giving it an application in the process of disinfecting of water contaminated with pathogenic microorganisms. In this research, we conducted a study of disinfection of water contaminated with a microbial consortium, from a zeolite rock clinoptilolite from a deposit located in the State of Guerrero. Initially, the zeolite prepared by the grinding and sieving, for conditioning with NaCl and subsequently with AgNO{sub 3}, finally to be characterized using the techniques of scanning electron microscopy and X-ray diffraction. Tests using columns packed with zeolite material, the effect of zeolite bactericidal conditioned with silver (ZGAg) against a microbial consortium consisting of Escherichia coli and Sthapyloccocus aureus in aqueous solution in the presence of ammonium ions used to increase the ion exchange with zeolite fitted with silver. To describe curves disinfecting a continuous flow system is adapted Gu pta model, which describes the kinetics and equilibrium adsorption process, considering the microorganisms as the adsorbate and the sanitizing agent (conditioned with silver zeolite) as the adsorbent. Characterization results show that in the scanning electron microscopy (Sem), no changes were obtained on the morphology of typical clinoptilolite crystals before and after that was modified with sodium and then with silver, it is worth mentioning however that fitted with silver zeolite (ZGAg), small particles are seen on the zeolite material which when analyzed by energy dispersive spectroscopy (EDS), we found a high concentration of Ag +. The disinfection period is increased as the concentration increased ammonium ions, this behavior is attributed to the ion exchange that occurs between the ammonium ions and silver ions. A lower percentage of inactivation is due, therefore, to a lesser amount of money available to be exchanged for ammonium ions, which leads to less disinfection. (Author)

  16. The annihilation of ortho-positronium in the {alpha} and {beta} cavities of the 4A zeolite and those CoZ4A and MnZ4A; La aniquilacion del orto-positronio en las cavidades {alpha} y {beta} de la zeolita 4A y en las de CoZ4A y MnZ4A

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I.; Jimenez B, J.; Solache R, M.; Bonifacio M, J.; Rodriguez F, C.; Bulbulian, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    The lifetime of the ortho-positronium in the zeolite 4A, partially dehydrated, changes to three characteristic modes. The first mode could be associated with the water elimination of the small {beta} cavity of this zeolite. At the end of this first dehydration process it is estimated a cavity radius, R = 33.8 nm. The other two types of variation of lifetime of ortho-positronium would be associated with the water elimination of the {alpha} great cavity and of the rest of the zeolite. From the zeolite 4A totally dehydrated and of the zeolite 4A exchanged with Co (II) and MN (II), also dehydrated radius are respectively determined for the {alpha} great cavity of R = 48.1, 54.5 and 56.5 nm. (Author)

  17. Stability and activity of doped transition metal zeolites in the hydrothermal processing

    Directory of Open Access Journals (Sweden)

    Thomas François Robin

    2015-12-01

    Full Text Available This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper and iron in under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered as a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds which have an impact on the physical and chemical propriety of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts but their stability and activity under hydrothermal conditions is not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350 °C. Catalysts have been characterised before and after treatment using XRD, BET physisorption and STEM microscopy. Metal leaching was determined by analysis of the water phase following hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5 for example molybdenum improves the crystallinity of the zeolite. In general, metal doped zeolites were relatively stable under subcritical water. Activity of the catalysts for processing lipids, protein and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella and P. ellipsoidea. The catalysts exhibited greater activity towards converting lipids for example MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  18. Stability and Activity of Doped Transition Metal Zeolites in the Hydrothermal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Robin, Thomas François, E-mail: thomas.cognac@gmail.com; Ross, Andrew B.; Lea-Langton, Amanda R.; Jones, Jenny M. [School of Chemical and Process Engineering, University of Leeds, Leeds (United Kingdom)

    2015-12-14

    This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper, and iron under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion-exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds that have an impact on the physical and chemical properties of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts, but their stability and activity under hydrothermal conditions are not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350°C. Catalysts have been characterized before and after treatment using X-ray diffraction, BET physisorption, and scanning transmission electronic microscopy. Metal leaching was determined by the analysis of the water phase following the hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5, for example, molybdenum improves the crystallinity of the zeolite. In general, metal-doped zeolites were relatively stable in subcritical water. The activity of the catalysts for processing lipids, protein, and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella, and Pseudochoricystis ellipsoidea. The catalysts exhibited greater activity toward converting lipids, for example, MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  19. Stability and Activity of Doped Transition Metal Zeolites in the Hydrothermal Processing

    International Nuclear Information System (INIS)

    Robin, Thomas François; Ross, Andrew B.; Lea-Langton, Amanda R.; Jones, Jenny M.

    2015-01-01

    This study investigates the stability and activity of HZSM-5 doped with metals such as molybdenum, nickel, copper, and iron under hydrothermal conditions used for the direct liquefaction of microalgae. Catalysts have been prepared by ion-exchange techniques, and MoZSM-5 was also prepared by wet incipient impregnation for comparison. Hydrothermal liquefaction is considered a potential route to convert microalgae into a sustainable fuel. One of the drawbacks of this process is that the bio-crude produced contains significant levels of nitrogen and oxygen compounds that have an impact on the physical and chemical properties of the fuel. Heterogeneous catalysts have been shown to improve the quality of the bio-crude by reducing nitrogen and oxygen contents. Zeolites, such as HZSM-5, are strong candidates due to their low cost compared to noble metal catalysts, but their stability and activity under hydrothermal conditions are not well understood. The stability of the catalysts has been determined under hydrothermal conditions at 350°C. Catalysts have been characterized before and after treatment using X-ray diffraction, BET physisorption, and scanning transmission electronic microscopy. Metal leaching was determined by the analysis of the water phase following the hydrothermal treatment. The inserted cation following ion-exchange can influence the physical properties of HZSM-5, for example, molybdenum improves the crystallinity of the zeolite. In general, metal-doped zeolites were relatively stable in subcritical water. The activity of the catalysts for processing lipids, protein, and microalgae has been assessed. Four feedstocks were selected: sunflower oil, soya proteins, Chlorella, and Pseudochoricystis ellipsoidea. The catalysts exhibited greater activity toward converting lipids, for example, MoZSM-5 enhanced the formation of aromatic compounds. NiZSM-5 and CuZSM-5 were observed to be more efficient for deoxygenation.

  20. Conversão catalítica do etanol sobre catalisadores suportados em ZSM-5

    Directory of Open Access Journals (Sweden)

    D. S. Lima

    Full Text Available Resumo O petróleo, fonte de energia não renovável, é a principal matéria-prima usada na produção de derivados como combustíveis, lubrificantes e petroquímicos básicos. Neste contexto o etanol, uma matéria-prima renovável, torna-se fonte para a obtenção de hidrocarbonetos de maior valor agregado, tais como, benzeno, tolueno, etc. Este trabalho teve como objetivo avaliar o efeito de diferentes metais suportados em zeólita HZSM-5 para a conversão do etanol em produtos com maior valor agregado. Duas séries de catalisadores foram preparadas com diferentes metais e diferentes teores de Ni em HZSM-5 comercial. As amostras foram caracterizadas por área específica SBET, DRX, TPD-NH3 e TPO. Os ensaios de atividade foram realizados em um reator tubular de leito fixo na faixa de temperatura entre 300 e 400 °C, usando etanol como reagente. Os resultados sugerem que o tipo e a quantidade de metal usado na modificação da zeólita HZSM-5 comercial influencia a seletividade para formação dos hidrocarbonetos superiores, bem como a temperatura de reação. A utilização de menores vazões favoreceu a formação de produtos pesados. A formação dos hidrocarbonetos superiores diminuiu ao longo da reação devido à deposição de carbono sobre a superfície do catalisador.

  1. Deoxygenation of methyl laurate over Ni based catalysts: Influence of supports

    Science.gov (United States)

    Xia, Xiaoqiang; Chen, Hui; Bi, Yadong; Hu, Jianli

    2017-10-01

    The use of a series of nickel based catalysts supported over HZSM-5, Al2O3, C and ZrO2 in the deoxygenation of methyl laurate shows that the deoxygenation activity and deoxygenation pathway of nickel based catalysts can be affected by properties of catalysts. In the absence of H2, β-elimination of methyl laurate is the dominant reaction and a small amount of laurate acid is converted into undecane by direct decarboxylation. At the same time, the highly acidic support HZSM-5 gave higher conversion and C11 alkane selectivity. In the presence of H2, Ni/HZSM-5 catalyst showed a significantly high deoxygenation activity, producing 71% alkanes by methyl laurate conversion at 280 °C and 4MPa H2. While as on mildly acidic (Al2O3) and neutral (C) supports, a restricted hydrodeoxygenation activity was achieved but more oxygenate products were yielded. According to the analysis of intermediate product, the deoxygenation reaction of methyl laurate follows three distinct pathways: in the absence of H2, decarboxylation: C11H23COOCH3→C11H23COOH→C11H24; in the presence of H2, decarbonylation: C11H23COOCH3→C11H23COOH→C11H23CHO→C11H24; and hydrodeoxygenation: C11H23COOCH3 →C11H23COOH→C11H23CHO→C12H25OH→C12H26

  2. Thermal and catalytic pyrolysis of a mixture of plastics from small waste electrical and electronic equipment (WEEE).

    Science.gov (United States)

    Santella, Chiara; Cafiero, Lorenzo; De Angelis, Doina; La Marca, Floriana; Tuffi, Riccardo; Vecchio Ciprioti, Stefano

    2016-08-01

    Pyrolysis seems a promising route for recycling of heterogeneous, contaminated and additives containing plastics from waste electrical and electronic equipment (WEEE). This study deals with the thermal and catalytic pyrolysis of a synthetic mixture containing real waste plastics, representative of polymers contained in small WEEE. Two zeolite-based catalysts were used at 400°C: HUSY and HZSM-5 with a high silica content, while three different temperatures were adopted for the thermal cracking: 400, 600 and 800°C. The mass balance showed that the oil produced by pyrolysis is always the main product regardless the process conditions selected, with yields ranging from 83% to 93%. A higher yield was obtained when pyrolysis was carried out with HZSM-5 at 400°C and without catalysts, but at 600 and 800°C. Formation of a significant amount of solid residue (about 13%) is observed using HUSY. The oily liquid product of pyrolysis, analysed by GC-MS and GC-FID, as well as by elemental analysis and for energy content, appeared lighter, less viscous and with a higher concentration of monoaromatics under catalytic condition, if compared to the liquid product derived from thermal degradation at the same temperature. HZSM-5 led to the production of a high yield of styrene (17.5%), while HUSY favoured the formation of ethylbenzene (15%). Energy released by combustion of the oil was around 39MJ/kg, thus suggesting the possibility to exploit it as a fuel, if the recovery of chemical compounds could not be realised. Elemental and proximate analysis of char and GC-TCD analysis of the gas were also performed. Finally, it was estimated to what extent these two products, showing a relevant ability to release energy, could fulfil the energy demand requested in pyrolysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Geração de mesoporos em zeólitas ZSM-5 e seus efeitos na conversão do etanol em olefinas

    Directory of Open Access Journals (Sweden)

    Ingryd Carvalho Alves

    2012-01-01

    Full Text Available Developing mesoporosity in HZSM-5 zeolites is an alternative for improving their catalytic performance on chemical reactions. In this work, alkaline and thermal treatments were used to produce mesoporosity. These treatments increased mesoporous area and volume. They also influenced the acid properties of the samples. Concerning catalytic performance, treatments modified reaction product distribution. Whereas alkaline treatment favored formation of olefins and increased propene ratio in the beginning of the reaction, thermal treatment resulted in formation of only ethylene due to the low acidity of the sample.

  4. Synthesis and characterization of mesoporous ZSM-5 core-shell particles for improved catalytic properties

    DEFF Research Database (Denmark)

    Kustova, Marina; Holm, Martin Spangsberg; Christensen, Claus H.

    2008-01-01

    samples were tested in the MTG reaction, and the results showed that both the shell-coated and the desilicated zeolites are significantly more resistant to coke formation. These results are ascribed to the effect of the removal of structural defects rather than to an improvement of the diffusion......HZSM-5 is a unique catalyst for the conversion of methanol, dimethyl ether and other oxygenates into gasoline. During this process, catalyst deactivation by coking requires frequent regeneration and the improvement of catalyst life time is one of the challenges in catalyst development...

  5. Hydrogen output from radiolytic split of water in the presence of some zeolites

    International Nuclear Information System (INIS)

    Cecal, A.; Colisnic, D.; Popa, K.; Paraschivescu, A.; Bilba, N.

    2002-01-01

    Radiolytic decomposition of water under the action of gamma rays in the presence of some zeolites such as ZSM-5, SAPO-5 and MOR was studied. The irradiation was performed using a gamma 60 Co source at an activity of 3 . 10 4 Ci and dose rate 8.3 KGy/h. The stable products of radiolysis as well as the other chemical species were identified by mass spectrometry. The calculated radiochemical yield decreased in order: H-ZSM-5 > Na-ZSM-5 > H-SAPO-5 > MOR and was higher in the presence of these catalysts than in their absence

  6. Studies of N{sub 2}0 adsorption and decomposition on Fe-ZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Benjamin R.; Reimer, Jeffrey A.; Bell, Alexis T.

    2002-03-08

    The interactions of N2O with H-ZSM-5 and Fe-ZSM-5 have been investigated using infrared spectroscopy and temperature-programmed reaction. Fe-ZSM-5 samples with Fe/Al ratios of 0.17 and 0.33 were prepared by solid-state exchange. It was determined that most of the iron in the samples of Fe-ZSM-5 is in the form of isolated cations, which have exchanged with Bronsted acid H+ in H-ZSM-5. The infrared spectrum of N2O adsorbed on H-ZSM-5 at 298 K exhibits bands at 2226 and 1308 cm-1 associated with vibrations of the N-N and N-O bonds, respectively. The positions of these bands relative to those seen in the gas phase suggest that N2O adsorbs through the nitrogen end of the molecule. The heat of N2O adsorption in H-ZSM-5 is estimated to be 5 kcal/mol. In the case of Fe-ZSM-5, additional infrared bands are observed at 2282 and 1344 cm-1 due to the interactions of N2O with the iron cations. Here too, the directions of the shifts in the vibrational features relative to those for gas-phase N2O suggest that the molecule adsorbs through its nitrogen end. The heat of adsorption of N2O on the Fe sites is estimated to be 16 kcal/mol. The extent of N2O adsorption on Fe depends on the oxidation state of Fe. The degree of N2O adsorption is higher following pretreatment of the sample in He or CO at 773 K, than following pretreatment in O2 or N2O at the same temperature. Temperature-programmed decomposition of N2O was performed on the Fe-ZSM-5 samples and revealed that N2O decomposes stoichiometrically to N2 and O2. A higher activity was observed if the catalysts were pretreated in He than if they were pretreated in N2O. For the He-pretreated samples, the activation energy for N2O decomposition was estimated to be 42 kcal/mol and the preexponential factor of the rate coefficient for this process was found to increase with Fe/Al ratio. This trend was attributed to the increasing auto reducibility of Fe3+ cations to Fe2+ cations with increasing Fe/Al ratio.

  7. Escolecita de aglomerados basálticos del complejo basal de Fuerteventura (Islas Canarias)

    OpenAIRE

    La Iglesia, Á.; Fernández Santín, Soledad; Hernández-Pacheco, A.

    1990-01-01

    Se caracteriza por análisis químico, microscopía óptica, difracción de Rayos X, análisis térmico diferencial, termogravimetría y espectroscopía de infrarrojos, una zeolita fibrosa perteneciente a la formación volcánica aglomerática del Complejo Basal de la isla de Fuerteventura. Los datos analíticos obtenidos confirman la identidad de esta zeolita fibrosa como escolecita. El análisis químico del mineral pone de manifiesto un elevado contenido en sodio, superior a los que aparecen en la biblio...

  8. Remoción de níquel, cadmio y zinc del agua, utilizando clinoptilolita heulandita

    Directory of Open Access Journals (Sweden)

    Thelma B. Pavón Silva

    2000-01-01

    Full Text Available Se aplica el proceso de intercambio iónico con una zeolita natural obtenida en Taxco, Guerrero, México, para la remoción de Zn, Cd y Ni de soluciones acuosas. Para este proceso, el mineral se homoionizó con cloruro de sodio y posteriormente se puso en contacto con soluciones 0.01 N de sales de nitratos de Zn, Cd y Ni, durante 8 días.

  9. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol

    Directory of Open Access Journals (Sweden)

    Debarpita Ghosal

    2015-07-01

    Full Text Available The performance of toluene methylation reaction was studied on H-ZSM-5 catalyst modified with La, Ce and Nb at different percentage loading. It was found that 10% metal loading produced the best performance in the reaction in terms of toluene conversion. The catalyst was coated on silicon carbide foam support which showed better conversion than the pelleted catalyst. Again, among the treated and untreated H-ZSM-5, the La-ZSM-5 catalyst is chosen for the reaction for its highest selectivity towards xylene, the main product. All catalysts were characterized in terms of surface properties, SEM, XRD and NH3-TPD. Kinetic study was done on La-ZSM-5 catalyst with 10% loading. In this kineticstudy, Langmuir Hinshelwood kinetic model with surface reaction as rate controlling step was selected as the rate equation. The activation energy was found to be 47 kJ/mol. © 2015 BCREC UNDIP. All rights reserved. Received: 9th December 2014; Revised: 27th April 2015; Accepted: 29th April 2015  How to Cite: Ghosal, D., Basu, J.K., Sengupta, S. (2015. Application of La-ZSM-5 Coated Silicon Carbide Foam Catalyst for Toluene Methylation with Methanol. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 201-209. (doi:10.9767/bcrec.10.2.7872.201-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7872.201-209  

  10. Structural Modification of Cobalt Catalysts: Effect of Wetting Studied by X-Ray and Infrared Techniques

    Directory of Open Access Journals (Sweden)

    Khodakov A.

    1999-07-01

    Full Text Available The effect of wetting on the structure and localisation of cobalt species on various supports (Al2O3, SiO2, TiO2, HZSM-5 zeolite was studied using X-ray diffraction, Fourier transform infrared spectroscopy with CO as a molecular probe, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. Aqueous impregnation to incipient wetness of reduced and passivated cobalt catalysts results, even in the absence of any promoter, in a considerable decrease in the concentration of Co crystalline phases and modifies the surface sites. The decrease in the concentration of Co3O4 crystallites was especially pronounced on silica supported catalysts prepared via impregnation of cobalt and on a mixture of Co3O4 and HZSM-5 zeolite. Saturation with water of the passivated Co/SiO2 sample results in an amorphous solid with a local structure close to that of Co2SiO4. For Co/Al2O3 and Co/TiO2 catalysts, the effect of wetting on the concentration of Co3O4 crystalline phase was considerably smaller.

  11. Optimizing the Production of Renewable Aromatics via Crop Oil Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Clancy Kadrmas

    2015-04-01

    Full Text Available While HZSM-5 catalytic cracking of crop oil toward aromatics have been well documented, this work adds to this body of knowledge with a full acid byproduct analysis that provides improved mass balance closure along with a design of experiment optimization of reaction conditions. Fatty acids are an inevitable byproduct when converting any triglyceride oil, but are most often overlooked; despite the impact fatty acids have on downstream processing. Acid analysis verified that only short chain fatty acids, mainly acetic acid, were present in low quantities when all feed oil was reacted. When relatively high fatty acid amounts were present, these were mainly uncracked C16 and C18 fatty acids. Optimization is a balance of aromatics formation vs. unwanted gas products, coke and residual fatty acids. A design of experiments approach was used to provide insight into where the optimal reaction conditions reside for HZSM-5 facilitated reactions. These conditions can then form the basis for further development into a commercially viable process for the production of renewable aromatics and other byproducts.

  12. Diethyl Ether Production Process with Various Catalyst Type

    Directory of Open Access Journals (Sweden)

    Widayat

    2013-01-01

    Full Text Available Several H-zeolite and HZSM-5 catalysts was preparated and their characters have also been investigated. H-zeolit Catalyst was preparated from Natural Zeolite that obtained from Malang District and Gunung Kidul District. Diethyl ether was produced by Ethanol with concentration of 95%. This research use fixed bed reactor that 1 gram of catalyst as bed catalyst, atmospheric pressure and temperature 140oC as the operating condition. Ethanol vapor from vaporization tank was driven by 200 ml/min Nitrogen stream. The responds in this research is liquid product concentration; diethyl ether, ethanol, methanol and water concentration. The results showed that the largest ethanol conversion was produced by the use of 56.44% HZSM-5 and the largest yield of diethyl ether diethyl was produced by the use of alumina and H-zeolite catalyst. The larger ratio between natural zeolite with HCl solvent will produce the larger surface area of catalyst and ethanol conversion. The largest ethanol conversion was produced at reactan ratio 1:20.

  13. Diethyl Ether Production Process with Various Catalyst Type

    Directory of Open Access Journals (Sweden)

    Widayat Widayat

    2012-12-01

    Full Text Available Several H-zeolite and HZSM-5 catalysts was preparated and their characters have also been investigated. H-zeolit Catalyst was preparated from Natural Zeolite that obtained from Malang District and Gunung Kidul District. Diethyl ether was produced by Ethanol with concentration of 95%. This research use fixed bed reactor that 1 gram of catalyst as bed catalyst, atmospheric pressure and temperature 140oC as the operating condition. Ethanol vapor from vaporization tank was driven by 200 ml/min Nitrogen stream. The responds in this research is liquid product concentration; diethyl ether, ethanol, methanol and water concentration. The results showed that the largest ethanol conversion was produced by the use of 56.44% HZSM-5 and the largest yield of diethyl ether diethyl was produced by the use of alumina and H-zeolite catalyst. The larger ratio between natural zeolite with HCl solvent will produce the larger surface area of catalyst and ethanol conversion. The largest ethanol conversion was produced at reactan ratio 1:20. [Keywords:  catalyst; ethanol conversion; dehydration process; yield of diethyl ether; natural zeolite].

  14. Direct liquefaction of plastics and coprocessing of coal with plastics

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, G.P.; Feng, Z.; Mahajan, V. [Univ. of Kentucky, Lexington, KY (United States)

    1995-12-31

    The objectives of this work were to optimize reaction conditions for the direct liquefaction of waste plastics and the coprocessing of coal with waste plastics. In previous work, the direct liquefaction of medium and high density polyethylene (PE), polypropylene (PPE), poly(ethylene terephthalate) (PET), and a mixed plastic waste, and the coliquefaction of these plastics with coals of three different ranks was studied. The results established that a solid acid catalyst (HZSM-5 zeolite) was highly active for the liquefaction of the plastics alone, typically giving oil yields of 80-95% and total conversions of 90-100% at temperatures of 430-450 {degrees}C. In the coliquefaction experiments, 50:50 mixtures of plastic and coal were used with a tetralin solvent (tetralin:solid = 3:2). Using approximately 1% of the HZSM-5 catalyst and a nanoscale iron catalyst, oil yields of 50-70% and total conversion of 80-90% were typical. In the current year, further investigations were conducted of the liquefaction of PE, PPE, and a commingled waste plastic obtained from the American Plastics Council (APC), and the coprocessing of PE, PPE and the APC plastic with Black Thunder subbituminous coal. Several different catalysts were used in these studies.

  15. In-situ catalytic upgrading of biomass pyrolysis vapor: Co-feeding with methanol in a multi-zone fixed bed reactor

    International Nuclear Information System (INIS)

    Asadieraghi, Masoud; Wan Daud, Wan Mohd Ashri

    2015-01-01

    Highlights: • Aromatics yield improved with increasing H/C eff ratio of the feed. • HZSM-5 catalyst was an effective catalyst for in-situ bio-oil upgrading. • Biomass/methanol co-feeding attenuated the coke formation. • Methanol co-feeding enhanced the bio-oil quality. - Abstract: The in-situ catalytic upgrading of the biomass pyrolysis vapor and its mixture with methanol were conducted in a fixed bed multi-zone reactor. The steps were comprised; thermally converting the biomass in the pyrolysis reactor, passing its vapor in contact with the HZSM-5 zeolite catalyst in the presence of methanol vapor, and transformation of the resulting upgraded pyrolysis vapor into the liquid product. The biomass pyrolysis and catalytic pyrolysis vapor upgrading were performed at 500 °C. The highly valuable chemicals production was a function of the hydrogen to carbon effective ratio (H/C eff ) of the feed. This ratio was regulated by changing the relative amount of biomass and methanol. More aromatic hydrocarbons (50.02 wt.%) and less coke deposition on the catalyst (1.3 wt.%) were yielded from the biomass, when methanol was co-fed to the catalytic pyrolysis process (H/C eff = 1.35). In this contribution, the deposited coke on the catalyst was profoundly investigated. The coke, with high contents of oxo-aromatics and aromatic compounds, was generated by polymerization of biomass lignin derived components activated by catalyst acid sites

  16. Hydrotreatment of bio-oil over Ni-based catalyst.

    Science.gov (United States)

    Zhang, Xinghua; Wang, Tiejun; Ma, Longlong; Zhang, Qi; Jiang, Ting

    2013-01-01

    Inexpensive non-sulfided Ni-based catalysts were evaluated for hydrotreatments using phenol as model compound. HZSM-5, a zeolite with different ratio of Si/Al and γ-Al(2)O(3) were impregnated with Ni(NO(3))(2) · 6H(2)O and calcined at 450 °C. Conversion rates and product distribution for treatment of phenol at 160-240 °C in the presence of catalysts with nickel loads of 6, 10, 14 and 17 wt.% were determined. Phenol conversion was highest (91.8%) at 240 °C in the presence of HZSM-5(Si/Al = 38) loaded with 10% Ni. When hydrotreatment was carried out with bio-oil obtained from pyrolysis of pine sawdust under the optimal conditions determined for phenol, the pH of bio-oil increased from 2.27 to 4.07, and the hydrogen content increased from 6.28 to 7.01 wt.%. The decrease in acidity is desirable for the use of upgraded bio-oil. Copyright © 2012. Published by Elsevier Ltd.

  17. Adsorção do complexo H[Ru(IIICl2(H2EDTA] sobre a superfície da sílica gel modificada com [3-(2-aminoetil aminopropil]trimetoxissilano em soluções etanólicas

    Directory of Open Access Journals (Sweden)

    Lazarin Angélica Machi

    1999-01-01

    Full Text Available Silica gel was functionalized with [3-(2-aminoethylaminopropyl]trimethoxysilane group (SF-AEATS and the characterization by chemical analysis (N and infrared spectroscopy confirmed the functionalization. The capacity of the modified silica to adsorb the complex Ru(III-EDTA from ethanolic solution was studied. The selectivity coefficients of the complex formed on the support obtained was (Gñ, 2,07 x 10(4 L/mol and the average number of ligand bonded by one metal ion on the support (ñ was ~ 1.

  18. Pre-treatment Of Thermoduric Spores In Co2 Modified Atmosphere And Their Survivability During Food Extrusion [pré-tratamento De Esporos Termodúricos Em Atmosfera Modificada De Co2 E Sua Sobrevivência Ao Processo De Extrusão

    OpenAIRE

    Fraiha M.; Ferraz A.C.O.; Biagi J.D.

    2011-01-01

    The aim of this experiment was to evaluate how susceptible spores become to mechanical damage during food extrusion after being submitted to CO2. B. stearothermophilus spores sowed to corn and soy mix were submitted to 99% CO2 for 10 days and extruded in a single-screw extruder. The treatments were: T1 - spore-containing samples, extruded at screw rotational speed of 65 rpm and barrel wall temperature of 80 °C; T2 - as T1, except for screw rotational speed of 150 rpm; and T3 - as T2, except t...

  19. Preparación y evaluación de formulaciones acrílicas autocurables de baja toxicidad modificadas con polímeros biodegradables para cirugía ortopédica y mínimamente invasiva

    OpenAIRE

    Franco Marquès, Elena

    2012-01-01

    En este trabajo se ha llevado a cabo el estudio de nuevas formulaciones de cementos óseos acrílicos (COA) para su posterior evaluación como sistema de liberación controlada de medicamentos útiles en el tratamiento terapéutico de la osteoporosis. El trabajo se ha fundamentado en la modificación parcial de la fase sólida de los COA, mediante la substitución parcial de las microesferas de PMMA, por diferentes micropartículas de polímeros biodegradables, tanto de naturaleza sintética como natural...

  20. Determinação das propriedades catalíticas em meio aquoso e orgânico da lipase de Candida rugosa imobilizada em celulignina quimicamente modificada por carbonildiimidazol Assessment of catalytic properties in aqueous and organic media of lipase from Candida rugosa immobilized on wood cellulignin activated with carbonyldiimidazole

    Directory of Open Access Journals (Sweden)

    Fabrício M. Gomes

    2006-07-01

    Full Text Available Microbial lipase from Candida rugosa was immobilized by covalent binding on wood cellulignin (Eucaliptus grandis chemically modified with carbonyldiimidazole. The immobilized system was fully evaluated in aqueous (olive oil hydrolysis and organic (ester synthesis media. A comparative study between free and immobilized lipase was carried out in terms of pH, temperature and thermal stability. A higher pH value (8.0 was found optimal for the immobilized lipase. The optimal reaction temperature shifted from 37 °C for the free lipase to 45 °C for the immobilized lipase. The pattern of heat stability indicated that the immobilization process tends to stabilize the enzyme. Kinetics tests at 37 °C following the hydrolysis of olive oil obeyed the Michaelis-Menten rate equation. Values for Km = 924.9 mM and Vmax = 198.3 U/mg were lower than for free lipase, suggesting that the affinity towards the substrate changed and the activity of the immobilized lipase decreased during the course of immobilization. The immobilized derivative was also tested in the ester synthesis from several alcohols and carboxylic acids.

  1. Effects of the modified atmosphere and irradiation on the microbiological, physical-chemical and sensory characteristics of the 'minas frescal' cheese;Efeitos da atmosfera modificada e da irradiacao sobre as caracteristicas microbiologicas, fisico-quimicas e sensoriais do queijo minas frescal

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Vanessa Pires da

    2004-07-01

    The experiment was divided into two parts. Initially, it was studied the 'Minas Frescal' cheeses packed under atmospheric air, modified atmosphere of 70% CO2 and 30% N2 (ATM) and vacuum. Second the cheeses packed under these three treatments had been radiated by doses of 2 KGy. In the two parts of the experiment, it was analyzed the microbial evolution and, the sensory and physical-chemical characteristics of the cheeses under the different treatments during a 4 deg C-storage. In the first phase of the experiment it was verified that the ATM and the vacuum decreased the intensity of the total population growth of aerobic mesophilic and psychotropic and had reduced the population of Staphylococcus positive coagulase, but they had not been efficient controlling the total coliforms and Escherichia coli, while in control all the populations had continuously grown, according to the sensory characteristics of the cheeses, color, odor and appearance. These characteristics were kept the same during the 40 days of storage, and the control decreased the acceptability levels gradually, being rejected in the 17{sup th} day. In the second part of the experiment, it was observed that a 2KGy-irradiation over the 'Minas Frescal' cheeses reduced the populations of aerobic mesophilic, aerobic and anaerobic psychotropic, Staphylococcus positive coagulase, total coliforms and Escherichia coli. The ATM and vacuum treatments were very efficient therefore they prevented the growth of these microorganisms during the storage, while in control, the aerobic mesophilic and psychotropic population grew during the storage. According to sensory aspects, the ATM treatment was the most efficient one, because it kept the appearance, texture and flavor for more than 43 days while the vacuum kept for 36 days and the control for only 8 days. The use of the irradiation with modified atmosphere and low temperatures of storage increased the shelf life of the cheeses, hindering the growth of the microbial populations in the product and keeping product sensory characteristics. (author)

  2. Determinação de cobre, ferro, níquel e zinco em querosene combustível após adsorção e preconcentração sobre sílica gel modificada com grupos 2-aminotiazol

    OpenAIRE

    Roldan, P. S. [UNESP; Alcântara, I. L. [UNESP; Rocha, Julio Cesar [UNESP; Padilha, C. C. F. [UNESP; Padilha, P. M. [UNESP

    2004-01-01

    Silica gel chemically modified with 2-Aminotiazole groups, abbreviated as SiAT, was used for preconcentration of copper, zinc, nickel and iron from kerosene, normally used as a engine fuel for airplanes. Surface characteristics and surface area of the silica gel were obtained before and after chemical modification using FT-IR, Kjeldhal and surface area analysis (B.E.T.). The retention and recovery of the analyte elements were studied by applying batch and column techniques. The experimental p...

  3. Corrosion behaviour of ductile cast irons partially modified with silicon in 0.03 M NaCl; Comportamiento frente a la corrosion de fundiciones con grafito laminar y esferoidal parcialmente modificadas con silicio en NaCl 0,03 M

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, M. A.; Niklas, A.; Conde, A.; Mendez, S.; Sertucha, J.; Damborenea, J. J. de

    2014-07-01

    NaCl. The increasing demand of ductile cast irons with extensive technological applications leads to enlarge the corrosion resistance of this group of metallic materials. In this sense, the use of different chemical compositions on such cast irons becomes one of the most interesting aspects among the different ways to improve their behaviour against corrosion due to the extra opportunity for increasing the mechanical properties. Additionally such improvements have to be made without any increase of processing costs to keep the interesting competitiveness of developed cast irons. In the present work the preliminary results obtained from corrosion tests made on a group of cast irons with different chemical compositions are presented. Among ductile cast irons, silicon content has been varied in order to investigate the effect of this element on corrosion resistance of the alloys. The obtained results show a slight improvement of this property for the alloys with high silicon content with respect to the conventional ones though such effect was found in the first time period of the corrosion tests. Interestingly this improvement was found for alloys that exhibit better tensile properties than the conventional ductile irons. Thus an important way for developing new ductile cast irons with improved corrosion properties by alloying has been opened. (Author)

  4. Custo-efetividade da escovação dental supervisionada convencional e modificada na prevenção da cárie em molares permanentes de crianças de 5 anos de idade Cost-effectiveness of conventional and modified supervised toothbrushing in preventing caries in permanent molars among 5-year-old children

    Directory of Open Access Journals (Sweden)

    Paulo Frazão

    2012-02-01

    Full Text Available O custo-efetividade de um programa modificado de escovação dental supervisionada foi comparado ao programa convencional. Participaram 284 crianças de 5 anos com, pelo menos, um molar permanente com a superfície oclusal irrompida/hígida. Nas unidades de controle, o programa convencional composto de atividade educativa com distribuição de escova e creme dental fluorado foi desenvolvido quatro vezes por ano. Nas unidades de teste, as crianças receberam também escovação profissional nas superfícies oclusais desses dentes, realizada por auxiliar de saúde bucal, empregando-se a técnica de escovação vestíbulo-lingual cinco vezes por ano. Cárie de esmalte/dentina foi registrada nas superfícies vestibular, oclusal e lingual dos molares permanentes durante 18 meses. A razão da densidade de incidência (RDI foi estimada usando o modelo de regressão de Poisson, sendo 50% menor entre os meninos no grupo de teste (p = 0,016. O programa modificado custou R$ 3,04 por criança. A razão de custo-efetividade marginal foi de R$ 10,71 por lesão evitada entre os meninos. O programa modificado foi custo-efetivo nos meninos.The cost-effectiveness of a modified supervised toothbrushing program was compared to a conventional program. A total of 284 five-year-old children presenting at least one permanent molar with emerged/sound occlusal surface participated. In the control group, oral health education and dental plaque dying followed by toothbrushing with fluoride dentifrice was carried outfour times per year. With the test group, children also underwent professional cross-brushing on surfaces of first permanent molar rendered by a dental assistant five times per year. Enamel/dentin caries were recorded on buccal, occlusal and lingual surfaces of permanent molars for a period of18 months. The incidence density (ID ratio was estimated using Poisson's regression model. The ID was 50% lower among boys in the test group (p = 0.016. The cost of the modified program was US$ 1.79 per capita. The marginal cost-effectiveness ratio among boys was US$ 6.30 per avoided carie. The modified supervised toothbrushing program was shown to be cost-effective in the case of boys.

  5. Thermal, mechanics and electrical characterization of the Al-0,6%Mg-08%Si alloy refined and modified with different copper contents; Caracterizacao termica, mecanica e eletrica da liga Al-0,6% Mg-0,8% Si refinada e modificada com diferentes teores de cobre

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, E.S. [Universidade Federal do Para (UFPA), Belem, PA (Brazil)], Email: mmanufreitas@gmail.com; Marques, P.R.R.; Santos, W.L.R.; Kamizono, K.A.; Quaresma, J. Maria V.

    2009-07-01

    The aluminum, magnesium and silicon alloys form a very important group, utilized as casted form and worked alloys, especially in 6201 alloy series. These alloys show applicability on cables and wires fabrication to electrical energy transmission. The present work analyzes the copper content variation and its influence in electrical conductivity, tensile strength and in studied alloy ductility. The refined Al-0,6% Mg-0,8% Si studied alloy was modified with the following contents: [0,05; 0,10; 0,20 e 0,30]% Cu and unidirectional solidified. The test specimen were machined to 10 mm diameter and rolled to 3,98 mm, whose deformation rate was 60,2%. The obtained wires were mechanical, electrical and structural characterized and the mechanical and electrical characterization results were associated to fractures of evaluated micro cavities. The highest observation was the Cu content in alloy increases the TS, decreases electrical conductivity and increases liquidus isotherm's velocity, forming micro cavities. (author)

  6. Caracterização química e física de batatas 'Ágata' minimamente processadas, embaladas sob diferentes atmosferas modificadas ativas Chemical and physical characterization of fresh-cut 'Ágata' potatoes packed under different active modified atmospheres

    Directory of Open Access Journals (Sweden)

    Lívia Lacerda Oliveira Pineli

    2005-10-01

    Full Text Available O objetivo deste trabalho foi avaliar as alterações químicas e físicas em batatas 'Ágata' minimamente processadas, embaladas sob diferentes atmosferas, durante o armazenamento refrigerado. Batatas 'Ágata' foram minimamente processadas como minibatatas e embaladas em filmes de náilon multicamadas. Os tratamentos aplicados no momento da embalagem foram o vácuo parcial e as misturas 10%CO2, 2%O2, 88%N2 ou 5%CO2, 5%O2, 90%N2. Em seguida, foram armazenadas a 5ºC. A cada três dias, amostras foram avaliadas quanto ao índice de escurecimento, atividade da polifenoloxidase e peroxidase, firmeza, sólidos solúveis totais e acidez titulável. O armazenamento sob vácuo parcial foi o mais eficaz no controle do escurecimento, da minimização da atividade da polifenoloxidase e da peroxidase, prevenindo alterações nos teores de sólidos solúveis totais, redução da firmeza, encharcamento da embalagem e maior acidez titulável. Os demais tratamentos apresentaram rápido desenvolvimento do escurecimento, aumento de firmeza em decorrência de ressecamento dos tubérculos, elevação nos sólidos solúveis totais e menor desenvolvimento da acidez em comparação ao tratamento sob vácuo parcial. A utilização de vácuo parcial foi a mais recomendada para a manutenção da qualidade das minibatatas. Todavia, outros tratamentos que busquem a manutenção da firmeza e frescor, sem o desenvolvimento de off-flavors e sem escurecimento, devem ser avaliados.The objective of this work was to evaluate chemical and physical characteristics of fresh-cut 'Ágata' potatoes packed under different active modified atmospheres, during refrigerated storage. 'Ágata' potatoes were minimally processed as baby potatoes and packed in nylon multilayer films. The treatments applied were partial vacuum, and atmospheres with 10%CO2, 2%O2, 88%N2 and 5%CO2, 5%O2, 90%N2. After that, they were stored at 5ºC. Every three days, tubers were evaluated for browning index, polyphenoloxidase and peroxidase activity, firmness, total soluble solids, and titratable acidity. Storage under partial vacuum was the best treatment to control browning and to reduce polyphenoloxidase and peroxidase activities as well as to prevent reduction of total soluble solids, loss of firmness, accumulation of water inside the package and higher titratable acidity. Active modified atmospheres showed faster and sharper browning development, increase of firmness due to tubers dehydration, increase in total soluble solids and lower acidity development comparing with tubers stored under partial vacuum. Storage under partial vacuum showed the best results for maintaining the quality of fresh cut baby potatoes. However, other treatments to maintain firmness freshness, without the development of off-flavors and browning, should be evaluated.

  7. Algunos aspectos del leasing inmobiliario: especialmente enfocados con relación al orden jurídico uruguayo, y particularmente a la Ley 16.072, de 9 de octubre de 1989, que reglamenta el contrato de crédito de uso, modificada por la Ley 16.205 de 6 de seti

    OpenAIRE

    Carlos López Fernández; Teresita Mercader Pizzorno

    2015-01-01

    Contenido: Introducción. Concepto y modalidades del leasing. Naturaleza jurídica del leasing financiero. Consideraciones sobre la ley uruguaya de "leasing financiero". La naturaleza jurídica del leasing inmobiliario.  La inscripción del contrato de leasing

  8. Algunos aspectos del leasing inmobiliario: especialmente enfocados con relación al orden jurídico uruguayo, y particularmente a la Ley 16.072, de 9 de octubre de 1989, que reglamenta el contrato de crédito de uso, modificada por la Ley 16.205 de 6 de seti

    Directory of Open Access Journals (Sweden)

    Carlos López Fernández

    2015-10-01

    Full Text Available Contenido: Introducción. Concepto y modalidades del leasing. Naturaleza jurídica del leasing financiero. Consideraciones sobre la ley uruguaya de "leasing financiero". La naturaleza jurídica del leasing inmobiliario.  La inscripción del contrato de leasing

  9. Influência de diferentes condições higrotérmicas na resistência à tração de compósitos de fibra de carbono/epóxi modificada Influence of different hygrothermal conditions on the tensile strength of carbon/epoxy 8552 composites

    Directory of Open Access Journals (Sweden)

    José Antônio P. Cunha

    2006-01-01

    Full Text Available Este trabalho foi direcionado para a análise dos efeitos higrotérmicos na resistência à tração de compósitos poliméricos termorrígidos. Foram investigados os efeitos da umidade e da temperatura sobre as resistências à tração longitudinal e à tração transversal de compósitos ([0/0]s de fita de carbono unidirecional impregnada com resina epóxi 8552. Os ensaios de resistência à tração longitudinal, realizados à temperatura ambiente, mostraram que as amostras não perderam sua resistência quando condicionadas. Porém, os compósitos apresentaram uma redução na sua resistência quando submetidos à câmara de climatização (80 °C e 90% de umidade e ensaiados à temperatura elevada. Já nos ensaios de tração transversal foi observado que as amostras submetidas à câmara de névoa salina e ensaiadas à temperatura ambiente apresentaram uma pequena redução na sua resistência, porém as amostras submetidas à câmara de climatização mostraram uma redução acentuada na resistência As amostras ensaiadas à temperatura elevada e submetidas à câmara de névoa salina apresentaram uma pequena diminuição na sua resistência (11%. Já uma acentuada diminuição da resistência à tração transversal (51% foi observada quando as amostras de compósitos poliméricos foram submetidas à câmara de climatização e ensaiadas à temperatura elevada. Também foram obtidas fotomicrografias via microscopia eletrônica de varredura (MEV das seções de fraturas das amostras ensaiadas em tração em todos os tipos de condicionamento estudados no presente trabalho. Todos estes fatos mostraram que a matriz polimérica é afetada nos ensaios à temperatura elevada.This work focused the analysis of hygrothermal ageing effects on the tensile strength of thermoset laminated composites. Humidity and temperature effects on the longitudinal and transversal tensile strengths of carbon fiber/epoxy 8552 unidirectional laminates tape composites ([0/0]s were investigated. The longitudinal tensile strength results at room temperature was not significantly affected by exposing the samples to either the humidity-controlled chamber or the salt spray chamber. However, the specimens submitted to the humidity-controlled chamber and tested at elevated temperature (80 °C and 90% RH presented a decrease in the longitudinal tensile strength. A small decrease in the transversal tensile strength results was observed during room temperature tests in the samples submitted to salt spray chamber. A higher decrease in the transversal tensile strength was verified in the samples submitted to the humidity-chamber. Samples submitted to the salt spray chamber tested at elevated temperature showed a small decrease in the transversal tensile strength (11%. A drastic reduction in the strength (51% was observed in the samples submitted to the humidity-chamber and tested at high temperature. A fractograph study by scanning electronic microscopy (SEM was performed in every single sample involved in the tests. These results highlight that the elevated temperatures affect the polymeric matrix.

  10. The prevalence of iridologic signs in individuals with Diabetes Mellitus Uso de la escala modificada de Borg en la crisis asmática A prevalência de sinais iridológicos em indivíduos com Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Léia Fortes Salles

    2008-01-01

    Full Text Available OBJECTIVE: To verify the prevalence of iridologic signs, such as the pancreas sign and the Cross of Andreas, in individuals with Diabetes mellitus and the association of these signs with three risk factors for the disease: obesity, sedentarism and heredity. METHODS: Collection occurred from April to June, 2006, involving 97 individuals over 30 years of age with Diabetes mellitus, cared for at Centro de Saúde Escola "Geraldo de Paula Souza", São Paulo. RESULTS: After having their irises analyzed, the adjusted prevalence of the pancreas sign and the Cross of Andreas was observed, with 98% and 89%, respectively. There were significant associations (p OBJETIVO: Verificar la prevalencia de signos iridológicos, como la señal del páncreas y Cruz de Andreas en individuos con Diabetes mellitus y la asociación de estos signos con los tres factores de riesgo para la enfermedad: obesidad, sedentarismo y herencia. MÉTODOS: La recolección de datos se llevó a cabo de abril a junio del 2006, con 97 individuos de edad superior a 30 años y portadores de Diabetes mellitus, atendidos en el Centro de Salud Escuela "Geraldo de Paula Souza", Sao Paulo. RESULTADOS: Después del análisis de las iris, se verificó que la prevalencia ajustada de la señal del páncreas y de la Cruz de Andreas, fueron respectivamente, 98% y 89%. Hubo asociaciones significativas (pOBJETIVO: Verificar a prevalência de sinais iridológicos, como o sinal do pâncreas e Cruz de Andréas em indivíduos com Diabetes mellitus e a associação destes sinais com os três fatores de risco para a doença: obesidade, sedentarismo e hereditariedade. MÉTODOS: A coleta ocorreu de abril a junho de 2006, com 97 indivíduos de idade superior a 30 anos e portadores de Diabetes mellitus, atendidos no Centro de Saúde Escola "Geraldo de Paula Souza", São Paulo. RESULTADOS: Após análise das íris, verificou-se que a prevalência ajustada do sinal do pâncreas e da Cruz de Andréas, foram respectivamente, 98% e 89%. Houve associações significativas (p<0,001 entre obesidade, sedentarismo e antecedente familiar para diabetes com ambos os sinais estudados. CONCLUSÃO: As evidências demonstram dados de interesse para a área preventiva e a necessidade de realização de novos estudos.

  11. Catalytic Fast Pyrolysis of Cellulose Using Nano Zeolite and Zeolite/Matrix Catalysts in a GC/Micro-Pyrolyzer.

    Science.gov (United States)

    Lee, Kyong-Hwan

    2016-05-01

    Cellulose, as a model compound of biomass, was catalyzed over zeolite (HY,.HZSM-5) and zeolite/matrix (HY/Clay, HM/Clay) in a GC/micro-pyrolyzer at 500 degrees C, to produce the valuable products. The catalysts used were pure zeolite and zeolite/matrix including 20 wt% matrix content, which were prepared into different particle sizes (average size; 0.1 mm, 1.6 mm) to study the effect of the particle size of the catalyst for the distribution of product yields. Catalytic pyrolysis had much more volatile products as light components and less content of sugars than pyrolysis only. This phenomenon was strongly influenced by the particle size of the catalyst in catalytic fast pyrolysis. Also, in zeolite and zeolite/matrix catalysts the zeolite type gave the dominant impact on the distribution of product yields.

  12. Catalytic conversion of 11C-labeled methanol over Cs-ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Salmi, T.; Murzin, D.Yu.

    2004-01-01

    Reaction mechanism of the conversion of 11 C labeled methanol over basic Cs-ZSM-5 zeolite catalyst was investigated and the reaction products obtained were compared with that of H-ZSM-5 acidic catalyst. The catalytic experiments were carried out by passing 11 C-labeled methanol with He as a carrier gas over Cs-ZSM-5 packed in a micro reactor. After adsorption of the radio methanol, the catalyst was heated up to 330 deg C. The products of the catalytic conversion of the 11 C-labeled methanol were analyzed by radio-gas chromatography (gas chromatograph with thermal conductivity detector on-line coupled with a radioactivity detector). (N.T.)

  13. Evaluation of LTA-, FAU- and MFI-type zeolites as sorbents of some toxic components of tobacco smoke

    International Nuclear Information System (INIS)

    Iucolano, F.; Caputo, D.; Monetta, T.; Bellucci, F.; Colella, C.

    2008-01-01

    Zeolites 3A, 4A, 13X, H-ZSM-5 were investigated in order to evaluate their possible use in removing toxic compounds from cigarette smoke. Ammonia and acetaldehyde were selected as representative of a wide range of possible sorbates. Adsorption equilibrium data at 313K were collected and analyzed by Langmuir and virial equations to estimate the relevant values of Henry's constant, a useful parameter to estimate the affinity sorbents-sorbates at low pressure. Unlike the Langmuir model, the virial equation provided a good fit for both ammonia and acetaldehyde equilibrium data for all sorbents in the whole range of pressures, especially at low pressure. As already assessed for nitrosamines, FAU- and MFI-type zeolites showed the highest affinity for ammonia and acetaldehyde, allowing these sorbents to be considered an effective potential resource for the removal of some of the main pollutants of tobacco smoke.

  14. Modeling methanol transfer in the mesoporous catalyst for the methanol-to-olefins reaction by the time-fractional diffusion equation

    Science.gov (United States)

    Zhokh, Alexey A.; Strizhak, Peter E.

    2018-04-01

    The solutions of the time-fractional diffusion equation for the short and long times are obtained via an application of the asymptotic Green's functions. The derived solutions are applied to analysis of the methanol mass transfer through H-ZSM-5/alumina catalyst grain. It is demonstrated that the methanol transport in the catalysts pores may be described by the obtained solutions in a fairly good manner. The measured fractional exponent is equal to 1.20 ± 0.02 and reveals the super-diffusive regime of the methanol mass transfer. The presence of the anomalous transport may be caused by geometrical restrictions and the adsorption process on the internal surface of the catalyst grain's pores.

  15. A review of catalytic upgrading of bio-oil to engine fuels

    DEFF Research Database (Denmark)

    Mortensen, Peter Mølgaard; Grunwaldt, Jan-Dierk; Jensen, Peter Arendt

    2011-01-01

    As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article...... are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS2/Al2O3, or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5...... produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms...

  16. Solvent-Free Biginelli Reactions Catalyzed by Hierarchical Zeolite Utilizing a Ball Mill Technique: A Green Sustainable Process

    Directory of Open Access Journals (Sweden)

    Ameen Shahid

    2017-03-01

    Full Text Available A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing of solvent was applied. The hierachical zeolite catalyst (MFI27_6 showed high yield (86%–96% of DHPMs in a very short time (10–30 min. The recyclability of the catalyst for the subsequent reactions was examined in four subsequent runs. The catalyst was shown to be robust without a detectable reduction in catalytic activity, and high yields of products showed the efficient protocol of the Biginelli reactions.

  17. Pyrolysis of rice husk over Zeolite based catalysts

    International Nuclear Information System (INIS)

    Bae, Yoon Ju; Kim, Jung Hwan; Cho, Hye Jung; Ko, Jeong Huy; Heo, Hyeon Su; Park, Hye Jin; Park, Young Kwon

    2010-01-01

    Full text: The utilization of biomass and other alternative fuel sources, rather than existing fossil fuels, would offer more environmentally acceptable processes for energy production and will aid in conserving the limited supplies of fossil fuels. Pyrolysis of biomass is one of the most promising tools to provide alternative energy sources. However, pyrolytic oils are not always completely volatile and contain high levels of oxygen, this being the major factor responsible for the high viscosity and corrosiveness. The upgrading of pyrolytic oils is a necessary process and involves the removal of oxygen by catalyst. In this study, various type of zeolites such as HZSM-5, HY, USY, Al-MCM-41; Al-SBA-15 etc. were applied. The upgraded oil was analyzed by GC-MS, GC, and elemental analysis etc. The results indicated that more stable oil was produced by transforming oxygen over various zeolite into H 2 O, CO and CO 2 . (author)

  18. Conversão do metanol em olefinas catalisada por zeólitas com diferentes características ácidas e estruturais

    OpenAIRE

    Flávia Figueiredo Almaraz

    2011-01-01

    A reação de transformação de metanol em olefinas leves foi investigada sobre as peneiras moleculares HZSM-5, HFER, SAPO-34 e HMCM-22. A caracterização físico-química das amostras foi realizada através das técnicas de FRX, DRX, fisissorção de nitrogênio, MEV, espectrometria no IV com adsorção de piridina e TPD de NH3. O desempenho catalítico das mesmas foi comparado em condições de isoconversão inicial de 755%. Verificou-se que as características ácidas e estruturais exerceram forte influência...

  19. Limpieza bucodental mediante técnicas de adsorción con material desechable: nueva alternativa de higiene oral

    OpenAIRE

    J.M. González-González

    2014-01-01

    El objetivo de este trabajo es mostrar diferentes materiales para hacer limpieza bucodental, con alto poder de adsorción, atóxicos y desechables (de usar y tirar), que masticados en la boca permitan arrastrar la placa bacteriana. Material y métodos: Se ha seleccionado información válida para el estudio en la base de datos medline, red de internet y bibliografía de archivos propios. Resultados: Entre los materiales hallados están: las sepiolitas, zeolitas, agares, carbón activo, polímeros de l...

  20. Remoción de Fe y Mn en aguas naturales por adsorción-oxidación sobre clinoptilolita

    Directory of Open Access Journals (Sweden)

    Carolina Cuchimaque Lugo

    2013-01-01

    Full Text Available En el presente trabajo de investigación se comprueba la eficiencia en la remoción de Fe y Mn de aguas naturales por el empleo de un medio adsorbente que consiste de zeolita natural (clinoptilolita, recubierta con Fe 2O3 y MnO2 a partir de FeCl3 y MnSO4, respectivamente. La zeolita por su gran capacidad de intercambio de cationes es un excelente soporte de estos óxidos. El mecanismo de la remoción es por adsorción-oxidación de estos metales sobre la superficie de la capa de óxido que cubre el grano de zeolita. En las pruebas de remoción mediante un sistema de filtración se estudiaron las variables pH, concentraciones de Fe y Mn, caudal en el a fluente y altura de la capa de la zeolita, resultando las dos últimas ser las de mayor relevancia en la remoción. Se utilizaron concentraciones de 1,0-7,0 mg/L para Fe y de 0,5-3,0 mg/L para Mn, en un rango de pH de 6,0-8,0. La eficiencia de la remoción disminuye con el aumento en la concentración de Fe, especialmente a valores de pH altos (> 7,5, por la formación de precipitados de Fe2O3 causando aceleración en la saturación del medio. No se obtuvo una diferencia significativa sobre la remoción con el empleo de los dos tipos de recubrimiento, aunque a altas concentraciones de estos metales, con la capa de Fe 2O3 se obtuvieron porcentajes de remoción un poco mayores, pero la desventaja es que con este tipo de óxido se obtuvo menor corrida de los filtros por la saturación del medio.