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Sample records for hydroxide coprecipitation system

  1. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

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    Barahuie, Farahnaz [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Hussein, Mohd Zobir, E-mail: mzobir@putra.upm.edu.my [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Arulselvan, Palanisamy [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Fakurazi, Sharida [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainal, Zulkarnain [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2014-09-15

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites

  2. Dysprosium(III) hydroxide coprecipitation system for the separation and preconcentration of heavy metal contents of table salts and natural waters

    Energy Technology Data Exchange (ETDEWEB)

    Peker, Dondu Serpil Kacar [Erciyes University, Faculty of Art and Science, Department of Chemistry, 38039 Kayseri (Turkey); Turkoglu, Orhan [Erciyes University, Faculty of Art and Science, Department of Chemistry, 38039 Kayseri (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Art and Science, Department of Chemistry, 38039 Kayseri (Turkey)]. E-mail: soylak@erciyes.edu.tr

    2007-05-08

    A procedure for the determination of trace amounts of Pb(II), Cu(II), Ni(II), Co(II), Cd(II) and Mn(II) is described, that combines atomic absorption spectrometry-dysprosium hydroxide coprecipitation. The influences of analytical parameters including amount of dysprosium(III), centrifugation time, sample volume, etc. were investigated on the recoveries of analyte ions. The effects of concomitant ions were also examined. The recoveries of the analyte ions were in the range of 95.00-104.00%. The detection limits corresponding to three times the standard deviation of the blank for the analytes were in the range of 14.1-25.3 {mu}g/L. The method was applied to the determination of lead, copper, nickel, cobalt, cadmium and manganese ions in natural waters and table salts good results were obtained (relative standard deviations <10%, recoveries >95%)

  3. Thermodynamic Analysis on the Coprecipitation of Ni-Co-Mn Hydroxide

    Science.gov (United States)

    Li, Ling; Li, Yunjiao; Li, Lin; Chen, Nanxiong; Han, Qiang; Zhang, Xianzhen; Xu, Hu

    2017-10-01

    The thermodynamic data of various species in Ni-H2O, Co-H2O, Mn-H2O, and Ni-Co-Mn-H2O systems were obtained by thermodynamic calculation. The potential-pH diagrams for Ni-H2O, Co-H2O, and Mn-H2O systems at different ion activities at 323 K (50 °C), as well as Ni-Co-Mn-H2O complex systems at activity 1.00 at 298 K, 323 K, and 373 K (25 °C, 50 °C, and 100 °C) were constructed, respectively. The costable regions of Ni(OH)2, Co(OH)2, and Mn(OH)2 are verified to be thermodynamically stable in aqueous solution, which indicates the thermodynamic possibility of Ni-Co-Mn hydroxide coprecipitation. The potential-pH diagrams show that the temperature and ion activity have significant effects on the coprecipitation process. As the temperature increases or the ion activity decreases, the coprecipitation region of the Ni-Co-Mn hydroxide narrows. Moreover, the metal oxides, rather than the metal hydroxide, are more easily formed when the temperature increases. Experimental confirmation was performed to further verify the constructed potential-pH diagrams. The Ni-Co-Mn hydroxide with typical hexagonal CdI2 structure and quasi-spherical morphology was successfully obtained, and the SEM results show the uniform distribution of the elements Ni, Co, and Mn. The experimental results confirm the reliability of the prediction of thermodynamics analysis.

  4. Speciation of Cr(III) and Cr(VI) in geological and water samples by ytterbium(III) hydroxide coprecipitation system and atomic absorption spectrometry.

    Science.gov (United States)

    Duran, Ali; Tuzen, Mustafa; Soylak, Mustafa

    2011-07-01

    A novel coprecipitation method with ytterbium(III) hydroxide has been established for speciation of Cr(III) and Cr(VI) in geological and water samples. At pH 10, while Cr(III) was quantitatively recovered, Cr(VI) was recovered under 10% levels. Total chromium was determined reducing of Cr(VI) to Cr(III) in acidic media with KI reagent. The concentration of Cr(VI) was calculated by the concentration difference between the total chromium and Cr(III). For the quantitative recovery of Cr(III), parameters such as pH, amount of ytterbium, centrifugation time and speed, matrix effect, KI amount, and sample volume were investigated. The preconcentration factor was 30. The limit of detection was obtained as 1.1 μg/L for Cr(III). The accuracy was checked by analyte addition and analyses of standard reference materials (TMDA-54.4 Certified Reference Water, NIST 2710 Montana Soil). Method has been successfully applied to the chromium speciation for industrial waste water of leather factories located in Bor-Nigde, and also for mine and soil samples. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Graphite Furnace Atomic Absorption Spectrometric Determination of Bismuth(III) after Coprecipitation with Hafnium Hydroxide

    OpenAIRE

    Ueda, Joichi; Takagi, Midori

    1990-01-01

    A method for the coprecipitation of bismuth(III) with hafnium hydroxide followed by a graphite-furnace atomic absorption spectrometric determination is described. Hafnium hydroxide coprecipitates quantitatively 0.05–3 μg of bismuth(III) from 50–400 cm3 of sample solution at pH 5.8–11.2. The presence of 2.5–50 mg of hafnium in 25 cm3 does not affect the atomic absorbance of bismuth(III). The calibration curve is linear for 0.05–3 μg of bismuth(III) in 25 cm3 and passes through the origin. Inte...

  6. Comparative study of the coprecipitation methods for the preparation of Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Crepaldi Eduardo L.

    2000-01-01

    Full Text Available Coprecipitation is the method most frequently applied to prepare Layered Double Hydroxides (LDHs. Two variations of this method can be used, depending on the pH control conditions during the precipitation step. In one case the pH values are allowed to vary while in the other they are kept constant throughout coprecipitation. Although research groups have their preferences, no systematic comparison of the two variations of the coprecipitation method is available in the literature. On this basis, the objective of the present study was to compare the properties of LDHs prepared using the two forms of pH control in the coprecipitation method. The results showed that even though coprecipitation is easier to perform under conditions of variable pH values, materials with more interesting properties, from the point of view of technological applications, are obtained at constant pH. Higher crystallinity, smaller particle size, higher specific surface area and higher average pore diameter were found for materials obtained by coprecipitation at constant pH, when compared to the materials obtained at variable pH.

  7. Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

    DEFF Research Database (Denmark)

    Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender

    2012-01-01

    Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence...... intercalated structure, but we here demonstrate it to be magnesium laurate (Mg-C12). The LDH-C12 compound showed high structural order with a basal spacing of 2.41nm. Fourier-transform IR-spectra confirmed the intercalation of the laurate anions in the interlayer. Transmission electron microscopy showed plate...

  8. Determination of tetracyclines in surface water and milk by the magnesium hydroxide coprecipitation method.

    Science.gov (United States)

    Tsai, Wen-Hsien; Huang, Tzou-Chi; Chen, Ho-Hsien; Huang, Joh-Jong; Hsue, Min-Hsien; Chuang, Hung-Yi; Wu, Yuh-Wern

    2010-01-15

    A simple coprecipitation method was developed for the determination of tetracyclines (TCs) in surface water and milk by high-performance liquid chromatography with diode-array detection (HPLC-DAD). Magnesium ion was added into the surface water or the acetonitrile (MeCN) extract of milk. After alkalinization, magnesium hydroxide precipitates which had been formed can be separated from the matrix solution easily by centrifuging and then a dissolution step was performed by adding a small amount of acid. The final solution could be introduced directly into HPLC system for the determination of the analytes. Under optimal conditions, recoveries for the analysis of spiked surface water samples ranged from 83.6% to 95.1% with relative standard deviation of 2.0-5.5%. For milk samples, relative recoveries were 95.9-104.6% with relative standard deviation of 3.4-6.7%. The enrichment factors ranged from 41.5 to 48.1 for 10 mL water samples, and from 3.6 to 4.4 for 1 mL MeCN extracts of milk. Limits of detection ranged from 0.13 to 0.51 ng/mL, and from 3.0 to 8.5 ng/g for four TCs in surface water and milk samples, respectively. 2009 Elsevier B.V. All rights reserved.

  9. Synthesis of high-density nickel cobalt aluminum hydroxide by continuous coprecipitation method.

    Science.gov (United States)

    Kim, Yongseon; Kim, Doyu

    2012-02-01

    Spherical nickel cobalt aluminum hydroxide (Ni(0.80)Co(0.15)Al(0.05)-hydroxide, NCA) was prepared by a continuous coprecipitation method. A new design of the Al solution and the feeding method was applied, which enabled to prevent rapid precipitation of Al(OH)(3) and to obtain spherical NCA with large enough particle size and high density. The active material (LiNi(0.80)Co(0.15)Al(0.05)O(2) or LNCA) prepared from it showed higher tap-density than that made from NCA prepared by general processes, and homogeneity of Al-distribution was also improved. It is expected that the electrode density of lithium ion batteries adopting LNCA could be improved with the new process proposed in this study.

  10. Bioavailability of adsorbed and coprecipitated Cu, Ni, Pb, and Cd on iron and iron/aluminum hydroxide to Phragmites australis.

    Science.gov (United States)

    Wang, He; Jia, Yongfeng

    2017-01-01

    The bioavailability of heavy metals strongly depends on their speciation in the environment. Adsorption (ADS) and coprecipitation (CPT) on amorphous metal hydroxides are important processes, controlling the fates of heavy metals in an aqueous environment. This work studied the bioavailability of Cu, Cd, Ni, and Pb adsorbed on and/or coprecipitated with amorphous iron and iron/aluminum mixed hydroxides to the wetland plant Phragmites australis. After a 13-day treatment, there was an apparent uptake of the heavy metals by the plant, and the amount of metal bioaccumulation was measurably different for different association forms (ADS vs. CPT). The bioaccumulation of Cd associated with Fe0.5Al0.5(OH)3 was greater than that with Fe(OH)3; the adsorbed metals were found to be more bioavailable than the coprecipitated forms for most of the treatments while the aging treatment significantly reduced the bioaccumulation of ADS metals. In the single metal treatment, root metal concentrations in the Fe(OH)3 ADS system followed the order Ni (68 mg kg-1) > Cu (32 mg kg-1) > Cd (28 mg kg-1) > Pb (9 mg kg-1), while the CPT system followed the order of Cu (30 mg kg-1) > Ni (22 mg kg-1) > Pb (9 mg kg-1) > Cd (7 mg kg-1). The order of metal accumulation in a combined metal treatment was similar to that for single metal treatments, but observed Ni concentration declines by 22 and 71 % and Cu and Cd concentrations increase by 30 and 50 % (for CPT and ADS treatments, respectively), while Pb concentrations increased by 30~50 % in both of them. When treated with low-molecular-weight organic acids (LMWOAs), metal desorption, indicative of metal oxide bonding strength and metal bioavailability, was consistent with metal accumulation in the plant.

  11. Determination of some heavy metals by flame atomic absorption spectrometry before coprecipitation with neodymium hydroxide.

    Science.gov (United States)

    Soylak, Mustafa; Kizil, Nebiye

    2011-01-01

    A procedure is described for the determination of trace amounts of Cd(II), Ni(II), Cu(II), Pb(II), Fe(III), Co(II), and Mn(II) that combines flame atomic absorption spectrometry with neodymium hydroxide coprecipitation. The influences of analytical parameters (amount of neodymium, pH of the model solutions, etc.) that affect quantitative recoveries of the analyte ions were investigated. The effects of concomitant ions were also examined. The detection limits for analytes were found in the range of 0.2-3.3 microg/L. The validation of the presented procedure was controlled by analysis of certified reference materials (National Institute of Standards and Technology 1570a spinach leaves and TMDA 54.4 fortified lake water). The applications of the procedure were performed by the analysis of water, food, and herbal plants from Turkey.

  12. Tunable Properties of Exfoliated Polyvinylalcohol Nanocomposites by In Situ Coprecipitation of Layered Double Hydroxides

    Science.gov (United States)

    Liu, Jiajia; Yuen, Richard K. K.; Hu, Yuan

    2017-10-01

    Poly(vinyl alcohol) (PVA) nanocomposites were prepared by a “one step” method based on the coprecipitation of layered double hydroxide (LDH) nanosheets in the polymer aqueous solution. The morphology, fire resistance properties, mechanical and optical properties of the PVA/LDH nanocomposites were studied. The LDH nanosheets were homogeneously dispersed in the PVA matrix as indicated by X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) characterization. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased by 58% and 28%, respectively. Storage modulus at 30 °C was increased, and the transmittance of more than 90% at the visible region was obtained upon addition of 5 wt% LDH.

  13. Determination of some trace elements in food and soil samples by atomic absorption spectrometry after coprecipitation with holmium hydroxide.

    Science.gov (United States)

    Saracoglu, Sibel; Soylak, Mustafa; Cabuk, Dilek; Topalak, Zeynep; Karagozlu, Yasemin

    2012-01-01

    The determination of trace elements in food and soil samples by atomic absorption spectrometry was investigated. A coprecipitation procedure with holmium hydroxide was used for separation-preconcentration of trace elements. Trace amounts of copper(II), manganese(II), cobalt(II), nickel(ll), chromium(lll), iron(Ill), cadmium(ll), and lead(ll) ions were coprecipitated with holmium hydroxide in 2.0 M NaOH medium. The optimum conditions for the coprecipitation process were investigated for several commonly tested experimental parameters, such as amount of coprecipitant, effect of standing time, centrifugation rate and time, and sample volume. The precision, based on replicate analysis, was lower than 10% for the analytes. In order to verify the accuracy of the method, the certified reference materials BCR 141 R calcareous loam soil and CRM 025-050 soil were analyzed. The procedure was successfully applied for separation and preconcentration of the investigated ions in various food and soil samples. An amount of the solid samples was decomposed with 15 mL concentrated hydrochloric acid-concentrated nitric acid (3 + 1). The preconcentration procedure was then applied to the final solutions. The concentration of trace elements in samples was determined by atomic absorption spectrometry.

  14. Coprecipitation experiment with Sm hydroxide using a multitracer produced by nuclear spallation reaction: A tool for chemical studies with superheavy elements.

    Science.gov (United States)

    Kasamatsu, Yoshitaka; Yokokita, Takuya; Toyomura, Keigo; Shigekawa, Yudai; Haba, Hiromitsu; Kanaya, Jumpei; Huang, Minghui; Ezaki, Yutaka; Yoshimura, Takashi; Morita, Kosuke; Shinohara, Atsushi

    2016-12-01

    To establish a new methodology for superheavy element chemistry, the coprecipitation behaviors of 34 elements with samarium hydroxide were investigated using multitracer produced by a spallation of Ta. The chemical reactions were rapidly equilibrated within 10s for many elements. In addition, these elements exhibited individual coprecipitation behaviors, and the behaviors were qualitatively related to their hydroxide precipitation behaviors. It was demonstrated that the ammine and hydroxide complex formations of superheavy elements could be investigated using the established method. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. A new coprecipitation methodology with lutetium hydroxide for preconcentration of heavy metal ions in herbal plant samples.

    Science.gov (United States)

    Soylak, Mustafa; Murat, Ipek

    2014-01-01

    A new coprecipitation methodology that used lutetium hydroxide as a precipitant for Cu(II), Pb(II), Mn(II), Co(II), Cd(II), Fe(III), and Ni(II) ions in herbal plant and water samples for analysis by atomic absorption spectrometry has been investigated. The parameters such as pH, amount of lutetium, and volume of aqueous sample were optimized for the recovery of these seven metals. The effects of concomitant ions on the separation-preconcentration of analytes were also checked. The validation of the procedure was checked with addition recovery tests and analysis of Standard Reference Material 1570a-Trace Elements in Spinach Leaves and TMDA-70 fortified lake water Certified Reference Material. The LODs for analyte ions were in the range of 1.7-7.2 microg/L. The application of the present procedure was successfully performed for the analysis of analyte contents of herbal plant samples from Turkey.

  16. [Mg/Al layered double hydroxides prepared by microwave-assisted co-precipitation method for the removal of bromate].

    Science.gov (United States)

    Zhong, Qiong; Li, Huan

    2014-04-01

    In this paper, Mg/Al layered double hydroxides (Mg/Al LDHs) were prepared by the microwave-assisted co-precipitation method and the conventional co-precipitation method. The samples were labeled as Mg/Al LDHs-MW and Mg/Al LDHs-H, respectively. Mg/Al LDHs were characterized by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The results showed that the application of microwave in the preparation process promoted the formation of smaller pore diameter and higher crystallinity particles. The pore size and particle size of Mg/Al LDHs-MW were 41.13 nm and 427.08 nm, respectively. Batch experiments were investigated to evaluate the effect of dosage, initial pH and regeneration frequencies for bromate removal. The conclusion showed that the process of bromate removal on Mg/Al LDHs could be described by the pseudo-second kinetic model. The Langmuir isotherm well described the experimental data, and the Mg/Al LDHs-MW has a stronger adsorption capacity while the maximum adsorption capacity (q(0)) of Mg/Al LDHs-MW for bromate was 321.26 microg x g(-1) which was larger than the q(0) (288.74 microg x g(-1)) of Mg/Al LDHs-H. For the continuous fixed-bed column, model simulations using the Thomas model showed that the experimental data obtained at three different columns packed with Mg/Al LDHs-MW were able to predict breakthrough curves. Simulating the maximum adsorption capacity of adsorption column for bromate removal was 288.81 microg x g(-1). When the bed depth was 10 cm, inlet concentration was 800 microg x L(-1) and flow rate was 4.0 mL x min, the correlation coefficient of model was 0.92, indicating that the experimental data was described well by the Thomas model.

  17. Application of dissolvable layered double hydroxides as sorbent in dispersive solid-phase extraction and extraction by co-precipitation for the determination of aromatic acid anions.

    Science.gov (United States)

    Tang, Sheng; Lee, Hian Kee

    2013-08-06

    Three types of magnesium-aluminum layered double hydroxides were synthesized and employed as solid-phase extraction (SPE) sorbents to extract several aromatic acids (protocatechuic acid, mandelic acid, phthalic acid, benzoic acid, and salicylic acid) from aqueous samples. An interesting feature of these sorbents is that they dissolve when the pH of the solution is lower than 4. Thus, the analyte elution step, as needed in conventional sorbent-based extraction, was obviated by dissolving the sorbent in acid after extraction and separation from the sample solution. The extract was then directly injected into a high-performance liquid chromatography-ultraviolet detection system for analysis. In the key adsorption process, both dispersive SPE and co-precipitation extraction with the sorbents were conducted and experimental parameters such as pH, temperature, and extraction time were optimized. The results showed that both extraction methods provided low limits of detection (0.03-1.47 μg/L) and good linearity (r(2) > 0.9903). The optimized extraction conditions were applied to human urine and sports drink samples. This new and interesting extraction approach was demonstrated to be a fast and efficient procedure for the extraction of organic anions from aqueous samples.

  18. Simultaneous coprecipitation of lead, cobalt, copper, cadmium, iron and nickel in food samples with zirconium(IV) hydroxide prior to their flame atomic absorption spectrometric determination.

    Science.gov (United States)

    Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2009-09-01

    A simple and new coprecipitation procedure is developed for the determination of trace quantities of heavy metals (lead, cobalt, copper, cadmium, iron and nickel) in natural water and food samples. Analyte ions were coprecipitated by using zirconium(IV) hydroxide. The determination of metal levels was performed by flame atomic absorption spectrometry (FAAS). The influences of analytical parameters including pH, amount of zirconium(IV), sample volume, etc. were investigated on the recoveries of analyte ions. The effects of possible matrix ions were also examined. The recoveries of the analyte ions were in the range of 95-100%. Preconcentration factor was calculated as 25. The detection limits for the analyte ions based on 3 sigma (n=21) were in the range of 0.27-2.50 microgL(-1). Relative standard deviation was found to be lower than 8%. The validation of the presented coprecipitation procedure was performed by the analysis certified reference materials (GBW 07605 Tea and LGC 6010 Hard drinking water). The procedure was successfully applied to natural waters and food samples like coffee, fish, tobacco, black and green tea.

  19. Preparation of nanocrystalline bismuth-substituted yttrium iron garnet films with enhanced Faraday magneto-optical figure of merit by pyrolysis of coprecipitated hydroxide slurry

    Science.gov (United States)

    Xiwen, Zhang; Raorong, Han

    2008-08-01

    Nanocrystalline Bi-substituted yttrium iron garnet films have been prepared by coprecipitation titration, once-through coating of hydroxide slurry, and pyrolysis. The resulting films with grain sizes of 10-20 nm are fabricated at a pH value of 12 and heat treated of 700 °C for 1 h. At the incident light wavelength of 633 nm, the maximum special Faraday rotation of 3.6×10 4°/cm and Faraday magneto-optical figure of merit of 6.7°/dB were obtained. The influence of pH value and heat treatment on film grain size, crystallinity, and magneto-optical properties is demonstrated.

  20. Determination of ultratrace levels of dissolved metals in seawater by reaction cell inductively coupled plasma mass spectrometry after ammonia induced magnesium hydroxide coprecipitation.

    Science.gov (United States)

    Ardini, Francisco; Magi, Emanuele; Grotti, Marco

    2011-11-07

    A method for the determination of ultratrace amounts of Cr, Fe, Mn, Pb and Zn in seawater has been developed. It combined the low-blank magnesium hydroxide coprecipitation procedure with quadrupole inductively coupled plasma mass spectrometry and used the dynamic reaction cell technique to resolve the polyatomic interferences arising from the residual matrix, the solvent and plasma gases. Detection limits (3σ(B), n=10) for Cr, Fe, Mn, Pb and Zn were 0.02, 0.10, 0.01, 0.002 and 0.19 nM, respectively, using 50 mL of seawater sample. The accuracy of the analytical procedure was verified by the analysis of the seawater reference materials CASS-4, NASS-5, SAFe D2 and SAFe S. The analytical precision ranged from 3% to 16% (n=6), with a sample throughput of about 6 samples h(-1). Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide.

    Science.gov (United States)

    Raso, Maria; Censi, Paolo; Saiano, Filippo

    2013-11-15

    Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement with a pre-concentration technique. To perform an ultra-trace analysis in seawater, we have validated an analytical procedure involving an improved modified co-precipitation on iron hydroxides to ensure the simultaneous quantitative recovery of YLOID, Zr and Hf contents with measurement by a quadrupole ICP-MS. The validity of the method was assessed through a series of co-precipitation experiments and estimation of several quality control parameters for method validation, namely working range and its linearity, detection limit, quantification limit, precision and spike recoveries, and the methodological blank choice, are introduced, evaluated and discussed. Analysis of NASS-6, is the first report on the latest seawater reference material for YLOID, hafnium and zirconium. © 2013 Elsevier B.V. All rights reserved.

  2. Coprecipitation of gold(III) complex ions with manganese(II) hydroxide and their stoichiometric reduction to atomic gold (Au(0)): analysis by Mössbauer spectroscopy and XPS.

    Science.gov (United States)

    Yamashita, Mamiko; Ohashi, Hironori; Kobayashi, Yasuhiro; Okaue, Yoshihiro; Kurisaki, Tsutomu; Wakita, Hisanobu; Yokoyama, Takushi

    2008-03-01

    To elucidate the formation process of precursor of gold-supported manganese dioxide (MnO2), the coprecipitation behavior of [AuCl4-n(OH)n](-) (n=0-4) (Au(III)) complex ions with manganese(II) hydroxide (Mn(OH)2 and the change in their chemical state were examined. The Au(III) complex ions were rapidly and effectively coprecipitated with Mn(OH)(2) at pH 9. According to the Mössbauer spectra for gold (Au) coprecipitated with Mn(OH)2, below an Au content of 60 wt% in the coprecipitates, all of the coprecipitated Au existed in the atomic state (Au(0)), while, above an Au content of 65 wt%, part of the gold existed in the Au(III) state, and the proportion increased with increasing coprecipitated Au content. Based on the results of X-ray photoelectron spectroscopy, Mn(II) in Mn(OH)2 converted to Mn(IV) in conjunction with coprecipitation of Au(III) complex ions. These results indicate that the rapid stoichiometric reduction of Au(III) to Au(0) is caused by electron transfer from Mn(II) in Mn(OH)2 to the Au(III) complex ion through an Mn-O-Au bond.

  3. Fe(II)–Al(III) layered double hydroxides prepared by ultrasound-assisted co-precipitation method for the reduction of bromate

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yu [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Yang, Qi, E-mail: yangqi@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Luo, Kun; Wu, Xiuqiong [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Li, Xiaoming, E-mail: xmli@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Liu, Yang [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Urban and Rural Garbage Disposal Technology Research Center, Hunan Province, Changsha 410082 (China); Tang, Wangwang; Zeng, Guangming; Peng, Bo [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China)

    2013-04-15

    Highlights: ► Fe(II)–Al(III) LDHs were synthesized by ultrasound-assisted co-precipitation method. ► The Fe–Al (30 min) exhibited highly reduction reactivity on bromate. ► Pseudo-first-order model described the experimental data well. ► The mechanisms of bromate removal were proposed. -- Abstract: Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)–Al(III) layered double hydroxides (Fe–Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe–Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry–differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56 μmol/L could be completely removed from solution by Fe–Al LDHs within 120 min. When the initial bromate concentration was 7.81 μmol/L, the Fe–Al LDHs with irradiation time of 30 min exhibited the optimum removal efficiency and the bromate removal capacity (q{sub e}) was 6.80 μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe{sup 2+} were the main mechanisms responsible for the bromate removal by Fe–Al LDHs.

  4. Fe(II)-Al(III) layered double hydroxides prepared by ultrasound-assisted co-precipitation method for the reduction of bromate.

    Science.gov (United States)

    Zhong, Yu; Yang, Qi; Luo, Kun; Wu, Xiuqiong; Li, Xiaoming; Liu, Yang; Tang, Wangwang; Zeng, Guangming; Peng, Bo

    2013-04-15

    Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)-Al(III) layered double hydroxides (Fe-Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe-Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry-differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56 μmol/L could be completely removed from solution by Fe-Al LDHs within 120 min. When the initial bromate concentration was 7.81 μmol/L, the Fe-Al LDHs with irradiation time of 30 min exhibited the optimum removal efficiency and the bromate removal capacity (qe) was 6.80 μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe(2+) were the main mechanisms responsible for the bromate removal by Fe-Al LDHs. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters.

    Science.gov (United States)

    Karatepe, Aslihan; Korkmaz, Esra; Soylak, Mustafa; Elci, Latif

    2010-01-15

    A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k=3, N=15) were 0.65 microg/L for chromium(III) and 0.78 microg/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials.

  6. Characterization of a dextran–coated layered double hydroxide acetylsalicylic acid delivery system and its pharmacokinetics in rabbit

    OpenAIRE

    Dong, Li-e; Gou, Guojing; Jiao, Lin

    2013-01-01

    The aim of this study was to prepare a dextran–coated layered double hydroxide acetylsalicylic acid (DEX–LDH–ASA) delivery system by co-precipitation of LDH–ASA and its in-situ compositing with DEX. The structure of the system was investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG). Its in vitro drug release properties and in vivo pharmacokinetics in rabbit were also determined. The results show that the DEX–LDH–ASA system reta...

  7. Determination of Ultra-trace Amounts of Arsenic(III) by Flow Injection Hydride Generation Atomic Absorption Spectrometry with On-line Preconcentration by Coprecipitation with Lanthanum Hydroxide or Hafnium Hydroxide

    DEFF Research Database (Denmark)

    Nielsen, Steffen; Sloth, Jens Jørgen; Hansen, Elo Harald

    1996-01-01

    . Subsequently the precipitate is eluted with 1 mol/l hydrochloric acid, allowing ensuing determination of the analyte via hydride generation. The preconcentration of As(III) was tested by coprecipitation with two different inorganic coprecipitating agents namely La(III) and Hf(IV). It was shown that As...

  8. Effect of preparation conditions on physicochemical, surface and catalytic properties of cobalt ferrite prepared by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    El-Shobaky, G.A., E-mail: elshobaky@yahoo.co [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); Turky, A.M.; Mostafa, N.Y.; Mohamed, S.K. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt)

    2010-03-18

    Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt-iron mixed hydroxides at 400-600 {sup o}C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH and temperature of coprecipitation and calcination temperature on the physicochemical, surface and catalytic properties of the prepared ferrites were studied. The prepared systems were characterized using TG, DTG, DTA, chemical analysis, atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) as well as surface and texture properties based on nitrogen adsorption-desorption isotherms. The prepared cobalt ferrites were found to be mesoporous materials that have crystallite size ranges between 8 and 45 nm. The surface and catalytic properties of the produced ferrite phase were strongly dependent on coprecipitation conditions of the mixed hydroxides and on their calcination temperature.

  9. Immobilization of Hg(II) by coprecipitation in sulfate-cement systems.

    Science.gov (United States)

    Serrano, Susana; Vlassopoulos, Dimitri; Bessinger, Brad; O'Day, Peggy A

    2012-06-19

    Uptake and molecular speciation of dissolved Hg during formation of Al- or Fe-ettringite-type and high-pH phases were investigated in coprecipitation and sorption experiments of sulfate-cement treatments used for soil and sediment remediation. Ettringite and minor gypsum were identified by XRD as primary phases in Al systems, whereas gypsum and ferrihydrite were the main products in Hg-Fe precipitates. Characterization of Hg-Al solids by bulk Hg EXAFS, electron microprobe, and microfocused-XRF mapping indicated coordination of Hg by Cl ligands, multiple Hg and Cl backscattering atoms, and concentration of Hg as small particles. Thermodynamic predictions agreed with experimental observations for bulk phases, but Hg speciation indicated lack of equilibration with the final solution. Results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt in ettringite as the primary immobilization mechanism. In Hg-Fe solids, structural characterization indicated Hg coordination by O atoms only and Fe backscattering atoms that is consistent with inner-sphere complexation of Hg(OH)(2)(0) coprecipitated with ferrihydrite. Precipitation of ferrihydrite removed Hg from solution, but the resulting solid was sufficiently hydrated to allow equilibration of sorbed Hg species with the aqueous solution. Electron microprobe XRF characterization of sorption samples with low Hg concentration reacted with cement and FeSO(4) amendment indicated correlation of Hg and Fe, supporting the interpretation of Hg removal by precipitation of an Fe(III) oxide phase.

  10. Characteristics of drug-phospholipid coprecipitates I: Physical properties and dissolution behavior of griseofulvin-dimyristoylphosphatidylcholine systems.

    Science.gov (United States)

    Venkataram, S; Rogers, J A

    1984-06-01

    Solid dispersions of griseofulvin and dimyristoylphosphatidylcholine (lecithin) have been prepared as both coprecipitates and physical mixtures, and their physical characteristics and dissolution behavior compared with pure griseofulvin. The dissolution of the physical mixtures was similar to pure drug, but the coprecipitates yielded a 3.5-fold greater initial dissolution rate and a limiting concentration after 60 min which was 72% greater at a griseofulvin-lecithin weight ratio of 19:1. Increasing the lecithin content to 1.5:1 compositions resulted in only a further 50% increase in the initial dissolution rate and a further 12% increase in the limiting concentration. The effect of the pH of the medium on dissolution was slight, but varied with the composition of the system. The phase diagram indicated that these systems have no significant eutectic or solid solution formation. X-ray diffraction spectra further showed that freshly prepared or aged coprecipitates contained griseofulvin crystals, and photomicrographs showed that the crystals essentially retained their characteristic shapes and sizes in all systems. Differential thermal analysis yielded heats of fusion that gave a good linear correlation with the percent of griseofulvin dissolved from coprecipitates at all time intervals, but not with physical mixtures. Furthermore, aged coprecipitates underwent a slower rate of dissolution compared with fresh samples. The results are interpreted to suggest that griseofulvin undergoes improved dissolution from coprecipitates due to the formation of crystals of lower stability. In addition, the rapid dispersion of lecithin in the aqueous medium (as seen microscopically) entraps griseofulvin in myelinic structures and liposomes and effectively increases the saturation concentration of drug in the diffusion layer during the dissolution process.

  11. Comparative evaluation of ketoconazole-β-cyclodextrin systems prepared by coprecipitation and kneading.

    Science.gov (United States)

    Marzouk, M A; Kassem, A A; Samy, A M; Amer, R I

    2010-10-01

    Ketoconazole (KZ), an imidazole antifungal, was formulated into inclusion complexes via coprecipitation and kneading with β-cyclodextrin (β-CD) as a carrier in 1:1 and 1:2 drug to carrier ratios. The KZ-β-CD solid complexes were characterized by X-ray diffraction and differential scanning calorimetry (DSC). The diffraction pattern of the pure drug revealed the drug to be highly crystalline in nature, as indicated by numerous distinctive peaks. The lack of numerous distinctive peaks of the drug in KZ-β-CD complexes prepared by the two methods revealed that a large number of the drug molecules were dissolved in a solid-state carrier matrix with an amorphous structure. The thermograms of the KZ-β-CD complexes showed a strong reduction in the intensity and broadening of drug peaks somewhat in both kneading and coprecipitation systems, suggesting that the drug is monomolecularly dispersed in the β-CD cavity. The prepared tablets of KZ-β-CD solid complexes prepared by the two methods were evaluated for their quality control testing, and an in vitro release study and the results of quality control complied with pharmacopeial requirements and the release profiles indicated complete drug release after 30 min. The kinetic parameters obtained from release data were analyzed in order to explain the mechanism of drug release and revealed non-Fickian transport. Accelerated stability testing at 35°C, 45°C, and 55°C and at 75% relative humidity was carried out for six months and revealed somewhat stable systems as indicated by a t(90) of about 2 years for both KZ-β-CD systems. A microbiological in vitro assay of KZ from the prepared tablets was performed using Candida albicans as a model fungus, and KZ had improved microbiological activity when administered as an inclusion complex with β-CD. The results confirmed the benefit of using CDs as a useful tool to enhance the dissolution and hence bioavailability of poorly water-soluble drugs by forming solubilizing systems

  12. Potential for Layered Double Hydroxides-Based, Innovative Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Kai Zhang

    2014-04-01

    Full Text Available Layered Double Hydroxides (LDHs-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications.

  13. High Tap Density Spherical Li[Ni0.5Mn0.3Co0.2]O2 Cathode Material Synthesized via Continuous Hydroxide Coprecipitation Method for Advanced Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Shunyi Yang

    2012-01-01

    Full Text Available Spherical [Ni0.5Mn0.3Co0.2](OH2 precursor with narrow size distribution and high tap density has been successfully synthesized by a continuous hydroxide coprecipitation, and Li[Ni0.5Mn0.3Co0.2]O2 is then prepared by mixing the precursor with 6% excess Li2CO3 followed by calcinations. The tap density of the obtained Li[Ni0.5Mn0.3Co0.2]O2 powder is as high as 2.61 g cm−3. The powders are characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning electron microscope (SEM, particle size distribution (PSD, and charge/discharge cycling. The XRD studies show that the prepared Li[Ni0.5Mn0.3Co0.2]O2 has a well-ordered layered structure without any impurity phases. Good packing properties of spherical secondary particles (about 12 μm consisted of a large number of tiny-thin plate-shape primary particles (less than 1 μm, which can be identified from the SEM observations. In the voltage range of 3.0–4.3 V and 2.5–4.6 V, Li[Ni0.5Mn0.3Co0.2]O2 delivers the initial discharge capacity of approximately 175 and 214 mAh g−1 at a current density of 32 mA g−1, and the capacity retention after 50 cycles reaches 98.8% and 90.2%, respectively. Besides, it displays good high-temperature characteristics and excellent rate capability.

  14. Endodontic Release System for Apexification with Calcium Hydroxide Microspheres

    Science.gov (United States)

    Strom, T.A.; Arora, A.; Osborn, B.; Karim, N.; Komabayashi, T.; Liu, X.

    2012-01-01

    The use of calcium hydroxide (CH) as an intracanal medicament for apexification is widespread. However, because of a short residence time in the root canal, the CH must be refreshed frequently, increasing the number of appointments required and leading to patient non-compliance. We hypothesized that a core-/shell-structured CH microsphere system would lead to sustained slow release of calcium and hydroxide ions of CH for long periods of time, eliminating the need for multiple visits for apexification. In this study, calcium hydroxide microspheres (CHMSs) with a core/shell structure were prepared by an emulsion method. The CHMS shell was composed of alginate, which was crosslinked by the Ca2+ released from the CH in the CHMSs. Therefore, this system provides a unique feedback loop that controls the release of ions from the CHMSs. The in vitro experiments from the root canals of extracted human teeth showed that the CHMSs had a sustained, slow release of Ca2+, at a constant rate of approximately 2 to 3% per month from day one to the six-month endpoint of the experiment. After 6 months, 72.1 ± 5.8% of the total CH from the CHMSs remained in the root canals of the teeth, while only 46.9 ± 10.9% and 36.8 ± 7.5% remained from a commercial product (UltraCal®XS) and CH powder alone, respectively (p formulations (CHMS, UltraCal® XS, and CH powder) in the extracted teeth never rose above 9 during the release period, indicating a buffering effect of the teeth. The core-/shell-structured CHMSs are, therefore, a promising delivery vehicle for the sustained slow release of Ca2+ and OH- in the root canal. PMID:22914537

  15. Bacterially induced calcium carbonate precipitation and strontium coprecipitation in a porous media flow system.

    Science.gov (United States)

    Lauchnor, Ellen G; Schultz, Logan N; Bugni, Steven; Mitchell, Andrew C; Cunningham, Alfred B; Gerlach, Robin

    2013-02-05

    Strontium-90 is a principal radionuclide contaminant in the subsurface at several Department of Energy sites in the Western U.S., causing a threat to groundwater quality in areas such as Hanford, WA. In this work, we used laboratory-scale porous media flow cells to examine a potential remediation strategy employing coprecipitation of strontium in carbonate minerals. CaCO(3) precipitation and strontium coprecipitation were induced via ureolysis by Sporosarcina pasteurii in two-dimensional porous media reactors. An injection strategy using pulsed injection of calcium mineralization medium was tested against a continuous injection strategy. The pulsed injection strategy involved periods of lowered calcite saturation index combined with short high fluid velocity flow periods of calcium mineralization medium followed by stagnation (no-flow) periods to promote homogeneous CaCO(3) precipitation. By alternating the addition of mineralization and growth media the pulsed strategy promoted CaCO(3) precipitation while sustaining the ureolytic culture over time. Both injection strategies achieved ureolysis with subsequent CaCO(3) precipitation and strontium coprecipitation. The pulsed injection strategy precipitated 71-85% of calcium and 59% of strontium, while the continuous injection was less efficient and precipitated 61% of calcium and 56% of strontium. Over the 60 day operation of the pulsed reactors, ureolysis was continually observed, suggesting that the balance between growth and precipitation phases allowed for continued cell viability. Our results support the pulsed injection strategy as a viable option for ureolysis-induced strontium coprecipitation because it may reduce the likelihood of injection well accumulation caused by localized mineral plugging while Sr coprecipitation efficiency is maintained in field-scale applications.

  16. Electrospun fibers of layered double hydroxide/biopolymer nanocomposites as effective drug delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yue-E.; Zhu Hong; Chen Dan; Wang Ruiyu [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China)

    2012-06-15

    Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on a combination of LDH-IBU with two kinds of biopolymers (i.e. PCL and PLA), to act as effective drug delivery systems. Ibuprofen (IBU) is chosen as a model drug, which is intercalated in MgAl-LDH by coprecipitation. Poly(oxyethylene-b-oxypropylene-b-oxyethylene) (Pluronic) is also added into PLA-based fibers as hydrophilicity enhancer and release modulator. LDH-IBU nanoparticles are uniformly dispersed throughout the nanocomposite fibers, as evidenced by transmission electron microscopy (TEM) observations. In vitro drug release studies show that initial IBU liberation from LDH-IBU/PCL composite fibers is remarkably slower than that from IBU/PCL fibers due to the sustained release property of LDH-IBU and heterogeneous nucleation effect of LDH-IBU on PCL chain segments. Surprisingly, the initial IBU release from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers is faster than that from the corresponding IBU/PLA and IBU/PLA/Pluronic fibers. This effect can be attributed to the strong interaction between alkyl groups in IBU molecules and methyl substituent groups of PLA as well as the hydrophilicity of LDH-IBU, which lead to an easier diffusion of water with a faster release of IBU from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers. - Graphical abstract: Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on the combination of LDHs with two kinds of biopolymers (i.e. PCL and PLA). LDH-IBU nanoparticles are uniformly dispersed throughout all the electrospun nanocomposite fibers even at a high loading level of 5 wt%. By combining the tunable drug release property of LDHs and electrospinning technique, the new drug delivery system is anticipated for effective loading and sustained release of drugs

  17. Pore Structure Evolution of Lanthana–Alumina Systems Prepared through Coprecipitation

    NARCIS (Netherlands)

    Nair, Jalajakumari; Nair, P.; Mizukami, Fujio; van Ommen, J.G.; Doesburg, Giel B.M.; Ross, Julian R.H.; Burggraaf, Anthonie J.

    Pure Al2O3 and different compositions of La2O3–Al2O3 samples have been prepared through coprecipitation. Even after heating at 1300°C, the compositions La2O3·11Al2O3 and La2O3·13Al2O3 had higher surface area compared to the pure Al2O3 and the La2O3·Al2O3 composition. Ethanol washing is an effective

  18. Characterization of a dextran–coated layered double hydroxide acetylsalicylic acid delivery system and its pharmacokinetics in rabbit

    Directory of Open Access Journals (Sweden)

    Li-e Dong

    2013-12-01

    Full Text Available The aim of this study was to prepare a dextran–coated layered double hydroxide acetylsalicylic acid (DEX–LDH–ASA delivery system by co-precipitation of LDH–ASA and its in-situ compositing with DEX. The structure of the system was investigated using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR and thermogravimetry (TG. Its in vitro drug release properties and in vivo pharmacokinetics in rabbit were also determined. The results show that the DEX–LDH–ASA system retained the crystal structure of LDH–ASA and gave a marked improvement in its dispersion. It also prolonged the release of ASA and shifted the release pattern from first-order to zero-order kinetics. The pharmacokinetics of ASA administered in the DEX–LDH–ASA system to rabbits produced two absorption peaks with a Cmax of 14.8±1.7 mg/L at 2.11±0.69 h and an elimination half-life of 2.25±0.84 h for the first peak. The fact that delivery of ASA in the DEX–LDH–ASA system was sustained with improved bioavailability indicates the potential of the system as a controlled release formulation with application to other drugs.

  19. Potential for layered double hydroxides-based, innovative drug delivery systems

    National Research Council Canada - National Science Library

    Zhang, Kai; Xu, Zhi Ping; Lu, Ji; Tang, Zhi Yong; Zhao, Hui Jun; Good, David A; Wei, Ming Qian

    2014-01-01

    Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo...

  20. Synthesis and In Vitro Characterization of Fe3+-Doped Layered Double Hydroxide Nanorings as a Potential Imageable Drug Delivery System

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2017-09-01

    Full Text Available Highly dispersed Fe3+-doped layered double hydroxide (LDH-Fe nanorings were obtained by a simple coprecipitation-acid etching approach. The morphology, structure, magnetic resonance imaging (MRI performance in vitro, drug loading and releasing, Fe3+ leakage, and cytotoxicity of the as-prepared LDH-Fe nanorings were characterized. The LDH-Fe nanorings showed good water dispersity and a well-crystallized structure. The DLS average size of nanoparticles was measured to be 94.5 nm. Moreover, the MRI tests showed a favourable T1-weighted MRI performance of the LDH-Fe nanoring with r1 values of 0.54 and 1.68, and low r2/r1 ratios of 10.1 and 6.3, pre- and after calcination, respectively. The nanoparticles also showed high model drug (ibuprofen loading capacities, low Fe3+ leakage, and negligible cytotoxicity. All these results demonstrate the potential of LDH-Fe nanorings as an imageable drug delivery system.

  1. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    Energy Technology Data Exchange (ETDEWEB)

    Arratia-Quijada, Jenny [Departamento de Ciencias de la Salud, Centro Universitario Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico No. 555, C.P. 48525, Tonalá, Jalisco (Mexico); Sánchez Jiménez, Cecilia [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, St. Petersburg State University, Universitetskiy pr. 26, 198504 St. Petersburg (Russian Federation); NMR Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Pérez Centeno, Armando; Ceja Andrade, Israel [Departamento de Física, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2016-01-15

    Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  2. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    KAUST Repository

    Arratia-Quijada, Jenny

    2015-10-23

    A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  3. Solid state and magnetochemistry of the SrO-Fe2O3 system IV. Synthesis of SrFe12O19 from coprecipitated precursors

    Science.gov (United States)

    Qian, Xueyu; Evans, B. J.

    1981-03-01

    By means of 57Fe Mössbauer spectroscopy and powder x-ray diffraction techniques, it has been determined that the formation of SrFe12O19 from coprecipitated ferric hydroxide and strontium laurate follows a reaction mechanism different from that when SrCO3 and Fe2O3 are used as starting materials. Upon heating at 300 C in vacuum, strontium laurate decomposes and further heating to 550 C leads to the formation of γ-Fe2O3 from the ferric hydroxide and solid solution of SrO in γ-Fe2O3. This solid solution phase behaves as an intermediate and undergoes further reaction with γ-Fe2O3 to give SrFe12O19. No paramagnetic Sr-Fe oxide intermediate is formed. The low temperature of the reactions and the absence of paramagnetic intermediates offer new possibilities for controlling the textures and magnetic properties SrFe12O19 ceramic bodies.

  4. Aluminum Hydroxide and Magnesium Hydroxide

    Science.gov (United States)

    Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They ... They combine with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription. ...

  5. Synthesis of protocatechuic acid–zinc/aluminium–layered double hydroxide nanocomposite as an anticancer nanodelivery system

    Energy Technology Data Exchange (ETDEWEB)

    Barahuie, Farahnaz [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Hussein, Mohd Zobir, E-mail: mzobir@upm.edu.my [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Gani, Shafinaz Abd [Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Fakurazi, Sharida [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Zainal, Zulkarnain [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia)

    2015-01-15

    Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al–layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al–NO{sub 3}–LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment. - Graphical abstract: Protocatechuate anions were arranged in monolayer mode with the angle of 24° for PZAE and 33° for PZAC from Z axis to maximize interaction between carboxylate groups and brucite-like layers. - Highlights: • Two methods gave nanocomposites with slightly different physico-chemical properties. • PZAE and PZAC have the potential to be used as a controlled release formulation. • The thermal stability of PA is markedly enhanced upon the intercalation process. • Higher cancer cell growth inhibition for PZAE and PZAC nanocomposites than for PA.

  6. Synthetic Coprecipitates of Exopolysaccharides and Ferrihydrite. Part I: Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Mikutta,C.; Mikutta, R.; Bonneville, S.; Wagner, F.; Voegelin, A.; Christl, I.; Kretzschmar, R.

    2008-01-01

    Iron(III) (hydr)oxides formed at extracellular biosurfaces or in the presence of exopolymeric substances of microbes and plants may significantly differ in their structural and physical properties from their inorganic counterparts. We synthesized ferrihydrite (Fh) in solutions containing acid polysaccharides [polygalacturonic acid (PGA), alginate, xanthan] and compared its properties with that of an abiotic reference by means of X-ray diffraction, transmission electron microscopy, gas adsorption (N2, CO2), X-ray absorption spectroscopy, 57Fe Moessbauer spectroscopy, and electrophoretic mobility measurements. The coprecipitates formed contained up to 37 wt% polymer. Two-line Fh was the dominant mineral phase in all precipitates. The efficacy of polymers to precipitate Fh at neutral pH was higher for polymers with more carboxyl C (PGA {approx} alginate > xanthan). Pure Fh had a specific surface area of 300 m2/g; coprecipitation of Fh with polymers reduced the detectable mineral surface area by up to 87%. Likewise, mineral micro- (<2 nm) and mesoporosity (2-10 nm) decreased by up to 85% with respect to pure Fh, indicative of a strong aggregation of Fh particles by polymers in freeze-dried state. C-1s STXM images showed the embedding of Fh particles in polymer matrices on the micrometer scale. Iron EXAFS spectroscopy revealed no significant changes in the local coordination of Fe(III) between pure Fh and Fh contained in PGA coprecipitates. 57Fe Moessbauer spectra of coprecipitates confirmed Fh as dominant mineral phase with a slightly reduced particle size and crystallinity of coprecipitate-Fh compared to pure Fh and/or a limited magnetic super-exchange between Fh particles in the coprecipitates due to magnetic dilution by the polysaccharides. The pHiep of pure Fh in 0.01 M NaClO4 was 7.1. In contrast, coprecipitates of PGA and alginate had a pHiep < 2. Considering the differences in specific surface area, porosity, and net charge between the coprecipitates and pure Fh

  7. Aluminum Hydroxide

    Science.gov (United States)

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  8. Magnesium Hydroxide

    Science.gov (United States)

    Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed for ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as needed ...

  9. Analytical Study of Oxalates Coprecipitation

    Directory of Open Access Journals (Sweden)

    Liana MARTA

    2003-03-01

    Full Text Available The paper deals with the establishing of the oxalates coprecipitation conditions in view of the synthesis of superconducting systems. A systematic analytical study of the oxalates precipitation conditions has been performed, for obtaining superconducting materials, in the Bi Sr-Ca-Cu-O system. For this purpose, the formulae of the precipitates solubility as a function of pH and oxalate excess were established. The possible formation of hydroxo-complexes and soluble oxalato-complexes was taken into account. A BASIC program was used for tracing the precipitation curves. The curves of the solubility versus pH for different oxalate excess have plotted for the four oxalates, using a logaritmic scale. The optimal conditions for the quantitative oxalate coprecipitation have been deduced from the diagrams. The theoretical curves were confirmed by experimental results. From the precursors obtained by this method, the BSCCO superconducting phases were obtained by an appropriate thermal treatment. The formation of the superconducting phases was identified by X-ray diffraction analysis.

  10. Determination of total chromium at ultratrace levels in water and soil samples by coprecipitation microsample injection system flame atomic absorption spectrometry.

    Science.gov (United States)

    Baig, Jameel Ahmed; Elci, Latif; Khan, Muhammad Irfan; Kazi, Tasneem Gul

    2014-01-01

    A simple, robust, and novel analytical procedure was developed for determination of total chromium (Cr) by carrier element coprecipitation (CECP) coupled microsample injection system with flame atomic absorption spectrometry. For this method, Cr(III) was oxidized by Ce(SO4)2 in acidic media, and the resulting solution formed coprecipitates with ammonium pyrrolidine dithiocarbamate in the presence of Ce(III). The effective parameters of the developed method have been optimized and studied in detail. The LOD and enrichment factor of CECP were 2.13 μg/L and 100 ± 2.8, respectively, with 40 mL initial volumes. The RSD values (n = 6) were 96%). The accuracy of total Cr by CECP after microwave acid digestion was checked by using a certified reference material (GBW 07309 Stream Sediment). The difference between the found and certified values was not significant (P > 0.05). The proposed method was successfully applied to natural drinking water, industrial effluent wastewater, and the exchangeable fraction of garden soil from Denizli, Turkey.

  11. Influence of adsorption versus coprecipitation on the retention of rice straw-derived dissolved organic carbon and subsequent reducibility of Fe-DOC systems

    Science.gov (United States)

    Sodano, Marcella; Lerda, Cristina; Martin, Maria; Celi, Luisella; Said-Pullicino, Daniel

    2016-04-01

    The dissimilatory reduction of Fe oxides is the main organic C-consuming process in paddy soils under anoxic conditions. The contribution of Fe(III) reduction to anaerobic C mineralization depends on many factors, but most importantly on the bioavailability of labile organic matter and a reducible Fe pool as electron donors and acceptors, respectively. On the other hand, the strong affinity of these minerals for organic matter and their capability of protecting it against microbial decomposition is well known. Natural Fe oxides in these soils may therefore play a key role in determining the C source/sink functions of these agro-ecosystems. Apart from contributing to C stabilization, the interaction between Fe oxides and dissolved organic C (DOC) may influence the structure and reactivity of these natural oxides, and selectively influence the chemical properties of DOC. Indeed, Fe-DOC associations may not only reduce the availability of DOC, but may also limit the microbial reduction of Fe oxides under anoxic conditions. In fact, the accessibility of these minerals to microorganisms, extracellular enzymes, redox active shuttling compound or reducing agents may be impeded by the presence of sorbed organic matter. In soils that are regularly subjected to fluctuations in redox conditions the interaction between DOC and Fe oxides may not only involve organic coatings on mineral surfaces, but also Fe-DOC coprecipitates that form during the rapid oxidation of soil solutions containing important amounts of DOC and Fe(II). However, little is known on how these processes influence DOC retention, and the structure and subsequent reducibility of these Fe-DOC associations. We hypothesized that the nature and extent of the interaction between DOC and Fe oxides may influence the accessibility of the bioavailable Fe pool and consequently its reducibility. We tested this hypothesis by synthesizing a series of Fe-DOC systems with increasing C:Fe ratios prepared by either surface

  12. Application of chitosan as flocculant for coprecipitation of Mn(II) and suspended solids from dual-alkali FGD regenerating process.

    Science.gov (United States)

    Wu, Zhong-Biao; Ni, Wei-Min; Guan, Bao-Hong

    2008-04-01

    Heavy metals and suspended solid (SS) needed to be removed from the recirculation of dual-alkali flue gas desulfurization (FGD) system. The feasibility of coprecipitation of heavy metal and SS by water-soluble chitosan was studied in a lab scale experiment. The association between chitosan and metal ions was verified through DSC and FT-IR. The pH investigation revealed that at the pH ranged from 5 to 9, there were three stages for different actions: adsorption of chitosan for Mn(II), precipitation of manganese hydroxide and coprecipitation of manganese hydroxide and chitosan-Mn(II) complex. The ion selectivity experiments showed that the occurrence of Ca(II) in the solution had little influence on the adsorption of chitosan for Mn(II). The decrease rate of adsorption capacity was about 0.0023 mmol g(-1) per 1 mg L(-1) Ca(II). When adsorption and flocculation of chitosan occurred at the same time and at the sufficient addition of chitosan, chitosan not only made solids flocculate but also enhanced sorption capacity of chitosan. Application of chitosan for coprecipitation of Mn(II) and SS could remove Mn(II) efficiently and improve the settling characteristics of SS from dual-alkali FGD regenerating process.

  13. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    Science.gov (United States)

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  14. Synthetic coprecipitates of exopolysaccharides and ferrihydrite. Part I: Characterization

    Science.gov (United States)

    Mikutta, Christian; Mikutta, Robert; Bonneville, Steeve; Wagner, Friedrich; Voegelin, Andreas; Christl, Iso; Kretzschmar, Ruben

    2008-02-01

    Iron(III) (hydr)oxides formed at extracellular biosurfaces or in the presence of exopolymeric substances of microbes and plants may significantly differ in their structural and physical properties from their inorganic counterparts. We synthesized ferrihydrite (Fh) in solutions containing acid polysaccharides [polygalacturonic acid (PGA), alginate, xanthan] and compared its properties with that of an abiotic reference by means of X-ray diffraction, transmission electron microscopy, gas adsorption (N 2, CO 2), X-ray absorption spectroscopy, 57Fe Mössbauer spectroscopy, and electrophoretic mobility measurements. The coprecipitates formed contained up to 37 wt% polymer. Two-line Fh was the dominant mineral phase in all precipitates. The efficacy of polymers to precipitate Fh at neutral pH was higher for polymers with more carboxyl C (PGA ˜ alginate > xanthan). Pure Fh had a specific surface area of 300 m 2/g; coprecipitation of Fh with polymers reduced the detectable mineral surface area by up to 87%. Likewise, mineral micro- (exopolysaccharides and Fe(III) (hydr)oxides are expected to differ in their geochemical reactivity from pure Fe(III) (hydr)oxides, even if the minerals have a similar crystallinity.

  15. Study of superparamagnetic nano particles of Mn x Co1‑x Fe2O4 ferrite system prepared by co-precipitation technique

    Science.gov (United States)

    Tanna, Ashish R.; Sosa, Khengar M.; Joshi, Hiren H.

    2017-11-01

    The ferrites with magnetic nano-particles of Mn x Co1‑x Fe2O4 (with x  =  0.0 to 1.0, step 0.2) system are prepared by the chemical co-precipitation method. Structural and magnetic properties of Mn2+ doped cobalt nano ferrites have been studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), saturation magnetization and low field AC susceptibility. The crystallite size is determined from the FWMH of the higher angle Bragg line (4 0 0) using the Scherer’s formula. The saturation magnetization at 300 K in the peak field of 5 kOe is measured using B  →  H loop technique. The observed saturation magnetic moment is found very low compared to the Neel’s magnetic moment. The lower value of observed magnetic moment is explained on the basis of high magneto-crystalline anisotropy and exchange disorder. The Curie temperatures are determined through thermal variation of low field (0.5 Oe) AC susceptibility. All the plots of thermal variation AC susceptibility exhibit large hump due to single domain to superparamagnetic transition which is the characteristic of high anisotropic ion present in the system. The ZFC-FC curves exhibit thermo-magnetic irreversibility. The magnetic behavior observed through Mossbauer spectra also supports the concept of fine particle superparamagnetism.

  16. Arsenic speciation in natural water samples by coprecipitation-hydride generation atomic absorption spectrometry combination.

    Science.gov (United States)

    Tuzen, Mustafa; Citak, Demirhan; Mendil, Durali; Soylak, Mustafa

    2009-04-15

    A speciation procedure for As(III) and As(V) ions in environmental samples has been presented. As(V) was quantitatively recovered on aluminum hydroxide precipitate. After oxidation of As(III) by using dilute KMnO(4), the developed coprecipitation was applied to determination of total arsenic. Arsenic(III) was calculated as the difference between the total arsenic content and As(V) content. The determination of arsenic levels was performed by hydride generation atomic absorption spectrometry (HG-AAS). The analytical conditions for the quantitative recoveries of As(V) including pH, amount of aluminum as carrier element and sample volume, etc. on the presented coprecipitation system were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was calculated as 25. The detection limits (LOD) based on three times sigma of the blank (N: 21) for As(V) was 0.012 microg L(-1). The satisfactory results for the analysis of arsenic in NIST SRM 2711 Montana soil and LGC 6010 Hard drinking water certified reference materials for the validation of the method was obtained. The presented procedure was successfully applied to real samples including natural waters for arsenic speciation.

  17. Evaluation of calcium hydroxide removal using EndoActivator system: An in vitro study

    Directory of Open Access Journals (Sweden)

    Saad Al-Garni

    2014-01-01

    Full Text Available Aim: The aim of this study was to compare the calcium hydroxide (Ca(OH 2 removal efficacy of the EndoActivator system with that of conventional irrigation with a syringe and hand file manipulation. Materials and Methods: A total of 44 extracted human single-rooted mandibular premolars were used. The root canal systems of all teeth were cleaned and shaped, then filled with Ca(OH 2 paste. The teeth were divided into two groups: Ca(OH 2 was removed using ethylenediaminetetraacetic acid (EDTA and sodium hypochlorite (NaOCl with hand filing and irrigation (Group 1 or the EndoActivator system (Group 2. Each tooth was split into two halves and examined under a scanning electron microscope. Results: Ca(OH 2 particles were completely removed at the coronal level in both experimental groups. More Ca(OH 2 particles were present in the apical third than in the middle-third in both groups. No significant interaction was observed between the two experimental groups or among the three examined levels (P > 0.05. Conclusion: Agitation with NaOCl and EDTA improved Ca(OH 2 removal only in the coronal third of the root canal. Use of the EndoActivator system did not improve the efficacy of Ca(OH 2 removal in the middle and apical thirds.

  18. Synthesis of Mfe12o19 (M=ba,sr) Hexaferrite Nano-particle Using Co-precipitation Method

    OpenAIRE

    Winatapura, Didin S; Sukirman, E; Ridwan

    2011-01-01

    Synthesis of MFe12O19 (M=Ba,Sr) hexaferrite nano-particle using co-precipitation method has been done. Base materials used has a high purity according to Merck catalog of Ba(NO3)2.6H2O, Sr(NO3).6H2O, dan Fe(NO3)3.9H2O powders. In co-precipitation method Ba(II), Sr(II) and Fe(II) hydroxide precursors were precipitated during the reaction between the aqueous solution of metal nitrates and 1-M aqueous solution of natrium hydroxide, which served as a precipitating reagent. The precipitation was p...

  19. Convenient purification of gold clusters by co-precipitation for improved sensing of hydrogen peroxide, mercury ions and pesticides.

    Science.gov (United States)

    Guan, Guijian; Zhang, Shuang-Yuan; Cai, Yongqing; Liu, Shuhua; Bharathi, M S; Low, Michelle; Yu, Yong; Xie, Jianping; Zheng, Yuangang; Zhang, Yong-Wei; Han, Ming-Yong

    2014-06-01

    An effective separation process is developed to remove free protein from the protein-protected gold clusters via co-precipitation with zinc hydroxide on their surface. After dialysis, the purified clusters exhibit an enhanced fluorescence for improved sensitive detection and selective visualization.

  20. Cold laboratory test on nuclide removal from Low-Level Radioactive Liquid Waste by lanthanum phosphate reduction coprecipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, T. [Nuclear Technology and Engineering Corp., Tokai, Ibaraki (Japan); Fukumoto, Masahiro; Murata, E.; Kobayashi, T.; Ikeda, Satoshi

    1999-02-01

    Low Level Radioactive Waste Treatment Facility (LWTF) for the removal of radionuclides contained in Low Level Radioactive Liquid Waste (LLLW) from reprocessing plant in JNC Tokai Works is now under construction. The primary process has now been designed to be complex processes: removal of iodine, of carbonic acid in solution, of lanthanides coprecipitated with ferric hydroxide and of remaining radionuclides such as strontium can cesium. However, the study on the behavior of ruthenium in the coprecipitation process revealed that it is insufficient for removal of ruthenium. As an alternative process, coprecipitation with lanthanum phosphate method substituting for ferric hydroxide was studied. As the result of test, it was confirmed that the method is practical to remove ruthenium with other lanthanides from LLLW except strontium. In this report, the preliminary cold test was described briefly. (H. Itami)

  1. Shape and size control of nano dispersed Mg/Al layered double hydroxide.

    Science.gov (United States)

    Panda, H S; Srivastava, R; Bahadur, D

    2008-08-01

    Controlling the shape and size of the layered inorganic-organic hybrid particles is a challenge with conventional methods of synthesis. The co-precipitation method has been modified to synthesize Mg/Al Layered double hydroxide by controlling the particle growth using ultrasonic wave at the time of nucleation. In this project, magnesium and aluminum ions were considered as model systems with carbonate anion as intercalating agent. The resulting particles are compared with those of LDHs produced by conventional co-precipitation method at constant pH. Powder X-ray diffraction confirmed formation of the layered double hydroxide phases having crystallite size 19-20 nm in both 'a' and 'c' crystallographic directions. Transmission electron microscope and dynamic light scattering revealed nano disperse hexagonal platelets with narrow size distribution and average size was around 48 nm. The modified method reduces the particle size, increases the surface charge, narrows down the size distribution and also reduces the aspect ratio of the particles. Therefore, it is suggested that low amplitude ultrasonic wave prevents the aggregation of the nuclei, thus restricting the particle growth and results in uniform size particles.

  2. Determination of cadmium in grains by isotope dilution ICP-MS and coprecipitation using sample constituents as carrier precipitants.

    Science.gov (United States)

    Inagaki, Kazumi; Narukawa, Tomohiro; Yarita, Takashi; Takatsu, Akiko; Okamoto, Kensaku; Chiba, Koichi

    2007-10-01

    A coprecipitation method using sample constituents as carrier precipitants was developed that can remove molybdenum, which interferes with the determination of cadmium in grain samples via isotope dilution inductively coupled plasma mass spectrometry (ID-ICPMS). Samples were digested with HNO3, HF, and HClO4, and then purified 6 M sodium hydroxide solution was added to generate colloidal hydrolysis compounds, mainly magnesium hydroxide. Cadmium can be effectively separated from molybdenum because the cadmium forms hydroxides and adsorbs onto and/or is occluded in the colloid, while the molybdenum does not form hydroxides or adsorb onto the hydrolysis colloid. The colloid was separated by centrifugation and then dissolved with 0.2 M HNO3 solution to recover the cadmium. The recovery of Cd achieved using the coprecipitation was >97%, and the removal efficiency of Mo was approximately 99.9%. An extremely low procedural blank (below the detection limit of ICPMS) was achieved by purifying the 6 M sodium hydroxide solution via Mg coprecipitation using Mg(NO3)2 solution. The proposed method was applied to two certified reference materials (NIST SRM 1567a wheat flour and SRM 1568a rice flour) and CCQM-P64 soybean powder. Good analytical results with small uncertainties were obtained for all samples. This method is simple and reliable for the determination of Cd in grain samples by ID-ICPMS.

  3. Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration-A Long Term Field Test Conducted in West Bengal.

    Science.gov (United States)

    Otter, Philipp; Malakar, Pradyut; Jana, Bana Bihari; Grischek, Thomas; Benz, Florian; Goldmaier, Alexander; Feistel, Ulrike; Jana, Joydev; Lahiri, Susmita; Alvarez, Juan Antonio

    2017-10-02

    Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved-without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.

  4. Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

    Science.gov (United States)

    Malakar, Pradyut; Jana, Bana Bihari; Benz, Florian; Goldmaier, Alexander; Feistel, Ulrike; Jana, Joydev; Lahiri, Susmita; Alvarez, Juan Antonio

    2017-01-01

    Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V) occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L), iron (5.5 ± 0.8 mg/L), manganese (1.5 ± 0.4 mg/L), phosphate (2.4 ± 1.3 mg/L) and ammonium (1.4 ± 0.5 mg/L) concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L), >99% for iron (0.03 ± 0.03 mg/L), 96% for manganese (0.06 ± 0.05 mg/L), 72% for phosphate (0.7 ± 0.3 mg/L) and 84% for ammonium (0.18 ± 0.12 mg/L) were achieved—without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas. PMID:28974053

  5. Remobilization of pentavalent antimony and vanadium from a granular iron hydroxide material--a comparative study of different leaching systems.

    Science.gov (United States)

    Kolbe, Falko; Weiss, Holger; Wennrich, Rainer; Lorenz, Wilhelm Georg; Daus, Birgit

    2011-09-30

    The remobilization of antimony and vanadium from previously loaded commercial granular ferric-hydroxide GEH material (intended for water treatment) was examined by using a sequential extraction procedure and three different leaching systems to evaluate their physicochemical mobility and potential availability under different simulated environmental conditions. A classical batch extraction, an extraction cell (EC) and rotating-coiled columns (RCC) were used as extraction systems. For each system it could be shown that the content of ion-exchangeable antimony and vanadium in previously loaded material is negligible (extraction time and the possibility of generating information to the leaching kinetics. It is shown that the efficiency of the three leaching systems is quite different employing Wenzel's sequential fractionation protocol. Only by working with RCC, the iron (hydr)oxide matrix was completely dissolved within four steps resulting in the total mobilization of antimony and vanadium. EC seems to be less suitable for leaching studies of Sb and V sorbed on iron(hydr)oxide. The remobilizable proportion of the several fractions was lower in comparison to batch and RCC and seems to be a result of an agglomeration of the GEH in the EC device. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. [Preparation and characterization of zirconium hydroxide powder for fluoride adsorption].

    Science.gov (United States)

    Yang, Shuo; Dou, Xiao-min; Liang, Wen-yan; Wang, Yi-li; Lin, Wei

    2010-07-01

    The method co-precipitation was applied to preparation the zirconium hydroxide as a type drinking-water defluoridation adsorbent. The effect of the preparation conditions on the adsorptive capacity was studied. The optimization of preparation condition for zirconium hydroxide concludes that co-precipitation time is 10 h, pH value is 7.0, drying time is 72 h, calcination temperature is below 100 degrees C. Also, the adsorbent samples were characterized. SEM measurements reveal that zirconium hydroxide powder are constructed by several small particles, with a diameter about 20-30 microm. XRD and TG/DTA measurements show that the zirconium hydroxide samples have amorphous phase and converse to tetragonal phase when calcined at 600 degrees C. Nitrogen adsorption/desorption measurements show that samples have large surface areas of 138.4 m2/g and a 2 nm average pore size distribution in the mesopore region. The performance of zirconium hydroxide regeneration process was investigated. The results show that the regeneration techniques are very suitable to restore the fluorine-removal ability for zirconium hydroxide.

  7. Preconcentration, separation and spectrophotometric determination of aluminium(III) in water samples and dialysis concentrates at trace levels with 8-hydroxyquinoline-cobalt(II) coprecipitation system.

    Science.gov (United States)

    Bulut, Volkan Numan; Arslan, Deniz; Ozdes, Duygu; Soylak, Mustafa; Tufekci, Mehmet

    2010-10-15

    A separation-preconcentration procedure was developed for the determination of trace amounts of aluminium in water samples and dialysis concentrates by UV-vis Spectrophotometry after coprecipitation using 8-hydroxyquinoline (8-HQ) as a chelating agent and Co(II) as a carrier element. This procedure is based on filtration of the solution containing precipitate on a cellulose nitrate membrane filter following aluminium(III) coprecipitation with Co/8-HQ and then the precipitates together with membrane filter were dissolved in concentrated nitric acid. The metal contents of the final solution were determined by UV-vis Spectrophotometry with Erio Chrome Cyanine-R standard method. Several parameters including pH of sample solution, amount of carrier element and reagent, standing time, sample volume for precipitation and the effects of diverse ions were examined. The enrichment factor was calculated as 50 and the detection limits, corresponding to three times the standard deviation of the blank (N: 10), was found to be 0.2 microg L(-1). The accuracy of the method was tested with standard reference material (CRM-TMDW-500) and spiked addition. Determination of aluminium(III) was carried out in sea water, river water, tap water and haemodialysis fluids samples. The recoveries were >95%. The relative standard deviations of determination were less than 6%. 2010 Elsevier B.V. All rights reserved.

  8. One-step synthesis of layered yttrium hydroxides in immiscible liquid–liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Mebae; Fujihara, Shinobu, E-mail: shinobu@applc.keio.ac.jp

    2014-02-15

    Inorganic–organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid–liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu{sup 3+} ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect. - Graphical abstract: The Eu{sup 3+}-doped layered yttrium hydroxide exhibits intense red photoluminescence after intercalation of benzoate ions. Display Omitted - Highlights: • Immiscible biphasic liquid systems were introduced to synthesize layered yttrium hydroxides. • The temperature of the biphasic systems does not exceed 80 °C in one step of the synthesis. • Hydrophobic organic anions were intercalated between the hydroxide layers in one pot. • Structure and morphology of the hydroxides were modulated by changing the kind of organic anions. • Eu{sup 3+}-doping led to red luminescence from the hydroxides in association with the intercalated organic anions.

  9. Synthetic coprecipitates of exopolysaccharides and ferrihydrite. Part II: Siderophore-promoted dissolution

    Science.gov (United States)

    Mikutta, Christian; Kretzschmar, Ruben

    2008-02-01

    electrostatically, thus increasing the mineral surface area accessible to LMWO ligands. In contrast, pure Fh was coagulated at pH 7 (pH iep of Fh = 7.1), and hence only a small fraction of the Fh surface underwent dissolution. The increase in ligand-accessible surface area of Fh upon coprecipitation with acid polysaccharides seems to primarily control the kinetics of the ligand-promoted dissolution at neutral pH. In pH environments where the solubility of Fe(III) is very low, dissolution rates of Fe(III) (hydr)oxides in such coprecipitates may therefore exceed those of pure minerals by several orders of magnitude, despite a similar crystallinity of the minerals.

  10. SEPARATION OF PLUTONIUM HYDROXIDE FROM BISMUTH HYDROXIDE

    Science.gov (United States)

    Watt, G.W.

    1958-08-19

    An tmproved method is described for separating plutonium hydroxide from bismuth hydroxide. The end product of the bismuth phosphate processes for the separation amd concentration of plutonium is a inixture of bismuth hydroxide amd plutonium hydroxide. It has been found that these compounds can be advantageously separated by treatment with a reducing agent having a potential sufficient to reduce bismuth hydroxide to metalltc bisinuth but not sufficient to reduce the plutonium present. The resulting mixture of metallic bismuth and plutonium hydroxide can then be separated by treatment with a material which will dissolve plutonium hydroxide but not metallic bismuth. Sodiunn stannite is mentioned as a preferred reducing agent, and dilute nitric acid may be used as the separatory solvent.

  11. Layered double hydroxide-enhanced luminescence in a Fenton-like system for selective sensing of cobalt in Hela cells

    Science.gov (United States)

    Yu, Mei; Yuan, Zhiqin; Lu, Chao

    2017-09-01

    This work presented a facile and eco-friendly method for the determination of cobalt ions (Co(II)) in living cells based on layered double hydroxides (Mg-Al CO3-LDHs) enhanced chemiluminescence (CL) emission of a Co(II)-hydrogen peroxide-sodium hydroxide system. The enhanced CL emission was attributed to the large specific surface area of Mg-Al CO3-LDHs, which facilitates the generation of an excited-stated intermediate. The proposed method displayed high selectivity toward Co(II) over other metal ions. Under the optimal conditions, the increased CL intensity showed a linear response versus Co(II) concentration in the range of 5.0-1000 nM with a detection limit of 3.7 nM (S/N = 3). The relative standard deviation for nine repeated measurements of 100 nM Co(II) was 3.2%. Furthermore, the proposed method was successfully applied to detect Co(II) in living cell samples, and the results were agreed with those obtained by the standard ICP-MS method.

  12. Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System

    Directory of Open Access Journals (Sweden)

    Aminu Umar Kura

    2014-01-01

    Full Text Available We incorporated anti-Parkinsonian drug, levodopa (dopa, in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay.

  13. Selective coprecipitation of polyphenols in bioactive/inorganic complexes.

    Science.gov (United States)

    Elabbadi, Amal; Jeckelmann, Nicolas; Haefliger, Olivier; Ouali, Lahoussine; Erni, Philipp

    2011-07-01

    We investigate the formation of bioactive/inorganic coprecipitates of polyphenols catechins with calcium carbonate and calcium phosphate. Extracted from the leaves of Camellia sinensis, green tea catechins are efficient free radical scavengers, but their purported benefits from the perspective of prevention, health, and nutritional physiology are accompanied by unpleasant organoleptic characteristics: they are notoriously bitter. Selective complexation of polyphenols with metal salts is a possibility to mask or inactivate bitterness and/or off-flavors. We produce such complexes using a continuous coprecipitation process. With excess calcium chloride present in the matrix we observe a correlation of the carbonate to total anions molar ratio with the catechin load. To characterize the composition and structure of the coprecipitates we combine elemental analysis, scanning electron microscopy, X-ray powder diffraction, and liquid chromatography coupled to tandem mass spectroscopy (LC/MS-MS). We quantify the release kinetics in different model environments to predict the behavior of the catechins from the coprecipitates in model media simulating the conditions during oral ingestion and storage. The dissolution data suggest that the release profile of these delivery systems can be influenced and fine-tuned via the anion composition of the mineral carrier.

  14. Indirect pulp treatment: in vivo outcomes of an adhesive resin system vs calcium hydroxide for protection of the dentin-pulp complex.

    Science.gov (United States)

    Falster, Caline A; Araujo, Fernando B; Straffon, Lloyd H; Nör, Jacques E

    2002-01-01

    The purpose of this prospective and randomized in vivo study was to compare the clinical and radiographic outcomes of an adhesive resin system vs a calcium hydroxide liner for protection of the dentin-pulp complex of primary molars treated with indirect pulp treatment. Forty-eight primary molars with deep occlusal caries, but without preoperative signs and symptoms of irreversible pulpitis, received indirect pulp treatment and were restored with a composite resin (Z100). The teeth were randomly divided into 2 groups according to the material used for protection of the dentin-pulp complex: (1) adhesive resin system (Scotchbond MultiPurpose); and (2) calcium hydroxide liner (Dycal). These teeth were evaluated clinically and radiographicaly for 2 years. After 2 years, 83% (19/23) of the teeth treated with calcium hydroxide and 96% (24/25) of teeth treated with only the adhesive resin system presented a successful outcome, as determined by clinical and radiographic examination. Interradicular and/or periapical lesions were the most predominant signs of treatment failure, since 3 out of 23 teeth treated with calcium hydroxide and 1 out of 25 teeth treated with only adhesive resin presented this outcome. One tooth treated with the calcium hydroxide liner was diagnosed with internal root resorption at the 18-month examination. Of the 5 teeth diagnosed from radiographs as a failure of the indirect pulp treatment, none presented clinical signs/symptoms of pulpitis or necrosis such as the presence of fistula, enhanced tooth mobility, or pain. This study demonstrates that protection of the dentin-pulp complex of primary molars with an adhesive resin system results in similar clinical and radiographic 2-year outcomes as compared to calcium hydroxide when indirect pulp treatment is performed in Class I composite restorations.

  15. A binary A(x)B(1-x) ionic alkaline pseudocapacitor system involving manganese, iron, cobalt, and nickel: formation of electroactive colloids via in situ electric field assisted coprecipitation.

    Science.gov (United States)

    Chen, Kunfeng; Yin, Shu; Xue, Dongfeng

    2015-01-21

    A new "combinatorial transition-metal cation pseudocapacitor" was demonstrated by designing combinatorial transition-metal cation pseudocapacitors with binary AxB1-x salt electrodes involving manganese, iron, cobalt, and nickel cations in an alkaline aqueous electrolyte. Binary multi-valence cations were crystallized in the colloidal state through an in situ coprecipitation under an electric field. These electroactive colloids absorbed by carbon black and the PVDF matrix are highly redox-reactive with high specific capacitance values, where the specific electrode configuration can create short ion diffusion paths to enable fast and reversible Faradaic reactions. This work shows huge promise for developing high-performance electrical energy storage systems via designing the colloidal state of electroactive cations. Multiple redox cations in the colloidal state can show high redox activities, making them more suitable for potential application in pseudocapacitor systems.

  16. Purification of alkaline solutions and wastes from actinides and technetium by coprecipitation with some carriers using the method of appearing reagents: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Peretrukhin, V.F.; Silin, V.I.; Kareta, A.V.; Gelis, A.V.; Shilov, V.P.; German, K.E.; Firsova, E.V.; Maslennikov, A.G.; Trushina, V.E. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

    1998-09-01

    The coprecipitation of transuranium elements (TRU) and technetium from alkaline solutions and from simulants of Hanford Site tank wastes has been studied in reducing and oxidizing conditions on uranium(IV,VI) hydroxocompounds, tetraalkylammonium perrhenate and perchlorate, and on hydroxides of Fe(III), Co(III), Mn(II), and Cr(III) using the method of appearing reagents (MAR). Coprecipitations in alkaline solution have been shown to give high decontamination factors (DF) at low content of carrier and in the presence of high salt concentrations. Uranium(IV) hydroxide in concentrations higher than 3 {times} 10{sup {minus}3} M coprecipitates Pu and Cm in any oxidation state from 0.2 to 4 M NaOH with DFs of 110 to 1000 and Np and Tc with DFs of 51 to 176. Technetium (VII) coprecipitates with (5 to 8) {times} 10{sup {minus}4} M tetrabutylammonium (TBA) perrhenate in 0.01 to 0.02 M TBA hydroxide from 0.5 to 1.5 M NaOH to give DFs of 150 to 200. Coprecipitations of Np and Pu with Co(OH){sub 3}, Fe(OH){sub 3}, Cr(OH){sub 3}, and Mn(OH){sub 2} obtained by the MAR from precursors in the range from pH 10.5 to 0.4 M NaOH give DFs from 80 to 400.

  17. Hexaferrite particles by coprecipitation and lyophilization

    Science.gov (United States)

    Calleja, A.; Tijero, E.; Martínez, B.; Piñol, S.; Sandiumenge, F.; Obradors, X.

    1999-05-01

    Fine strontium hexaferrite particles were prepared by lyophilization (known as freeze-drying) and coprecipitation of nitrates and chloride salts, respectively. The resulting powders were calcined at different temperatures between 700°C and 1100°C. As concluded from the measured hysteresis loops at 300 K, the freeze-dried hexaferrite showed good magnetic characteristics, the coercivity being as high as 5690 Oe. However, coprecipitated hexaferrite displayed poor coercivity values, around 1300 Oe at best.

  18. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  19. An organic coprecipitation route to synthesize high voltage LiNi0.5Mn1.5O4.

    Science.gov (United States)

    Feng, Jijun; Huang, Zhipeng; Guo, Chao; Chernova, Natasha A; Upreti, Shailesh; Whittingham, M Stanley

    2013-10-23

    High-voltage cathode material LiNi0.5Mn1.5O4 has been prepared with a novel organic coprecipitation route. The as-prepared sample was compared with samples produced through traditional solid state method and hydroxide coprecipitation method. The morphology was observed by scanning electron microscopy, and the spinel structures were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. Besides the ordered/disordered distribution of Ni/Mn on octahedral sites, the confusion between Li and transition metal is pointed out to be another important factor responsible for the corresponding performance, which is worthy further investigation. Galvanostatic cycles, cyclic voltammetry, and electrochemical impedance spectroscopy are employed to characterize the electrochemical properties. The organic coprecipitation route produced sample shows superior rate capability and stable structure during cycling.

  20. Formation of nematic liquid crystals of sterically stabilized layered double hydroxide platelets

    NARCIS (Netherlands)

    Mourad, M.C.D.|info:eu-repo/dai/nl/304837563; Devid, E.J.; van Schooneveld, M.M.|info:eu-repo/dai/nl/315032863; Vonk, Ch.; Lekkerkerker, H.N.W.|info:eu-repo/dai/nl/159054885

    2008-01-01

    Colloidal platelets of hydrotalcite, a layered double hydroxide, have been prepared by coprecipitation at pH 11−12 of magnesium nitrate and aluminum nitrate at two different magnesium to aluminum ratios. Changing the temperature and ionic strength during hydrothermal treatment, the platelets were

  1. Electrochemical Performance of Zn-Al Double Layered Hydroxide for Supercapacitor Application

    Science.gov (United States)

    Wen, Yang; Zhao, Yu; Lu, Lu; Zhang, Shuo Jia; Xu, Bing

    2017-10-01

    Zn-Al double layered hydroxide (Zn-Al-LDH) was synthesized by a facile coprecipitation method. The morphology and microstructure of samples were characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM), respectively. The results show that the sample is uniform nanosheet with the diameter of ∼400 nm and the thickness of ∼80 nm. XRD characterization confirms that it is Zn6A12(OH)16CO3.4H2O and belongs to Rhombohedral crystallographic system. Electrochemical performances of the sample were investigated by cyclic voltammery (CV) and charge/discharge. The Pure Zn-Al-LDH nanocomposites achieves a specific capacitance of 37.0 F g-1 at the current density of 1.0 A/g.

  2. Novel biohybrids of layered double hydroxide and lactate dehydrogenase enzyme: Synthesis, characterization and catalytic activity studies

    Science.gov (United States)

    Djebbi, Mohamed Amine; Braiek, Mohamed; Hidouri, Slah; Namour, Philippe; Jaffrezic-Renault, Nicole; Ben Haj Amara, Abdesslem

    2016-02-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biomolecule such as enzyme to produce bioinorganic system. Lactate dehydrogenase (Lac Deh) has been chosen as a model enzyme, being immobilized onto MgAl and ZnAl LDH materials via direct ion-exchange (adsorption) and co-precipitation methods. The immobilization efficiency was largely dependent upon the immobilization methods. A comparative study shows that the co-precipitation method favors the immobilization of great and tunable amount of enzyme. The structural behavior, chemical bonding composition and morphology of the resulting biohybrids were determined by X-ray diffraction (XRD) study, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. The free and immobilized enzyme activity and kinetic parameters were also reported using UV-Visible spectroscopy. However, the modified LDH materials showed a decrease in crystallinity as compared to the unmodified LDH. The change in activity of the immobilized lactate dehydrogenase was considered to be due, to the reduced accessibility of substrate molecules to the active sites of the enzyme and the partial conformational change of the Lac Deh molecules as a result of the immobilization way. Finally, it was proven that there is a correlation between structure/microstructure and enzyme activity dependent on the immobilization process.

  3. Efficacy of 3 different irrigation systems on removal of calcium hydroxide from the root canal: a scanning electron microscopic study.

    Science.gov (United States)

    Alturaiki, Sami; Lamphon, Hebah; Edrees, Hadeel; Ahlquist, Michael

    2015-01-01

    The purpose of this study was to evaluate the effectiveness of different irrigation systems on removing calcium hydroxide (Ca[OH]2) from the root canal by using a scanning electron microscope. Forty extracted single-rooted teeth were divided randomly into 4 groups. Canal instrumentation was done, and the teeth were filled with Ca(OH)2 paste. One week later, 4 techniques were used for Ca(OH)2 removal. In the first group, the canals were cleaned with a master apical file. The second, third, and fourth groups were irrigated using the EndoVac (Discus Dental, Culver City, CA), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK), and ProUltra (Dentsply Tulsa, Tulsa, OK) systems, respectively. All the groups were irrigated with 3 mL (18%) EDTA and 3 mL (1%) NaOCl for 1 minute. The canal walls were viewed, and the remaining amount of Ca(OH)2 was evaluated using a scanning electron microscope. A scoring system was used to assess the amount of residue Ca(OH)2 on each third of the canal. The obtained data for comparisons between the conventional irrigation needle and each device were statistically analyzed using the Mann-Whitney U test. To compare the 4 devices, the results were statistically analyzed using the analysis of variance test. None of the investigated techniques removed the Ca(OH)2 dressing completely. However, the EndoActivator System showed better results in removing Ca(OH)2 in each third of the root canals in comparison with the other techniques. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. Can a hydroxide ligand trigger a change in the coordination number of magnesium ions in biological systems?

    Science.gov (United States)

    Kluge, Stefan; Weston, Jennie

    2005-03-29

    Density functional (B3LYP) calculations indicate that a hydroxide ligand is capable of triggering a reduction in the coordination number of Mg(2+) ions from 6 to 5. Since this could be quite relevant in the mode of action of magnesium-containing enzymes (especially hydrolases in which a metal-bound hydroxide species is believed to play a crucial role), we have performed a systematic deprotonation study of biologically relevant magnesium complexes. We explicitly calculated the preferred coordination number of [MgL(1)(x)L(2)(y)L(3)(z)](2)(-)(n) species at the B3LYP/aug-cc-pVTZ level of theory. L(1), L(2), and L(3) represent combinations of water, hydroxide, carboxylate (models Glu and Asp), ammonia ligands (models Lys and His residues), and fluoride ions. As expected, Mg(2+) exclusively prefers an octahedral coordination geometry with H(2)O, HCO(2)(-), or NH(3). Surprisingly, one hydroxide ligand triggers a change to a trigonal bipyramidal geometry. The isoelectronic fluoride ion behaves similarly. When two OH(-) are present, a tetrahedral coordination geometry is preferred. We postulate that a hydroxide (in addition to its role as an active nucleophile) could be employed by magnesium-containing enzymes to trigger a differential coordination behavior.

  5. Organic–inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides with intercalated phacolysin as ocular delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhiguo; Zhang, Jie; Chi, Huibo; Cao, Feng, E-mail: cpufengc@163.com [China Pharmaceutical University, Department of Pharmaceutics, School of Pharmacy (China)

    2015-12-15

    This study was mainly aimed to evaluate the potential use of a novel ocular drug delivery system, organic–inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides (LDH). Organic polymers of chitosan–glutathione (CG) and pre-activated chitosan–glutathione (CG-2MNA) were successfully synthesized and characterized. LDH with intercalated phacolysin (PCL), including larger hexagonal LDH–PCL (Lh-LDH–PCL), larger spherical LDH–PCL (Ls-LDH–PCL), smaller hexagonal LDH–PCL (Sh-LDH–PCL), CG hybrid LDH–PCL (LDH–PCL-CG), and CG-2MNA hybrid LDH–PCL (LDH–PCL-CG-2MNA), were prepared. The nanocomposites with particle size of 107.2–274.9 nm were characterized by powder X-ray diffraction, Fourier transform infrared, transmission electron micrographs, etc. In vivo precorneal retention studies showed that the detectable time of all nanocomposites was prolonged from 2 to 6 h in comparison to PCL saline. Accordingly, the AUC{sub 0–6h} values of Lh-LDH–PCL, Ls-LDH–PCL, Sh-LDH–PCL, LDH–PCL-CG, and LDH–PCL-CG-2MNA nanocomposites were increased by 2.27-, 2.08-, 3.08-, 4.67-, and 3.36-fold, respectively. The Draize test and hematoxylin and eosin staining demonstrated that modified LDH had no eye irritation after single and repeated administration. These results indicated that chitosan derivatives-LDH hybrid nanocomposite dispersion could be a promising ocular drug delivery system to improve precorneal retention time of drugs.Graphical AbstractThiolated chitosan-LDH hybrid nanocomposite dispersion could be a promising ocular drug delivery system to improve precorneal retention time of drugs and may facilitate penetration of drugs into tissues of the eyes.

  6. One-step synthesis of layered yttrium hydroxides in immiscible liquid-liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    Science.gov (United States)

    Watanabe, Mebae; Fujihara, Shinobu

    2014-02-01

    Inorganic-organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid-liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu3+ ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect.

  7. Co-precipitation synthesis and upconversion luminescence ...

    Indian Academy of Sciences (India)

    ZrO2:Yb3+-Ho3+ phosphors with different Yb3+ doping concentration have been prepared by coprecipitation method. X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectra were used to characterize the properties of ZrO2:Yb3+-Ho3+ phosphors. Different phases of ZrO2 can be ...

  8. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, Robert W. [Univ. of California, Berkeley, CA (United States); Muller, Rolf H. [Univ. of California, Berkeley, CA (United States)

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 - 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  9. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, R.W.; Muller, R.H.

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  10. Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

    Directory of Open Access Journals (Sweden)

    Philipp Otter

    2017-10-01

    Full Text Available Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the findings of a long term field test conducted in West Bengal. The system applies an inline-electrolytic cell for in situ chlorine production using the natural chloride content of the water and by that substituting the external dosing of strong oxidants. Co-precipitation of As(V occurs on freshly formed iron hydroxide, which is removed by Manganese Greensand Plus® filtration. The test was conducted for ten months under changing source water conditions considering arsenic (187 ± 45 µg/L, iron (5.5 ± 0.8 mg/L, manganese (1.5 ± 0.4 mg/L, phosphate (2.4 ± 1.3 mg/L and ammonium (1.4 ± 0.5 mg/L concentrations. Depending on the system setting removal rates of 94% for arsenic (10 ± 4 µg/L, >99% for iron (0.03 ± 0.03 mg/L, 96% for manganese (0.06 ± 0.05 mg/L, 72% for phosphate (0.7 ± 0.3 mg/L and 84% for ammonium (0.18 ± 0.12 mg/L were achieved—without the addition of any chemicals/adsorbents. Loading densities of arsenic on iron hydroxides averaged to 31 µgAs/mgFe. As the test was performed under field conditions and the here proposed removal mechanisms work fully autonomously, it poses a technically feasible treatment alternative, especially for rural areas.

  11. Law of mass action for co-precipitation; Loi d'action de masse de la co-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Vitorge, P

    2008-07-01

    Coprecipitation is often understood as the incorporation of elements at trace concentrations into -initially pure- solid compounds. Coprecipitation has typically been used to identify radioactive isotopes. Coprecipitation can result in lowering solubility as compared to the solubility, when controlled by pure compounds. For this reason it is also important for geochemistry, waste management and de-pollution studies. The solid obtained with coprecipitation is a new homogeneous solid phase called solid solution. The 2 formula needed to calculate the aqueous solubility when controlled by the ideal AB{sub b(1-x)}C{sub cx} solid solutions are K{sub s,B}{sup 1-x}*K{sub s,C}{sup x} equals [A{sup z{sub A}}]*[B{sup z{sub B}}]{sup b(1-x)}*[C{sup z{sub C}}]{sup cx}/((1-x){sup b(1-x)}x{sup cx}) and K{sub s,C}/K{sub s,B} equals (1-x){sup b}*[C{sup z{sub C}}]{sup c}/[B{sup z{sub B}}]{sup b}*x{sup c}), where K{sub s,B} and K{sub s,C} are the classical constant solubility products of the AB{sub b} and AC{sub c} end-members, the b and c values are calculated from the (z{sub i}) charges of the ions and from charge balance. This report is essentially written to provide a thermodynamic demonstration of the law of mass action in attempts to confirm scientific bases for solubility calculations in geosciences (as typically retention of radio-nuclides by co-precipitation), and to facilitate such calculations. Note that the law of mass action is here a set of 2 equations (not only 1) for the ideal or near ideal systems. Since they are consistent with the phase rule, no extra formula (beside mass balance) is needed to calculate the concentrations of all the species in both phases, namely: [A{sup z{sub A}}], [B{sup z{sub B}}], [C{sup z{sub C}}] and specially x.

  12. Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

    Science.gov (United States)

    Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

    2012-01-01

    The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

  13. Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

    Energy Technology Data Exchange (ETDEWEB)

    Krot, N.; Shilov, V.; Bessonov, A.; Budantseva, N.; Charushnikova, I.; Perminov, V.; Astafurova, L. [Russian Academy of Science (Russian Federation). Inst. of Physical Chemistry

    1996-06-06

    Highly alkaline radioactive waste solutions originating from production of plutonium for military purposes are stored in underground tanks at the U.S. Department of Energy Hanford Site. The purification of alkaline solutions from neptunium and plutonium is important in the treatment and disposal of these wastes. This report describes scoping tests with sodium hydroxide solutions, where precipitation techniques were investigated to perform the separation. Hydroxides of iron (III), manganese (II), cobalt (II, III), and chromium (III); manganese (IV) oxide, and sodium uranate were investigated as carriers. The report describes the optimum conditions that were identified to precipitate these carriers homogeneously throughout the solution by reductive, hydrolytic, or catalytic decomposition of alkali-soluble precursor compounds by a technique called the Method of Appearing Reagents. The coprecipitation of pentavalent and hexavalent neptunium and plutonium was investigated for the candidate agents under optimum conditions and is described in this report along with the following results. Plutonium coprecipitated well with all tested materials except manganese (IV) oxide. Neptunium only coprecipitated well with uranate. The report presents a hypothesis to explain these behaviors. Further tests with more complex solution matrices must be performed.

  14. Application of magnesium hydroxide and barium hydroxide for the ...

    African Journals Online (AJOL)

    Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water. ... equivalent to the Ba(OH)2 dosage. During CO2-dosing, CaCO3 is precipitated to the saturation level of CaCO3. Keywords: Magnesium hydroxide; barium hydroxide; sulphate removal; water treatment ...

  15. Phosphate adsorption from wastewater using zirconium (IV) hydroxide: Kinetics, thermodynamics and membrane filtration adsorption hybrid system studies.

    Science.gov (United States)

    Johir, M A H; Pradhan, M; Loganathan, P; Kandasamy, J; Vigneswaran, S

    2016-02-01

    Excessive phosphate in wastewater should be removed to control eutrophication of water bodies. The potential of employing amorphous zirconium (Zr) hydroxide to remove phosphate from synthetic wastewater was studied in batch adsorption experiments and in a submerged membrane filtration adsorption hybrid (MFAH) reactor. The adsorption data satisfactorily fitted to Langmuir, pseudo-first order and pseudo-second order models. Langmuir adsorption maxima at 22 °C and pHs of 4.0, 7.1, and 10.0 were 30.40, 18.50, and 19.60 mg P/g, respectively. At pH 7.1 and temperatures of 40 °C and 60 °C, they were 43.80 and 54.60 mg P/g, respectively. The thermodynamic parameters, ΔG° and ΔS° were negative and ΔH° was positive. FTIR, zeta potential and competitive phosphate, sulphate and nitrate adsorption data showed that the mechanism of phosphate adsorption was inner-sphere complexation. In the submerged MFAH reactor experiment, when Zr hydroxide was added at doses of 1-5 g/L once only at the start of the experiment, the removal of phosphate from 3 L of wastewater containing 10 mg P/L declined after 5 h of operation. However, when Zr hydroxide was repeatedly added at 5 g/L dose every 24 h, satisfactory removal of phosphate was maintained for 3 days. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Determination of some heavy metals in food and environmental samples by flame atomic absorption spectrometry after coprecipitation.

    Science.gov (United States)

    Soylak, Mustafa; Aydin, Ayse

    2011-06-01

    A novel preconcentration procedure based coprecipitation of Cu(II), Co(II), Cd(II), Ni(II), Mn(II), Fe(III) and Pb(II) on thulium hydroxide precipitate has been presented prior to flame atomic absorption spectrometric determination of them in environmental samples. The analytical parameters that influenced the quantitative coprecipitation of analytes including amount of thulium, pH, duration time, etc. were investigated. The effects of alkali, earth alkali, and some transition metals on the recoveries were also studied. Under the optimized conditions, the detection limits (3 sigma, N=10) for the analytes were in the range of 0.1-1.6 μg/L, respectively. The validation of the presented coprecipitation method was checked by the analysis of certified reference materials (TMDA 54.4 fortified lake water and HR-1 Humber river sediment). The proposed coprecipitation method has been successfully applied for the determination of traces of copper, cobalt, cadmium, nickel, manganese, iron and lead in food and environmental samples. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling

    DEFF Research Database (Denmark)

    Lim, Ai Wei; Löbmann, Korbinian; Grohganz, Holger

    2016-01-01

    OBJECTIVES: The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling. METHODS: Powder X-ray diffraction (PXRD) and DSC were used to characterise...... by quench cooling (ln τ(β) = 2.4) and co-evaporation (ln τ(β) = 2.5). In contrast, molecular mobility of the naproxen-cimetidine samples followed the order co-evaporation (ln τ(β) = 0.8), quench cooling (ln τ(β) = 1.6) and ball milling (ln τ(β) = 1.8). CONCLUSION: The estimated relaxation times by the DSC...

  18. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling.

    Science.gov (United States)

    Lim, Ai Wei; Löbmann, Korbinian; Grohganz, Holger; Rades, Thomas; Chieng, Norman

    2016-01-01

    The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling. Powder X-ray diffraction (PXRD) and DSC were used to characterise the samples. Structural relaxation (i.e. molecular mobility) behaviour was obtained from the Kohlrausch-Williams-Watts (KWW) relationship. A glass transition temperature (Tg ), on average 20 °C higher than the predicted Tg (calculated from the Fox equation), was observed in all samples. The structural relaxation was dependent on the preparative methods. At a storage temperature of 40 °C, a comparatively higher molecular mobility was observed in indomethacin-cimetidine samples prepared by ball milling (ln τ(β) = 0.8), while similar molecular mobility was found for the same sample prepared by quench cooling (ln τ(β) = 2.4) and co-evaporation (ln τ(β) = 2.5). In contrast, molecular mobility of the naproxen-cimetidine samples followed the order co-evaporation (ln τ(β) = 0.8), quench cooling (ln τ(β) = 1.6) and ball milling (ln τ(β) = 1.8). The estimated relaxation times by the DSC-KWW method suggest that different preparative methods resulted in a variation of structural characteristics. Despite the differences in molecular mobility, all sample remained co-amorphous for up to 7 months. © 2015 Royal Pharmaceutical Society.

  19. Arsenic Removal from Groundwater by Solar Driven Inline-Electrolytic Induced Co-Precipitation and Filtration—A Long Term Field Test Conducted in West Bengal

    OpenAIRE

    Philipp Otter; Pradyut Malakar; Bana Bihari Jana; Thomas Grischek; Florian Benz; Alexander Goldmaier; Ulrike Feistel; Joydev Jana; Susmita Lahiri; Juan Antonio Alvarez

    2017-01-01

    Arsenic contamination in drinking water resources is of major concern in the Ganga delta plains of West Bengal in India and Bangladesh. Here, several laboratory and field studies on arsenic removal from drinking water resources were conducted in the past and the application of strong-oxidant-induced co-precipitation of arsenic on iron hydroxides is still considered as the most promising mechanism. This paper suggests an autonomous, solar driven arsenic removal setting and presents the finding...

  20. CALCIUM REMOVAL FROM PAPER MACHINE EFFLUENT BY PRECIPITATION/COPRECIPITATION

    Directory of Open Access Journals (Sweden)

    José Carlos Leandro de Sousa

    2011-09-01

    Full Text Available In integrates pulp and paper mills, the effluent generated by the paper machine can be considered as a sector effluent, called white water, due to the high concentration of calcium. In this work, experiments were conducted to understand the behavior of the effluent in different pH values and to develop removal methods of calcium from the white water, aiming the reuse of water and the calcium recovery. Potentiometric titrations were carried out with HCl 0.022 mol L-1 and NaOH 0.025 mol L-1 standards, after adjusting the effluent pH at 12.0 and 2.0; respectively, which indicated inflection points for the carbonate, bicarbonate and kaolin, components capable of interaction with the soluble calcium. The methods for calcium removal consisted of coprecipitation/adsorption with iron (III and aluminum hydroxides, and precipitation in the presence of sodium oxalate. The results indicated that at low concentrations of ferric sulfate and aluminum sulfate, the removal of calcium is low. In the adsorption assays in the presence of Fe(OH3 and Al(OH3, the increased of the ferric sulfate concentration enabled a slight increase in the calcium removal (16.5 to 31.0 %, reaching 65.0% in the adsorption more precipitation process in pH 10.0. In case of aluminum sulfate, the removal percentages were indifferent (close to 10.0%. In the precipitation of Ca2+ in the oxalate presence, the possibility of satisfactory percentages of removal was observed (75 to 87%, keeping the effluent with the conductivity and pH unchanged, it’s very important, because the increase of effluent conductivity to reuse cause break of paper made. The calcium oxalate recuperated can be heated excessively and changed and calcium carbonate and to be reused. Tests in the highest scale have to be realized to approve the reuse of water and calcium of paper machine.

  1. Antimicrobial Activity of Calcium Hydroxide in Endodontics: A Review

    OpenAIRE

    Mohammadi, Z; Shalavi, S; Yazdizadeh, M

    2012-01-01

    The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5...

  2. Antimicrobial activity of calcium hydroxide in endodontics: a review.

    Science.gov (United States)

    Mohammadi, Z; Shalavi, S; Yazdizadeh, M

    2012-12-01

    The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. Calcium hydroxide has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also a valuable anti-endotoxin agent. However, its effect on microbial biofilms is controversial.

  3. Antimicrobial Activity of Calcium Hydroxide in Endodontics: A Review

    Science.gov (United States)

    Shalavi, S; Yazdizadeh, M

    2012-01-01

    The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. Calcium hydroxide has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also a valuable anti-endotoxin agent. However, its effect on microbial biofilms is controversial. PMID:23323217

  4. Coprecipitation of Arsenate and Arsenite with Green Rust Minerals

    Science.gov (United States)

    The objectives of this experiment were to evaluate the extent and nature of arsenic co-precipitation with green rusts and to examine the influence of arsenic incorporation on the mineralogy of formed solid phases. Stoichiometric green rusts were obtained by coprecipitation of fe...

  5. Microstructure and hysteresis curves of samarium-holmium-iron garnet synthesized by coprecipitation

    Directory of Open Access Journals (Sweden)

    Caffarena Valeska da Rocha

    2003-01-01

    Full Text Available An investigation was made into the synthesis and magnetic properties of Sm(3-xHo xFe5O12 (samarium-holmium-iron garnet ferrite, as yet absent from the literature. The material in question was synthesized by co-precipitation, starting from hydrated chlorides of rare-earth elements and ferrous sulfate, and the mixed hydroxide co-precipitate was calcined at 1000 °C. Using PVA as a binder, rectangular cross section-shaped compacts were produced by means of steel-die pressing, drying and sintering from 1200 to 1450 °C. The main conclusions of this study were that the coercive force decreases as the sintering temperature increases, and that the effect of substituting holmium for samarium in SmIG is entirely different from that provided by replacing yttrium by gadolinium in YIG, which is the most important result of this work. An in-depth investigation will be necessary to determine the correlation between microstructure/magnetic properties and ceramic processing variables.

  6. Preparation of ITO Nanoparticles by Liquid Phase Coprecipitation Method

    Directory of Open Access Journals (Sweden)

    Zhanlai Ding

    2010-01-01

    Full Text Available The nanoscale indium tin oxide (ITO particles are synthesied by liquid phase coprecipitation method under given conditions with solution of indium chloride, tin chloride, and ammonia. The absolute ethyl alcohol or deionized water was used as solvent and the dodecylamine or hexadecylamine surfactant was used as a dispersant in the reaction system. The sample powder was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and high-resolution electron microscopy (HRTEM. Based on the transmission electron micrograph, the influences of the two different solvents and the two different dispersants on the nanoparticle size and dispersion were studied, respectively. The results showed that the ITO particles are finely crystallized body-centered cubic structure. The particle size has distributed in 30 nm to 90 nm.

  7. Síntese de hidróxidos duplos lamelares do sistema Cu, Zn, Al-CO3: propriedades morfológicas, estruturais e comportamento térmico Synthesis of layered double hydroxides of the Cu, Zn, Al-CO3 system: morphological and structural properties and thermal behavior

    Directory of Open Access Journals (Sweden)

    S. S. dos Santos

    2011-09-01

    Full Text Available Hidrotalcitas são argilas aniônicas, também conhecidas como Hidróxidos Duplos Lamelares (HDLs e possuem estrutura semelhante ao mineral brucita. Os HDLs do sistema Cu, Zn, Al-CO3 foram sintetizados em condições que favorecem a formação de cristais pequenos e de elevada área superficial. A caracterização foi feita por difração de raios X, análise termogravimétrica, espectroscopia na região do infravermelho e microscopia eletrônica de varredura. A síntese foi feita pelo método de coprecipitação em pH variável, utilizando sulfatos de cobre e zinco, soluções de alumínio e solução de hidróxido sódio. Os difratogramas de raios X mostram que os compostos sintetizados possuem alta cristalinidade; a intensidade e a largura dos picos comprovam que os materiais se apresentam bem organizados e com empilhamento das lamelas. Os espectros de infravermelho apresentaram bandas associadas ao ânion carbonato presente na região interlamelar dos HDLs.Hydrotalcite-like compounds are anionic clays, also known as layered double hydroxides (LDH, which have structure similar to brucite mineral. The LDHs of the system Cu, Zn, Al-CO3 were synthesized under conditions to promote the formation of small crystals with high surface area. The characterization was done by X-ray diffraction, thermogravimetric analysis, FTIR spectroscopy, and scanning electron microscopy. The synthesis were based on the co-precipitation method, under different conditions (hydrothermal bath, titration time using copper and zinc sulfate, aluminum and sodium hydroxide solutions. The X-ray diffraction patterns show that synthesized compounds have high crystallinity, the peak intensities show that they are well organized and stacked with the lamellae. The infrared spectrum shows bands associated with carbonate anion in the interlayer region.

  8. Magnesium hydroxide extracted from a magnesium-rich mineral for CO2 sequestration in a gas-solid system.

    Science.gov (United States)

    Lin, Pao-Chung; Huang, Cheng-Wei; Hsiao, Ching-Ta; Teng, Hsisheng

    2008-04-15

    Magnesium hydroxide extracted from magnesium-bearing minerals is considered a promising agent for binding CO2 as a carbonate mineral in a gas-solid reaction. An efficient extraction route consisting of hydrothermal treatment on serpentine in HCl followed by NaOH titration for Mg(OH)2 precipitation was demonstrated. The extracted Mg(OH)2 powder had a mean crystal domain size as small as 12 nm and an apparent surface area of 54 m2/g. Under one atmosphere of 10 vol% CO2/N2, carbonation of the serpentine-derived Mg(OH)2 to 26% of the stoichiometric limit was achieved at 325 degrees C in 2 h; while carbonation of a commercially available Mg(OH)2, with a mean crystal domain size of 33 nm and an apparent surface area of 3.5 m2/g, reached only 9% of the stoichiometric limit. The amount of CO2 fixation was found to be inversely proportional to the crystal domain size of the Mg(OH)2 specimens. The experimental data strongly suggested that only a monolayer of carbonates was formed on the crystal domain boundary in the gas-solid reaction, with little penetration of the carbonates into the crystal domain.

  9. Experimental Investigation of the Coprecipitation Method: An Approach to Obtain Magnetite and Maghemite Nanoparticles with Improved Properties

    Directory of Open Access Journals (Sweden)

    Wilson Sacchi Peternele

    2014-01-01

    Full Text Available Iron oxides that exhibit magnetic properties have been widely studied not only from an academic standpoint, but also for numerous applications in different fields of knowledge, such as biomedical and technological research. In this work, magnetite and maghemite nanoparticles were synthesized by chemical coprecipitation of FeCl2·4H2O and FeCl3·6H2O (proportion of 1 : 2 in three different cases using two bases (sodium hydroxide and hydroxide ammonium as precipitants. The chemical coprecipitation method was selected for its simplicity, convenience, reproducibility, and low cost in the use of glassware. The nanostructured materials were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD and magnetometry (VSM. The objective of this work is to study the variation in the morphological characteristics and physical properties of nanoparticles magnetic as a function of the different production processes. As observed by TEM, the materials obtained from the precipitating agent NH4OH are more uniform than those obtained with NaOH. From XRD pattern analysis, it appears that the obtained materials correspond to magnetite and maghemite and, from magnetometry VSM analysis, show high magnetization as a function of the magnetic field at room temperature, indicating that these materials are superparamagnetic.

  10. Coprecipitation of radionuclides: basic concepts, literature review and first applications

    Energy Technology Data Exchange (ETDEWEB)

    Curti, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-11-01

    Coprecipitation of radionuclides with solid products is currently not analysed quantitatively in safety assessments for nuclear waste repositories, although this process is thought to be an important mechanism for limiting nuclide concentrations in solution. This is due to the fact that neither the solid phases controlling coprecipitation nor the parameter values necessary to describe this process are known sufficiently. This introductory report provides basic knowledge on this subject and a review of experimental data from the literature. Emphasis is placed on experiments of trace metal coprecipitation with calcite, because this mineral is a dominating alteration product of cement in the Swiss L/ILW repository. This resulted in a database of partition coefficients, which allow to describe empirically the distribution of trace elements between calcite and solution and thus to quantify coprecipitation processes. Since laboratory data on coprecipitation with calcite are lacking for many safety-relevant radioelements, their partition coefficients were inferred with the help of estimation techniques. Such techniques rely on empirical correlations, which relate the uptake of trace metals in calcite (measured in laboratory tests) with selected chemical properties of the coprecipitated metals (e.g. ionic radius, sorption properties, solubility products of the pure trace metal carbonates). The combination of these correlations with independent geochemical evidence allows the extrapolation of radioelement-specific partition coefficients, which are then used for the quantitative modelling. In a first step the potential role of radionuclide coprecipitation during cement degradation in the L/ILW repository planned at Wellenberg is assessed. (author) figs., tabs., refs.

  11. Technetium Removal Using Tc-Goethite Coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Wang, Guohui; Jung, Hun Bok; Peterson, Reid A.

    2013-11-18

    This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Low temperature waste forms coupled with technetium removal using an alternative immobilization process such as Fe(II) treated-goethite precipitation” to increase our understanding of 99Tc long-term stability in goethite mineral form and the process that controls the 99Tc(VII) reduction and removal by the final Fe (oxy)hydroxide forms. The overall objectives of this task were to 1) evaluate the transformation process of Fe (oxy)hydroxide solids to the more crystalline goethite (α-FeOOH) mineral for 99Tc removal and 2) determine the mechanism that limits 99Tc(IV) reoxidation in Fe(II)-treated 99Tc-goethite mineral and 3) evaluate whether there is a long-term 99Tcoxidation state change for Tc sequestered in the iron solids.

  12. Development of spray-dried co-precipitate of amorphous celecoxib containing storage and compression stabilizers.

    Science.gov (United States)

    Dhumal, Ravindra S; Shimpi, Shamkant L; Paradkar, Anant R

    2007-09-01

    The purpose of this study was to obtain an amorphous system with minimum unit operations that will prevent recrystallization of amorphous drugs since preparation, during processing (compression) and further storage. Amorphous celecoxib, solid dispersion (SD) of celecoxib with polyvinyl pyrrollidone (PVP) and co-precipitate with PVP and carrageenan (CAR) in different ratios were prepared by the spray drying technique and compressed into tablets. Saturation solubility and dissolution studies were performed to differentiate performance after processing. Differential scanning calorimetry and X-ray powder difraction revealed the amorphous form of celecoxib, whereas infrared spectroscopy revealed hydrogen bonding between celecoxib and PVP. The dissolution profile of the solid dispersion and co-precipitate improved compared to celecoxib and amorphous celecoxib. Amorphous celecoxib was not stable on storage whereas the solid dispersion and co-precipitate powders were stable for 3 months. Tablets of the solid dispersion of celecoxib with PVP and physical mixture with PVP and carrageenan showed better resistance to recrystallization than amorphous celecoxib during compression but recrystallized on storage. However, tablets of co-precipitate with PVP and carageenan showed no evidence of crystallinity during stability studies with comparable dissolution profiles. This extraordinary stability of spray-dried co-precipitate tablets may be attributed to the cushioning action provided by the viscoelastic polymer CAR and hydrogen bonding interaction between celecoxib and PVP. The present study demonstrates the synergistic effect of combining two types of stabilizers, PVP and CAR, on the stability of amorphous drug during compression and storage as compared to their effect when used alone.

  13. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 1. Optimization and controlled synthesis of chloride-intercalated LDH.

    Science.gov (United States)

    Sun, Xiaodi; Neuperger, Erica; Dey, Sandwip K

    2015-12-01

    Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl(-)-intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation method followed by hydrothermal treatment (HT) was achieved in three steps. First, a 2(4-1) design enabled the identification of influential parameters for MPS (i.e., salt concentration, molar ratio of carbonate to aluminum, solution addition rate, and interaction between salt concentration and stirring rate) and PSD (i.e., salt concentration and stirring rate), as well as the optimum coprecipitation conditions that result in a monodispersed PSD (i.e., low salt concentration and high stirring rate). Second, a preliminary explanation of the HT was suggested and the optimum HT conditions for obtaining ideal Gaussian PSD with chi-squared (χ(2))nanoparticles with MPS ∼200-500 nm. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Charging and ion adsorption behaviour of different iron (hydr)oxides

    NARCIS (Netherlands)

    Venema, P.

    1997-01-01

    Metal (hydr)oxides are of importance for many soil systems. All metal (hydr)oxides have a surface charge that varies with the pH. The variation in this surface charge is caused by adsorption and desorption of protons. The adsorption of cat- and anions on the metal (hydr)oxide surface is

  15. Hydroxide Solvation and Transport in Anion Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen [Univ. of Chicago, IL (United States); Wuhan Univ. (China); Tse, Ying-Lung Steve [Univ. of Chicago, IL (United States); Lindberg, Gerrick E. [Northern Arizona Univ., Flagstaff, AZ (United States); Knight, Chris [Argonne National Lab. (ANL), Argonne, IL (United States); Voth, Gregory A. [Univ. of Chicago, IL (United States)

    2016-01-27

    Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationic groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.

  16. PREPARATION OF LAYERED DOUBLE HYDROXIDES

    National Research Council Canada - National Science Library

    OGAWA, MAKOTO; INOMATA, KAZUYA

    2011-01-01

    Layered double hydroxides (LDHs) are class of materials with useful properties associated with their anion exchange abilities for a wide range of applications including bio and environmental problems...

  17. Incorporation of oxidized uranium into Fe (hydr)oxides during Fe(II) catalyzed remineralization

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Stewart, Brandy D.; Fendorf, Scott

    2009-07-01

    The form of solid phase U after Fe(II) induced anaerobic remineralization of ferrihydrite in the presence of aqueous and absorbed U(VI) was investigated under both abiotic batch and biotic flow conditions. Experiments were conducted with synthetic ground waters containing 0.168 mM U(VI), 3.8 mM carbonate, and 3.0 mM Ca{sup 2+}. In spite of the high solubility of U(VI) under these conditions, appreciable removal of U(VI) from solution was observed in both the abiotic and biotic systems. The majority of the removed U was determined to be substituted as oxidized U (U(VI) or U(V)) into the octahedral position of the goethite and magnetite formed during ferrihydrite remineralization. It is estimated that between 3% and 6% of octahedral Fe(III) centers in the new Fe minerals were occupied by U(VI). This site specific substitution is distinct from the non-specific U co-precipitation processes in which uranyl compounds, e.g. uranyl hydroxide or carbonate, are entrapped with newly formed Fe oxides. The prevalence of site specific U incorporation under both abiotic and biotic conditions and the fact that the produced solids were shown to be resistant to both extraction (30 mM KHCO{sub 3}) and oxidation (air for 5 days) suggest the potential importance of sequestration in Fe oxides as a stable and immobile form of U in the environment.

  18. Facile synthesis of radial-like macroporous superparamagnetic chitosan spheres with in-situ co-precipitation and gelation of ferro-gels.

    Directory of Open Access Journals (Sweden)

    Chih-Hui Yang

    Full Text Available Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan and co-precipitation (ferrous cations and ferric cations of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe(3O(4 nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0∼1000 µg/mL of the macroporous chitosan spheres. The result showed good viability (above 80% with alginate chitosan particles below 1000 µg/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.

  19. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun

    2017-01-01

    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...... the long-term Zn release capacity of LDHs complying with a release-on-demand behavior and serves as proof-of-concept that Zn-doped Mg-Fe-LDHs can be used as Zn fertilizers....

  20. Calcium phosphate coprecipitation greatly enhances transduction of cardiac myocytes and vascular smooth muscle cells by lentivirus vectors

    Science.gov (United States)

    Sakoda, Tsuyoshi; Kasahara, Nori; Kedes, Larry; Ohyanagi, Mitsumasa

    2007-01-01

    BACKGROUND Lentivirus vectors provide a delivery system that can both transduce nondividing cells and integrate transgenes into the genome of target cells without cytotoxicity. However, their relatively low transduction efficiency presents a significant obstacle to progress. OBJECTIVES In the present paper, a simple and easy method using calcium phosphate (CaPi) to enhance the efficiency of lentivirus gene transfer in both vascular smooth muscle cells and cardiac myocytes is reported. METHODS AND RESULTS Delivery of lentivirus vectors in the presence of CaPi coprecipitates increased vector-encoded transgene expression up to 13-fold. Of interest, the magnitudes of enhancement of transgene expression by CaPi coprecipitates in 293T cells, vascular smooth muscle cells and cardiac myocytes were greater during brief periods (10 min and 120 min) of virus-cell contact than during long periods (16 h). Moreover, with a short duration of incubation with CaPi coprecipitates (up to 120 min), there was little evidence of direct cell toxicity. CaPi coprecipitates had no effect on host range specificity of ecotropic viruses and thus appears to enhance transduction efficiency physiologically by facilitating physical interaction between virus and cell. CONCLUSIONS These data show that lentivirus with CaPi coprecipitates increases both the efficiency and the speed of gene transfer. These approaches provide an efficient method and an improved tool for research and possibly for therapy of cardiovascular diseases. PMID:18650994

  1. Neptunium(V) coprecipitation with calcite.

    Science.gov (United States)

    Heberling, Frank; Denecke, Melissa A; Bosbach, Dirk

    2008-01-15

    Coprecipitation experiments of Np(V) and U(VI) with calcite were performed in mixed-flow reactors under steady state conditions at room temperature for up to 400 h at precipitation rates of 1.0 x 10(-8) to 6.8 x 10(-8) mol/(m2 s). The saturation index with respect to calcite varied between 0.04 and 0.95. Initial Np(V) or U(VI) concentrations were 1 micromol/L, 0.01 mol/L NaCl was used as background electrolyte, and pH ranged from 7.8 to 12.8. Partition coefficients for Np(V) were in the range of 0.5-10.3, compared to 0.02 for U(VI). Np L(III) and U L(III) EXAFS were used to characterize the local structural environment of the incorporated actinides. In the case of U(VI), the structural environment is not unambiguously characterized. Our data suggest that Np(V) ions occupy calcium lattice sites. The two axial oxygen atoms of the linear neptunyl moiety substitute two calcite carbonate groups in the first coordination sphere. Thus, four carbonate groups coordinate the neptunyl-ion in a monodentate fashion with four equatorial oxygen atoms (Oeq) at 2.4 A and associated carbon atoms (C) at 3.2 A. The interatomic distances indicate slight structural relaxation of the carbonate groups from their ideal sites. A similar structural model has been reported for U(VI) incorporated into natural calcite.

  2. A coprecipitation-based validation methodology for interactions identified using protein microarrays.

    Science.gov (United States)

    Marina, Ovidiu; Duke-Cohan, Jonathan S; Wu, Catherine J

    2011-01-01

    Candidate interactions identified by high-throughput protein microarray screening require rigorous -confirmation. Such validation is time-consuming and labor-intensive using conventional techniques. We describe a medium-throughput validation protocol based on coprecipitation of biotin-labeled -proteins synthesized in vitro using a rabbit reticulocyte lysate-coupled transcription and translation system. As our experimental system is based on screening for serum antibodies, we also present methods on purifying immunoglobulin from serum and quantifying the amount of coprecipitated (immunoprecipitated) target protein on Western blot. This technique provides a sensitive confirmatory test allowing for the rapid elimination of false positives prior to more extensive validation and analysis of target interactions in their native environment.

  3. Synthesis and structure refinement of layered double hydroxides of ...

    Indian Academy of Sciences (India)

    Administrator

    water (specific resistance, 15 MΩ cm, Millipore Elix 3 water purification system) and dried at 60°C for 24 h. Detailed experimental conditions used for the synthesis of different LDHs are given in table 1. Control samples were obtained by co-precipitation using the Reichle. (1986) procedure. The mixed metal nitrate solutions ...

  4. Pulsed laser deposition of functionalized Mg-Al layered double hydroxide thin films

    Science.gov (United States)

    Vlad, A.; Birjega, R.; Tirca, I.; Matei, A.; Mardare, C. C.; Hassel, A. W.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.

    2018-02-01

    In this paper, magnesium-aluminium layered double hydroxide (LDH) has been functionalized with sodium dodecyl sulfate (DS) and deposited as thin film by pulsed laser deposition (PLD). Mg, Al-LDH powders were prepared by co-precipitation and used as reference material. Intercalation of DS as an anionic surfactant into the LDHs host layers has been prepared in two ways: co-precipitation (P) and reconstruction (R). DS intercalation occurred in LDH powder via both preparation methods. The films deposited via PLD, in particular at 532 and 1064 nm, preserve the organic intercalated layered structure of the targets prepared from these powders. The results reveal the ability of proposed deposition technique to produce functional composite organo-modified LDHs thin films.

  5. Ex vivo antimicrobial efficacy of the EndoVac system plus photodynamic therapy associated with calcium hydroxide against intracanal Enterococcus faecalis.

    Science.gov (United States)

    Miranda, R G; Santos, E B; Souto, R M; Gusman, H; Colombo, A P V

    2013-06-01

    To evaluate the ex vivo efficacy of the EndoVac system and photodynamic treatment (PDT) as adjuncts to chemomechanical debridement associated with calcium hydroxide (CaOH2 ) in reducing the levels of intracanal Enterococcus faecalis. One hundred and twenty-five sterile premolar teeth were conventionally accessed, prepared and then contaminated with E. faecalis (ATCC 29212) for 30 days. Teeth were randomly divided into 4 groups: Control (chemomechanical debridement with conventional irrigation); Endovac (chemomechanical debridement with EndoVac system); PDT (chemomechanical debridement with conventional irrigation and PDT) and Endovac+PDT (chemomechanical debridement with EndoVac and PDT). The irrigants used in all groups were 5.25% sodium hypochlorite and 17% EDTA. After treatment, an intracanal dressing (CaOH2 ) was applied in all canals for 7 days. Samples were obtained before (T1) and after the therapeutic procedures (T2) and, after intracanal medication (T3), plated onto BHI media and incubated (37 °C, 48 h) to determine the colony-forming units (CFU mL(-1) ). The overall mean cell counts (CFU mL(-1) ) of E. faecalis were high at the initial contamination (T1). A significant reduction (P < 0.05) of E. faecalis mean counts was observed in all groups from baseline (T1) to both post-therapy samplings (T2 and T3); no differences amongst the groups were detected. No significant change in bacterial counts from T2 to T3 was detected. The adjunctive use of the EndoVac system and the photodynamic treatment, in combination or not, was as effective as the conventional chemomechanical debridement associated with CaOH2 on reducing the counts of intracanal E. faecalis. © 2012 International Endodontic Journal. Published by Blackwell Publishing Ltd.

  6. Layered double hydroxides

    DEFF Research Database (Denmark)

    López Rayo, Sandra; Imran, Ahmad; Hansen, Hans Chr. Bruun

    2017-01-01

    A novel zinc (Zn) fertilizer concept based on Zn doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthetized, their chemical composition was analyzed and their nutrient release was studied in buffered solutions with different pH values. Uptake...... of Zn by barley (Hordeum vulgare cv. Antonia) was evaluated in short- (8 weeks), medium- (11 weeks) and long-term (28 weeks) experiments in quartz sand and in a calcareous soil enriched with Zn-doped Mg-Fe-LDHs. The Zn release rate of the Zn-doped Mg-Fe-LDHs was described by a first-order kinetics...

  7. Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abasht, Behzad, E-mail: abasht@gmail.com [Space Thruster Research Institute, Iranian Space Research Center, Tabriz (Iran, Islamic Republic of); Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Beitollahi, Ali; Mirkazemi, Seyyed Mohammad [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2016-12-15

    La-substituted hexagonal calcium ferrite, Ca{sub 1−X}La{sub X}Fe{sub 12}O{sub 19} (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe{sup 3+}/(Ca{sup 2+}+La{sup 2+}) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5 M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200 °C for constant calcination time of 1 h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200 °C for 1 h, indicates the formation of calcium hexaferrite and also α-Fe{sub 2}O{sub 3} besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe{sub 4}O{sub 7} and α-Fe{sub 2}O{sub 3} phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1–2 µm. The magnetic properties such as maximum magnetization (M{sub Max}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were measured from the hysteresis loops. Low values of coercive field (16.3 kA m{sup −1}) and maximum magnetization (50.6 A m{sup 2} kg{sup −1}) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200 °C. - Highlights: • In this

  8. Aspects of Solvent Chemistry for Calcium Hydroxide Medicaments

    Directory of Open Access Journals (Sweden)

    Basil Athanassiadis

    2017-10-01

    Full Text Available Calcium hydroxide pastes have been used in endodontics since 1947. Most current calcium hydroxide endodontic pastes use water as the vehicle, which limits the dissolution of calcium hydroxide that can be achieved and, thereby, the maximum pH that can be achieved within the root canal system. Using polyethylene glycol as a solvent, rather than water, can achieve an increase in hydroxyl ions release compared to water or saline. By adopting non-aqueous solvents such as the polyethylene glycols (PEG, greater dissolution and faster hydroxyl ion release can be achieved, leading to enhanced antimicrobial actions, and other improvements in performance and biocompatibility.

  9. Sorption mechanisms of chromate with coprecipitated ferrihydrite in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Mamun, Abdullah Al, E-mail: mamun@toki.waseda.jp [Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Morita, Masao, E-mail: masao.swimer@akane.waseda.jp [Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Matsuoka, Mitsuaki, E-mail: m-matsuoka@aoni.waseda.jp [Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Tokoro, Chiharu, E-mail: tokoro@waseda.jp [Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2017-07-15

    Highlights: • Coprecipitation showed twice the sorption density of simple adsorption at pH 5. • Mechanism shift from outer- to inner-sphere surface complexation at high Cr/Fe. • In coprecipitation the mechanism shift occurs at lower Cr/Fe ratios than adsorption. • Higher-molar-ratio bidentate binuclear Cr−Fe bonds; yielded ferrihydrite expansion. - Abstract: Hexavalent chromium (Cr(VI)) attracted researchers’ interest for its toxicity, natural availability and removal difficulty. Nevertheless, its sorption mechanism is not clearly understood yet. In this work, we elucidated the sorption mechanism of the co-precipitation of chromates with ferrihydrite through quantitative analysis. The influence of Cr/Fe molar ratio on sorption was investigated by zeta potential measurements, X-ray diffraction (XRD) and X-ray adsorption fine-structure analysis (XAFS). Coprecipitation at pH 5 showed almost twice the sorption density of adsorption at pH 5. In co-precipitation, a shift of the XRD peak due to inner-sphere sorption of chromate was observed at Cr/Fe molar ratio 0.5. For adsorption, the same peak shift was confirmed at Cr/Fe molar ratio of 1. Zeta potential at pH 5 suggested that the sorption mechanism changed at Cr/Fe molar ratio 0.25 for coprecipitation and at Cr/Fe molar ratio of 1 for adsorption. Fitting of Cr and Fe K-edge extended X-ray adsorption fine-structure suggested that ferrihydrite immobilized Cr(VI) via outer sphere surface complexation for lower Cr/Fe ratios and via inner-sphere surface complexation for higher molar ratios. At higher molar ratios, bidentate binuclear Cr−Fe bonds were well established, thus resulting in the expansion of the ferrihydrite structure.

  10. Review of the synthesis of layered double hydroxides: a thermodynamic approach

    Directory of Open Access Journals (Sweden)

    Bravo-Suárez Juan J.

    2004-01-01

    Full Text Available The synthesis of layered double hydroxides (LDHs by hydrothermal-LDH reconstruction and coprecipitation methods is reviewed using a thermodynamic approach. A mixture model was used for the estimation of the thermodynamics of formation of LDHs. The synthesis and solubility of LDHs are discussed in terms of standard molar Gibbs free energy change of reaction. Data for numerous divalent and trivalent metals as well as for some monovalent and tetravalent metals that may be part of the LDH structure have been compiled. Good agreement is found between theoretical and experimental data. Diagrams and tables for the prediction of possible new LDH materials are provided.

  11. Antituberculosis nanodelivery system with controlled-release properties based on para-amino salicylate–zinc aluminum-layered double-hydroxide nanocomposites

    Directory of Open Access Journals (Sweden)

    Saifullah B

    2013-11-01

    Full Text Available Bullo Saifullah,1 Mohd Zobir Hussein,1 Samer Hasan Hussein-Al-Ali,2 Palanisamy Arulselvan,3 Sharida Fakurazi3,41Materials Synthesis and Characterization Laboratory, 2Laboratory of Molecular Biomedicine, 3Laboratory of Vaccines and Immunotherapeutics, 4Department of Human Anatomy, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: We report the intercalation and characterization of para-amino salicylic acid (PASA into zinc/aluminum-layered double hydroxides (ZLDHs by two methods, direct and indirect, to form nanocomposites: PASA nanocomposite prepared by a direct method (PASA-D and PASA nanocomposite prepared by an indirect method (PASA-I. Powder X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis revealed that the PASA drugs were accommodated within the ZLDH interlayers. The anions of the drug were accommodated as an alternate monolayer (along the long-axis orientation between ZLDH interlayers. Drug loading was estimated to be 22.8% and 16.6% for PASA-D and PASA-I, respectively. The in vitro release properties of the drug were investigated in physiological simulated phosphate-buffered saline solution of pH 7.4 and 4.8. The release followed the pseudo-second-order model for both nanocomposites. Cell viability (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide [MTT] assays was assessed against normal human lung fibroblast MRC-5 and 3T3 mouse fibroblast cells at 24, 48, and 72 hours. The results showed that the nanocomposite formulations did not possess any cytotoxicity, at least up to 72 hours.Keywords: drug-delivery system, slow-release nanocarrier, tuberculosis, biocompatible nanocomposites

  12. 21 CFR 184.1428 - Magnesium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium hydroxide. 184.1428 Section 184.1428 Food... Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide (Mg(OH)2, CAS... a white precipitate by the addition of sodium hydroxide to a water soluble magnesium salt or by...

  13. Buffer storage of thermal energy using the reaction heat of the system calcium oxide/calcium hydroxide

    Science.gov (United States)

    Lehmann, B.

    1986-12-01

    The reaction heat of the system CaO/Ca(OH)2 was investigated as storage effect for thermal energy. The heat from the chemical system is used as a buffer facility for thermal energy, i.e., sensible heat is stored without thermal losses to the environment. In the forward reaction by adding water to the CaO, sensible heat is released, which can be used for heating houses or water, and for generation of steam for industrial purposes. The necessary heat to be fed to the Ca(OH)2 in order to run the reaction inversely can be supplied by solar collector, high temperature reactors, geothermal energy, or combustion of wastes. Heat at temperatures less than 450 C has to be furnished for the loading phase of the reaction. The discharging reaction delivers temperatures up to 400 C. A gas loop was designed, built, and operated to test this kind of heat storage. The quantities which determine the storage and release of energy were deduced and documented. Pressure drops and storage mass behavior are discussed.

  14. Hydroxide catalysts for lignin depolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Beckham, Gregg T.; Biddy, Mary J.; Chmely, Stephen C.; Sturgeon, Matthew

    2017-04-25

    Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

  15. Hydroxide catalysts for lignin depolymerization

    Science.gov (United States)

    Beckham, Gregg T; Biddy, Mary J.; Kruger, Jacob S.; Chmely, Stephen C.; Sturgeon, Matthew

    2017-10-17

    Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

  16. K (Na)-promoted Ni, Al layered double hydroxide catalysts for the steam reforming of methanol

    Science.gov (United States)

    Qi, Caixia; Amphlett, John C.; Peppley, Brant A.

    Production of hydrogen by methanol steam reforming has been studied over a series of Ni/Al layered double hydroxide catalysts prepared by the co-precipitation method, with the aim to develop a stable catalyst that can be used in a membrane-joint performer at temperatures greater than 300 °C. H 2, CO and CO 2 are generally the major products together with trace amounts of CH 4. The presence of potassium and/or sodium cations was found to improve the activity of methanol conversion. The selectivity for CO 2 rather than CO was better with K ions than Na ions, especially at higher temperatures (e.g. 390-400 °C). Methanol steam reforming over a K-promoted Ni/Al layered double hydroxide catalyst resulted in better activity and similar stability compared to a commercial Cu catalyst.

  17. Dissolution and pharmacokinetics of baicalin-polyvinylpyrrolidone coprecipitate.

    Science.gov (United States)

    Li, Bibo; He, Mei; Li, Wei; Luo, Zhibin; Guo, Ying; Li, Yajun; Zang, Chunbao; Wang, Bo; Li, Fang; Li, Shaolin; Ji, Ping

    2013-11-01

    Baicalin-polyvinylpyrrolidone coprecipitate was prepared with the aim of improving the dissolution and bioavailability of the baicalin. The dissolution of the coprecipitate in capsule form was tested and compared with baicalin active pharmaceutical ingredient (API) capsules. A sensitive high-performance liquid chromatography-ultraviolet detection method was established to determine the concentration of baicalin in plasma. The liquid-liquid extraction and solid phase extraction methods were used to pretreat the baicalin plasma sample. The pharmacokinetics of the coprecipitate capsules were tested and compared with the API capsules in six beagle dogs after crossover oral administration. The results of the dissolution demonstrated that the dissolution of the coprecipitate capsules was 21.02, 2.02 and 3.29 times that of the API capsules in 0.1 mol/l HCl solution, pH 4.5 solution and water, respectively, but it was slightly lower than that of the API capsules in a pH 6.8 solution. The calibration curve showed a good linearity at concentrations between 3.648 ng/mL and 364.8 ng/mL (r = 0.998). The baicalin plasma sample was successfully pretreated, with endogenous impurities almost completely removed. The pharmacokinetics of the coprecipitate capsules and the API capsules indicated that the mean values of Cmax were 127.04 ± 10.6 and 27.49 ± 36 μg/l, and those of AUC(0-24h) were 1080.23 ± 336.43 and 337.84 ± 127.64 μg/l × h, respectively. Compared with the baicalin API capsules, the relative bioavailability of the coprecipitate capsules was 338.2% ± 93.2%. From these observations of improved dissolution and pharmacokinetic behaviours, a good relationship was found in vitro and in vivo, indicating that the coprecipitate could be a promising formulation strategy for insoluble baicalin. © 2013 Royal Pharmaceutical Society.

  18. Delivery System For Mefenamic Acid Based On The Nanocarrier Layered Double Hydroxide: Physicochemical Characterization And Evaluation Of Anti-inflammatory And Antinociceptive Potential

    OpenAIRE

    Cunha; Vanessa R. R.; Guilherme; Viviane A.; de Paula; Eneida; de Araujo; Daniele R.; Silva; Renan O.; Medeiros; Jand V. R.; Leite; Jose R. S. A.; Petersen; Philippe A. D.; Foldvari; Marianna; Petrilli; Helena M.; Constantino; Vera R. L.

    2016-01-01

    Purpose: The anionic form of the drug mefenamic acid intercalated into the nanocarrier layered double hydroxide (LDH-Mef) was evaluated by anti-inflammatory and antinociceptive assays. Methods: The LDH-Mef material was characterized by a set of physicochemical techniques, which was supported by Density Functional Theory calculations. The pharmacological effects of LDH-Mef (40 wt% of drug) were evaluated by hemolytic, anti-inflammatory activity and antinociceptive assays. Results: In vivo assa...

  19. Nanocomposites of Magnetite and Layered Double Hydroxide for Recyclable Chromate Removal

    Directory of Open Access Journals (Sweden)

    Gyeong-Hyeon Gwak

    2016-01-01

    Full Text Available Nanocomposites containing magnetic iron oxide (magnetite nanoparticles and layered double hydroxide (LDH nanosheets were prepared by two different methods, exfoliation-reassembly and coprecipitation, for aqueous chromate adsorbent. According to X-ray diffraction, scanning electron microscopy, and atomic force microscopy, both nanocomposites were determined to develop different nanostructures; LDH nanosheets well covered magnetite nanoparticles with house-of-cards-like structure in exfoliation-reassembly method, while coprecipitation resulted in LDH particle formation along with magnetite nanoparticles. Zeta-potential measurement also revealed that the magnetite surface was effectively covered by LDH moiety in exfoliation-reassembly compared with coprecipitation. Time, pH, concentration dependent chromate adsorption tests, and magnetic separation experiments exhibited that both nanocomposites effectively adsorb and easily collect chromate. However, exfoliation-reassembly nanocomposite was determined to be slightly effective in chromate removal by ~10%. Chromate adsorbed nanocomposites could be regenerated by treating with bicarbonate and the regenerated nanocomposites preserved ~80% of chromate adsorption efficacy after three times of recycling.

  20. Organo-layered double hydroxides composite thin films deposited by laser techniques

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Vlad, A., E-mail: angela.vlad@gmail.com [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Zavoianu, R. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest 030018 (Romania); Raditoiu, V.; Corobea, M.C. [National R.& D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest (Romania)

    2016-06-30

    Highlights: • PLD and MAPLE was successfully used to produce organo-layered double hydroxides. • The organic anions (dodecyl sulfate-DS) were intercalated in co-precipitation step. • Zn2.5Al-LDH (Zn/Al = 2.5) and Zn2.5Al-DS thin films obtained in this work could be suitable for further applications as hydrophobic surfaces. - Abstract: We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn{sup 2+}/Al{sup 3+} ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  1. Effects of salinity and humic acid on the sorption of Hg on Fe and Mn hydroxides.

    Science.gov (United States)

    Liang, Peng; Li, Yi-Chun; Zhang, Chan; Wu, Sheng-Chun; Cui, Hao-Jie; Yu, Shen; Wong, Ming H

    2013-01-15

    The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg(2+) on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl(2) complexes in solution. Moreover, Cl(-) inhibited the Hg(2+) adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg(2+) adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg(2+) and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg(2+) adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl(-) and HA, and therefore the reducing of Cl(-) promoted more Hg(2+) on Fe and Mn hydroxides. In addition, the influence of HA on Hg(2+) adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Wet milling versus co-precipitation in magnetite ferrofluid preparation

    Directory of Open Access Journals (Sweden)

    Almásy László

    2015-01-01

    Full Text Available Various uses of ferrofluids for technical applications continuously raise the interest in improvement and optimization of preparation methods. This paper deals with preparation of finely granulated magnetite particles coated with oleic acid in hydrocarbon suspensions following either chemical co-precipitation from iron salt precursors or wet milling of micron size magnetite powder with the goal to compare the benefits and disadvantages of each method. Microstructural measurements showed that both methods gave similar magnetite particle size of 10-15 nm. Higher saturation magnetization was achieved for the wet-milled magnetite suspension compared to relatively rapid co-precipitation synthesis. Different efficacies of ferrophase incorporation into kerosene could be related to the different mechanisms of oleic acid bonding to nanoparticle surface. The comparative data show that wet milling represents a practicable alternative to the traditional co-precipitation since despite of longer processing time, chemicals impact on environment can be avoided as well as the remnant water in the final product.

  3. Study of calcium carbonate and sulfate co-precipitation

    KAUST Repository

    Zarga, Y.

    2013-06-01

    Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms. © 2013 Elsevier Ltd.

  4. Effect of agglomeration during coprecipitation: Delayed ...

    Indian Academy of Sciences (India)

    Administrator

    In the continuous technique (Samaddar et al 1979), pH was controlled by an automatic pH control system con- sisting of motorized ball valve, needle valve, spray gun and flow cell. The gel was precipitated at pH 9⋅2 ± 0⋅05, filtered, dried at 110°C until constant weight, and then the hard dried powder lumps were agated.

  5. Advances in aluminum hydroxide-based adjuvant research and its mechanism

    Science.gov (United States)

    He, Peng; Zou, Yening; Hu, Zhongyu

    2015-01-01

    In the past few decades, hundreds of materials have been tried as adjuvant; however, only aluminum-based adjuvants continue to be used widely in the world. Aluminum hydroxide, aluminum phosphate and alum constitute the main forms of aluminum used as adjuvants. Among these, aluminum hydroxide is the most commonly used chemical as adjuvant. In spite of its wide spread use, surprisingly, the mechanism of how aluminum hydroxide-based adjuvants exert their beneficial effects is still not fully understood. Current explanations for the mode of action of aluminum hydroxide-based adjuvants include, among others, the repository effect, pro-phagocytic effect, and activation of the pro-inflammatory NLRP3 pathway. These collectively galvanize innate as well as acquired immune responses and activate the complement system. Factors that have a profound influence on responses evoked by aluminum hydroxide-based adjuvant applications include adsorption rate, strength of the adsorption, size and uniformity of aluminum hydroxide particles, dosage of adjuvant, and the nature of antigens. Although vaccines containing aluminum hydroxide-based adjuvants are beneficial, sometimes they cause adverse reactions. Further, these vaccines cannot be stored frozen. Until recently, aluminum hydroxide-based adjuvants were known to preferentially prime Th2-type immune responses. However, results of more recent studies show that depending on the vaccination route, aluminum hydroxide-based adjuvants can enhance both Th1 as well as Th2 cellular responses. Advances in systems biology have opened up new avenues for studying mechanisms of aluminum hydroxide-based adjuvants. These will assist in scaling new frontiers in aluminum hydroxide-based adjuvant research that include improvement of formulations, use of nanoparticles of aluminum hydroxide and development of composite adjuvants. PMID:25692535

  6. Advances in aluminum hydroxide-based adjuvant research and its mechanism.

    Science.gov (United States)

    He, Peng; Zou, Yening; Hu, Zhongyu

    2015-01-01

    In the past few decades, hundreds of materials have been tried as adjuvant; however, only aluminum-based adjuvants continue to be used widely in the world. Aluminum hydroxide, aluminum phosphate and alum constitute the main forms of aluminum used as adjuvants. Among these, aluminum hydroxide is the most commonly used chemical as adjuvant. In spite of its wide spread use, surprisingly, the mechanism of how aluminum hydroxide-based adjuvants exert their beneficial effects is still not fully understood. Current explanations for the mode of action of aluminum hydroxide-based adjuvants include, among others, the repository effect, pro-phagocytic effect, and activation of the pro-inflammatory NLRP3 pathway. These collectively galvanize innate as well as acquired immune responses and activate the complement system. Factors that have a profound influence on responses evoked by aluminum hydroxide-based adjuvant applications include adsorption rate, strength of the adsorption, size and uniformity of aluminum hydroxide particles, dosage of adjuvant, and the nature of antigens. Although vaccines containing aluminum hydroxide-based adjuvants are beneficial, sometimes they cause adverse reactions. Further, these vaccines cannot be stored frozen. Until recently, aluminum hydroxide-based adjuvants were known to preferentially prime Th2-type immune responses. However, results of more recent studies show that depending on the vaccination route, aluminum hydroxide-based adjuvants can enhance both Th1 as well as Th2 cellular responses. Advances in systems biology have opened up new avenues for studying mechanisms of aluminum hydroxide-based adjuvants. These will assist in scaling new frontiers in aluminum hydroxide-based adjuvant research that include improvement of formulations, use of nanoparticles of aluminum hydroxide and development of composite adjuvants.

  7. 21 CFR 582.1428 - Magnesium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium hydroxide. 582.1428 Section 582.1428 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1428 Magnesium hydroxide. (a) Product. Magnesium hydroxide. (b) Conditions of use. This...

  8. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    Science.gov (United States)

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  9. Magnetically retrievable nickel hydroxide functionalised AFe2O4 (A = Mn, Ni) spinel nanocatalyst for alcohol oxidation

    Science.gov (United States)

    Bhat, Pooja B.; Bhat, Badekai Ramachandra

    2016-03-01

    Ultrasmall nickel hydroxide functionalised AFe2O4 (A = Mn, Ni) nanocatalyst was synthesized by traditional co-precipitation method and was examined for oxidation of aromatic alcohols to carbonyls using hydrogen peroxide as terminal oxidant. A very high surface area of 104.55 m2 g-1 was achieved for ferromagnetic MnFe2O4 and 100.50 m2 g-1 for superparamagnetic NiFe2O4, respectively. Efficient oxidation was observed due to the synergized effect of nickel hydroxide (bronsted base) on Lewis center (Fe) of the nanocatalyst. Catalyst recycling experiments revealed that the ultrasmall nanocatalyst can be easily recovered by external magnet and applied for nearly complete oxidation of alcohols for at least five successive cycles. Furthermore, the nickel hydroxide functionalised ultrasmall nanocatalyst exhibited higher efficiency for benzyl alcohol oxidation compared to Ni(OH)2, bare MnFe2O4 and NiFe2O4. Higher conversion rate was observed for nickel hydroxide functionalised NiFe2O4 compared to MnFe2O4. Ultrasmall magnetic nickel hydroxide functionalised nanocatalyst showed environmental friendly, greener route for the oxidation of alcohols without significant loss in activity and selectivity within successive runs.

  10. Sites of Lu(III) sorbed to and coprecipitated with hectorite.

    Science.gov (United States)

    Finck, Nicolas; Schlegel, Michel L; Bosbach, Dirk

    2009-12-01

    The Lu(III) binding mechanisms by trioctahedral smectite hectorite in aqueous systems were investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy. Coprecipitated hectorite (Lu755Hec), its precursor phase (Lu/Brucite), and the surface sorbed hectorite (Lu/SHCa1) were prepared as oriented samples to collect polarized EXAFS (P-EXAFS) data. EXAFS analysis indicated that Lu(III) is 6-fold coordinated by oxygen in Lu/Brucite and in Lu755Hec, and surrounded by Mg/Si shells. The angular dependence of the O and Mg coordination numbers for Lu/Brucite hinted an Lu(III) incorporation in brucite layers. Mg and Si cationic shells were detected at distances suggesting a clay-like octahedral environment in Lu755Hec. EXAFS data for Lu/SHCa1 were consistent with Lu(III) forming inner-sphere surface complexes at hectorite platelets edges, but slightly above/below the octahedral plane. Finally, Lu(III) polyhedra share edge(s) and corner(s) with Si tetrahedra upon sorption to silica (Lu/Silica). Lu(III) binding to silicate oligomers or to silicate groups of the clay basal planes and formation of Lu(III) surface complexes during the coprecipitation experiment are marginal.

  11. Homogeneous nucleation of magnesium hydroxide.

    Science.gov (United States)

    Klein, D H; Smith, M D; Driy, J A

    1967-08-01

    The rate of homogeneous nucleation of magnesium hydroxide has been determined as a function of solution concentration, using a quasi-homogeneous precipitation technique and electronic particle counting. The nucleation rate becomes measurable at super-saturations of about 4, and is dependent on the 33rd power of the product aMgaOH(2). The experimental results are consistent with nucleation theory. The nucleus-solution interfacial energy is calculated to be 115 erg/cm(2).

  12. Pulsed laser deposition of Mg-Al layered double hydroxide with Ag nanoparticles

    Science.gov (United States)

    Matei, A.; Birjega, R.; Vlad, A.; Luculescu, C.; Epurescu, G.; Stokker-Cheregi, F.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2013-03-01

    Powdered layered double hydroxides (LDHs)—also known as hydrotalcite-like (HT)—compounds have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic or organic molecules. Assembling thin films of nano-sized LDHs onto flat solid substrates is an expanding area of research, with promising applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. The exploitation of LDHs as vehicles to carry dispersed metal nanoparticles onto a substrate is a new approach to obtain composite thin films with prospects for biomedical and optical applications. We report the deposition of thin films of Ag nanoparticles embedded in a Mg-Al layered double hydroxide matrix by pulsed laser deposition (PLD). The Ag-LDH powder was prepared by co-precipitation at supersaturation and pH = 10 using aqueous solutions of Mg and Al nitrates, Na hydroxide and carbonate, and AgNO3, having atomic ratios of Mg/Al = 3 and Ag/Al = 0.55. The target to be used in laser ablation experiments was a dry pressed pellet obtained from the prepared Ag-LDH powder. Three different wavelengths of a Nd:YAG laser (266, 532 and 1064 nm) working at a repetition rate of 10 Hz were used. X-Ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and secondary ions mass spectrometry (SIMS) were used to investigate the structure, surface morphology and composition of the deposited films.

  13. [Sorption of nitrobenzene to anionic surfactant modified layered double hydroxides].

    Science.gov (United States)

    Xia, Yan; Zhu, Run-Liang; Tao, Qi; Liu, Han-Yang

    2013-01-01

    Sodium dodecyl sulfate (SDS) modified MgAl layered double hydroxides (LDHs) were synthesized at different surfactant concentrations (0.5-2.0 TAEC) by the co-precipitation method. The LDH-DS samples obtained were characterized by powder X-ray diffraction and FT-IR spectroscopy. The results showed that SDS was successfully intercalated into the interlayer of the LDH, and the basal spacing was expanded from 0.80 nm to 3.98 nm. The intercalated SDS was considered consistent with a paraffin bilayers arrangement. The sorption of nitrobenzene on LDH-DS was examined, and the results showed that linear model could fit the sorption isotherms well (R2 > 0.99), which implied a partitioning sorption process. The sorption coefficient of nitrobenzene (K(d)) on LDH-DS was positively related to the DS - loading amount, but the organic carbon content normalized sorption coefficient of nitrobenzene (K(oc)) was shown to remain relatively constant. The sorption thermodynamics results showed that the sorption of nitrobenzene on LDH-DS was an endothermic process, and the increase of entropy was the driving force for the sorption process.

  14. Copper removal from oil-field brine by coprecipitation.

    Science.gov (United States)

    Khosravi, Jafar; Alamdari, Abdolmohammad

    2009-07-30

    The present study aims at investigation of copper removal from oil-field brine by coprecipitation process. The produced brine containing heavy metals is usually returned to the reservoir for water flooding or is discarded to the surroundings. Therefore, surface waters or underground waters may be polluted due to probable contact to these discarded waters. Removal experiments were carried out at room temperature in a bench-scale crystallizer equipped with a draft tube. In order to gain an insight into the influence of soluble compounds in the industrial natural brine on the precipitation process, some comparative experiments were performed both on a sample of natural brine and on a synthetic simulated brine in the absence of natural impurities. A metal removal practice by coprecipitation of copper through CaCO(3) precipitates induced by reaction of Na(2)CO(3) and CaCl(2) reduced the copper concentration (Cu(2+)) from 0.27 ppm in the synthetic brine to 0.06 ppm. This removal of 78% required only 1g of precipitate per 0.15 mg copper metal. Analysis of the experimental results suggested that about 5% of the copper removal from the synthetic brine was through the mechanism of incorporation into the crystal lattice, and around 95% was through the adsorption on the crystal faces.

  15. Study of the Influence Between Barium Ions and Calcium Ions on Morphology and Size of Coprecipitation in Microemulsion

    Science.gov (United States)

    Wang, Nong; Meng, Qing Luo

    2015-03-01

    In this paper, we systematically drew a series of inverse-microemulsion quasi-ternary system phase diagrams of OP-10+C8H17OH+C6H12+brine (CaCl2/BaCl2) by adjusting the ratio of CaCl2 and BaCl2. On this basis, microemulsions have been prepared with seven different molar ratios of Ca2+/Ba2+, and calcium carbonate and barium carbonate coprecipitation products were obtained by reaction with an equimolar amount of sodium carbonate. The influence of barium ion to morphology and composition of nanometer calcium carbonate were studied. These samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca2+ was higher, some incomplete large cube of coprecipitation particles were formed in solution, but with the content of Ba2+ increased gradually, they formed a large number of small spherical particles, with the further increase of Ba2+ concentration, the particles mainly had structures of irregular polyhedron eventually. The measurement results of FTIR and XRD indicated that CaCO3 coprecipitation products gradually changed from calcite to the vaterite, eventually turned into being aragonite with the further increase of Ba2+ concentration.

  16. Producing Amorphous Solid Dispersions via Co-Precipitation and Spray Drying: Impact to Physicochemical and Biopharmaceutical Properties.

    Science.gov (United States)

    Mann, Amanda K P; Schenck, Luke; Koynov, Athanas; Rumondor, Alfred C F; Jin, Xiaoling; Marota, Melanie; Dalton, Chad

    2018-01-01

    Many small-molecule active pharmaceutical ingredients (APIs) exhibit low aqueous solubility and benefit from generation of amorphous dispersions of the API and polymer to improve their dissolution properties. Spray drying and hot-melt extrusion are 2 common methods to produce these dispersions; however, for some systems, these approaches may not be optimal, and it would be beneficial to have an alternative route. Herein, amorphous solid dispersions of compound A, a low-solubility weak acid, and copovidone were made by conventional spray drying and co-precipitation. The physicochemical properties of the 2 materials were assessed via X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, and scanning electron microscopy. The amorphous dispersions were then formulated and tableted, and the performance was assessed in vivo and in vitro. In human dissolution studies, the co-precipitation tablets had slightly slower dissolution than the spray-dried dispersion, but both reached full release of compound A. In canine in vitro dissolution studies, the tablets showed comparable dissolution profiles. Finally, canine pharmacokinetic studies showed that the materials had comparable values for the area under the curve, bioavailability, and Cmax. Based on the summarized data, we conclude that for some APIs, co-precipitation is a viable alternative to spray drying to make solid amorphous dispersions while maintaining desirable physicochemical and biopharmaceutical characteristics. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  17. Effect of pH variation on the stability and structural properties of In(OH){sub 3} nanoparticles synthesized by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Kian Wei; Wong, Yew Hoong [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia); Johan, Mohd Rafie [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia); University of Malaya, Nanotechnology and Catalysis Research Centre, Kuala Lumpur (Malaysia)

    2016-10-15

    Indium hydroxide (In(OH){sub 3}) nanoparticles were synthesized at various pH values (8-11) by co-precipitation method. Its properties were characterized by X-ray diffractometer, Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscope. The electrostatic stability of nanoparticles is carried out through zeta potential measurement. The crystallite size of nanoparticles calculated by Scherrer equation has similar trend with the values obtained from William-Hall plot. TEM images show that the particles size is within the range of 11.76-20.76 nm. The maximum zeta potential is 3.68 mV associated with the smallest particle size distribution of 92.6 nm occurred at pH 10. Our work clearly confirms the crystallite size, stability and the morphology of In(OH){sub 3} NPs are strongly depending on the pH of precursor solution. (orig.)

  18. Study of the hyperfine properties of the nickel-zinc ferrite using coprecipitation process; Estudo das propriedades hiperfinas de ferrita de niquel e zinco obtida por coprecipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Adriana Silva de; Almeida Macedo, Waldemar Augusto de [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1996-09-01

    In this work were studied the synthesis by coprecipitation of the Ni Zn ferrite, Ni {sub 0,5} Zn{sub 0,5} Fe{sub 2} O{sub 4}``, and its hyperfine properties. The ferrite specimens were prepared using metallic nitrates in aqueous solutions as precursor agents and the precipitation processes were promoted by addition of ammonium or sodium hydroxide. The obtained powders were calcined and characterized by X-ray diffraction and fluorescence, and by {sup 57} Fe Moessbauer spectroscopy. The liquid phase was analysed by atomic absorption. The samples of stoichiometric Ni Zn ferrite were obtained using Na O H as precipitating agent. The ferrite powders presented different particles size related with changing in the preparation method,and then, different hyperfine properties. Moessbauer effect measurements reveled the superparamagnetic nature of the ferrite samples that presented particles size smaller than 30 nm. (author) 9 refs., 3 figs., 3 tabs.

  19. Dynamic monitoring of structural changes in nickel hydroxide electrodes during discharge in batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, M.; Becker, D.; Garaventta, G.; Visintin, A.; Castro, E.B. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata (Argentina); Real, S.G., E-mail: sreal@inifta.unlp.edu.ar [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 16, Suc. 4, 1900 La Plata (Argentina)

    2011-09-30

    The nickel hydroxide electrode is used as the positive plate of many rechargeable battery systems such as the nickel/cadmium, nickel/hydrogen, and nickel/metal hydrides. The electrochemical energy storage in the nickel hydroxide electrodes is related to the reversible characteristics of the redox couple nickel hydroxide/ox hydroxide. In the present work we describe the use of the electrochemical impedance spectroscopy (EIS) technique as a tool to characterize the dynamic behaviour of nickel hydroxide electrodes at different states of discharge (SOD) in KOH 7 M electrolytic solutions. The parameter identification procedure allows the estimation of the active area per unit volume, the solution conductivity as well as diffusion and kinetic constants related to the process, that represent very important parameters to evaluate the electrode performance.

  20. FACILE SYNTHESIS OF SEMICONDUCTING NANOSIZED 0D AND 2D LEAD OXIDES USING A MODIFIED CO-PRECIPITATION METHOD

    Directory of Open Access Journals (Sweden)

    Ahmet Güngör

    2017-09-01

    Full Text Available Nano-sized lead has many versatile applications that could be applied in daily life. In the current study, we report a comprehensive study for preparation of nanosized lead oxide using the co-precipitation method and optimization of reaction parameters to obtain lead oxide (PbO nanoparticles with homogeneously distributed size, shape and structure. When aqueous solution of lead (II acetate reduced with sodium hydroxide at elevated temperatures, alpha form of lead oxide nanoparticles, with spherical shape were achieved. Decreasing the ratio of sodium hydroxide to lead (II acetate concentration at moderate temperatures resulted with a gradual change in crystal structure from quasi -spherical α-PbO nanoparticles and two dimensional nanoflakes of beta PbO with a thickness below 100 nm was synthesized for the first time. The obtained particles in both α and b forms were characterized by X-ray powder diffraction (XRD, dynamic light scattering equipment (Zetasizer, transmission electron microscopy (TEM, scanning electron microscopy (SEM and Fourier transform infrared spectroscopy (FTIR. Finally, thin layers of freeze-dryer α-PbO and β-PbO particle powder on glass and filter paper were formed by the help of nail polisher and conductivity measurements were performed using four-point probes method. Produced layers β-PbO particles with a below 100 nm showed higher conductivity on both supports as compared to the ones produced from spherical α-PbO nanoparticles. This altered conductivity of the material in the semiconducting zone, which is probably due to a more effective electron transfer facilitated by 2D alignment of the molecules, could rose the potential use of this material in voltaic and catalysis.

  1. Influencing factors in the CO-precipitation process of superparamagnetic iron oxide nano particles: A model based study

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Hans-Christian; Schwaminger, Sebastian P.; Schindler, Michael [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany); Wagner, Friedrich E. [Technische Universität München, Physics Department El5, Garching d-85748 (Germany); Berensmeier, Sonja, E-mail: s.berensmeier@tum.de [Bioseparation Engineering Group, Technische Universität München, Boltzmannstraße 15, Garching d-85748 (Germany)

    2015-03-01

    The study, presented here, focuses on the impact of synthesis parameters on the co-precipitation process of superparamagnetic iron oxide nanoparticles. Particle diameters between 3 and 17 nm and saturation magnetizations from 26 to 89 Am{sup 2} kg{sup −1} were achieved by variation of iron salt concentration, reaction temperature, ratio of hydroxide ions to iron ions and ratio of Fe{sup 3+}/Fe{sup 2+}. All synthesis assays were conceived according to the “design of experiments” method. The results were fitted to significant models. Subsequent validation experiments could confirm the models with an accuracy>95%. The characterization of the chemical composition, as well as structural and magnetic properties was carried out using powder X-ray diffraction, transmission electron microscopy, Raman and Mössbauer spectroscopy and superconducting quantum interference device magnetometry. The results reveal that the particles' saturation magnetization can be enhanced by the employment of high iron salt concentrations and a molar ratio of Fe{sup 3+}/Fe{sup 2+} below 2:1. Furthermore, the particle size can be increased by higher iron salt concentrations and a hyperstoichiometric normal ratio of hydroxide ions to iron ions of 1.4:1. Overall results indicate that the saturation magnetization is directly related to the particle size. - Highlights: • We model the impact of synthesis parameters in the Massart process. • Optimization of synthesis parameters according to particle size and magnetization. • Particles are fully characterized with XRD, TEM and SQUID magnetometry.

  2. A magnesium hydroxide preconcentration/matrix reduction method for the analysis of rare earth elements in water samples using laser ablation inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Hsieh, Hui-Fang; Chen, Yi-Hsiang; Wang, Chu-Fang

    2011-08-15

    This paper describes a simple method for simultaneous preconcentration and matrix reduction during the analysis of rare earth elements (REEs) in water samples through laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). From a systematic investigation of the co-precipitation of REEs using magnesium hydroxide, we optimized the effects of several parameters - the pH, the amount of magnesium, the shaking time, the efficiency of Ba removal, and the sample matrix - to ensure quantitative recoveries. We employed repetitive laser ablation to remove the dried-droplet samples from the filter medium and introduce them into the ICP-MS system for determinations of REEs. The enrichment factors ranged from 8 to 88. The detection limit, at an enrichment factor of 32, ranged from 0.03 to 0.20 pg mL(-1). The relative standard deviations for the determination of REEs at a concentration of 1 ng mL(-1) when processing 40 mL sample solution were 2.0-4.8%. We applied this method to the satisfactory determination of REEs in lake water and synthetic seawater samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Solid-state 29Si NMR and FTIR analyses of lignin-silica coprecipitates

    DEFF Research Database (Denmark)

    Cabrera Orozco, Yohanna; Cabrera, Andrés; Larsen, Flemming Hofmann

    2016-01-01

    investigated by characterizing lignin and silica coprecipitates by FTIR and solid state NMR. Silica particles were coprecipitated with three different lignins, three lignin model compounds, and two silanes representing silica-in-lignin model compounds. Comparison of 29Si SP/MAS NMR spectra revealed differences...

  4. Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Harzali, Hassen, E-mail: harzali@mines-albi.fr [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Saida, Fairouz; Marzouki, Arij; Megriche, Adel [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Baillon, Fabien; Espitalier, Fabienne [Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, F-81013 Albi CT cedex 09 (France); Mgaidi, Arbi [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Taibah University, Faculty of Sciences & art, Al Ula (Saudi Arabia)

    2016-12-01

    Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P{sub diss}=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

  5. Determination of rare earth elements and other trace elements (Y, Mn, Co, Cr) in seawater using Tm addition and Mg(OH)₂ co-precipitation.

    Science.gov (United States)

    Freslon, Nicolas; Bayon, Germain; Birot, Dominique; Bollinger, Claire; Barrat, Jean Alix

    2011-07-15

    This paper reports on a novel procedure for determining trace element abundances (REE and Y, Cr, Mn, Co) in seawater by inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The procedure uses a combination of pre-concentration using co-precipitation onto magnesium hydroxides and addition of thulium spike. The validity of the method was assessed onto 25 ml volumes of certified reference materials (NASS- and CASS-4) and in house seawater standard. Procedural blanks were determined by applying the same procedure to aliquots of seawater previously depleted in trace elements by successive Mg(OH)(2) co-precipitations, yielding estimated contributions to the studied samples better than 1.1% for all elements, with the exception of Cr (<3.3%) and Co (up to 8%). The reproducibility of the method over the six month duration of the study was smaller than 11% RSD for all the studied elements. Results obtained for NASS-5 and CASS-4 agree well with published working values for trace elements. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Modeling packed bed sorbent systems with the Pore Surface Diffusion Model: Evidence of facilitated surface diffusion of arsenate in nano-metal (hydr)oxide hybrid ion exchange media.

    Science.gov (United States)

    Dale, Sachie; Markovski, Jasmina; Hristovski, Kiril D

    2016-09-01

    This study explores the possibility of employing the Pore Surface Diffusion Model (PSDM) to predict the arsenic breakthrough curve of a packed bed system operated under continuous flow conditions with realistic groundwater, and consequently minimize the need to conduct pilot scale tests. To provide the nano-metal (hydr)oxide hybrid ion exchange media's performance in realistic water matrices without engaging in taxing pilot scale testing, the multi-point equilibrium batch sorption tests under pseudo-equilibrium conditions were performed; arsenate breakthrough curve of short bed column (SBC) was predicted by the PSDM in the continuous flow experiments; SBC tests were conducted under the same conditions to validate the model. The overlapping Freundlich isotherms suggested that the water matrix and competing ions did not have any denoting effect on sorption capacity of the media when the matrix was changed from arsenic-only model water to real groundwater. As expected, the PSDM provided a relatively good prediction of the breakthrough profile for arsenic-only model water limited by intraparticle mass transports. In contrast, the groundwater breakthrough curve demonstrated significantly faster intraparticle mass transport suggesting to a surface diffusion process, which occurs in parallel to the pore diffusion. A simple selection of DS=1/2 DP appears to be sufficient when describing the facilitated surface diffusion of arsenate inside metal (hydr)oxide nano-enabled hybrid ion-exchange media in presence of sulfate, however, quantification of the factors determining the surface diffusion coefficient's magnitude under different treatment scenarios remained unexplored. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Tribological performance of Mg/Al/Ce layered double hydroxides nanoparticles and intercalated products as lubricant additives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo; Qin, Haojing; Zuo, Ranfang; Bai, Zhimin, E-mail: zhimibai@cugb.edu.cn

    2015-10-30

    Highlights: • Mg/Al/Ce layered double hydroxides (LDHs) were synthesized by coprecipitation. • Mg/Al/Ce LDHs were intercalated with succinic acid and lauric acid respectively. • LDHs intercalated with lauric acid had the best friction properties among products. • Sliding of layers, good dispersity and a protective film decided the performance. - Abstract: Mg/Al/Ce ternary layered double hydroxides (LDHs) were synthesized via coprecipitation and intercalated by succinic acid and lauric acid through ion exchange method respectively. The LDHs products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). Tribological properties of LDHs as lubricant additives were evaluated by four-ball friction and air compressor test. The results indicated that Mg/Al/Ce LDHs were prepared successfully with Ce/Al molar ratio of 0.05 and crystallization temperature of 140 °C. The interlayer spacing of LDHs precursor was expanded by succinic acid and lauric acid to 8.838 and 17.519 Å respectively. All the three LDHs products can reduce friction and wear of engine lubricating oil in the tests. LDHs intercalated with lauric acid showed best tribological performance among them which was attributed to sliding each other between laminates, good dispersibility in oil medium and a protective tribofilm formed on the worn surface.

  8. [Inclusion of proteins into polyelectrolyte microcapsules by coprecipitation and adsorption].

    Science.gov (United States)

    Kochetkova, O Iu; Kazakova, L I; Moshkov, D A; Vinokurov, M G; Shabarchina, L I

    2013-01-01

    In present study microcapsules composed of synthetic (PSS and PAA) and biodegradable (DS and PAr) polyelectrolytes on calcium carbonate microparticles were obtained. The ultrastructural organization of biodegradable microcapsules was studied using transmission electron microscopy. The envelope of such capsules consisting of six polyelectrolyte layers is already well-formed, having the average thickness of 44 ± 3.0 nm, and their internal polyelectrolyte matrix is sparser compared to the synthetic microcapsules. Spectroscopy was employed to evaluate the efficiency of incorporation of FITC-labeled BSA into synthetic microcapsules by adsorption, depending on the number of polyelectrolyte layers. It was shown that the maximal amount of protein incorporated into the capsules with 6 or 7 polyelectrolyte layers (4 and 2 pg/capsule, correspondingly). As a result we conclude that, in comparison with co-precipitation, the use of adsorption allows to completely avoid the loss of protein upon encapsulation.

  9. Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

    2015-01-01

    Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track....... The fractionation of Cr isotopes during calcium carbonate coprecipitation was assumed to be small, based on previously published data of modern seawater and modern non-skeletal marine carbonates. However, results from this study for rapidly precipitated calcium carbonate in the presence of chromate show a tendency...... showed the presence of vaterite. Calcium carbonate crystals were also precipitated in a double diffusion silica hydrogel over a longer period of time resulting in samples consisting of micrometric-millimetric calcite crystals, which were again significantly enriched in heavy Cr isotopes compared...

  10. Removal of calcium hydroxide from Weine Type II systems using photon-induced photoacoustic streaming, passive ultrasonic, and needle irrigation: a microcomputed tomography study

    Directory of Open Access Journals (Sweden)

    Adam LLOYD

    Full Text Available ABSTRACT Objective This study compared the effectiveness of Er:YAG laser-activated irrigation (PIPS, passive ultrasonic irrigation (PUI with EndoUltra and standard needle irrigation (SNI in the removal of calcium hydroxide [Ca(OH2] from the mesial roots of Weine Type II mandibular molars. Material and Methods Thirty mandibular molars were screened by µCT for the presence of mesial roots with complex intra-canal anatomy and a common apical foramen. The teeth were enlarged to a standardized 25/.06 preparation and filled with Ca(OH2 paste. Specimens were divided into three groups (n=10 according to the technique used for Ca(OH2 removal: PIPS, at 15 Hz and 20 mJ using a 9 mm long, 600 µm diameter tip; PUI using a 15/.02 tip; and SNI (30 Ga. side-vented needle. Equal volumes of 8.25% NaOCl and 17% EDTA were used in all groups. µCT was used to measure the initial amount of Ca(OH2 present and to assess the residual volume of Ca(OH2 following each irrigation protocol. Data were analyzed using Tukey HSD and Kruskal-Wallis tests (α=5%. Results The mean volume of Ca(OH2 before removal was significantly higher in the coronal third than in the middle and apical third (p0.05. PIPS (median 0%; IQR: 0-0 showed significant higher Ca(OH2 removal in the apical third than PUI (median 100%, IQR: 85-100 and SNI (median 47%; IQR: 16-72 (p<0.001. Conclusions PIPS laser-activation was more effective for the removal of Ca(OH2 from mesial roots of mandibular molars with Weine Type II canal configurations than PUI with EndoUltra and SNI.

  11. Ultrasonically Activated Irrigation to Remove Calcium Hydroxide from Apical Third of Human Root Canal System: A Systematic Review of In Vitro Studies.

    Science.gov (United States)

    Ethem Yaylali, Ibrahim; Kececi, Ayse Diljin; Ureyen Kaya, Buglem

    2015-10-01

    The aim of this systematic review was to summarize the outcomes of in vitro studies comparing ultrasonically activated irrigation versus other irrigation techniques for removing calcium hydroxide (Ca[OH]2) from the apical third of root canals. The research question was developed according to the PICO strategy. A comprehensive literature search was performed. The Medline, Embase, and TRIP electronic databases were searched. A hand search of the reference lists of identified articles was performed to isolate relevant articles. Two reviewers critically assessed the studies against our inclusion and exclusion criteria. Evaluation of the risk of bias of the studies was performed independently by the 2 reviewers. After study selection, 62 were assessed for eligibility. Of these, 9 met the inclusion criteria and were included in the systematic review. Because considerable heterogeneity was found in the methodologies, it was not possible to combine the results of studies in a meta-analysis. Ultrasonically activated irrigation was found to be superior to syringe irrigation and apical negative pressure irrigation, but insufficient evidence was found to indicate its superiority over the other irrigation techniques such as sonically activated irrigation, the Self-Adjusting File, (ReDent-Nova, Ra'anana, Israel) and the RinsEndo, (Dürr Dental, Bietigheim, Germany). On the basis of available evidence, we determined the effectiveness of ultrasonically activated irrigation compared with syringe and apical negative pressure irrigation. Because of the small sample sizes, low number of included studies, and limitations, further research is needed to confirm our results. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Preparation and characterization of polyol assisted ultrafine Cu–Ni–Mg–Ca mixed ferrite via co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Boobalan, T. [Park College of Engineering and Technology, Coimbatore (India); Pavithradevi, S. [Department of Physics, Government College of Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: nsuri22@gmail.com [Department of Physics, PSG Polytechnic College, Coimbatore (India); Manivel Raja, M. [Defence Metallurgical Research Laboratory, Ministry of Defence, Govt. of India, Hyderabad (India); Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Dr. NGP Institute of Technology, Coimbatore (India)

    2017-04-15

    Nanocrystalline spinel ferrite of composition Cu{sub 0.2}Ni{sub 0.2}Mg{sub 0.2}Ca{sub 0.4}Fe{sub 2}O{sub 4} is synthesized by wet hydroxyl co-precipitation method in ethylene glycol as chelating agent and sodium hydroxide as precipitator at pH 8. Ethylene glycol is utilized as the medium which serves as the dissolvable and in addition a complexing specialist. The synthesized particles are annealed at various temperatures. Thermogravimetric investigation affirms that at 280 °C ethylene glycol is dissipated totally and stable phase arrangement happens over 680 °C. FTIR spectra of as synthesized and annealed at 1050 °C recorded between 400 cm{sup −1} and 4000 cm{sup −1}. Structural characterizations of all the samples are carried out by X-ray diffraction (XRD) technique. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) affirm that the particles are spherical and cubic shape with the crystallite size of 12 nm to 32 nm. Magnetic measurements are performed utilizing vibrating sample magnetometer at room temperature. - Highlights: • Polyol improves purity of the spinel ferrite. • TG curves confirm the single phase ferrite is obtained above 680 °C. • Super paramagnetic behavior is seen at lower annealing temperature. • Soft ferromagnetic behavior is obtained at 1050 °C.

  13. Preparation and inhibition properties of molybdate intercalated ZnAlCe layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Huajie; Wang, Jihui, E-mail: jhwang@tju.edu.cn; Zhang, Yu; Hu, Wenbin

    2016-09-05

    ZnAlCe layered double hydroxide intercalated by molybdate (ZnAlCe−MoO{sub 4} LDH) was successfully synthesized by using co-precipitation method, and the morphology, structure of ZnAlCe−MoO{sub 4} LDH were observed and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. The inhibition behavior of ZnAlCe−MoO{sub 4} LDH for Q235 steel in 3.5%NaCl solution was determined by polarization curves, electrochemical impedance spectroscopy (EIS), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray photoelectron spectrometer (XPS) methods. The results shows that the synthesized ZnAlCe−MoO{sub 4} LDH has a lamellar structure with a particle size of 0.1–2.0 μm, an average thickness of 30 nm, and a basal plane spacing of 0.898 nm. Compared with the addition of ZnAl layered double hydroxide intercalated by nitrate (ZnAl−NO{sub 3} LDH) and ZnAl layered double hydroxide intercalated by molybdate (ZnAl−MoO{sub 4} LDH) in 3.5% NaCl solution, Q235 steel in 3.5%NaCl + ZnAlCe−MoO{sub 4} LDH solution has a lower corrosion current density, larger polarization resistance and a higher inhibition efficiency. The addition of ZnAlCe−MoO{sub 4} LDH will reduce the chloride concentration in 3.5% NaCl solution by the anion exchanged with molybdate, and improve the corrosion resistance of Q235 steel owing to the formation of passive film with the composition of ferrous or iron molybdate and deposition film with zinc and cerium hydroxides. - Highlights: • ZnAlCe−MoO{sub 4} LDH compound was successfully synthesized by co-precipitation method. • ZnAlCe−MoO{sub 4} LDH has a better inhibition effect to Q235 steel in 3.5%NaCl solution. • The Cl{sup −} ions in solution was partially exchanged with MoO{sub 4}{sup 2−} ions in host layers. • The passive film and deposition film were formed by the release of LDH compound.

  14. Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides

    Directory of Open Access Journals (Sweden)

    V. Jovanov

    2017-02-01

    Full Text Available The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %, was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency after the water rinsing procedure.

  15. Silver Orthophosphate Immobilized on Flaky Layered Double Hydroxides as the Visible-Light-Driven Photocatalysts

    Directory of Open Access Journals (Sweden)

    Xianlu Cui

    2012-01-01

    Full Text Available Flaky layered double hydroxide (FLDH was prepared by the reconstruction of its oxide in alkali solution. The composites with FLDH/Ag3PO4 mass ratios at 1.6 : 1 and 3 : 1 were fabricated by the coprecipitation method. The powders were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscope, and UV-vis diffuse reflectance spectroscopy. The results indicated that the well-distributed Ag3PO4 in a fine crystallite size was formed on the surface of FLDH. The photocatalytic activities of the Ag3PO4 immobilized on FLDH were significantly enhanced for the degradation of acid red G under visible light irradiation compared to bare Ag3PO4. The composite with the FLDH/Ag3PO4 mass ratio of 3 : 1 showed a higher photocatalytic efficiency.

  16. Zn-Al LAYERED DOUBLE HYDROXIDE PILLARED BY DIFFERENT DICARBOXYLATE ANIONS

    Directory of Open Access Journals (Sweden)

    S. Gago

    2004-12-01

    Full Text Available Zn-Al layered double hydroxides (LDHs intercalated by terephthalate (TPH and biphenyl-4,4'-dicarboxylate (BPH anions have been synthesized by direct co-precipitation from aqueous solution. The Zn/Al ratio in the final materials was 1.8. The products were characterized by powder X-ray diffraction, thermogravimetric analysis, FTIR and FT Raman spectroscopy, and MAS NMR spectroscopy. The basal spacing for the TPH-LDH intercalate was 14.62 Å, indicating that the guest anions stack to form a monolayer with the aromatic rings perpendicular to the host layers. For the LDH intercalate containing BPH anions, a basal spacing of at least 19.2 Å would be expected if the anions adopted an arrangement similar to that for the TPH anions. The observed spacing was 18.24 Å, suggesting that the anions are tilted slightly with respect to the host layers.

  17. Immobilization of HRP Enzyme on Layered Double Hydroxides for Biosensor Application

    Directory of Open Access Journals (Sweden)

    Zouhair M. Baccar

    2011-01-01

    Full Text Available We present a new biosensor for hydrogen peroxide (H2O2 detection. The biosensor was based on the immobilization of horseradish peroxidase (HRP enzyme on layered double hydroxides- (LDH- modified gold surface. The hydrotalcite LDH (Mg2Al was prepared by coprecipitation in constant pH and in ambient temperature. The immobilization of the peroxidase on layered hybrid materials was realized via electrostatic adsorption autoassembly process. The detection of hydrogen peroxide was successfully observed in PBS buffer with cyclic voltammetry and the chronoamperometry techniques. A limit detection of 9 μM of H2O2 was obtained with a good reproducibility. We investigate the sensitivity of our developed biosensor for H2O2 detection in raw milk.

  18. Removal of lead from aqueous solution on glutamate intercalated layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Shen Yanming

    2017-05-01

    Full Text Available Glutamate intercalated Mg–Al layered double hydroxide (LDH was prepared by co-precipitation and the removal of Pb2+ in the aqueous solution was investigated. The prepared samples were characterized by XRD, FT-IR and SEM. It was shown that glutamate can intercalate into the interlayer space of Mg–Al LDH. The glutamate intercalated Mg–Al LDH can effectively adsorb Pb2+ in the aqueous solution with an adsorption capacity of 68.49 mg g−1. The adsorption of Pb2+ on glutamate intercalated Mg–Al LDH fitted the pseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.

  19. Fluoride removal by Al, Ti, and Fe hydroxides and coexisting ion effect.

    Science.gov (United States)

    Zhang, Jianfeng; Brutus, Timothy E; Cheng, Jiemin; Meng, Xiaoguang

    2017-07-01

    Batch experiments were conducted to evaluate fluoride removal by Al, Fe, and Ti-based coagulants and adsorbents, as well as the effects of coexisting ions and formation of aluminum-fluoride complexes on fluoride removal by co-precipitation with alum (Al2(SO4)3·18H2O). Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8. Nano-crystalline TiO2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3-5. Coexisting anions in water decreased the removal of fluoride in the order: phosphate (2.5mg/L)>arsenate (0.1mg/L)>bicarbonate (200mg/L)>sulfate (100mg/L)=nitrate (100mg/L)>silicate (10mg/L) at a pH of 6.0. The effect of silicate became more significant at pH>7.0. Calcium and magnesium improved the removal of fluoride. Zeta-potential measurements determined that the adsorption of fluoride shifted the PZC of Al(OH)3 precipitates from 8.9 to 8.4, indicating the chemical adsorption of fluoride at the surface. The presence of fluoride in solution significantly increased the soluble aluminum concentration at pHfluoride during co-precipitation with aluminum sulfate. Copyright © 2017. Published by Elsevier B.V.

  20. Structure, molecular simulation, and release of aspirin from intercalated Zn-Al-layered double hydroxides.

    Science.gov (United States)

    Meng, Zilin; Li, Xiaowei; Lv, Fengzhu; Zhang, Qian; Chu, Paul K; Zhang, Yihe

    2015-11-01

    Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn-Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4(-) and H2PO4(-) can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Fractionation of organic matter due to reaction with ferrihydrite: coprecipitation versus adsorption.

    Science.gov (United States)

    Eusterhues, Karin; Rennert, Thilo; Knicker, Heike; Kögel-Knabner, Ingrid; Totsche, Kai U; Schwertmann, Udo

    2011-01-15

    In soil and water, ferrihydrite frequently forms in the presence of dissolved organic matter. This disturbs crystal growth and gives rise to coprecipitation of ferrihydrite and organic matter. To compare the chemical fractionation of organic matter during coprecipitation with the fractionation involved in adsorption onto pristine ferrihydrite surfaces we prepared ferrihydrite-organic matter associations by adsorption and coprecipitation using (i) a forest-floor extract or (ii) a sulfonated lignin. The reaction products were studied by (13)C CPMAS NMR, FTIR, and analysis of hydrolyzable neutral polysaccharides. Relative to the original forest-floor extract, the ferrihydrite-associated organic matter was enriched in polysaccharides, especially when adsorption took place. Moreover, mannose and glucose were bound preferentially to ferrihydrite, while fucose, arabinose, xylose, and galactose accumulated in the supernatant. This fractionation of sugar monomers was more pronounced during coprecipitation and led to an enhanced ratio of (galactose + mannose)/(arabinose + xylose). Experiments with lignin revealed that the ferrihydrite-associated material was enriched in its aromatic components but had a lower ratio of phenolic C to aromatic C than the original lignin. A compositional difference between the adsorbed and coprecipitated lignin is obvious from a higher contribution of methoxy C in the coprecipitated material. Coprecipitated organic matter may thus differ in amount and composition from adsorbed organic matter.

  2. The Preparation of ZnGa2O4 Nano Crystals by Spray Coprecipitation and Its Gas Sensitive Characteristics

    OpenAIRE

    Jinhuai Liu; Mingqiang Li; Feng Chen; Gang Ye; Zheng Jiao

    2002-01-01

    ZnGa2O4 nano crystals were prepared by an improved coprecipitation method, which we call ‘spray coprecipitation’. XRD results shows the resulting crystal size using the new method is under 10nm, whereas the powder prepared by ordinary coprecipitation is about 30nm. XRD results also shows ZnO peaks exists in ZnGa2O4 powder prepared by traditional coprecipitation, but disappears in ZnGa2O4 nano crystal prepared by spraying coprecipitation. SEM and TEM were used to analysis the structu...

  3. Technetium (VII) Co-precipitation with Framework Aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Harsh, James B. [Washington State Univ., Pullman, WA (United States); Dickson, Johnbull Otah [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pierce, Eric M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bargar, John [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-07-13

    Technetium-99 (99Tc), a long-lived radionuclide, is one of the most widespread contaminants within the Hanford subsurface. At some depths, it is only extractable with strong acids, suggesting incorporation into a solid phase. We hypothesized that Tc may have coprecipitated with feldspathoid aluminosilicates under waste tanks that had leaked caustic solutions into the vadose zone. Our objectives were to determine if Tc could be incorporated into the feldspathoids cancrinite and sodalite and under what conditions coprecipitation could occur. Our hypothesis was that sodalite was more likely to incorporate and retain Tc. Our approach was to use known methods of feldspathoid formation in solutions resembling those in Hanford waste tanks contacting sediments in terms of major ion (Na, NO3, OH, Al(OH)4, and Si(OH)4 concentrations. In some cases, Al and Si were supplied from zeolite. We used perrhenate (ReO4) as a surrogate for pertechnetate (TcO4) to avoid the radioactivity. The major findings of this study were 1) ReO4 could be incorporated into either sodalite or cancrinite but the concentration in the solid was < 1% of the competing ion Cl, NO3, or NO2. 2) The small amount of ReO4 incorporated was not exchangeable with NO3 or NO2. 3) In sodalite, NO3 was highly preferred over ReO4 but significant Re-sodalite was formed when the mole fraction in solution (Re/Re+N) exceeded 0.8. 4) A nonlinear relation between the unit cell parameter and amount of Re incorporated suggested that a separate Re-sodalite phase was formed rather than a solid solution. 5) We determined that sodalite preference for sodalite in the presence of different anions increased with the ionic size of the competing anion: Cl < CO3 < NO3 < SO4 < MnO4 < WO4 and significant incorporation did not occur unless the difference in anion radii was less than 12%. 6) Re(VII) was not significantly reduced to Re(IV) under the conditions of this experiment and Re appeared to be a good surrogate for Tc under oxidizing

  4. Uranium Isotope Fractionation During Coprecipitation with Aragonite and Calcite

    Science.gov (United States)

    Chen, X.; Romaniello, S. J.; Herrmann, A. D.; Wasylenki, L. E.; Anbar, A. D.

    2014-12-01

    Natural variations in the 238U/235U ratio of marine carbonates may provide a useful way of constraining past variations in ocean redox conditions. However, before applying this novel redox proxy, it is essential to explore possible isotopic fractionation during U coprecipitation with aragonite and calcite. We investigated these effects in laboratory experiments. Aragonite and calcite coprecipitation experiments were conducted at pH 8.5±0.1 using a constant addition method [1]. More than 90% of the U was incorporated into the solid phase at the end of each experiment. Samples were purified using UTEVA chemistry and δ238/235U was measured using 233U-236U double-spike MC-ICP-MS with a precision of ±0.10‰ [2]. The aragonite experiment demonstrated a 238U/235U Rayleigh fractionation factor of α=1.00008±0.00002 with the 238U preferentially incorporated. In contrast, the calcite experiment demonstrated no resolvable U isotope fractionation (α=1.00001±0.00003). To determine if U isotopes are affected during the early diagenetic conversion of aragonite to calcite, natural carbonate samples were collected along an aragonite-calcite transition across a single coral head in the Key Largo limestone, and characterized for U concentration and δ238/235U [3]. We found that the mean δ238/235U in aragonite (-0.33±0.07‰ 2se) was slightly heavier than that in calcite (-0.37±0.02‰ 2se). Further work is needed to address the mechanisms leading to differential isotopic fractionation of U(VI) during incorporation into aragonite and calcite. Possible drivers include differences in coordination in the crystal structure or equilibrium isotopic fractionation between various aqueous U(VI) species prior to incorporation. [1] Reeder et al. (2001) GCA 65, 3491-3503. [2] Weyer et al., (2008) GCA 72, 345-359. [3] Gill et al., (2008) GCA 72, 4699-4722.

  5. Revisiting Pocos de Caldas. Application of the co-precipitation approach to establish realistic solubility limits for performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, J.; Duro, L.; Jordana, S.; Cera, E. [QuantiSci, Barcelona (Spain)

    1996-02-01

    Solubility limits constitute a critical parameter for the determination of the mobility of radionuclides in the near field and the geosphere, and consequently for the performance assessment of nuclear waste repositories. Mounting evidence from natural system studies indicate that trace elements, and consequently radionuclides, are associated to the dynamic cycling of major geochemical components. We have recently developed a thermodynamic approach to take into consideration the co-precipitation and co-dissolution processes that mainly control this linkage. The approach has been tested in various natural system studies with encouraging results. The Pocos de Caldas natural analogue was one of the sites where a full testing of our predictive geochemical modelling capabilities were done during the analogue project. We have revisited the Pocos de Caldas data and expanded the trace element solubility calculations by considering the documented trace metal/major ion interactions. This has been done by using the co-precipitation/co-dissolution approach. The outcome is as follows: A satisfactory modelling of the behaviour of U, Zn and REEs is achieved by assuming co-precipitation with ferrihydrite. Strontium concentrations are apparently controlled by its co-dissolution from Sr-rich fluorites. From the performance assessment point of view, the present work indicates that calculated solubility limits using the co-precipitation approach are in close agreement with the actual trace element concentrations. Furthermore, the calculated radionuclide concentrations are 2-4 orders of magnitude lower than conservative solubility limits calculated by assuming equilibrium with individual trace element phases. 34 refs, 18 figs, 13 tabs.

  6. Arsenate sorption on monohydrocalcite by coprecipitation during transformation to aragonite.

    Science.gov (United States)

    Fukushi, Keisuke; Sakai, Minoru; Munemoto, Takashi; Yokoyama, Yuka; Takahashi, Yoshio

    2016-03-05

    The metastability of monohydrocalcite (CaCO3·H2O: MHC) suggests high reactivity to dissolved trace elements. Using kinetic and isotherm sorption experiments with different reaction times (24h, 48h), As(V) sorption on MHC was examined to elucidate As(V) uptake by MHC. Although the MHC was transformed to aragonite with time, the MHC in higher As(V) loading conditions was able to persist longer than in lower loading conditions. Actually, As(V) uptake was negligible for samples in which the MHC remained. However, remarkable uptake of As(V) was observed for samples in which a complete transformation of MHC to aragonite occurred. Results of kinetic study confirmed that the timing of the MHC transformation coincided perfectly with that of As(V) removal from the solution. XAFS measurements showed that the local structure of As after the MHC transformation was almost identical to that of As in the As(V) coprecipitated aragonite. Sorption behavior of As(V) during the transformation is explainable theoretically by the substitution of As(V) into the aragonite structure. The distribution coefficient and (apparent) maximum sorption capacity of As(V) sorption on MHC after 48h at low-to-moderate As(V) concentrations are 500L/kg and 25μmol/g, respectively, which are much higher than those of simple adsorption of As(V) on calcite. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Cerium doped hydroxyapatite nanoparticles synthesized by coprecipitation method

    Directory of Open Access Journals (Sweden)

    Ciobanu Carmen Steluta

    2016-01-01

    Full Text Available The present work reports a simple coprecipitation adapted method for the synthesis of stable Ce substituted to Ca hydroxyapatite (HAp nanoparticles. The structural and morphological properties of Ce doped hydroxyapatite (Ce:HAp were characterized by X-ray diffraction (XRD, Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM and Energy Dispersive X-ray analysis (EDAX. The optical properties of Ce doped hydroxyapatite were also investigated using Fourier Transform Infrared (FTIR spectroscopy, FT Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a- and c-axes with increasing of Ce concentrations. In the FTIR studies of Ce:HAp powders a similar structure to hydroxyapatite was observed. IR and Raman wavenumbers and the peak strength of the bands associated to the P-O and O-H bonds decreases progressively with the increase of Ce concentration. All the emission maxima could be attributed to the 5d-4f transitions of Ce ions. The displacement of maximum emission bands with the increase of Cerium in the samples is in agreement with the results obtained by XRD studies. The Ce:HAp samples with xCe =0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli 714 bacterial strains compared to Ce:HAp samples with xCe =0 (pure HAp and 0.01.

  8. Advanced oxidation of rhodamine B with hydrogen peroxide over ZnCr layered double hydroxide catalysts

    Directory of Open Access Journals (Sweden)

    Nguyen Tien Thao

    2017-09-01

    Full Text Available Zn/Cr layered zinc hydroxide materials with different molar ratios of Cr/Zn have been synthesized through the coprecipitation method at pH of 9.0–9.5. At high Cr/Zn molar ratios of 0.5/1–1/3, the materials possess some layered structure with carbonate anions between the interlayer galleries. The catalysts present uniform particle sizes and quite high surface area. An isomorphous substitution of Zn2+ by Cr3+ in the brucite-like sheets makes the layered Cr-doped zinc hydroxides potential catalysts for efficient oxidation of rhodamine B with H2O2 solution. The experimental results indicated that the intra-lattice Cr3+ ions are more active than Cr2O3 components in the oxidative removal of rhodamine B. The degradation efficiency is dependent on the intra lattice Cr3+ contents and reaction variables. The Cr/Zn LDH gave a high decolorization (99% of rhodamine B at near neutral pH and room temperature.

  9. Defluoridation of groundwater by calcined Mg/Al layered double hydroxide

    Directory of Open Access Journals (Sweden)

    A. Elhalil

    2016-03-01

    Full Text Available The present study evaluated calcined Mg/Al layered double hydroxide (CLDH availability for the removal of fluoride from local groundwaters. The Mg/Al layered double hydroxide (LDH was synthesized by co-precipitation method and characterized by XRD, FT-IR and TGA-TDA analyses. Batch defluoridation experiments were performed under various conditions such as calcination, solution pH, contact time, temperature, material dosage and reuse. Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600 °C. The maximum fluoride removal was obtained at solution pH of 6.85. Kinetics of fluoride removal followed the pseudo-second order kinetic model. The rise in solution temperature strongly enhances the removal efficiency. The adsorption mechanism involved surface adsorption, ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region. The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L, respectively, for Bejaad and Settat goundwaters. A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.

  10. Coprecipitation Technique for Preconcentration of Some Metal Ions prior to Graphite Furnace Atomic Absorption Spectrometric Determination

    OpenAIRE

    上田, 穣一

    1998-01-01

    Summary-for the preconcentration of trace ions in the graphite furnace atomic absorption spectrometric determination (GFAAS), a rapid and simple coprecipitation method which does not need the filtration

  11. Aluminum hydroxide nanoparticles show a stronger vaccine adjuvant activity than traditional aluminum hydroxide microparticles

    OpenAIRE

    Li, Xinran; Aldayel, Abdulaziz M.; Cui, Zhengrong

    2013-01-01

    Aluminum hydroxide is used as a vaccine adjuvant in various human vaccines. Unfortunately, despite its favorable safety profile, aluminum hydroxide can only weakly or moderately potentiate antigen-specific antibody responses. When dispersed in an aqueous solution, aluminum hydroxide forms particulates of 1–20 µm. There is increasing evidence that nanoparticles around or less than 200 nm as vaccine or antigen carriers have a more potent adjuvant activity than large microparticles. In the prese...

  12. Properties of Fe-organic matter associations via coprecipitation versus adsorption.

    Science.gov (United States)

    Chen, Chunmei; Dynes, James J; Wang, Jian; Sparks, Donald L

    2014-12-02

    The association of organic matter (OM) with minerals is recognized as the most important stabilization mechanism for soil organic matter. This study compared the properties of Fe-OM complexes formed from adsorption (reaction of OM to postsynthesis ferrihydrite) versus coprecipitation (formation of Fe solids in the presence of OM). Coprecipitates and adsorption complexes were synthesized using dissolved organic matter (DOM) extracts from a forest little layer at varying molar C/Fe ratios of 0.3-25.0. Sample properties were studied by N2 gas adsorption, XRD, FTIR, Fe EXAFS, and STXM-NEXAFS techniques. Coprecipitation resulted in much higher maximum C contents (∼130 mg g(-1) C difference) in the solid products than adsorption, which may be related to the formation of precipitated insoluble Fe(III)-organic complexes at high C/Fe ratios in the coprecipitates as revealed by Fe EXAFS analysis. Coprecipitation led to a complete blockage of mineral surface sites and pores with ≥177 mg g(-1) C and molar C/Fe ratios ≥2.8 in the solid products. FTIR and STXM-NEXAFS showed that the coprecipitated OM was similar in composition to the adsorbed OM. An enrichment of aromatic C was observed at low C/Fe ratios. Association of carboxyl functional groups with Fe was shown with FTIR and STXM-NEXAFS analysis. STXM-NEXAFS analysis showed a continuous C distribution on minerals. Desorption of the coprecipitated OM was less than that of the adsorbed OM at comparable C/Fe ratios. These results are helpful to understand C and Fe cycling in the natural environments with periodically fluctuating redox conditions, where coprecipitation can occur.

  13. Aluminum hydroxide nanoparticles show a stronger vaccine adjuvant activity than traditional aluminum hydroxide microparticles.

    Science.gov (United States)

    Li, Xinran; Aldayel, Abdulaziz M; Cui, Zhengrong

    2014-01-10

    Aluminum hydroxide is used as a vaccine adjuvant in various human vaccines. Unfortunately, despite its favorable safety profile, aluminum hydroxide can only weakly or moderately potentiate antigen-specific antibody responses. When dispersed in an aqueous solution, aluminum hydroxide forms particulates of 1-20μm. There is increasing evidence that nanoparticles around or less than 200nm as vaccine or antigen carriers have a more potent adjuvant activity than large microparticles. In the present study, we synthesized aluminum hydroxide nanoparticles of 112nm. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, we showed that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced a stronger antigen-specific antibody response than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3μm. The potent adjuvant activity of the aluminum hydroxide nanoparticles was likely related to their ability to more effectively facilitate the uptake of the antigens adsorbed on them by antigen-presenting cells. Finally, the local inflammation induced by aluminum hydroxide nanoparticles in the injection sites was milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant into nanometers represents a novel and effective approach to improve its adjuvanticity. © 2013.

  14. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    The synthesis of layered double hydroxides (LDHs) provides a relatively easy and traditional way to build versatile chemical compounds with a rough control of the bulk structure. The delamination of LDHs to form their single host layers (2D nanosheets) and the capability to reassemble them offer ......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

  15. Effects of natural organic matter on the coprecipitation of arsenic with iron.

    Science.gov (United States)

    Kim, Eun Jung; Hwang, Bo-Ram; Baek, Kitae

    2015-12-01

    Natural organic matter (NOM) can affect arsenic speciation and mobility in the environment. In this study, the effects of NOM on the coprecipitation of arsenic with iron were investigated in order to better understand the fate and transport of arsenic in natural environments. The coprecipitation of arsenic with iron was studied in the presence and absence of NOM under various arsenic-to-iron molar ratios (As/Fe) and pH conditions. The addition of humic acid (HA) hindered the As-Fe coprecipitation under high pH and high As/Fe conditions by forming a soluble As-Fe-HA complex. The X-ray diffraction and Fourier transform infrared studies showed that the As-Fe-coprecipitated solid phase was highly affected by pH and As/Fe. The arsenic was coprecipitated with iron as an amorphous ferric arsenate phase at a low pH level or high As/Fe conditions, while the formation of ferrihydrite phase and the arsenic incorporation to the ferrihydrite by adsorption was predominant at high pH levels or low As/Fe conditions. The HA affected the As-Fe-coprecipitated solid phase depending on the As/Fe molar ratio under neutral and alkaline conditions.

  16. Sorption mechanisms of arsenate during coprecipitation with ferrihydrite in aqueous solution.

    Science.gov (United States)

    Tokoro, Chiharu; Yatsugi, Yohei; Koga, Hajime; Owada, Shuji

    2010-01-15

    Dilute arsenate (As(V)) coprecipitation by ferrihydrite was investigated to determine if treatment of acid mine drainage containing dilute As(V) using coprecipitation is feasible. The sorption density obtained at pH 5 and 7 was nearly identical when As(V) was coprecipitated with ferrihydrite, while it was higher at pH 5 when As(V) was adsorbed on the ferrihydrite. The high sorption density of As(V) to ferrihydrite in coprecipitation with 1-h reaction time suggested that coprecipitation occurs via both adsorption and precipitation. Furthermore, the relationship between residual As(V) and sorption density revealed a BET-type isotherm, with a transition point from a low residual As(V) concentration to a high residual As(V) concentration being observed for all initial As(V) concentrations between 0.15 and 0.44 mmol/dm(3) when the initial molar ratio was 0.56 at pH 5 and 7. X-ray diffraction and the zeta potential revealed that the transition point from surface complexation to precipitation was obtained when the initial As/Fe ratio was 0.4 or 0.5. When dilute As(V) was coprecipitated with ferrihydrite at pH 5 and 7, it was primarily adsorbed as a surface complex when the initial molar ratio was As/Fe or= 0.4.

  17. Mixed CuFe and ZnFe (hydr)oxides as reactive adsorbents of chemical warfare agent surrogates.

    Science.gov (United States)

    Florent, Marc; Giannakoudakis, Dimitrios A; Wallace, Rajiv; Bandosz, Teresa J

    2017-05-05

    Two sets of zinc-iron and copper-iron mixed (hydr)oxides were prepared by a simple co-precipitation method. Either nitrate or chloride was a source of the metals. The decontamination ability of the materials was tested in closed vials saturated with vapors of 2-chloroethyl ethyl sulfide (CEES) or dimethyl chlorophosphate (DMCP), a blister agent and a nerve agent surrogate, respectively. In both cases, the weight uptakes on the mixed oxides were superior to the ones reported for the pure metal oxides or hydroxides. When exposed to CEES for 5days, zinc-iron (hydr)oxides show much higher activity than the copper-iron ones. The products of reactions in the vessel headspace were investigated by GC/MS and on the surface by FTIR. Ethyl vinylsulfide and chloromethane are the main products of the reactive adsorption of CEES and DMCP, respectively. This indicates that CEES is mainly degraded by dehydrochlorination and DMCP- by hydrolysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Synthesising methods of layered double hydroxides and its use in the fabrication of dye Sensitised solar cell (DSSC): A short review

    Science.gov (United States)

    George, Giphin; Saravanakumar, M. P.

    2017-11-01

    The layered double hydroxides (LDH) which are anionic clay substances comprising of stacked cationic layers and interlayer anions. The cationic sheets contain octahedral structure consisting the divalent and trivalent ions in the center and hydroxyl bunches in the corners, gathered by three bonding with the neighbouring octahedra on every side of the layer. The ratio between the quantity of cations and OH‑ ions is 2:1, so a positive charge shows up on the layer because of the presence of trivalent cations. The interlayer space gives the compensation anions and water molecules, assuring a balanced out layered structure. The LDH materials were successfully synthesised from magnesium, aluminium, zinc and chromium chloride salts utilizing the co-precipitation technique. A Zn-Al LDH was researched as a potential sorbent material. This article reviews the recent advances in the preparation and intercalation of layered double hydroxides and its application in the fabrication of Dye Sensitized Solar Cell (DSSC).

  19. CALCIUM HYDROXIDE IN ENDODONTIC TREATMENT OF PERIAPICALLY INFECTED TEETH

    Directory of Open Access Journals (Sweden)

    Rahmi Alma Farah Adang

    2006-04-01

    Full Text Available An inadequate endodontic treatment may affect the root canal system and spread beyond its apical foramina that elicit periodontal tissue developing into abscess, granuloma and radicular cyst. Periodical lesions can be treated with non surgical endodontic treatment using calcium hydroxide dressing. This case study is reporting teeth 11 with periodical lesions and infection. Evidence of a clinical healing and radiographic assessments were followed by a non surgical endodontic therapy. Successful treatment outcome is related to the elimination of infection agents from the root canal. This can activate a stimulation zone to promote regeneration. Calcium hydroxide used as a root canal dressing may promote alkalinity at the adjacent tissue , create favourable environmental condition in which hard tissue formation can occur, interfere the bactericidal activity, increase mineralization, and induce healing.

  20. Coprecipitation of arsenate with metal oxides. 3. Nature, mineralogy, and reactivity of iron(III)-aluminum precipitates.

    Science.gov (United States)

    Violante, Antonio; Pigna, Massimo; Del Gaudio, Stefania; Cozzolino, Vincenza; Banerjee, Dipanjan

    2009-03-01

    Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied (i)the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/ Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 degrees C and (ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibitthe transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-range ordered materials. Chemical composition of all samples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater

  1. Formation of electroactive colloids via in situ coprecipitation under electric field: erbium chloride alkaline aqueous pseudocapacitor.

    Science.gov (United States)

    Chen, Kunfeng; Xue, Dongfeng

    2014-09-15

    For the first time, a new ErCl3 alkaline aqueous pseudocapacitor system was demonstrated by designing commercial ErCl3 salt electrode in alkaline aqueous electrolyte, where the materials synthesis and subsequently integrating into practical electrode structures occur at the same spatial and temporal scale. Highly electroactive ErOOH colloids were in-situ crystallized via electric field assisted chemical coprecipitation of ErCl3 in KOH aqueous electrolyte. These electroactive ErOOH colloids absorbed by carbon black and PVDF matrix were highly redox-reactive with higher cation utilization ratio of 86 % and specific capacitance values of 1811F/g, exceeding the one-electron redox theoretical capacitance (Er(3+)↔Er(2+)). We believe that additional two-electron (Er(2+)↔Er) or three-electron (Er(3+)↔Er) reactions can occur in our designed ErCl3 alkaline aqueous pseudocapacitor system. The specific electrode configuration with ErOOH colloids grown among the carbon black/PVDF matrix can create short ion diffusion and electron transfer length to enable the fast and reversible Faradaic reactions. This work shows promising for finding high-performance electrical energy storage systems via designing the colloidal state of electroactive cations with the utilization of in-situ crystallization route. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Homogeneous Precipitation of Nickel Hydroxide Powders

    Energy Technology Data Exchange (ETDEWEB)

    Mavis, Bora [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with urea precipitation method. Model predictions on Ni2+ precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility product data of nickel hydroxides was found to be the large contributor to the error. There were demonstrable compositional variations across the particle cross-sections and the growth mechanism was determined to be the aggregation of primary crystallites. This implied that there is a change in the intercalate chemistry of the primary crystallites with digestion time. Predicted changes in the concentrations of simple and complex ions in the solution support the proposed mechanism. The comprehensive set of hydrolysis reactions used in the model described above allows the investigation of other systems provided that accurate reaction constants are available. the fact that transition metal ions like Ni2+ form strong complexes with ammonia presents a challenge in the full recovery of the Ni2+. On the other hand, presence of Al3+ facilitates the complete precipitation of Ni2+ in about 3 hours of digestion. A challenge in their predictive modeling studies had been the fact that simultaneous incorporation of more than one metal ion necessitates a different approach than just using the equilibrium constants of hydrolysis, complexation and precipitation reactions. Another limitation of using equilibrium constants is that the nucleation stage of digestion, which is controlled mainly by kinetics, is not fully justified. A new program released by IBM Almaden Research Center (Chemical Kinetics Simulator™, Version 1.01) lets the user change

  3. Synthesis of composite nanoparticles using co-precipitation of a magnetic iron-oxide shell onto core nanoparticles

    Science.gov (United States)

    Primc, Darinka; Belec, Blaž; Makovec, Darko

    2016-03-01

    Composite nanoparticles can be synthesized by coating a shell made of one material onto core nanoparticles made of another material. Here we report on a novel method for coating a magnetic iron oxide onto the surface of core nanoparticles in an aqueous suspension. The method is based on the heterogeneous nucleation of an initial product of Fe3+/Fe2+ co-precipitation on the core nanoparticles. The close control of the supersaturation of the precipitating species required for an exclusively heterogeneous nucleation and the growth of the shell were achieved by immobilizing the reactive Fe3+ ions in a nitrate complex with urea ([Fe((CO(NH2)2)6](NO3)3) and by using solid Mg(OH)2 as the precipitating reagent. The slow thermal decomposition of the complex at 60 °C homogeneously releases the reactive Fe3+ ions into the suspension of the core nanoparticles. The key stage of the process is the thermal hydrolysis of the released Fe3+ ions prior to the addition of Mg(OH)2. The thermal hydrolysis results in the formation of γ-FeOOH, exclusively at the surfaces of the core nanoparticles. After the addition of the solid hydroxide Mg(OH)2, the pH increases and at pH 5.7 the Fe2+ precipitates and reacts with the γ-FeOOH to form magnetic iron oxide with a spinel structure (spinel ferrite) at the surfaces of the core nanoparticles. The proposed low-temperature method for the synthesis of composite nanoparticles is capable of forming well-defined interfaces between the two components, important for the coupling of the different properties. The procedure is environmentally friendly, inexpensive, and appropriate for scaling up to mass production.

  4. Synthesis of composite nanoparticles using co-precipitation of a magnetic iron-oxide shell onto core nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Primc, Darinka [ETH Zürich, Laboratory for Multifunctional Materials (Switzerland); Belec, Blaž; Makovec, Darko, E-mail: Darko.Makovec@ijs.si [Jožef Stefan Institute and Jožef Stefan International Postgraduate School, Department for Materials Synthesis (Slovenia)

    2016-03-15

    Composite nanoparticles can be synthesized by coating a shell made of one material onto core nanoparticles made of another material. Here we report on a novel method for coating a magnetic iron oxide onto the surface of core nanoparticles in an aqueous suspension. The method is based on the heterogeneous nucleation of an initial product of Fe{sup 3+}/Fe{sup 2+} co-precipitation on the core nanoparticles. The close control of the supersaturation of the precipitating species required for an exclusively heterogeneous nucleation and the growth of the shell were achieved by immobilizing the reactive Fe{sup 3+} ions in a nitrate complex with urea ([Fe((CO(NH{sub 2}){sub 2}){sub 6}](NO{sub 3}){sub 3}) and by using solid Mg(OH){sub 2} as the precipitating reagent. The slow thermal decomposition of the complex at 60 °C homogeneously releases the reactive Fe{sup 3+} ions into the suspension of the core nanoparticles. The key stage of the process is the thermal hydrolysis of the released Fe{sup 3+} ions prior to the addition of Mg(OH){sub 2}. The thermal hydrolysis results in the formation of γ-FeOOH, exclusively at the surfaces of the core nanoparticles. After the addition of the solid hydroxide Mg(OH){sub 2}, the pH increases and at pH ~ 5.7 the Fe{sup 2+} precipitates and reacts with the γ-FeOOH to form magnetic iron oxide with a spinel structure (spinel ferrite) at the surfaces of the core nanoparticles. The proposed low-temperature method for the synthesis of composite nanoparticles is capable of forming well-defined interfaces between the two components, important for the coupling of the different properties. The procedure is environmentally friendly, inexpensive, and appropriate for scaling up to mass production.Graphical abstract.

  5. Фізико-хімічні характеристики продуктів сумісного осадження магній, ферум та хром гідроксидів і продуктів їх термічного розкладу

    OpenAIRE

    Луцась, Анна Віталіївна; Яремій, Іван Петрович; Яремій, Софія Іванівна; Матківський, Микола Петрович

    2016-01-01

    Magnesium ferrite-chromites of the system  were synthesized from aqueous solutions of the corresponding chlorides using the coprecipitation method. It was obtained homogeneous reactive active hydroxides with a high specific surface area, the value of which increases with the chromium content in the system.The conditions of magnesium, iron and chromium hydroxides co-precipitation are defined. The presence of chemical hydroxide interactions in co-precipitation and formation of polymer type hydr...

  6. Molecular dynamics simulation of layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    KALINICHEV,ANDREY G.; WANG,JIANWEI; KIRKPATRICK,R. JAMES; CYGAN,RANDALL T.

    2000-05-19

    The interlayer structure and the dynamics of Cl{sup {minus}} ions and H{sub 2}O molecules in the interlayer space of two typical LDH [Layered Double Hydroxide] phases were investigated by molecular dynamics computer simulations. The simulations of hydrocalumite, [Ca{sub 2}Al(OH){sub 6}]Cl{center_dot}2H{sub 2}O reveal significant dynamic disorder in the orientations of interlayer water molecules. The hydration energy of hydrotalcite, [Mg{sub 2}Al(0H){sub 6}]Cl{center_dot}nH{sub 2}O, is found to have a minimum at approximately n = 2, in good agreement with experiment. The calculated diffusion coefficient of Cl{sup {minus}} as an outer-sphere surface complex is almost three times that of inner-sphere Cl{sup {minus}}, but is still about an order of magnitude less than that of Cl{sup {minus}} in bulk solution. The simulations demonstrate unique capabilities of combined NMR and molecular dynamics studies to understand the structure and dynamics of surface and interlayer species in mineral/water systems.

  7. Eu(3+)-doped gadolinium oxide nanoparticles synthesized by chemical coprecipitation predicted by thermodynamic modeling.

    Science.gov (United States)

    Hong, Seung Pyo; Kang, Seung Hee; Kim, Do Kyung; Kang, Bo Sun

    2014-11-01

    Thermodynamic modeling of the Gd(3+)-Eu(3+)-O(2-)-CO3(2-)-Cl- system has been adopted as a rational approach to establish routes to the better synthesis conditions for pure phase Eu(3+)-doped Gd2O3 nanoparticles. Quantitative analyses of the different reaction equilibria involved in the coprecipitation of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O from aqueous solutions have been used to determine the optimum synthesis conditions. The characterization and photoluminescence spectra of Gd2O3 nanoparticles doped with Eu3+ activator ions at the concentrations of 1, 2, 3, 4 and 5 mol% synthesized by urea-based homogeneous coprecipitation are presented. The surface of the as-prepared mixture of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O particles are coated with silica to avoid the agglomeration followed by annealing the carbonate precursors at 800 degrees C for 3 hours. Subsequently, the silica shell is removed with an alkali solution resulting in well-crystallized Eu(3+)-doped Gd2O3 nanoparticles. X-ray diffraction (XRD) results show that all the diffraction peaks are well indexed to the cubic Gd2O3 with high crystallinity. The photoluminescence spectra exhibit a characteristic f-f transition band that corresponds to Eu3+. The sharp red emission at 616 nm corresponds to the transition identified as 5D0 __7F2. Both the emission intensity at 616 nm and asymmetry factor of [I(5D0 --> 7F2)/I(5D0 --> 7F1)] exhibit clearly Eu(3+)-doping concentration-dependent luminescence behaviors. The rather fast decay time is closely correlated to the proper occupation of the Eu3+ activator ions in the C2 sites of the Gd2O3 cage, resulting in strong dependence on small changes of the total electric density and defect density. Thus, the best concentration of Eu3+ activator ions for the maximum brightness are the 3 mol% Eu(3+)-doped Gd2O3 at 5D0 --> 7F2 because it shows the longest decay time and more luminescent intensity than the other doping concentrations.

  8. Synthesis of layered double hydroxides from eggshells

    Energy Technology Data Exchange (ETDEWEB)

    Li Songnan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Fangyong [College of Engineering and Technology, Northeast Forestry University, 150001 (China); Jing Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Jun, E-mail: zhqw1888@sohu.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Saba, Jamil; Liu Qi; Ge Lan; Song Dalei; Zhang Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China)

    2012-01-16

    Graphical abstract: This is the XRD pattern and TEM image of 4Ca-Al layered double hydroxide, which is obtained from eggshells. It can be seen that the sample is of layered double hydroxide and shows the plate-like agglomerations with an average size of 20-100 nm. Highlights: Black-Right-Pointing-Pointer We synthesize layered double hydroxides from eggshells. Black-Right-Pointing-Pointer Eggshells are the mainly material in this method. Black-Right-Pointing-Pointer The additional alkaline solution is not required. - Abstract: Ca-Al and Ca-Fe layered double hydroxides (LDHs) were successfully synthesized from chicken eggshells by an ultrasonic wave assistant method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. XRD and TEM analyses showed that the 4Ca-Al LDHs were of high purity but other samples were not. The present study provides a simple, efficient and environmental friendly method to obtain LDHs from biowaste eggshells, in which additional alkaline solution is not required for synthesis. Moreover, eggshells provide all the requisite bivalent metal ions, which are needed to form layered double hydroxides.

  9. The effect of a combination antacid preparation containing aluminium hydroxide and magnesium hydroxide on rosuvastatin pharmacokinetics.

    Science.gov (United States)

    Martin, Paul D; Schneck, Dennis W; Dane, Aaron L; Warwick, Michael J

    2008-04-01

    Rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor used for the treatment of dyslipidaemia, may be co-administered with antacids in clinical practice. This trial assessed the effect of simultaneous and separated administration of an antacid preparation containing aluminium hydroxide 220 mg/5 mL and magnesium hydroxide 195 mg/5 mL (co-magaldrox 195/220) on the pharmacokinetics of rosuvastatin. A randomised, open-label, three-way crossover trial was performed. Healthy male volunteers (n = 14) received a single dose of rosuvastatin 40 mg alone, rosuvastatin 40 mg plus 20 mL antacid suspension taken simultaneously, and rosuvastatin 40 mg plus 20 mL antacid suspension taken 2 h after rosuvastatin on three separate occasions with a washout of > or = 7 days between each. The primary parameters were area under the rosuvastatin plasma concentration-time curve from time zero to the last quantifiable concentration (AUC(0-t)) and maximum observed rosuvastatin plasma concentration (C(max)) in the absence and presence of antacid. When rosuvastatin and antacid were given simultaneously, the antacid reduced the rosuvastatin AUC(0-t) by 54% (90% confidence interval [CI] for the treatment 0.40-0.53) and C(max) by 50% (90% CI 0.41-0.60). When the antacid was given 2 h after rosuvastatin, the antacid reduced the rosuvastatin AUC(0-t) by 22% (90% CI 0.68-0.90) and the C(max) by 16% (90% CI 0.70-1.01). The effect of repeated antacid administration was not studied and it cannot be discounted that this may have resulted in a stronger interaction than that observed here. Simultaneous dosing with rosuvastatin and antacid resulted in a decrease in rosuvastatin systemic exposure of approximately 50%. This effect was mitigated when antacid was administered 2 h after rosuvastatin.

  10. Iodine Sequestration Using Delafossites and Layered Hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    J.D. Pless; J.B. Chwirka; J.L. Krumhansl

    2006-03-28

    The objective of this document is to report on early success for sequestering {sup 129}I. Sorption coefficients (K{sub d}) for I{sup -} and IO{sub 3}{sup -} onto delafossites, spinels and layered metal hydroxides were measured in order to compare their applicability for sequestering {sup 129}I. The studies were performed using a dilute fluid composition representative of groundwater indigenous to the Yucca mountain area. Delafossites generally exhibited relatively poor sorption coefficients (< 10{sup 1.7} mL/g). In contrast, the composition of the layered hydroxides significantly affects their ability to sorb I. Cu/Al and Cu/Cr layered hydroxide samples exhibit K{sub d}'s greater than 10{sup 3} mL/g for both I{sup -} and IO{sub 3}{sup -}.

  11. Highly efficient miniaturized coprecipitation screening (MiCoS) for amorphous solid dispersion formulation development.

    Science.gov (United States)

    Hu, Qingyan; Choi, Duk Soon; Chokshi, Hitesh; Shah, Navnit; Sandhu, Harpreet

    2013-06-25

    Microprecipitated bulk powder (MBP) is a novel solid dispersion technology to manufacture amorphous formulations of poorly soluble compounds that cannot be processed by spray drying or melt extrusion. An efficient high-throughput screening method has been developed to aid the selection of polymer type, drug loading and antisolvent to solvent ratio for MBP formulation development. With a 96-well platform, the miniaturized coprecipitation screening (MiCoS) includes mixing of drug and polymer in dimethylacetamide, controlled precipitation to generate MBP, filtration/washing, drying and high throughput characterization. The integrated MiCoS approach has been demonstrated with a model compound, glybenclamide. Based on the solid state stability and kinetic solubility of the MBP, hydroxypropylmethylcellulose acetate succinate polymer with 40% or lower drug loading, and antisolvent (0.01 N HCl) to solvent (dimethylacetamide) ratio of 5:1 or higher were selected to make glybenclamide MBP. MiCoS can be applied to both early and late stage formulation processing. In early stage research programs, the system can be used to enable efficacy, pharmacokinetics or mini-toxicology studies for poorly water soluble molecules using minimal amount of drug substance (2-10mg). In late stage development programs, MiCoS can be used to optimize MBP formulation by expanding the experimental design space to include additional formulation variants. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Preparation of Cerium Orthophosphate Nanosphere by Coprecipitation Route and Its Structural, Thermal, Optical, and Electrical Characterization

    Directory of Open Access Journals (Sweden)

    Seema Verma

    2014-01-01

    Full Text Available Cerium orthophosphate (CePO4 nanoparticles were synthesized via wet chemical coprecipitation technique using cerium nitrate hexahydrate for Ce3+ ion and ammonium dihydrogen phosphate for PO43- ion source. X-ray diffraction (XRD analysis suggests that the material belongs to monoclinic crystal system with crystallite size of 49.3 nm. Scanning electron microscope (SEM and transmission electron microscope (TEM reveal the surface morphology of the prepared nanoparticles as nanospheres having grain size in the range of 30–50 nm. The energy dispersive X-ray analysis (EDAX gives elemental composition present in the grown nanomaterial. Thermogravimetric analysis suggests that the structural phase transition is above 800°C. The optical properties include UV-VIS-NIR absorption and the photoluminescence spectrum shows the absorption and emission peaks in the ultraviolet region. The dielectric constant (ε/  and ac conductivity properties were investigated with regard to change in temperature (40 to 500°C and frequency (5 kHz to 1 MHz. The dielectric measurement indicates that the transition is diffused and the activation energy values decrease suggesting that the conduction mechanism is due to hopping of the charge carriers from one site to another.

  13. Synthesis, spectroscopic analysis and electrochemical performance of modified β-nickel hydroxide electrode with CuO

    Directory of Open Access Journals (Sweden)

    B. Shruthi

    2017-03-01

    Full Text Available In the present work, a modified β-nickel hydroxide (β-Ni(OH2 electrode material with CuO has been prepared using a co-precipitation method. The structure and property of the modified β-Ni(OH2 with CuO were characterized by X-ray diffraction (XRD, Fourier Transform infra-red (FT-IR, Raman and thermal gravimetric-differential thermal analysis (TG-DTA techniques. The results of the FT-IR spectroscopy and TG-DTA indicate that the modified β-Ni(OH2 electrode materials contain intercalated water molecules and anions. A pasted–type electrode was prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry (CV and Electrochemical impedance spectroscopy (EIS studies were undertaken to assess the electrochemical behavior of pure β-Ni(OH2 and modified β-Ni(OH2 electrode with CuO in a 6 M KOH electrolyte. The addition of CuO into β-nickel hydroxide was found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. The modified nickel hydroxide with CuO was also found to exhibit a higher proton diffusion coefficient and a lower charge transfer resistance. These findings suggest that the modified β-Ni(OH2 with CuO possesses an enhanced electrochemical response and thus can be recognized as a promising candidate for battery electrode applications.

  14. Reductive dehalogenation by layered iron(II)-iron(III) hydroxides and related iron(II) containing solids

    DEFF Research Database (Denmark)

    Yin, Weizhao

    sulphate green rust formation by aerial oxidation of FeII or co-precipitation by adding Fe(III) salt to Fe(II). In comparison with traditional green rust synthesis, pure GRs were synthesized in minutes. 2. Enhanced dehalogenation of CT by GR in presence of selected amino acids. In presence of glycine......In the present PhD project, novel synthesis and modifications of layered Fe(II)-Fe(III) hydroxides (green rusts, GRs) were investigated with focus on improved dehalogenation of carbon tetrachloride by using modified green rusts and/or altered reaction conditions. The Ph.D. project has comprised: 1....... New strategy for synthesis of green rusts that enables upscaling. Larger scale application of GRs requires upscaling, including fast and reproducible production of GRs. In this study, we have adopted a homogenous precipitation approach where glycine is used as a buffering and complexing agent during...

  15. Corrosion Resistance of the Superhydrophobic Mg(OH2/Mg-Al Layered Double Hydroxide Coatings on Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Fen Zhang

    2016-04-01

    Full Text Available Coatings of the Mg(OH2/Mg-Al layered double hydroxide (LDH composite were formed by a combined co-precipitation method and hydrothermal process on the AZ31 alloy substrate in alkaline condition. Subsequently, a superhydrophobic surface was successfully constructed to modify the composite coatings on the AZ31 alloy substrate using stearic acid. The characteristics of the composite coatings were investigated by means of X-ray diffractometer (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, scanning electronic microscope (SEM and contact angle (CA. The corrosion resistance of the coatings was assessed by potentiodynamic polarization, the electrochemical impedance spectrum (EIS, the test of hydrogen evolution and the immersion test. The results showed that the superhydrophobic coatings considerably improved the corrosion resistant performance of the LDH coatings on the AZ31 alloy substrate.

  16. Signal molecules-calcium phosphate coprecipitation and its biomedical application as a functional coating.

    Science.gov (United States)

    Wang, Xiupeng; Ito, Atsuo; Li, Xia; Sogo, Yu; Oyane, Ayako

    2011-06-01

    In this review, the current knowledge of signal molecules-calcium phosphate coprecipitation and its biomedical application as a functional coating are described. Although signal molecules regulate a variety of cellular processes, it is difficult to sustain the regulation activity for a long term when the signal molecules are only injected in a free form. The signal molecules-calcium phosphate coprecipitation on a substrate surface is a very promising process to achieve sustained regulation activity of the signal molecules by controlled and localized delivery of the signal molecules to specific body sites (implantation sites). However, the significance of immobilizing signal molecules with calcium phosphate coatings and their biomedical application are not systematically illustrated. For this purpose, the presently existing coprecipitation methods and strategies on biomedical application are summarized and discussed.

  17. Armoring Enzymes by Metal-Organic Frameworks by the Coprecipitation Method.

    Science.gov (United States)

    Hou, Miao; Ge, Jun

    2017-01-01

    Enzymatic processes have great potential for applications in industrial biocatalysis, biosensing, and biomedical engineering. However, poor stability and difficulty in the reuse of enzymes still create challenges for their use in catalysis and other applications. In recent years, enzyme-incorporated metal-organic frameworks (enzyme@MOF) have emerged as a new type of armored enzymes and are thought to be an appealing solution to the above challenges. To date, the preparation of enzyme-MOF composites can be divided into three categories, including physical adsorption, covalent conjugation, and coprecipitation. The coprecipitation method integrates the synthesis of MOFs and encapsulation of enzymes into one step, allowing common MOFs with regular pore sizes to be used as carriers for enzyme binding. In this chapter, we present a protocol for the synthesis of enzyme@MOF composites using the coprecipitation approach with particular details. © 2017 Elsevier Inc. All rights reserved.

  18. Method for determination of neptunium in large-sized urine samples using manganese dioxide coprecipitation and 242Pu as yield tracer.

    Science.gov (United States)

    Qiao, Jixin; Hou, Xiaolin; Roos, Per

    2013-02-05

    A novel method for bioassay of large volumes of human urine samples using manganese dioxide coprecipitation for preconcentration was developed for rapid determination of (237)Np. (242)Pu was utilized as a nonisotopic tracer to monitor the chemical yield of (237)Np. A sequential injection extraction chromatographic (SI-EC) system coupled with inductively coupled plasma mass spectrometry (ICPMS) was exploited to facilitate the rapid column separation and quantification. The analytical results demonstrated satisfactory performance of the MnO(2) coprecipitation as indicated by the high chemical yields close to 100% and high separation capacity of processing up to 5 L of human urine samples. The MnO(2) coprecipitation process is simple and straightforward in which a batch (8-12) of samples can be pretreated within 4 h (i.e., <0.5 h/sample). In connection with the automated column separation and ICPMS quantification, which takes less than 1.5 h in total, the overall analytical time was on average less than 2 h for each sample. The high effectiveness and sample throughput make the developed method well suited for urine bioassay of (237)Np in routine monitoring of occupationally internal radiation exposure and rapid analysis of neptunium contamination level for emergency preparedness.

  19. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 2. Formation mechanisms of LDH.

    Science.gov (United States)

    Sun, Xiaodi; Dey, Sandwip K

    2015-11-15

    This study demonstrates the effect of (co)intercalated anion compositions on nanostructure evolution to understand the formation mechanisms of layered double hydroxide (LDH) nanoparticles following coprecipitation and hydrothermal treatments (HT). Initially, the room temperature coprecipitation resulted in amorphous primary nanoparticles that agglomerated at the edges due to low surface charge densities. The reversibility of such agglomeration was determined by the crystalline quality upon HT and consequent surface charge density, which in turn were strongly influenced by the composition of the intercalated anions. Upon crystallization, the agglomerated Zn2Al(OH)6(NO3)0.3(CO3)0.35⋅xH2O primary nanoparticles re-dispersed, but the Zn2Al(OH)6(NO3)⋅xH2O nanoparticles with much lower stability and higher disorder (especially at the edges) exhibited irreversible agglomeration, and transformed into secondary nanoparticles via aggregational growth. Additionally, the stability studies on Zn2Al(OH)6(NO3)y(CO3)0.5(1-y)⋅xH2O nanoparticles (y=0-1) showed that the size difference between the cointercalated anions caused phase separation when 0.9⩾y⩾0.6, leading to bimodal size distributions. Moreover, the coarsening rates were controlled through the cointercalated anion compositions. By gradually varying the ratio of cointercalated NO3(-) to CO3(2-), monodispersed Zn2Al(OH)6(NO3)y(CO3)0.5(1-y)⋅xH2O (0.5⩾y⩾0) nanoparticles with systematic variation in the particle size of ∼200-400nm were obtained after HT at 85°C for 12h. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Soft-chemical synthesis and catalytic activity of Ni-Al and Co-Al layered double hydroxides (LDHs intercalated with anions with different charge density

    Directory of Open Access Journals (Sweden)

    Takahiro Takei

    2014-09-01

    Full Text Available Co-Al and Ni-Al layered double hydroxides (LDHs intercalated with three types of anionic molecules, dodecylsulfate (C12H25SO4−, DS, di-2-ethylsulfosuccinate ([COOC2H3EtBu]2C2H3SO3−, D2ES, and polytungstate (H2W12O4210−, HWO were prepared by means of ion-exchange and co-precipitation processes. With the use of DS and D2ES as intercalation agents, high crystallinity was maintained after intercalation into the LDHs. In the case of HWO, the intercalated LDHs could be obtained by ion-exchange as well as co-precipitation with a decline in the crystallinity; however, unreacted LDH was detected in the ion-exchange samples, and some unwanted phases such as hydroxide and pyrochlore were generated by the co-precipitation process. The maximum specific surface area and pore volume of the Ni-Al sample with intercalated HWO, prepared by the ion-exchange process were 74 m2/g and 0.174 mL/g, respectively. The occupancies of DS, D2ES, and HWO within the interlayer space were approximately 0.3–0.4, 0.5–0.6, and 0.1–0.2, respectively, in the Co-Al and Ni-Al LDHs. Analysis of the catalytic activity demonstrated that the DS-intercalated Ni-Al LDH sample exhibited relatively good catalytic activity for conversion of cyclohexanol to cyclohexanone.

  1. Stabilization of extracellular polymeric substances ( Bacillus subtilis) by adsorption to and coprecipitation with Al forms

    Science.gov (United States)

    Mikutta, Robert; Zang, Ulrich; Chorover, Jon; Haumaier, Ludwig; Kalbitz, Karsten

    2011-06-01

    Extracellular polymeric substances (EPS) are continuously produced by bacteria during their growth and metabolism. In soils, EPS are bound to cell surfaces, associated with biofilms, or released into solution where they can react with other solutes and soil particle surfaces. If such reaction results in a decrease in EPS bioaccessibility, it may contribute to stabilization of microbial-derived organic carbon (OC) in soil. Here we examined: (i) the chemical fractionation of EPS produced by a common Gram positive soil bacterial strain ( Bacillus subtilis) during reaction with dissolved and colloidal Al species and (ii) the resulting stabilization against desorption and microbial decay by the respective coprecipitation (with dissolved Al) and adsorption (with Al(OH) 3(am)) processes. Coprecipitates and adsorption complexes obtained following EPS-Al reaction as a function of pH and ionic strength were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stability of adsorbed and coprecipitated EPS against biodegradation was assessed by mineralization experiments for 1100 h. Up to 60% of the initial 100 mg/L EPS-C was adsorbed at the highest initial molar Al:C ratio (1.86), but this still resulted only in a moderate OC mass fraction in the solid phase (17 mg/g Al(OH) 3(am)). In contrast, while coprecipitation by Al was less efficient in removing EPS from solution (maximum values of 33% at molar Al:C ratios of 0.1-0.2), the OC mass fraction in the solid product was substantially larger than that in adsorption complexes. Organic P compounds were preferentially bound during both adsorption and coprecipitation. Data are consistent with strong ligand exchange of EPS phosphoryl groups during adsorption to Al(OH) 3(am), whereas for coprecipitation weaker sorption mechanisms are also involved. X-ray photoelectron analyses indicate an intimate mixing of EPS with Al in the coprecipitates, which is not observed in the case

  2. Polysulfide intercalated layered double hydroxides for metal capture applications

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G.; Ma, Shulan

    2017-04-04

    Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

  3. 21 CFR 73.2326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to the...

  4. 21 CFR 73.1326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide (Cr2O3·XH2O...

  5. 40 CFR 721.4600 - Recovered metal hydroxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Recovered metal hydroxide. 721.4600... Substances § 721.4600 Recovered metal hydroxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a recovered metal hydroxide (PMN P-91-809...

  6. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white, odorless...

  7. KINETICS OF HYDROXIDE PHOMOTED DECOMPOSITION 0F ...

    African Journals Online (AJOL)

    1991-04-26

    (Received July 2?. 1990; revised April 26, 1991). ABSTRACT. The effects of varying concentrations of dimethyl sulphoxide in mixture with water on rates and activation parameters for the hydroxide promoted decomposition of tetraphenylphosphonium chloride have been studied. Increasing the DMSO content of the reaction ...

  8. COMBINED ALUMINIUM SULFATE/HYDROXIDE PROCESS FOR ...

    African Journals Online (AJOL)

    community level. KEY WORDS: Nalgonda Technique, Aluminium sulfate, Aluminium hydroxide, Fluoride, Drinking water. INTRODUCTION. Fluoride is a common constituent in natural waters or wastewaters. It may originate from either natural geological sources or industries that use fluoride-containing compounds as raw.

  9. 21 CFR 184.1763 - Sodium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the... following current good manufacturing practice conditions of use: (1) The ingredient is used as a pH control... manufacturing practice. (d) Prior sanctions for this ingredient different from the uses established in this...

  10. Thermal formation of corundum from aluminium hydroxides ...

    Indian Academy of Sciences (India)

    Aluminium hydroxides have been precipitated from various aluminium salts and the differences in their thermal behaviour have been investigated. Pseudoboehmite derived from the nitrate, sulfate and chloride all form -Al2O3 at ∼ 400°C but the formation of -Al2O3 at 1200°C occurs more readily in the material derived ...

  11. Hydroxide catalysis bonding of silicon carbide

    NARCIS (Netherlands)

    Veggel, A.A. van; Ende, D.A. van den; Bogenstahl, J.; Rowan, S.; Cunningham, W.; Gubbels, G.H.M.; Nijmeijer, H.

    2008-01-01

    For bonding silicon carbide optics, which require extreme stability, hydroxide catalysis bonding is considered [Rowan, S., Hough, J. and Elliffe, E., Silicon carbide bonding. UK Patent 040 7953.9, 2004. Please contact Mr. D. Whiteford for further information: D.Whiteford@admin.gla.ac.uk]. This

  12. Pectin-coated chitosan-LDH bionanocomposite beads as potential systems for colon-targeted drug delivery.

    Science.gov (United States)

    Ribeiro, Lígia N M; Alcântara, Ana C S; Darder, Margarita; Aranda, Pilar; Araújo-Moreira, Fernando M; Ruiz-Hitzky, Eduardo

    2014-03-10

    This work introduces results on a new drug delivery system (DDS) based on the use of chitosan/layered double hydroxide (LDH) biohybrid beads coated with pectin for controlled release in the treatment of colon diseases. Thus, the 5-aminosalicylic acid (5ASA), the most used non-steroid-anti-inflammatory drug (NSAID) in the treatment of ulcerative colitis and Crohn's disease, was chosen as model drug aiming to a controlled and selective delivery in the colon. The pure 5ASA drug and the hybrid material prepared by intercalation in a layered double hydroxide of Mg2Al using the co-precipitation method, were incorporated in a chitosan matrix in order to profit from its mucoadhesiveness. These compounds processed as beads were further treated with the polysaccharide pectin to create a protective coating that ensures the stability of both chitosan and layered double hydroxide at the acid pH of the gastric fluid. The resulting composite beads presenting the pectin coating are stable to water swelling and procure a controlled release of the drug along their passage through the simulated gastrointestinal tract in in vitro experiments, due to their resistance to pH changes. Based on these results, the pectin@chitosan/LDH-5ASA bionanocomposite beads could be proposed as promising candidates for the colon-targeted delivery of 5ASA, with the aim of acting only in the focus of the disease and minimizing side effects. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Cyclic voltammetric studies of electrodeposited solid solution and composite oxide/hydroxide electrodes in 1 M KOH: the Co(OH) 2-Ni(OH) 2-MnO 2 system

    Science.gov (United States)

    Ismail, J.; Ahmed, M. F.; Vishnu Kamath, P.

    Solid solutions of the type Ni 1- xCo x(OH) 2 ( x = 0.1 to 0.9) obtained by cathodic deposition from a mixed nitrate bath show a redox behaviour that is completely different to that of the pure components. The solid obtained from a bath containing a Ni/Co ratio of 40/60 exhibits the lowest Erev and the smallest difference between the anodic and cathodic peak potentials (0.03 V). This is indicative of the high reversibility achieved at this composition. A layer-by-layer deposited composite electrode Pt/Ni(OH) 2/MnO 2 shows the migration of the active nickel oxide species from the inner layer to the surface and a marked lowering in the Erev of the nickel hydroxide reaction. By contrast, the cobalt counterpart of this electrode does not show any of these interesting features. The Pt/MnO 2/Ni(OH) 2 electrode does not hold much promise as it exhibits a markedly reduced reversibility of the nickel hydroxide reaction. In the cobalt counterpart Pt/MnO 2/Co(OH) 2, MnO 2 profoundly affects the reactions of cobalt hydroxide: first anodic reaction is suppressed and the second anodic reaction is less reversible. These observations suggest that there is a common chemical reaction mechanism for all oxide electrodes in alkaline media.

  14. Determination of adsorbed protein concentration in aluminum hydroxide suspensions by near-infrared transmittance Spectroscopy

    DEFF Research Database (Denmark)

    Lai, Xuxin; Zheng, Yiwu; Jacobsen, Susanne

    2008-01-01

    Analysis of aluminum hydroxide based vaccines is difficult after antigen adsorption. Adsorbed protein is often assessed by measuring residual unadsorbed protein for quality control. A new method for the direct determination of adsorbed protein concentration in suspension using near-infrared (NIR...... in vaccine production as a method for quality control and quality assurance.......) transmittance spectroscopy is proposed here. A simple adsorption system using albumin from bovine serum (BSA) and aluminum hydroxide as a model system is employed. The results show that the NIR absorbance at 700-1300 nm is correlated to the adsorbed BSA concentration, measured by the ultraviolet (UV) method...

  15. The Preparation of ZnGa2O4 Nano Crystals by Spray Coprecipitation and Its Gas Sensitive Characteristics

    Directory of Open Access Journals (Sweden)

    Jinhuai Liu

    2002-03-01

    Full Text Available ZnGa2O4 nano crystals were prepared by an improved coprecipitation method, which we call ‘spray coprecipitation’. XRD results shows the resulting crystal size using the new method is under 10nm, whereas the powder prepared by ordinary coprecipitation is about 30nm. XRD results also shows ZnO peaks exists in ZnGa2O4 powder prepared by traditional coprecipitation, but disappears in ZnGa2O4 nano crystal prepared by spraying coprecipitation. SEM and TEM were used to analysis the structural characteristics of ZnGa2O4 nano crystals. The gas sensitive characteristics of ZnGa2O4 nano crystals are reported.

  16. A novel method for speciation of chromium: coprecipitation without carrier element by using a triazole derivative.

    Science.gov (United States)

    Duran, Celal; Bulut, Volkan N; Ozdes, Duygu; Gundogdu, Ali; Soylak, Mustafa

    2009-01-01

    A coprecipitation method has been established for speciation of chromium(III) and chromium(VI) in real samples. The procedure is based on the coprecipitation of Cr(III), by using a new organic coprecipitant, 3-phenyl-4-o-hydroxybenzyl-idenamino-4,5-dihydro-1,2,4-triazole-5-one, without adding any carrier element. After reduction of Cr(VI) by concentrated H2SO4 and ethanol, the method was applied to the determination of total Cr. The level of Cr(VI) was calculated by the difference of total Cr and Cr(III) levels. For optimum recovery of Cr(III), different analytical factors such as pH, amount of coprecipitant, centrifugation rate and time, and effect of sample volume, were investigated. The influences of some anions, cations, and transition metals on the recoveries were also investigated, and no significant interferences were observed. The preconcentration factor was 100. The detection limit based on 3 times standard deviation (sigma) of the blank (n = 10) for Cr(III) was 0.50 microg/L. In order to evaluate the accuracy of the method, certified reference materials (CRM-TMDW-500 Drinking Water and National Institute of Standards and Technology Standard Reference Material 1573a Tomato Leaves) were analyzed, and the results obtained were in good agreement with certified values. The presented procedure was applied for Cr speciation in various solid and liquid samples with successful results.

  17. Enhancement of MgAl2 O4 spinel formation from coprecipitated ...

    Indian Academy of Sciences (India)

    Although low temperature fast coprecipitation technique has been used to synthesize stoichiometric (MgO–nAl2O3, = 1) MgAl2O4 spinel forming precursor, delayed spinellization has always been the concern in this process. In this article, the precursor of this 'fast technique' has been used for bulk production by further ...

  18. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  19. Uncertainties in the oxygen isotopic composition of barium sulfate induced by coprecipitation of nitrate.

    Science.gov (United States)

    Michalski, Greg; Kasem, Michelle; Rech, Jason A; Adieu, Sabine; Showers, William S; Genna, Bernie; Thiemens, Mark

    2008-10-01

    Coprecipitation of nitrate and sulfate by barium has probably resulted in significant error in numerous studies dealing with the oxygen isotopic composition of natural sulfates using chemical/thermal conversion of BaSO(4) and analysis by isotope ratio mass spectrometry. In solutions where NO(3) (-)/SO(4) (2-) molar ratios are above 2 the amount of nitrate coprecipitated with BaSO(4) reaches a maximum of approximately 7% and decreases roughly linearly as the molar ratio decreases. The fraction of coprecipitated nitrate appears to increase with decreasing pH and is also affected by the nature of the cations in the precipitating solution. The size of the oxygen isotope artifact in sulfate depends both on the amount of coprecipitated nitrate and the delta(18)O and Delta(17)O values of the nitrate, both of which can be highly variable. The oxygen isotopic composition of sulfate extracted from atmospheric aerosols or rain waters are probably severely biased because photochemical nitrate is usually also present and it is highly enriched in (18)O (delta(18)O approximately 50-90 per thousand) and has a large mass-independent isotopic composition (Delta(17)O approximately 20-32 per thousand). The sulfate delta(18)O error can be 2-5 per thousand with Delta(17)O artifacts reaching as high as 4.0 per thousand.

  20. Enhancement of MgAl2 O4 spinel formation from coprecipitated ...

    Indian Academy of Sciences (India)

    Administrator

    Flow chart depicting the preparation procedure of processed spinel precur- sors through coprecipitation technique. process manipulation such as control of precipitation rate, adjustment of pH value and use of dispersing agents etc, it is possible to prepare submicron or even nano level alumina powders with high purity i.e. ...

  1. Studies on the promotion of nickel—alumina coprecipitated catalysts: I. Titanium oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Mercera, P.D.L.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    A series of TiO2-promoted nickel—alumina catalysts has been prepared and characterized. The promoter was added in various proportions to a calcined coprecipitated nickel—alumina material by adsorption of the acetylacetonate complex of titanium, followed by further calcination and reduction. The

  2. Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

  3. COMPARATIVE MAGNETIC AND PHOTOCATALYTIC PROPERTIES OF COPRECIPITATED ZINC FERRITE NANOPARTICLES BEFORE AND AFTER CALCINATION

    Directory of Open Access Journals (Sweden)

    M. Ebrahimi

    2017-03-01

    Full Text Available In this work, the effects of co-precipitation temperature and post calcination on the magnetic properties and photocatalytic activities of ZnFe2O4 nanoparticles were investigated. The structure, magnetic and optical properties of zinc ferrite nanoparticles were characterized by X-ray diffraction (XRD, vibrating sample magnetometry and UV–Vis spectrophotometry techniques.  The XRD results showed that the coprecipitated as well as calcined nanoparticles are single phase with partially inverse spinel structures. The magnetization and band gap decreased with the increasing of co-precipitation temperature through the increasing of the crystallite size. However, the post calcination at 500 °C was more effective on the decreasing of magnetization and band gap. Furthermore, photocatalytic activity of zinc ferrite nanoparticles was studied by the degradation of methyl orange under UV-light irradiation. Compare with the coprecipitated ZnFe2O4 nanoparticles with 5% degradation of methyl orange after 5 h UV-light light radiation, the calcined ZnFe2O4 nanoparticles exhibited a better photocatalytic activity with 20% degradation.

  4. Speciation analysis of 129I in seawater using coprecipitation and accelerator mass spectrometry and its applications

    DEFF Research Database (Denmark)

    Xing, Shan; Hou, Xiaolin; Aldahan, Ala

    2017-01-01

    Speciation analysis of long-lived 129I in seawater can provide useful information on the source of water masses. This paper presents an improved method for speciation analysis of 129I based on coprecipitation of iodide as AgI with Ag2SO3 and AgCl. By adding a small amount of 127I carrier, the sep...

  5. Speciation of Mn(II), Mn(VII) and total manganese in water and food samples by coprecipitation-atomic absorption spectrometry combination.

    Science.gov (United States)

    Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2010-01-15

    A speciation procedure based on the coprecipitation of manganese(II) with zirconium(IV) hydroxide has been developed for the investigation of levels of manganese species. The determination of manganese levels was performed by flame atomic absorption spectrometry (FAAS). Total manganese was determined after the reduction of Mn(VII) to Mn(II) by ascorbic acid. The analytical parameters including pH, amount of zirconium(IV), sample volume, etc., were investigated for the quantitative recoveries of manganese(II). The effects of matrix ions were also examined. The recoveries for manganese(II) were in the range of 95-98%. Preconcentration factor was calculated as 50. The detection limit for the analyte ions based on 3 sigma (n=21) was 0.75 microg L(-1) for Mn(II). The relative standard deviation was found to be lower than 7%. The validation of the presented procedure was performed by analysis of certified reference material having different matrices, NIST SRM 1515 (Apple Leaves) and NIST SRM 1568a (Rice Flour). The procedure was successfully applied to natural waters and food samples.

  6. Co-precipitation synthesis and characterization of NiO-Ce0.8Sm0.2O1.9 nanocomposite powders: effect of precipitation agents.

    Science.gov (United States)

    Ding, Changsheng; Lin, Hongfei; Sato, Kazuhisa; Hashida, Toshiyuki

    2011-03-01

    NiO-Ce0.8Sm0.2O1.9 (NiO-SDC) nanocomposite powders applied as promising anode material for low-temperature solid oxide fuel cells (SOFCs) were synthesized by hydroxide co-precipitation method using NH3 x H2O, NaOH and NH3 x H2O + NaOH as precipitation agents. The crystal phases, morphologies and sintering behavior of the synthesized NiO-SDC nanocomposite powders were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and sintering experiments. The effect of precipitation agents on the synthesis of the NiO-SDC nanocomposite powders was discussed. Results show that different precipitation agents influence greatly the synthesis and characteristics of the NiO-SDC nanocomposite powders. The NiO-SDC nanocomposite powders synthesized with NH3 x H2O deviate from the original composition due to the loss of Ni. The loss of Ni is avoided and nano-sized NiO-SDC composite powders are synthesized, when NaOH and NH3 x H2O + NaOH are used as precipitation agents. The NiO-SDC nanocomposite powders can be synthesized at relatively low temperature using NH3 x H2O + NaOH as precipitation agent, and the synthesized NiO-SDC nanocomposite powders show good sintering characteristics.

  7. Sintering study of NiO-YSZ composite obtained by coprecipitation route; Estudo de sinterabilidade do composito de NiO-YSZ obtido pela rota de coprecipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Yoshito, W.K.; Resitivo, T.A.G.; Ussui, V.; Lazar, D.R.R.; Paschoal, J.O.A., E-mail: wyoshito@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

    2009-07-01

    NiO-YSZ composite is a widely used anode material for solid oxide fuel cell. The main purpose of the present work was the evaluation of the appropriate conditions of ceramic processing, by sintering behavior study of NiO-YSZ pressed powders, synthesized by hydroxide coprecipitation route. Using the empirical rate equation developed by Makipirtti-Meng, it was analyzed shrinkage rate in the temperature ranges of 900-1400 deg C as function of time. The powders were characterized by X-ray diffraction, scanning electron microscopy, gas adsorption, laser diffraction and helium picnometry. The microstructural characterization of the samples was evaluated by X-ray diffraction, scanning electron microscopy and relative density by the Archimedes method. It was found that activation energy value is 48,3 kJ.mol{sup -1} in the temperature range of 900-950 deg C and 604,83 kJ.mol{sup -1} for 1000-1200 deg C. These values correspond to the change that occurs in the microstructure during the heat treatment process. The sintering process was evaluated by the dilatometry date treatment. (author)

  8. Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

    Science.gov (United States)

    Djebbi, Mohamed Amine; Braiek, Mohamed; Namour, Philippe; Ben Haj Amara, Abdesslem; Jaffrezic-Renault, Nicole

    2016-11-01

    Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However, MgAl LDH shows better performance than ZnAl LDH, due to the presence of magnesium cations in the layers. Following the structural, morphological and electrochemical behavior studies of both synthesized LDHs, the prepared LDH modified electrodes were tested through microbial fuel cell configuration, revealing a remarkable, potential new pathway for high-performance and cost-effective electrode use in electrochemical power devices.

  9. Mixed oxides derived from layered double hydroxides as novel catalysts for phenol photodegradation

    Science.gov (United States)

    Puscasu, C. M.; Carja, G.; Mureseanu, M.; Zaharia, C.

    2017-08-01

    The removal of organic pollutants is nowadays a very challenging aspect of the environmental research. There are strong interests to develop novel semiconducting photocatalysts able to efficiently promote advanced oxidation reactions. The development of photocatalysts based on the mixtures of mixed oxides derived from layered double hydroxides (LDHs) - a family of naturally occurring anionic clays - might offer novel environmental-friendly solutions for the cost effective removal of organic pollutants. This work presents ZnO/ZnAl2O4, ZnO/Zn2TiO4 and ZnO/ZnCr2O4 as novel photocatalytic formulations for phenol degradation under UV irradiation. They were obtained by the controlled thermal treatment of the layered double hydroxides matrices (LDHs), as precursors materials, type ZnM-LDH (M = Al3+, Cr3+ or Ti4+). The LDHs were synthesized by the co-precipitation method at a constant pH. Controlled calcination at 650°C gives rise to solutions of mixed metal oxides. The structural and nanoarchitectonics characteristics of the studied catalysts were described by: XRD, SEM/TEM and TG/DTG techniques. Results show that in the photocatalytic process of the phenol degradation from aqueous solutions, ZnO/ZnCr2O4 and ZnO/ZnAl2O4 showed the best performance degrading ∼98% of phenol after 3.5 hs and 5 hs, respectively; while ZnO/Zn2TiO4 has degraded almost 80 % after 7.5 hs of UV irradiation. These results open new opportunities in the development of new cost effective photoresponsive formulations able to facilitate the photo-degradation of the organic pollution as “green” solution for removal of dangerous pollutants.

  10. Relationship between sealing ability of Activ GP and Gutta Flow and methods of calcium hydroxide removal.

    Science.gov (United States)

    Nikhil, Vineeta; Singh, Vijay; Singh, Simranjeet

    2012-01-01

    To evaluate the effect of method of calcium hydroxide intracanal dressing removal, on sealing ability of Gutta Flow and Activ GP. Seventy extracted mandibular premolars were sectioned at CEJ and canals were prepared with profile 4% rotary file till #40. Canals were filled with calcium hydroxide, coronally sealed with Cavit G and stored at 37°C. After 7 days, samples were divided on the basis of calcium hydroxide removal method (Master apical file, Navi Tip FX, and F File) and obturating material (Activ GP and Gutta Flow). Three coats of nail polish were applied except 2 mm around apical foramen and samples were immersed in India ink dye, sectioned, and observed under stereomicroscope for microleakage. The results were statistically analyzed with one way ANOVA-F with Tukey HSD test with the null hypothesis set as 5%. The seal of the canal system was adversely impacted by residual calcium hydroxide when Activ GP and Gutta Flow were used as obturating material and the sealing ability of Activ GP and Gutta Flow was better when MAF was used for removal of calcium hydroxide than F file or Navi tip FX.

  11. Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation

    Science.gov (United States)

    Fuller, C.C.; Dadis, J.A.; Waychunas, G.A.

    1993-01-01

    The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (kinetics of As(V) desorption after an increase in pH were also consistent with diffusion as a rate-limiting process. Aging of pure ferrihydrite prior to As(V) adsorption caused a decrease in adsorption sites on the precipitate owing to crystallite growth. In coprecipitation experiments, the initial As(V) uptake was significantly greater than in post-synthesis adsorption experiments, and the rate of uptake was not diffusion limited because As(V) was coordinated by surface sites before crystallite growth and coagulation processes could proceed. After the initial adsorption, As(V) was slowly released from coprecipitates for at least one month, as crystallite growth caused desorption of As(V). Adsorption densities as high as 0.7 mole As(V) per mole of Fe were measured in coprecipitates, in comparison to 0.25 mole As(V) per mole of Fe in post-synthesis adsorption experiments. Despite the high Concentration of As(V) in the precipitates, EXAFS spectroscopy (Waychunas et al., 1993) showed that neither ferric arsenate nor any other As-bearing surface precipitate or solid solution was formed. The high adsorption densities are possible because the ferrihydrite particles are extremely small, approaching the size of small dioctahedral chains at the highest As(V) adsorption density. The results suggest that the solid solution model proposed by Fox (1989, 1992) for control of arsenate and phosphate concentrations in natural waters may be invalid. ?? 1993.

  12. Influence of carbonate intercalation in the surface-charging behavior of Zn-Cr layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, R., E-mail: rrojas@mail.fcq.unc.edu.ar [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Barriga, C. [Departamento de Quimica Inorganica e Ingenieria Quimica, Edificio Marie Curie, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain); De Pauli, C.P. [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Avena, M.J. [Departamento de Quimica, Universidad Nacional del Sur, Avenida Alem 1253, 8000 Bahia Blanca (Argentina)

    2010-01-15

    The influence of interlayer composition in the surface charge and reactivity of layered double hydroxides (LDHs) has been explored. With this purpose, a chloride-intercalated Zn-Cr-LDH has been synthesized by the constant pH coprecipitation method and afterwards exchanged with carbonate to obtain solids with different Cl{sup -}/CO{sub 3}{sup 2-} ratios. The solids structure has been characterized by elemental chemical analysis, powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity have been studied by acid-base potentiometric titrations and electrophoretic mobility determinations. The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and decreasing support electrolyte concentration and the particles present positive electrophoretic mobility in the measured pH range. As carbonate content increases in the samples, the total OH{sup -} uptake diminishes and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at around pH 10. A LDH-water interface model has been used to give an interpretation to the experimental data. The model indicates that as carbonate content increases, the sample behavior becomes similar to that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acid-base reactions.

  13. Layered double hydroxides as electrode materials for Ni based batteries and as novel inorganic/organic hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Caravaggio, G.

    2002-07-01

    This study examined the electrochemical properties of layered double hydroxides (LDH) in half-cells to determine if they can be used in nickel-cadmium (Ni-Cd) and nickel-metal hydride (NiMH) batteries. The LDHs were prepared by coprecipitation and were characterized by X-ray diffraction analysis. The nickel-aluminium LDHs were found to be the most stable during potassium hydroxide electrolyte discharge because the aluminium acted in a two fold manner. The high charge to radius ratio increased the electrostatic interaction between the anions and the metal layers. The acidity of the hydroxyl groups was due to the high exchange of electrons. The powders had lower discharge capacity compared to commercial electrode materials because of their low density. The nickel-vanadium LDHs exchanged only up to 1.2 electrons and were stable only up to a maximum of 14 days in electrolytic solutions of the cells. Zinc-aluminium LDHs were also synthesized and intercalated with phenyl phosphonic acid or 1,4-phenylene bis phosphonic acid to create microporous materials. X-ray diffraction, infra-red spectroscopy and nuclear magnetic resonance was used to characterize the compounds and determine crystallographic spacing. Grafting of both phosphonates to the metal layers had occurred and both materials showed little or no microporosity.

  14. Synthesis and characterization of terephthalate-intercalated NiAl layered double hydroxides with high Al content.

    Science.gov (United States)

    Arias, Santiago; Eon, Jean Guillaume; San Gil, Rosane A S; Licea, Yordy E; Palacio, Luz Amparo; Faro, Arnaldo C

    2013-02-14

    Terephthalate-intercalated nickel-aluminum layered double hydroxides (LDHs) were prepared by a co-precipitation method, with nominal x values in the general formula Ni((1-x))Al(x)(OH)(2)(C(8)H(4)O(4))(x/2) in the range 0.3-0.8. The materials were characterized by X-ray diffraction, X-ray fluorescence spectroscopy, CHN analysis, thermogravimetric analysis, FTIR spectroscopy, EXAFS at the Ni edge and (27)Al NMR spectroscopy. A combination of XRD, XRF and CHN analysis indicated that crystalline LDHs with true x values up to 0.5 were obtained, along with increasing segregation of an aluminum hydroxide phase with increasing aluminum content. The EXAFS analysis indicated an upper limit of ca. 0.6 for the atomic fraction of aluminum at the second nickel coordination sphere. The (27)Al NMR analysis suggested that a phase containing octahedrally co-ordinated Al(3+) is segregated for nominal x values from 0.6 upwards.

  15. Structural and magnetic properties Co{sub 3}O{sub 4} obtained by the coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Junior, M.E.; Junior, F.A.; Hernandez, E.P.; Barbosa, F.C.G.; Paulo, V.I.M.; Junior, J.N.A.; Almeida, J.C. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

    2016-07-01

    Full text: The study shows a structural and magnetic properties of cobalt oxide Co3O4 doped with Cr as a function of the parameters adopted during the synthesis by chemical co-precipitation were flowing neutralizing NaOH and calcination temperature to 800 °C and 1000 °C. First, a series of samples of this oxide in which the flow was changed neutralization of the NaOH solution was generated. Thermal treatments were carried out at 800 °C and 1000 °C in anticipation of changing voltages on the network, average crystal size, etc. XRD observed in this case that the major phase and Co3O4 was found that the change of flow, the average crystallite size of network parameters and changes suffered distorted. In magnetic measurements MxT for samples to 800 °C and 1000 °C we observed behavioral evidence of a ferri / ferromagnetic-paramagnetic transition. On the other hand, the Curie-Weiss parameter was found negative for all samples associated with the major phase Co3O4 antiferromagnetic. Thus, we could correlate these phenomena the possible presence of phase clusters / nanoclusters amorphous ferri / ferromagnetic with CoCr2O4 / CrO2 generated with the incorporation of Cr under different NaOH flows. These coupling steps leading to the observed behavior. Have the MXH measures to 1000 °C in 50K presented a characteristic hysteresis loop system ferri / ferromagnetic well pronounced and could associate this, beyond the coupling phase, the fact that higher temperatures increase the grain size decreasing the surface anisotropy and favoring phases ferri / ferromagnetic. We are convinced that the results of our research is an important contribution to the field. (author)

  16. Isothermal decomposition kinetics of nickel (II) hydroxide powder

    Energy Technology Data Exchange (ETDEWEB)

    Carney, C.S., E-mail: Casey.Carney@CONTR.NETL.DOE.GOV [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States); Chinn, R.E.; Doğan, Ö.N. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); Gao, M.C. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States)

    2015-09-25

    Highlights: • A first order random nucleation model was proposed for the decomposition of nickel hydroxide. • Trapped lattice product water greatly suppressed high conversion reaction rates. • Annealing experiments of the Ni–Ni(OH){sub 2}–NiO phase triangle yielded only two phases: Ni and NiO. • This Ni–Ni(OH){sub 2}–NiO phase triangle in the Ni-rich corner of the Ni–O–H system was confirmed. - Abstract: Nickel (II) hydroxide powder was investigated by thermogravimetry for isothermal decomposition kinetics and verification of the Ni–O–H ternary phase diagram at low temperatures. The activation energy and frequency factor were measured as E{sub a} = 134 kJ/mol and A = 1.27 × 10{sup 10} s{sup −1}, respectively. The validity of the first-order random nucleation model was confirmed, as opposed to diffusion and or moving-boundary models. The dependence of TGA results on specimen size was noted. The Ni–Ni(OH){sub 2}–NiO phase triangle was confirmed. Accordingly, a thermodynamic description of the system was established in the Ni-rich corner, and the isotherm at room temperature is calculated.

  17. In situ preparation of Calcium hydroxide films

    Energy Technology Data Exchange (ETDEWEB)

    Dahle, S.; Voigts, F. [Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Maus-Friedrichs, W., E-mail: w.maus-friedrichs@pe.tu-clausthal.de [Institut fuer Physik und Physikalische Technologien, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany); Clausthaler Zentrum fuer Materialtechnik, Technische Universitaet Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld (Germany)

    2011-10-31

    The in situ preparation of Calcium hydroxide films in an ultra high vacuum (UHV) is constrained by the decomposition of species at the surface and the absence of OH bulk diffusion. Therefore, it is not possible to prepare such films simply by water exposure to a Calcium layer. We present four different approaches for the preparation of Ca(OH){sub 2} films in an UHV. Two of these methods are found to be ineffective for the preparation, the other two are shown to produce Calcium hydroxide films. Both of the two effective procedures make use of H{sub 2} gas exposure. Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, and X-ray Photoelectron Spectroscopy are employed to verify quality and purity of the films.

  18. Accidental periapical extrusion of non-setting calcium hydroxide: Unusual bone response and management

    Directory of Open Access Journals (Sweden)

    Divya S Sharma

    2014-01-01

    Full Text Available Premixed non-setting calcium hydroxide is frequently used as interim root canal dressing in endodontically involved permanent teeth and as obturating paste in deciduous teeth in pediatric dentistry. Wide apex in both cases makes it more prone for deliberate extrusion especially when applied with pressure delivery systems. Contrary to common belief the mix was not resorbed in two years with the complaint of insufficiency in mastication. Large mass of calcium hydroxide in bone delayed healing process even after its removal. The present case report intends to demonstrate unusual behavior of bone in response to oily non-setting preparation of calcium hydroxide. Therefore its application with pressure syringe should be reconsidered in pediatric dentistry.

  19. Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

    Science.gov (United States)

    Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

    2014-04-15

    Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far

  20. Reversible flocculation of microalgae using magnesium hydroxide

    OpenAIRE

    Vandamme, Dries; Beuckels, Annelies; Markou, Giorgos; Foubert, Imogen; Muylaert, Koenraad

    2015-01-01

    Flocculation of microalgae is a promising low-cost strategy to harvest microalgae for bulk biomass production. However, residual flocculants can interfere in further downstream processes or influence biomass quality. In this study, a new concept is demonstrated based on reversible magnesium hydroxide flocculation, using Chlorella vulgaris and Phaeodactylum tricornutum as, respectively, a freshwater and a marine model species. We show that flocculation was induced by precipitation of magnesium...

  1. Pressure-induced decomposition of indium hydroxide.

    Science.gov (United States)

    Gurlo, Aleksander; Dzivenko, Dmytro; Andrade, Miria; Riedel, Ralf; Lauterbach, Stefan; Kleebe, Hans-Joachim

    2010-09-15

    A static pressure-induced decomposition of indium hydroxide into metallic indium that takes place at ambient temperature is reported. The lattice parameter of c-In(OH)(3) decreased upon compression from 7.977(2) to approximately 7.45 A at 34 GPa, corresponding to a decrease in specific volume of approximately 18%. Fitting the second-order Birch-Murnaghan equation of state to the obtained compression data gave a bulk modulus of 99 +/- 3 GPa for c-In(OH)(3). The c-In(OH)(3) crystals with a size of approximately 100 nm are comminuted upon compression, as indicated by the grain-size reduction reflected in broadening of the diffraction reflections and the appearance of smaller (approximately 5 nm) incoherently oriented domains in TEM. The rapid decompression of compressed c-In(OH)(3) leads to partial decomposition of indium hydroxide into metallic indium, mainly as a result of localized stress gradients caused by relaxation of the highly disordered indium sublattice in indium hydroxide. This partial decomposition of indium hydroxide into metallic indium is irreversible, as confirmed by angle-dispersive X-ray diffraction, transmission electron microscopy imaging, Raman scattering, and FTIR spectroscopy. Recovered c-In(OH)(3) samples become completely black and nontransparent and show typical features of metals, i.e., a falling absorption in the 100-250 cm(-1) region accompanied by a featureless spectrum in the 250-2500 cm(-1) region in the Raman spectrum and Drude-like absorption of free electrons in the region of 4000-8000 cm(-1) in the FTIR spectrum. These features were not observed in the initial c-In(OH)(3), which is a typical white wide-band-gap semiconductor.

  2. Pharmacokinetic Profile of Oral Magnesium Hydroxide.

    Science.gov (United States)

    Dolberg, Mette Konow Bøgebjerg; Nielsen, Lars Peter; Dahl, Ronald

    2017-03-01

    Despite the presumption of a beneficial effect of magnesium (Mg) supplementation on various diseases, little is known concerning the pharmacokinetics of Mg hydroxide. This study was designed to provide a pharmacokinetic profile of Mg hydroxide after a single oral dose. Ten healthy male adults participated in this cross-over study with three 24-hr study days. Interventions were (i) none (baseline), (ii) oral intake of three (3 × 360 mg) tablets of Mg hydroxide (Mablet ® ) and (iii) IV bolus infusion of 2 g Mg sulphate (index drug). Blood samples were collected before the single dose, after (i.e. after treatment administration) 15, 30, 60, 90 and 120 min. and after 3, 4, 6, 8, 12 and 24 hr. Urine was collected in four 6-hr periods per study day. Blood (N = 10) and urine (N = 6) Mg were analysed by descriptive statistics. Bioavailability was 14.9% (CI: 8.3; 26.8), blood clearance was 5.1 L/hr (CI: 2.1; 17.0), apparent volume of distribution was 60.2 L (CI: 35.6; 102.0), elimination constant was 0.08 per hour (CI: 0.05; 0.14), half-life was 8.3 hr (CI: 4.8; 14.1), C max was 0.11 mmol/L (CI: 0.07; 0.14), and AUC [0-24] was 92.3 mmol/L × min. (CI: 45.5; 139.1). Urine Mg excretion augmented by 17.7% (CI: 8.9; 35.0) from baseline. No severe side effects were observed. The bioavailability of Mg hydroxide was 15%, and it constitutes a clinically relevant option for oral Mg supplementation. No severe side effects were seen. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  3. Calcium hydroxide silylation reaction with trimethylchlorosilane

    Directory of Open Access Journals (Sweden)

    Novoselnov Anatoliy A.

    2016-01-01

    Full Text Available The silylation reaction of a calcium hydroxide with a trimethylchlorosilane is studied as a silylation model by the gas-liquid chromatography. The silylation process is divided into three stages. A material balance of these stages is calculated. The schemes of the reactions at each stage of the process are proposed. The modified calcium hydroxide obtained at three repetitive stages of the silylation reaction has been investigated by the x-ray phase analysis, IR spectroscopy, thermal analysis, electron microscopy in a combination with the elemental analysis. It has been determined that at the first stage of the interaction the processes of the trimethylchlorosilane hydrolysis and of the hydrolysis products condensation dominate, and at the same time an adsorption process of the trimethylchlorosilane and its derivatives starts. Further, the hydrolysis of the trimethylchlorosilane by the «new» portions of a water formed in the reaction of a calcium hydroxide with a hydrogen chloride takes place, simultaneously the secondary reactions of the Si-O-Ca – ties’ formation and cleavage occur including as a silylation-desilylation dynamic equilibrium process.

  4. Nickel hydroxide modified electrodes for urea determination

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Dall´Antonia

    2007-03-01

    Full Text Available Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO32 0,05 mol L ?¹ on ITO electrodes (Tin oxide doped with Indium on PET-like plastic film, applying a current of - 0,1 A cm ?² during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?¹, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II/Ni(III. A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?¹ and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?¹, the behavior is linear and the sensibility found was of 20,3 mA cm?² (mol L?¹?¹, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.

  5. Relationship between the coprecipitation mechanism, doping structure and physical properties of Zn(1-x)Co(x)S nanocrystallites.

    Science.gov (United States)

    Ren, Guoqiang; Lin, Zhang; Wang, Chen; Liu, Weizhen; Zhang, Jing; Huang, Feng; Liang, Jingkui

    2007-01-24

    Zn(1-x)Co(x)S nanocrystallites synthesized by the coprecipitation method have been studied. X-ray powder diffraction analysis shows that the solid solubility limit of sphalerite Zn(1-x)Co(x)S can reach x = 16.4%. It is found that when the Co(2+) percentage in the starting solution (Co:(Co+Zn)(solution)) is less than 15% only 20% of Co(2+) ions can be coprecipitated. Otherwise, around 50% of Co(2+) ions will be effectively coprecipitated. The surface exchange experiments and the optical absorption characteristics reveal that Co(2+) ions are in the form of internal dopants and substitute for tetrahedral Zn sites. Further optical and magnetic measurements indicate significant differences for samples with different coprecipitation ratios. Distorted lattice structure and low temperature super-paramagnetism are observed for high coprecipitation ratio samples, while a crystallized structure with high photoluminescence efficiency and abnormal effective magnetic moment (3.3 mu(B)/Co) are found in low coprecipitation ratio samples. A mechanism relating to different nucleation and crystal growth kinetics in two coprecipitation regions has been proposed to accommodate the differences in structural and physical properties of Zn(1-x)Co(x)S nanocrystallites.

  6. Synthesis of Al doped ZnO nanoparticles by aqueous coprecipitation

    OpenAIRE

    Giovannelli, Fabien; Ngo Ndimba, P.; Diaz-Chao, P.; Motelica-Heino, Mikael; Raynal, P.I.; Autret, C.; Delorme, F.

    2014-01-01

    International audience; Al-doped ZnO particles were obtained by a simple route: soda addition in aqueous cationic solution. The effects of temperature, hydrolysis duration, reagent concentration and time were investigated. A non-topotactic reaction mechanism, involving firstly the precipitation of various hydroxide compounds depending on the route (low or high pH), followed by the dissolution-recrystallization of the hydroxide species into ZnO was demonstrated. The Al concentration in the fin...

  7. ZnO/Mg-Al Layered Double Hydroxides as a Photocatalytic Bleaching of Methylene Orange - A Black Box Modeling by Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Seyed Ali Hosseini

    2016-10-01

    Full Text Available The paper reports the development of ZnO-MgAl layered double hydroxides as an adsorbent-photo catalyst to remove the dye pollutants from aqueous solution and the experiments of a photocatalytic study were designed and modeled by response surface methodology (RSM and artificial neural network (ANN. The co-precipitation and urea methods were used to synthesize the ZnO-MgAl layered double hydroxides and FT-IR, XRD and SEM analysis were done for characterization of the catalyst.The performance of the ANN model was determined and showed the efficiency of the model in comparison to the RSM method to predict the percentage of dye removal accurately with a determination coefficient (R2 of 0.968. The optimized conditions were obtained as follows: 600 oC, 120 min, 0.05 g and 20 ppm for the calcination temperature, irradiation time, catalyst amount and dye pollutant concentration, respectively. Copyright © 2016 BCREC GROUP. All rights reserved Received: 22nd January 2016; Revised: 14th March 2016; Accepted:15th March 2016 How to Cite: Hosseini, S.A., Akbari, M. (2016. ZnO/Mg-Al Layered Double Hydroxides as a Photocatalytic Bleaching of Methylene Orange - A Black Box Modeling by Artificial Neural Network. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 299-315 (doi: 10.9767/bcrec.11.3.570.299-315 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.570.299-315

  8. Enhanced Phosphorus Locking by Novel Lanthanum/Aluminum-Hydroxide Composite: Implications for Eutrophication Control.

    Science.gov (United States)

    Xu, Rui; Zhang, Meiyi; Mortimer, Robert J G; Pan, Gang

    2017-03-21

    Lanthanum (La) bearing materials have been widely used to remove phosphorus (P) in water treatment. However, it remains a challenge to enhance phosphate (PO4) adsorption capacity and La usage efficiency. In this study, La was coprecipitated with aluminum (Al) to obtain a La/Al-hydroxide composite (LAH) for P adsorption. The maximum PO4 adsorption capacities of LAH (5.3% La) were 76.3 and 45.3 mg P g-1 at pH 4.0 and 8.5, which were 8.5 and 5.3 times higher than those of commercially available La-modified bentonite (Phoslock, 5.6% La), respectively. P K-edge X-ray absorption near edge structure analysis showed that PO4 was preferentially bonded with Al under weakly acid conditions (pH 4.0), while tended to associate with La under alkaline conditions (pH 8.5). La LIII-edge extended X-ray absorption fine structure analysis indicated that PO4 was bonded on La sites by forming inner sphere bidentate-binuclear complexes and oxygen defects exhibited on LAH surfaces, which could be active adsorption sites for PO4. The electrostatic interaction, ligand exchange, and oxygen defects on LAH surfaces jointly facilitated PO4 adsorption but with varied contribution under different pH conditions. The combined contribution of two-component of La and Al may be an important direction for the next generation of commercial products for eutrophication mitigation.

  9. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping, E-mail: lishuping@njnu.edu.cn; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. - Highlights: • Surfactants could be used to modify the dispersing state of MTX/LDHs hybrids. • Surfactants have great effect on the morphology of MTX/LDHs hybrids. • MTX/LDHs with good monodisperse degree are more efficient in the suppression of the tumor cells.

  10. Catalytic performance of Ni-Al layered double hydroxides in CO purification processes

    Science.gov (United States)

    Gabrovska, M.; Idakiev, V.; Tenchev, K.; Nikolova, D.; Edreva-Kardjieva, R.; Crisan, D.

    2013-12-01

    Ni-Al layered double hydroxides with Ni2+/Al3+ molar ratios of 1.5 and 3.0 have been synthesized by co-precipitation and studied as catalyst precursors for purification of CO-containing gas-mixtures by means of CO oxidation to CO2 and conversion of CO by water vapor (water-gas shift reaction). The influence of the alkali additives (K+ ions) on the water-gas shift activity has been also examined. It was established that the catalytic activity of both reactions increases with the temperature and the nickel content. Hypothetic schemes are proposed about activation of the catalysts in the WGSR and CO oxidation including redox Ni2+ ↔ Ni3+ transition on the catalyst surface. The activity in WGSR is positively affected by the presence of potassium promoter, depending on its amount. The sample with higher nickel loading is the most effective catalyst as for CO oxidation as well as for WGSR at intermediate temperatures after potassium promotion.

  11. Zinc layered hydroxide salts: intercalation and incorporation into low-density polyethylene

    Directory of Open Access Journals (Sweden)

    Silvia Jaerger

    2014-12-01

    Full Text Available In this study, polymer composites using low-density polyethylene (LDPE and layered hydroxide salts (LHS were synthesized. The following compositions of LHS were obtained Zn5(OH8(An-2/n.yH2O, where A was varied in order to obtain hydrophilic (A = NO3- or hydrophobic (A = DDS- - dodecyl sulfate or DBS- - dodecyl benzene sulfonate. Synthesis was carried out by co-precipitation in alkaline medium and drying, being followed by characterization via Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. A variable amount of filler was then incorporated into the LDPE via extrusion, which was then injection molded to obtain specimens for evaluating tensile properties (Young's modulus, tensile strength, strain at break and toughness. For comparison, the sodium salts of the surfactants (NaDDS and NaDBS were also used as fillers in LDPE. The X-ray diffraction results indicated that the hydrophobic LHS were exfoliated in the polymer matrix, whereas the hydrophilic LHS was only delaminated. In the LDPE composites, melting and crystallization temperatures were nearly constant, along with the crystallinity indexes. The mechanical properties were mainly varied when the organophilic LHS was used. Overall, fillers based on LHS, especially those containing hydrophobic anions, may be interesting alternatives in the production of reinforced thermoplastics.

  12. Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

    Science.gov (United States)

    Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

    2017-08-01

    This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Cu Binding to Iron Oxide-Organic Matter Coprecipitates in Solid and Dissolved Phases

    Science.gov (United States)

    Vadas, T. M.; Koenigsmark, F.

    2015-12-01

    Recent studies indicate that Cu is released from wetlands following storm events. Assymetrical field flow field fractionation (AF4) analyses as well as total and dissolved metal concentration measurements suggest iron oxide-organic matter complexes control Cu retention and release. Coprecipitation products of Fe oxide and organic matter were prepared under conditions similar to the wetland to assess Cu partitioning to and availability from solid phases that settle from solution as well as phases remaining suspended. Cu coprecipitation and sorption to organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca2+, glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. Suspended Fe oxide-organic matter coprecipitates were assessed using AF4 coupled to online TOC analysis and ICP-MS. In laboratory prepared samples, Cu was observed in a mixture of small 1-5 nm colloids of Fe oxide-organic matter precipitates, but the majority was observed in larger organic matter colloids and were not UV absorbing, suggesting more aliphatic carbon materials. In field samples, up to 60% of the dissolved Cu

  14. Application of the SCC-DFTB method to hydroxide water clusters and aqueous hydroxide solutions.

    Science.gov (United States)

    Choi, Tae Hoon; Liang, Ruibin; Maupin, C Mark; Voth, Gregory A

    2013-05-02

    The self-consistent charge density functional tight binding (SCC-DFTB) method has been applied to hydroxide water clusters and a hydroxide ion in bulk water. To determine the impact of various implementations of SCC-DFTB on the energetics and dynamics of a hydroxide ion in gas phase and condensed phase, the DFTB2, DFTB2-γ(h), DFTB2-γ(h)+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus, and DFTB3-3OB implementations have been tested. Energetic stabilities for small hydroxide clusters, OH(-)(H2O)n, where n = 4-7, are inconsistent with the results calculated with the B3LYP and second order Møller-Plesset (MP2) levels of ab initio theory. The condensed phase simulations, OH(-)(H2O)127, using the DFTB2, DFTB2-γ(h), DFTB2-γ(h)+gaus, DFTB3-diag, DFTB3-diag+gaus, DFTB3-Full+gaus and DFTB3-3OB methods are compared to Car-Parrinello molecular dynamics (CPMD) simulations using the BLYP functional. The SCC-DFTB method including a modified O-H repulsive potential and the third order correction (DFTB3-diag/Full+gaus) is shown to poorly reproduce the CPMD computational results, while the DFTB2 and DFTB2-γ(h) method somewhat more closely describe the structural and dynamical nature of the hydroxide ion in condensed phase. The DFTB3-3OB outperforms the MIO parameter set but is no more accurate than DFTB2. It is also shown that the overcoordinated water molecules lead to an incorrect bulk water density and result in unphysical water void formation. The results presented in this paper point to serious drawbacks for various DFTB extensions and corrections for a hydroxide ion in aqueous environments.

  15. Effect of aluminum hydroxide/magnesium hydroxide antacid and bismuth subsalicylate on gastric pH in horses.

    Science.gov (United States)

    Clark, C K; Merritt, A M; Burrow, J A; Steible, C K

    1996-05-15

    To assess the effect of aluminum hydroxide/magnesium hydroxide antacid and bismuth subsalicylate on gastric pH in clinically normal horses and to develop guidelines on the use of these agents for treatment of peptic ulcer disease in horses. Prospective, randomized, controlled trial. 5 clinically normal adult horses with chronically implanted gastric cannulas. Each horse received all 5 treatments (30 g of aluminum hydroxide/15 g of magnesium hydroxide, 12 g of aluminum hydroxide/6 g of magnesium hydroxide, 10.5 g of bismuth subsalicylate, 26.25 g of bismuth subsalicylate, and 5% methylcellulose control) with only 1 experiment performed each day. Gastric pH was measured via a glass electrode inserted through the gastric cannula for 1 hour before treatment and continued for 2 hours after treatment. Food or water was not given to the horses during the experiment. Measurements of gastric pH obtained during posttreatment hours were compared with pretreatment gastric pH values. Only a dose of 30 g of aluminum hydroxide/ 15 g of magnesium hydroxide resulted in a significant increase in gastric pH over baseline or control values. Mean pH was 5.2 +/- 0.62 and 4.59 +/- 0.48 for posttreatment hours 1 and 2, respectively. Oral administration of 30 g of aluminum hydroxide/15 g of magnesium hydroxide to adult horses should result in a mean hourly gastric pH > or = 4.0 for at least 2 hours.

  16. Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

    Science.gov (United States)

    Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

    2017-01-01

    This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l-1. Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L-1. The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

  17. Synthesis of alumina/YAG 20 vol% composite by co-precipitation

    Directory of Open Access Journals (Sweden)

    Radosław Lach

    2011-12-01

    Full Text Available Co-precipitation of alumina/YAG precursor from aluminum and yttrium nitrate solution with ammonium carbonate results in dawsonite. Its crystallographic parameters differ from the compound precipitated with no yttrium additive. It suggests that yttrium ions become incorporated into the dawsonite structure. The DSC/TG and X-ray diffraction measurements show decomposition of dawsonite at elevated temperatures resulting in γ-Al2O3 and then δ- and θ-alumina modifications. Full transformation to α-Al2O3 and YAG occurs at temperatures higher than 1230°C. Starting powder for the sintering experiments was prepared using the coprecipitated precursor calcined at 600°C. Seeding of such powder with 5 wt.% α-Al2O3 results in material of 98% density at 1500°C. Much lower densification show compacts of unseeded powder.

  18. Coprecipitation synthesis of zinc ferrit (FE 2 O 3 /ZNO) nanoparticles ...

    African Journals Online (AJOL)

    Zinc ferrite (Fe2O3/ZnO) nanocomposites were successfully synthesized by simple co-precipitation method via iron (III) nitrate 9-hydrate (Fe(NO3)3.9H2O) and zinc nitrate hexahydrate (Zn(NO3)2.6H2O) as precursor in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The samples were characterized by ...

  19. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Xue Bi

    2014-06-01

    Full Text Available Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS. In this article, we review developments in the use of layered double hydroxides (LDHs for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i DDS with cardiovascular drugs as guests; (ii DDS with anti-inflammatory drugs as guests; and (iii DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed.

  20. Biological evaluation of layered double hydroxides as efficient drug vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan; Liu Dan; Chang Qing; Liu Dandan; Xia Ying; Liu Shuwen; Peng Nanfang; Yang Xu [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Ai Hanhua [College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079 (China); Xi Zhuge, E-mail: yangxu@mail.ccnu.edu.cn [Tianjin Institutes of Health and Environmental Medicine, Tianjin 300050 (China)

    2010-03-12

    Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

  1. Synthesis of yttria-doped bismuth oxide powder by carbonate coprecipitation for IT-SOFC electrolyte.

    Science.gov (United States)

    Lee, J G; Kim, S H; Yoon, H H

    2011-01-01

    Yttria-doped bismuth oxide (YBO) powders were synthesized by ammonium carbonate coprecipitation for the preparation of electrolytes of an intermediate temperature solid oxide fuel cell (IT-SOFC). The starting salts were yttrium and bismuth nitrate. The crystal structures and the morphological characteristics of the particles were analyzed by XRD and SEM, respectively. The ionic conductivity of the sintered pellet was measured by an electrochemical impedance analyzer. The size of the calcined YBO powders were in the range of 20-100 nm as measured by SEM images. The YBO pellets had a face-centered cubic structure, and their crystallite size was about 54-88 nm. The ionic conductivity of the YBO pellets sintered at 800 degrees C was observed to be 2.7 x 10(-1) Scm-(-1) at 700 degrees C. The ball-milling of the YBO powder before it was pelletized was found to have been unrequired probably because of a good sinterability of the YBO powders that was prepared via the ammonium carbonate coprecipitation method. The results showed that the ammonium carbonate coprecipitation process could be used as the cost-efficient method of producing YBO electrolytes for IT-SOFC.

  2. Aluminium hydroxide-induced granulomas in pigs

    DEFF Research Database (Denmark)

    Valtulini, S; Macchi, C; Ballanti, P

    2005-01-01

    in the muscles of the neck (group slaughtered). The pigs had been injected with a vaccine containing 40 mg/2 ml dose of aluminium hydroxide as adjuvant. Research consisted of two phases: first, an epidemiological study was carried out, aimed at determining the risk factors for the granulomas. The results...... indicated that the vaccine was to be held responsible for the formation of granulomas. A clinical trial was then performed to further substantiate the initial hypothesis, by comparing pigs, which were aseptically inoculated twice with either the original vaccine or the adjuvant alone (groups vaccine...... was the cause of the granulomas....

  3. Coprecipitation and redox reactions of manganese oxides with copper and nickel

    Science.gov (United States)

    Hem, J.D.; Lind, Carol J.; Roberson, C.E.

    1989-01-01

    Open-system, continuous-titration experiments have been done in which a slow flux of ???0.02 molar solution of Mn2+ chloride, nitrate, or perchlorate with Cu2+ or Ni2+ in lesser concentrations was introduced into an aerated reactor solution held at constant temperature and at constant pH by a pH-stat titrator that added dilute NaOH. The resulting mixtures of metal oxyhydroxides and their native solutions were aged for periods as long as 2 1/2 years. Fresh and aged precipitates were characterized by chemical analysis, oxidation state determinations, X-ray and electron diffraction, and electron microscopy. The precipitates can be described as mixtures of oxide and oxyhydroxide species, using concepts of equilibrium and nonequilibrium chemical thermodynamics. The metal-ion content of the aged precipitates in systems that contained copper is distributed among three principal components. One of these is a mixed oxide Cu2Mn3O8 in which all Mn is in the 4+ oxidation state. A major component in all precipitates is feitknechtite, ??MnOOH. These forms are supplemented by CuO or by birnessite or ramsdellite forms of MnO2 where stoichiometry and thermodynamic calculations predict them. In systems that contained nickel and manganese, identifiable components included ??MnOOH, Ni(OH)2, and the same two forms of MnO2. The oxidation number of the precipitated manganese increased during aging, and the pH of the supernatant solution decreased. The maximum Mn oxidation number observed was 3.55 in an Mn + Cu precipitate aged for 18 months. Concentrations of Cu2+ and Ni2+ generally decreased to values substantially below those predicted by oxide or hydroxide equilibrium. Scavenging effects of this type are common in natural aqueous systems. ?? 1989.

  4. Occurrence and characterization of CaCO3-P coprecipitation on the leaf surface of Potamogeton crispus in water.

    Science.gov (United States)

    Liu, Guanglong; Guo, Wenwen; Yuan, Shaobo; Zhu, Hong; Yang, Tewu; Zhou, Yiyong; Zhu, Duanwei

    2016-11-01

    In this paper, the characterization of CaCO3-P coprecipitation on the leaf surface of Potamogeton crispus at various temperatures in pot experiments was investigated. White precipitates occurred on the leaf surfaces during the P. crispus growth period, and the chemical analysis demonstrates that the white precipitates contain Ca and P. The primary constituent of the white precipitates on the leaf of P. crispus was octacalcium phosphate (OCP) and hydroxyapatite. XRD characterization showed that the precipitates mostly consisted of crystals formed by calcium carbonate and hydroxyapatite, and the high calcium/phosphorus ratio indicated that the white coprecipitates were CaCO3-P. The scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX) results confirmed that the precipitates on the surface of P. crispus leaves were carbonate-containing hydroxylapatite. In addition, no significant differences was observed in the structure of CaCO3-P coprecipitation between room temperature and consistent temperature treatments, which means that a little change in the temperature cannot change the process of Ca-P coprecipitation. Finally, coprecipitation of CaCO3-P on the leaf surface of P. crispus was proposed based on the morphology and structure analysis of CaCO3-P coprecipitation.

  5. Inductively coupled plasma atomic emission spectrometric determination of 27 trace elements in table salts after coprecipitation with indium phosphate.

    Science.gov (United States)

    Kagaya, Shigehiro; Mizuno, Toshiyuki; Tohda, Koji

    2009-07-15

    The coprecipitation method using indium phosphate as a new coprecipitant has been developed for the separation of trace elements in table salts prior to their determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). Indium phosphate could quantitatively coprecipitate 27 trace elements, namely, Be, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, in a table salt solution at pH 10. The rapid coprecipitation technique, in which complete recovery of the precipitate was not required in the precipitate-separation process, was completely applicable, and, therefore, the operation for the coprecipitation was quite simple. The coprecipitated elements could be determined accurately and precisely by ICP-AES using indium as an internal standard element after dissolution of the precipitate with 5 mL of 1 mol L(-1) nitric acid. The detection limits (three times the standard deviation of the blank values, n=10) ranged from 0.001 microg (Lu) to 0.11 microg (Zn) in 300 mL of a 10% (w/v) table salt solution. The method proposed here could be applied to the analyses of commercially available table salts.

  6. Chromium isotope fractionation during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

    the Archaean and Protoerozoic, needs careful assessment of the signal robustness and necessitates a thorough understanding of the Cr cycle in Earth system processes. We conducted experiments testing the incorporation and isotopic fractionation of chromate into the calcite lattice. Our experiments indicate...... to no Cr isotope fractionation in the oceans. These experiments represent a first step toward understanding the Cr isotope signal of carbonates where fractionations will likely be ≤ 0.3 ‰ and as such, pave the way for future work to enable a reliable application of the Cr isotope proxy. References: [1] Hua...... et al., 2007, Water Air Soil Poll. 179, 381-390. [2] Sánchez-Pastor et al., 2011, Cryst. Growth Des. 11, 3081-3089....

  7. Particle size and shape of calcium hydroxide.

    Science.gov (United States)

    Komabayashi, Takashi; D'souza, Rena N; Dechow, Paul C; Safavi, Kamran E; Spångberg, Larz S W

    2009-02-01

    The aim of this study was to examine the particle length, width, perimeter, and aspect ratio of calcium hydroxide powder using a flow particle image analyzer (FPIA). Five sample groups each with 10 mg of calcium hydroxide were mixed with 15 mL of alcohol and sonicated. Digital images of the particle samples were taken using the FPIA and analyzed with a one-way analysis of variance. The overall averages +/- standard deviation among the five groups for particle length (microm), width (microm), perimeter (microm), and aspect ratio were 2.255 +/- 1.994, 1.620 +/- 1.464, 6.699 +/- 5.598, and 0.737 +/- 0.149, respectively. No statistical significance was observed among the groups for all parameters. When the total of 46,818 particles from all five groups were classified into the five length categories of 0.5-microm increments, there were significant differences in width, perimeter, and aspect ratio (all p values particles have a size and shape that may allow direct penetration into open dentin tubules.

  8. Simultaneous intercalation and release of 2,4-dichloro- and 4-chloro-phenoxy acetates into Zn/Al layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Abbas Matrod Bashi

    2016-11-01

    Full Text Available A new nanohybrid compound was formed by the concurrent insertion of 2,4-dichlorophenoxy acetate (DPA used as herbicides and 4-chlorophenoxy acetate (CPA as plant growth regulator, the two guest anions into the interlamellar space of the host Zn/Al layered double hydroxide (LDH using co-precipitation or spontaneous self-assembly method. Two different basal spacings of 2.54 and 1.97 nm were detected by PXRD of the nanohybrid accounting for the presence of two distinct intercalated phases. Direct insertion mass spectroscopy (DIMS analyses confirm that both anions are intercalated to give a biphasic well ordered nanohybrid material. The study of the release properties shows that both ions were released, but with different rates. This opens up the possibility of using such a biphasic nanohybrid for controlled release of more than one active anionic agent at different controlled rates.

  9. A novel two-step coprecipitation process using Fe(III) and Al(III) for the removal and immobilization of arsenate from acidic aqueous solution.

    Science.gov (United States)

    Jia, Yongfeng; Zhang, Danni; Pan, Rongrong; Xu, Liying; Demopoulos, George P

    2012-02-01

    Lime neutralization and coprecipitation of arsenate with iron is widely practiced for the removal and immobilization of arsenic from mineral processing effluents. However, the stability of the generated iron-arsenate coprecipitate is still of concern. In this work, we developed a two-step coprecipitation process involving the use of iron and aluminum and tested the stability of the resultant coprecipitates. The two-step Fe-As-Fe or Fe-As-Al coprecipitation process involved an initial Fe/As = 2 coprecipitation at pH4 to remove arsenic from water down to 0.25 mg/L, followed by introduction of iron or aluminum (Fe/As = 2, Al/As = 1.5 or 2). The two-step coprecipitates showed higher stability than traditional Fe/As = 4 coprecipitate under both oxic and anoxic conditions. Leaching stability was enhanced when aluminum was applied in the second step. The use of aluminum in the second step also inhibited microbial mediated arsenate reduction and arsenic remobilization. The results suggest that the two-step coprecipitation process is superior to conventional coprecipitation methods with respect to the stability of the generated arsenic-bearing solid waste. The use of Al in the second step is better than Fe to enhance the stability. This work may have important implications to the development of new technologies for efficient arsenic removal from hydrometallurgical solutions and safe disposal in both oxic and anoxic environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Acid mine water neutralisation with ammonium hydroxide and ...

    African Journals Online (AJOL)

    This study showed that NH4OH can be used for treatment of acid mine drainage rich in sulphates and NH4OH can be recycled in the process. Hydrated lime treatment resulted in removal of the remaining ammonia using a rotary evaporator. Keywords: acid mine water, ammonium hydroxide, barium hydroxide, sulphate ...

  11. Pulp capping with adhesive resin-based composite vs. calcium hydroxide: a review.

    Science.gov (United States)

    Schuurs, A H; Gruythuysen, R J; Wesselink, P R

    2000-12-01

    The results of some short-term experiments suggest that direct capping of a vital pulp with the modern resin-based composite systems may be as effective as capping with calcium hydroxide. Total cavity etching with 10% phosphoric acid seems to be safe for the exposed pulp, but unless annulled by calcium hydroxide 35% phosphoric acid may be disastrous. For hemostasis and cleaning of the pulp wound both sodium hypochlorite and saline seem suitable, whereas the effectiveness of a 2% chlorhexidine solution is questionable. Although hard-setting calcium hydroxide cements may induce the formation of dentin bridges, they appear not to provide an effective long-term seal against bacterial factors. Within a few years, the majority of mechanically exposed and capped pulps show infection and necrosis due to microleakage of such capping materials and tunnel defects in the dentin bridges. It is unknown whether newer types of resin containing calcium-hydroxide-products will act as a permanent barrier. The cytotoxicity of the resin-based composites and the temperature rise during polymerisation may not be of concern, but microleakage, sensitisation and allergic reactions may pose problems. Based on available data, pulp capping with resin-based composites may be said to be promising, but more and long-term research is mandatory before the method can be recommended.

  12. Hydroxide depletion in dilute supernates stored in waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T.

    1985-10-10

    Free hydroxide ion in dilute supernates are depleted by reaction with atmospheric carbon dioxide to form bicarbonate and carbonate species and by reaction with acidic compounds formed by the radiolytic decomposition of tetraphenylborate salts. A model of the kinetics and thermodynamics of absorption of carbon dioxide in the waste tanks has been developed. Forecasts of the rate of hydroxide depletion and the requirements for sodium hydroxide to maintain technical standards have been made for the washed sludge and washed precipitate storage tanks. Hydroxide depletion is predicted to have a minimal impact on sludge processing operations. However, in-tank precipitation and downstream DWPF operations are predicted to be significantly affected by hydroxide depletion in Tank 49H. The installation of a carbon dioxide scrubber on Tank 49H may be justified in view of the decrease in alkali content and variation in the melter feed.

  13. Paradoxical hypomagnesemia caused by excessive ingestion of magnesium hydroxide.

    Science.gov (United States)

    Joo Suk, Oh

    2008-09-01

    Excessive ingestion of magnesium may lead to hypermagnesemia even without kidney dysfunction. Several cases of development of hypermagnesemia after overdose of magnesium hydroxide have been reported. Although magnesium hydroxide is widely used as laxative, its overdose may induce diarrhea, which is followed by excessive magnesium loss. I report a case of paradoxical hypomagnesemia developed after excessive ingestion of magnesium hydroxide. A 39-year-old woman was presented to the emergency department complaining of severe watery diarrhea and carpopedal spasm after ingesting a handful of magnesium hydroxide tablets. The laboratory tests detected hypomagnesemia, hypocalcemia, and normokalemia. Calcium gluconate was given to the patient, but her symptom did not improve shortly. The symptom disappeared spontaneously 2 days after the watery diarrhea subsided. This case shows that overdose of magnesium hydroxide, which leads to massive diarrhea, might induce hypomagnesemia unexpectedly. This case also suggests that it should be treated, as well as typical magnesium deficiency.

  14. Density-Functional Tight-Binding Investigation of the Structure, Stability and Material Properties of Nickel Hydroxide Nanotubes.

    Science.gov (United States)

    Jahangiri, Soran; Mosey, Nicholas J

    2017-11-03

    Nickel hydroxide is a material composed of two-dimensional layers that can be rolled up to form cylindrical nanotubes belonging to a class of inorganic metal hydroxide nanotubes that are candidates for applications in catalysis, energy storage, and microelectronics. The stabilities and other properties of this class of inorganic nanotubes have not yet been investigated in detail. The present study uses self-consistent-charge density-functional tight-binding calculations to examine the stabilities, mechanical properties, and electronic properties of nickel hydroxide nanotubes along with the energetics associated with the adsorption of water by these systems. The tight-binding model was parametrized for this system based on the results of first-principles calculations. The stabilities of the nanotubes were examined by calculating strain energies and performing molecular dynamics simulations. The results indicate that single-walled nickel hydroxide nanotubes are stable at room temperature, which is consistent with experimental investigations. The nanotubes possess size-dependent mechanical properties that are similar in magnitude to those of other inorganic nanotubes. The electronic properties of the nanotubes were also found to be size-dependent and small nickel oxyhydroxide nanotubes are predicted to be semiconductors. Despite this size-dependence, both the mechanical and electronic properties were found to be almost independent of the helical structure of the nanotubes. The calculations also show that water molecules have higher adsorption energies when binding to the interior of the nickel hydroxide nanotubes when compared to adsorption in nanotubes formed from other two-dimensional materials such as graphene. The increased adsorption energy is due to the hydrophilic nature of nickel hydroxide. Due to the broad applications of nickel hydroxide, the nanotubes investigated here are also expected to be used in catalysis, electronics, and clean energy production.

  15. Density-functional tight-binding investigation of the structure, stability and material properties of nickel hydroxide nanotubes

    Science.gov (United States)

    Jahangiri, Soran; Mosey, Nicholas J.

    2018-01-01

    Nickel hydroxide is a material composed of two-dimensional layers that can be rolled up to form cylindrical nanotubes belonging to a class of inorganic metal hydroxide nanotubes that are candidates for applications in catalysis, energy storage, and microelectronics. The stabilities and other properties of this class of inorganic nanotubes have not yet been investigated in detail. The present study uses self-consistent-charge density-functional tight-binding calculations to examine the stabilities, mechanical properties, and electronic properties of nickel hydroxide nanotubes along with the energetics associated with the adsorption of water by these systems. The tight-binding model was parametrized for this system based on the results of first-principles calculations. The stabilities of the nanotubes were examined by calculating strain energies and performing molecular dynamics simulations. The results indicate that single-walled nickel hydroxide nanotubes are stable at room temperature, which is consistent with experimental investigations. The nanotubes possess size-dependent mechanical properties that are similar in magnitude to those of other inorganic nanotubes. The electronic properties of the nanotubes were also found to be size-dependent and small nickel oxyhydroxide nanotubes are predicted to be semiconductors. Despite this size-dependence, both the mechanical and electronic properties were found to be almost independent of the helical structure of the nanotubes. The calculations also show that water molecules have higher adsorption energies when binding to the interior of the nickel hydroxide nanotubes when compared to adsorption in nanotubes formed from other two-dimensional materials such as graphene. The increased adsorption energy is due to the hydrophilic nature of nickel hydroxide. Due to the broad applications of nickel hydroxide, the nanotubes investigated here are also expected to be used in catalysis, electronics, and clean energy production.

  16. Action of hydrochloric acid on aluminum hydroxide-magnesium hydroxide gels and magaldrate: quasi-elastic light scattering studies.

    Science.gov (United States)

    Guterman, L R; Falzone, J; Wilson, G E

    1986-05-01

    The effects of hydrochloric acid on mixed gels of aluminum and magnesium hydroxide and on magaldrate have been examined using quasi-elastic light scattering. Particles of magaldrate and mixed gels behave differently. The magaldrate particles initially decrease in size in response to increasing amounts of hydrochloric acid up to that sufficient to neutralize all the magnesium hydroxide present, then increase in size to approximately 2 microns. The composition of the mixed gels appears to be particularly important in determining the reaction with limited amounts of acid. For these particles, which are thought to consist of a magnesium hydroxide core surrounded by an aluminum hydroxide sheath, slow erosion of the aluminum hydroxide was apparently followed by complete disintegration of the particles. Particles which remain grow in size to approximately 3 microns.

  17. Evaluation of Co-precipitation Processes for the Synthesis of Mixed-Oxide Fuel Feedstock Materials

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Emory D [ORNL; Voit, Stewart L [ORNL; Vedder, Raymond James [ORNL

    2011-06-01

    The focus of this report is the evaluation of various co-precipitation processes for use in the synthesis of mixed oxide feedstock powders for the Ceramic Fuels Technology Area within the Fuels Cycle R&D (FCR&D) Program's Advanced Fuels Campaign. The evaluation will include a comparison with standard mechanical mixing of dry powders and as well as other co-conversion methods. The end result will be the down selection of a preferred sequence of co-precipitation process for the preparation of nuclear fuel feedstock materials to be used for comparison with other feedstock preparation methods. A review of the literature was done to identify potential nitrate-to-oxide co-conversion processes which have been applied to mixtures of uranium and plutonium to achieve recycle fuel homogeneity. Recent studies have begun to study the options for co-converting all of the plutonium and neptunium recovered from used nuclear fuels, together with appropriate portions of recovered uranium to produce the desired mixed oxide recycle fuel. The addition of recycled uranium will help reduce the safeguard attractiveness level and improve proliferation resistance of the recycled fuel. The inclusion of neptunium is primarily driven by its chemical similarity to plutonium, thus enabling a simple quick path to recycle. For recycle fuel to thermal-spectrum light water reactors (LWRs), the uranium concentration can be {approx}90% (wt.), and for fast spectrum reactors, the uranium concentration can typically exceed 70% (wt.). However, some of the co-conversion/recycle fuel fabrication processes being developed utilize a two-step process to reach the desired uranium concentration. In these processes, a 50-50 'master-mix' MOX powder is produced by the co-conversion process, and the uranium concentration is adjusted to the desired level for MOX fuel recycle by powder blending (milling) the 'master-mix' with depleted uranium oxide. In general, parameters that must be

  18. Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate: Implications for their use as paleoclimatic proxy

    Science.gov (United States)

    Rodler, A.; Sánchez-Pastor, N.; Fernández-Díaz, L.; Frei, R.

    2015-09-01

    Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track paleoenvironmental changes, for example related to the rise of oxygen during the Archaean and Protoerozoic, needs careful assessment of the signal robustness and necessitates a thorough understanding of the Cr cycle in Earth system processes. We conducted experiments testing the incorporation of chromate into the calcite lattice to investigate isotopic changes facilitated by the coprecipitation process. Our experiments indicate enrichment in Cr concentration in the precipitates compared to the solutions, consistent with previous reports of Cr enrichment in chemical sediments compared to ambient seawater. The fractionation of Cr isotopes during calcium carbonate coprecipitation was assumed to be small, based on previously published data of modern seawater and modern non-skeletal marine carbonates. However, results from this study for rapidly precipitated calcium carbonate in the presence of chromate show a tendency for preferential incorporation of heavy Cr isotopes in the precipitates resulting in increasing relative isotope difference between precipitate and initial solution (Δ53Cr[p-is]) from +0.06‰ to +0.18‰, with increasing initial Cr concentration of the solution. Sample precipitation in the presence of chromate also showed the presence of vaterite. Calcium carbonate crystals were also precipitated in a double diffusion silica hydrogel over a longer period of time resulting in samples consisting of micrometric-millimetric calcite crystals, which were again significantly enriched in heavy Cr isotopes compared to the initial solutions. They average, irrespective of the initial Cr concentration, a relative isotope difference (Δ53Cr[p-is]) of +0.29 ± 0.08‰ (2σ), whereas

  19. and aluminum-substituted cobalt ferrite prepared by co-precipitation ...

    Indian Academy of Sciences (India)

    (2 M) solution of NaOH was prepared as a precipitant. It has been suggested that the solubility product constant Ksp of all the constituents always exceed when the starting solution is added into the precipitant. Therefore, in order to achieve si- multaneous precipitation of all the hydroxides, Co(OH)2, Zn(OH)2, Al(OH)3 and.

  20. Arsenate and cadmium co-adsorption and co-precipitation on goethite

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei [Environment Research Institute, Shandong University, Jinan 250100 (China); Lv, Jitao; Luo, Lei [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Yang, Kun [Department of Environmental Science, Zhejiang University, Hangzhou 310058 (China); Lin, Yongfeng; Hu, Fanbao [Environment Research Institute, Shandong University, Jinan 250100 (China); Zhang, Jing [State Key Laboratory of Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Zhang, Shuzhen, E-mail: szzhang@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2013-11-15

    Highlights: • As enhances Cd adsorption amount on goethite. • Cd fixed through precipitation is more difficult to get released. • As in co-precipitates is easier to release than in its adsorption complexes. -- Abstract: Arsenate (As(V), AsO{sub 4}{sup 3−}) and cadmium (Cd) are among the toxic elements of most concern. Their sorption behaviors on goethite were studied by batch experiments (pH edges, isotherms and kinetics) and X-ray diffraction (XRD). Arsenic coordination environment was explored by X-ray absorbance fine structure (EXAFS) analysis. Sorption isotherms of both As(V) and Cd on goethite could be divided into the adsorption-dominated and precipitation-dominated parts, while their sorption showed different pH-dependency and sorption reversibility. Cadmium adsorption was enhanced in the presence of AsO{sub 4}{sup 3−}, which could be explained by the decrease in the electrostatic potential due to the sorption of AsO{sub 4}{sup 3−} and the formation of a ternary Cd–As(V)–goethite complex. Based on the EXAFS study, AsO{sub 4}{sup 3−} adsorbed on goethite mainly formed bidentate–binuclear complex. The high loadings of Cd changed the As(V)–Fe distance and its coordination number. However, Cd did not affect the As(V) adsorption amount in the adsorption-dominated region. When As(V) and Cd formed co-precipitates, their sorption amounts were both increased. The formation of co-precipitates decreased the mobility of Cd but increased the mobility of As(V) because less As(V) was sorbed on goethite through surface complexation. This study will provide better understandings on As(V) and Cd transport and useful information on their remediation strategies.

  1. Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

    Science.gov (United States)

    Leenheer, Jerry A.; Reddy, Michael M.

    2008-01-01

    Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

  2. Zimmer slipstream magnesium hydroxide recovery demonstration. Volume I of II. Final report, April 1, 1993--May 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Dravo Lime has for many years supplied magnesium containing lime in the ranges of 3-6% MgO. Several years ago Dravo Lime realized the potential operating savings its FGD customers could benefit from if magnesium could be recovered from FGD waste streams. As a result, several different proprietary processes have been developed for the recovery of magnesium hydroxide. These recovery processes include steps for magnesium hydroxide separation, purification, and crystal growth. The process implemented at The Cincinnati Gas Electric Company`s Wm. H. Zimmer Station was piloted by Dravo Lime Company at Allegheny Power System`s Mitchell Station near Monongahela, PA during the fourth quarter in 1989 and first quarter in 1990. This pilot work was the foundation for further development of the ThioClear process at Dravo`s pilot plant at CG&E Miami Fort Station. The ThioClear process is a closed loop version of the magnesium hydroxide recovery process with the same unit operations and products but also including an absorber tower for scrubbing flue gas. Testing at Miami Fort of the ThioClear process led to improvements in separation of magnesium hydroxide from gypsum that are part of the magnesium hydroxide recovery process installed at Zimmer Station.

  3. An integrated device for coprecipitation and filtration of radiocesium in seawater.

    Science.gov (United States)

    He, Jianhua

    2016-12-01

    To improve the pretreatment efficiency of radiocesium in seawater, a prototype machine based on a new design of an integrated device for coprecipitation and filtration was developed and tested in the laboratory for its possibility and efficiency, the results show the that the efficiency of pretreatment of radiocesium can be improved more than one orders of magnitude compared to traditional methods. And the results from experiments on effect of settle time show that immediately filtration of solution after reaction will not affect the absorption of AMP to radiocesium in seawater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Avrami behavior of magnetite nanoparticles formation in co-precipitation process

    Directory of Open Access Journals (Sweden)

    Ahmadi R.

    2011-01-01

    Full Text Available In this work, magnetite nanoparticles (mean particle size about 20 nm were synthesized via coprecipitation method. In order to investigate the kinetics of nanoparticle formation, variation in the amount of reactants within the process was measured using pH-meter and atomic absorption spectroscopy (AAS instruments. Results show that nanoparticle formation behavior can be described by Avrami equations. Transmission electron microscopy (TEM and X-ray diffraction (XRD were performed to study the chemical and morphological characterization of nanoparticles. Some simplifying assumptions were employed for estimating the nucleation and growth rate of magnetite nanoparticles.

  5. Enhanced removal of arsenic from a highly laden industrial effluent using a combined coprecipitation/nano-adsorption process.

    Science.gov (United States)

    Jiang, Yingnan; Hua, Ming; Wu, Bian; Ma, Hongrui; Pan, Bingcai; Zhang, Quanxing

    2014-05-01

    Effective arsenic removal from highly laden industrial wastewater is an important but challenging task. Here, a combined coprecipitation/nano-adsorption process, with ferric chloride and calcium chloride as coprecipitation agents and polymer-based nanocomposite as selective adsorbent, has been validated for arsenic removal from tungsten-smelting wastewater. On the basis of operating optimization, a binary FeCl3 (520 mg/L)-CaCl2 (300 mg/L) coprecipitation agent could remove more than 93% arsenic from the wastewater. The resulting precipitate has proved environmental safety based on leaching toxicity test. Fixed-bed column packed with zirconium or ferric-oxide-loaded nanocomposite was employed for further elimination of arsenic in coprecipitated effluent, resulting in a significant decrease of arsenic (from 0.96 to less than 0.5 mg/L). The working capacity of zirconium-loaded nanocomposite was 220 bed volumes per run, much higher than that of ferric-loaded nanocomposite (40 bed volumes per run). The exhausted zirconium-loaded nanocomposite could be efficiently in situ regenerated with a binary NaOH-NaCl solution for reuse without any significant capacity loss. The results validated the combinational coprecipitation/nano-adsorption process to be a potential alternative for effective arsenic removal from highly laden industrial effluent.

  6. Decreasing pH results in a reduction of anthocyanin coprecipitation during cold stabilization of purple grape juice.

    Science.gov (United States)

    Manns, David C; Siricururatana, Passaporn; Padilla-Zakour, Olga I; Sacks, Gavin L

    2015-01-05

    Anthocyanin pigments in grape juice can coprecipitate with potassium bitartrate (KHT) crystals during cold stabilization, but factors that reduce these adsorptive losses are not well understood. We hypothesized that coprecipitation on a % w/w basis should be decreased at lower pH. In initial experiments, model juice solutions containing an anthocyanin monoglucoside extract and varying pH values were subjected to cold-storage to induce KHT crystallization, and anthocyanins in the resulting precipitant were characterized by HPLC. The pH of the model juice was directly correlated with the % w/w concentration of anthocyanins in the KHT crystals, with a maximum observed at pH 3.40 (0.20% w/w) and a minimum at pH 2.35 (0.01% w/w). A pH dependency was also observed for anthocyanin-KHT coprecipitation in purple Concord grape juice, although the effect was smaller. Coprecipitation was significantly greater for anthocyanin monoglucosides and acylated anthocyanins as compared to anthocyanin diglucosides at pH > 3.05, but coprecipitation of mono- and acylated forms declined more sharply at lower pH values.

  7. Sorption and coprecipitation of copper to ferrihydrite and humic acid organomineral complexes and controls on copper availability.

    Science.gov (United States)

    Seda, Neila N; Koenigsmark, Faye; Vadas, Timothy M

    2016-03-01

    Coprecipitation of Fe oxide and organic matter in redox dynamic sediments controls the net retention and form of Cu in the solid precipitates. In this study, coprecipitation and sorption of Cu with organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca(2+), glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. This has implications for the assumption of additivity in binding phases and for researchers conducting binding or exposure experiments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. The study of processes of iron hydroxide coagulation and sedimentation

    Science.gov (United States)

    Fedorova, A. S.; Nedobukh, T. A.; Mashkovtsev, M. A.; Semenishchev, V. S.

    2017-09-01

    Migration behavior of radionuclides forming pseudoradiocolloids with iron hydroxide depends on physicochemical behavior of iron hydroxide. It was determined that pH of the solution and iron concentration are the main parameters affecting processes coagulation and sedimentation of iron hydroxide. Time dependences of iron hydroxide coagulation and sedimentation being obtained using ultrafiltration and turbidimetry methods were analyzed. Integral and differential curves of size distribution of iron hydroxide particles were obtained using the method of laser diffraction. At the whole pH range studied, monomodal size distribution was observed in the solution containing 25 mg L-1 of iron; whereas in the solution containing 100 mg L-1 of iron bimodal size distribution was observed. This difference indicates different mechanisms of coagulation that was additionally confirmed by analysis of kinetic curves. It was found that the best conditions for formation and further sedimentation of iron hydroxide were pH 6-8 and iron concentration of at least 50 mg L-1. At these conditions, the time of half-precipitation of the iron hydroxide precipitate did not exceed five minutes.

  9. Layered double hydroxide materials coated carbon electrode: New challenge to future electrochemical power devices

    Energy Technology Data Exchange (ETDEWEB)

    Djebbi, Mohamed Amine, E-mail: mohamed.djebbi@etu.univ-lyon1.fr [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Braiek, Mohamed [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Namour, Philippe [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France); Irstea, 5 rue de la Doua, 69100 Villeurbanne (France); Ben Haj Amara, Abdesslem [Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Jaffrezic-Renault, Nicole [Institut des Sciences Analytiques UMR CNRS 5280, Université Claude Bernard-Lyon 1, 5 rue de la Doua, 69100 Villeurbanne (France)

    2016-11-15

    Highlights: • MgAl and ZnAl LDH nanosheets were chemically synthesized and deposited over carbon electrode materials. • Catalytic performance of both LDHs was investigated for Fe(II) reduction reaction. • Satisfactory results have been achieved with the MgAl LDH material. • MgAl and ZnAl LDH modified carbon felt were applied in MFC as an efficient anode catalyst. • The LDH-modified anode significantly increased power performance of MFC. - Abstract: Layered double hydroxides (LDHs) have been widely used in the past years due to their unique physicochemical properties and promising applications in electroanalytical chemistry. The present paper is going to focus exclusively on magnesium-aluminum and zinc-aluminum layered double hydroxides (MgAl & ZnAl LDHs) in order to investigate the property and structure of active cation sites located within the layer structure. The MgAl and ZnAl LDH nanosheets were prepared by the constant pH co-precipitation method and uniformly supported on carbon-based electrode materials to fabricate an LDH electrode. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy revealed the LDH form and well-crystallized materials. Wetting surface properties (hydrophilicity and hydrophobicity) of both prepared LDHs were recorded by contact angle measurement show hydrophilic character and basic property. The electrochemical performance of these hybrid materials was investigated by mainly cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques to identify the oxidation/reduction processes at the electrode/electrolyte interface and the effect of the divalent metal cations in total reactivity. The hierarchy of the modified electrode proves that the electronic conductivity of the bulk material is considerably dependent on the divalent cation and affects the limiting parameter of the overall redox process. However

  10. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Ming; Liu, Haiqiang, E-mail: Liuhaiqiang1980@126.com

    2015-07-15

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAl

  11. Comparison of final irrigation techniques in removal of calcium hydroxide.

    Science.gov (United States)

    Yücel, Ali Çağın; Gürel, Melek; Güler, Eda; Karabucak, Bekir

    2013-12-01

    The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter-appointment calcium hydroxide [Ca(OH)2 ]. Forty-seven extracted human single-rooted teeth were instrumented, and Ca(OH)2 paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30-gauge slot-tipped needle, EndoVac system and ProUltra® PiezoFlow™ ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5-grade scale. The influence of the irrigation system was evaluated using a two-way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

  12. Triethylamine-assisted Mg(OH)2 coprecipitation/preconcentration for determination of trace metals and rare earth elements in seawater by inductively coupled plasma mass spectrometry (ICP-MS).

    Science.gov (United States)

    Arslan, Zikri; Oymak, Tulay; White, Jeremy

    2018-05-30

    In this paper, we report an improved magnesium hydroxide, Mg(OH)2, coprecipitation method for the determination of 16 trace elements (Al, V, Cr, Mn, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sb, Sn and Pb) and 18 rare earth elements (REEs), including Sc, Y, U and Th in seawater and estuarine water samples. The procedure involves coprecipitation of the trace elements and REEs on Mg(OH)2 upon addition of a small volume of triethylamine (TEA) followed by analysis of the dissolved pellet solutions by inductively coupled plasma mass spectrometry (ICP-MS). Three-step sequential coprecipitation was carried out on 10 mL aliquots of seawater to eliminate the matrix ions and to preconcentrate the analytes of interest into a 1 mL final volume. Spike recoveries varied from 85% (Th) to 105% (Y). Calcium (Ca), sodium (Na) and potassium (K) matrices were virtually eliminated from the analysis solutions. Collision reaction interface (CRI) technology utilizing H2 and He gases was employed to determine its effectiveness in removing the spectral interferences originating from the residual Mg matrix, TEA and plasma gases. H2 was more effective than He in reducing spectral interferences from TEA and plasma gases. Limits of detection (LODs) ranged from 0.01 ng L-1 (Ho) to 72 ng L-1 (Al). The method was validated by using certified seawater (CASS-4) and estuarine water (SLEW-3) reference materials. Precision for five (n = 5) replicate measurements were between 1.2% (Pr) and 18% (Lu). Fe, Pb, Sn, and Zn impurities in TEA were significant in comparison to the levels in CASS-4 and SLEW-3, while relatively high background signals impacted determinations of low levels of Sc and Th. The effects of these hurdles on precision and accuracy were alleviated by measuring these elements in spiked CASS-4 and SLEW-3. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Structural characterization, formation mechanism and stability of curcumin in zein-lecithin composite nanoparticles fabricated by antisolvent co-precipitation.

    Science.gov (United States)

    Dai, Lei; Sun, Cuixia; Li, Ruirui; Mao, Like; Liu, Fuguo; Gao, Yanxiang

    2017-12-15

    Curcumin (Cur) exhibits a range of bioactive properties, but its application is restrained due to its poor water solubility and sensitivity to environmental stresses. In this study, zein-lecithin composite nanoparticles were fabricated by antisolvent co-precipitation technique for delivery of Cur. The result showed that the encapsulation efficiency of Cur was significantly enhanced from 42.03% in zein nanoparticles to 99.83% in zein-lecithin composite nanoparticles. The Cur entrapped in the nanoparticles was in an amorphous state confirmed by differential scanning calorimetry and X-ray diffraction. Fourier transform infrared analysis revealed that hydrogen bonding, electrostatic interaction and hydrophobic attraction were the main interactions among zein, lecithin, and Cur. Compared with single zein and lecithin nanoparticles, zein-lecithin composite nanoparticles significantly improved the stability of Cur against thermal treatment, UV irradiation and high ionic strength. Therefore, zein-lecithin composite nanoparticles could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and chemical stability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Immobilization of ibuprofen and copper-ibuprofen drugs on layered double hydroxides.

    Science.gov (United States)

    Gordijo, Cláudia R; Barbosa, César A S; Da Costa Ferreira, Ana M; Constantino, Vera R L; de Oliveira Silva, Denise

    2005-05-01

    The immobilization of the NSAID ibuprofen (Hibp) and the Cu(II)-ibp compound on magnesium-aluminum layered double hydroxides (Mg3Al-LDH) is described. Ibuprofen was intercalated on LDHs by three routes (ion exchange, co-precipitation, and reconstruction). The organic drug and the Cu(II)-ibp were also immobilized by adsorption on LDH external surfaces. Materials were characterized by elemental analysis, UV/VIS, FTIR, and Raman spectroscopies, powder X-ray diffractometry (XRD), thermogravimetry, and electronic paramagnetic resonance (EPR). Mg3Al-(ibp)(cop) (30% w/w of drug/material) and Mg3Al-(ibp)(ie) (33%) materials exhibit bilayer arrangements of ibp anions intercalated between the host layers. Mg3Al-(ibp)(rec) and Mg3Al-(ibp)(ads) contain 13% and 6.2% of ibuprofenate, respectively. Mg3Al-(Cu-ibp)(ads) exhibits two Cu centers in different environments interacting with host layers. Pharmacological potential of materials are compared considering the amounts of immobilized drugs and their buffering properties. Mg3Al-(ibp)(ie) and Mg3Al-(ibp)(cop) exhibit poor buffering property, but contain high ibp amounts. Mg3Al-(ibp)(ads) despite having buffering property, contains low amount of ibuprofen. Mg3Al-(ibp)(rec) combines significant amount of immobilized ibp with good buffering property. Mg3Al-(Cu-ibp)(ads), due to the buffering property, may be an interesting new formulation aiming to decrease gastric irritation. Copyright 2005 Wiley-Liss, Inc

  15. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hyun; Oh, Jae-Min, E-mail: jaemin.oh@yonsei.ac.kr

    2016-01-15

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV–vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca{sub 1.30}Al(OH){sub 4.6}FA{sub 0.74}·3.33H{sub 2}O and Ca{sub 1.53}Fe(OH){sub 5.06}FA{sub 2.24}·9.94H{sub 2}O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca. - Highlights: • We successfully intercalated FA molecules into Ca-containing LDHs. • Exfoliation-reassembly was proven to be the most effective. • The interaction between LDH and FA were studied by FT-IR and UV–vis spectra. • Thermal stability of FA were enhanced by electrostatic interaction with LDH layers.

  16. Hexavalent chromium removal from aqueous solution by adsorption on aluminum magnesium mixed hydroxide.

    Science.gov (United States)

    Li, Yujiang; Gao, Baoyu; Wu, Tao; Sun, Dejun; Li, Xia; Wang, Biao; Lu, Fengjuan

    2009-07-01

    A series of sols consisting of aluminum magnesium mixed hydroxide (AMH) nanoparticles with various Mg/Al molar ratios were prepared by coprecipitation. The use of AMH as adsorbent to remove Cr(VI) from aqueous solution was investigated. Adsorption experiments were carried out as a function of the Mg/Al molar ratio, pH, contact time, concentration of Cr(VI) and temperature. It was found that AMH with Mg/Al molar ratio 3 has the largest adsorption efficiency due to the smallest average particle diameter and the highest zeta potential; AMH was particularly effective for the Cr(VI) removal in a pH range from acid to slightly alkaline, even though the most effective pH range was between 2.5 and 5.0. The adsorption of Cr(VI) on AMH reached equilibrium within 150 min. The saturated adsorption capacities of AMH for Cr(VI) were 105.3-112.0mg/g at 20-40 degrees C. The interaction between the surface sites of AMH and the Cr(VI) ions may be a combination of both anion exchange and surface complexation. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto AMH. The results showed that AMH can be used as a new adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH values close to that at which pollutants are usually found in the environment.

  17. Removal of boron from oilfield wastewater via adsorption with synthetic layered double hydroxides.

    Science.gov (United States)

    Delazare, Thais; Ferreira, Letícia P; Ribeiro, Nielson F P; Souza, Mariana M V M; Campos, Juacyara C; Yokoyama, Lídia

    2014-01-01

    Hydrotalcite is a layered double hydroxide (LDH) consisting of brucite-like sheets of metal ions (Mg-Al). In this work, hydrotalcites were synthesized, and boron removal from oilfield wastewater was evaluated. LDHs were synthesized using the co-precipitation method. The calcined products (CLDHs) were obtained by heating at 500°C and characterized using X-ray diffraction, X-ray fluorescence, thermogravimetric analysis and the specific surface area (BET). The affinity of LDHs for borate ions was evaluated for calcined and uncalcined LDHs as a function of contact time, initial pH of the oilfield wastewater (pH ∼ 9) and the LDH surface area. The tests were conducted at room temperature (approximately 25ºC). The results indicated that 10 min were needed to reach a state of equilibrium during boron removal for calcined LDHs due to the high surface area (202.3 m(2) g(-1)) regardless of the initial pH of the oilfield wastewater, which resulted from the high buffering capacity of the LDHs. The adsorption capacity increased as the adsorbents levels increased for the range studied. After treatment of the oilfield wastewater containing 30 mg L(-1) of boron with Mg-Al-CO3-LDHs, the final concentration of boron was within the discharge limit set by current Brazilian environmental legislation, which is 5 mg L(-1). Pseudo-first-order and pseudo-second-order kinetic models were tested, and the latter was found to fit the experimental data better. Isotherms for boron adsorption by CLDHs were well described using the Langmuir and Freundlich equations.

  18. A new chelating reagent and application for coprecipitation of some metals in food samples by FAAS.

    Science.gov (United States)

    Yıldız, Esra; Saçmacı, Şerife; Kartal, Şenol; Saçmacı, Mustafa

    2016-03-01

    A new, simple and rapid coprecipitation method has been developed to separate and preconcentrate traces of Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) in different samples prior to their determinations by flame atomic absorption spectrometry (FAAS). 2-[(E)-(8-hydroxy-2-methylquinolin-5-yl) diazenyl] benzoic acid (QAN) was firstly synthesized and characterized as a new chelating reagent for determination of some metals. IR spectra, (1)H-NMR spectrum and elemental analysis were evaluated for the characterization of the reagent. These metals were quantitatively recovered with Ni(II)/QAN precipitate in pH range of 8-10. Different factors such as sample volume, amount of QAN, and Ni(II) as carrier element, sample volume, and matrix effects for improving the quality of the preconcentration procedure were optimized. Under optimized experimentally established conditions, analytical detection limits were in the range of 0.03-0.83μgL(-1), while precision (RSD) was coprecipitation method was verified by the analysis of certified reference materials. The method was applied to the determination of the analytes in real samples such as food samples and make up products, and accuracy was found high (recoveries >95%). Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative "autocatalytic" electroless coprecipitation route.

    Science.gov (United States)

    Oliveira, J M; Costa, S A; Leonor, I B; Malafaya, P B; Mano, J F; Reis, R L

    2009-02-01

    A developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the "autocatalytic" electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20-500 microm. Furthermore, the Fourier transform infra-red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X-ray diffraction pattern of composite scaffolds demonstrated that calcium-phosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% +/- 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the water-uptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired, as in the case of bone tissue-engineering scaffolding applications.

  20. Preparation and Characterization of Ato Nanoparticles by Coprecipitation with Modified Drying Method

    Science.gov (United States)

    Liu, Shimin; Liang, Dongdong; Liu, Jindong; Jiang, Weiwei; Liu, Chaoqian; Ding, Wanyu; Wang, Hualin; Wang, Nan

    Antimony-doped tin oxide (ATO) nanoparticles were prepared by coprecipitation by packing drying and traditional direct drying (for comparison) methods. The as-prepared ATO nanoparticles were characterized by TG, XRD, EDS, TEM, HRTEM, BET, bulk density and electrical resistivity measurements. Results indicated that the ATO nanoparticles obtained by coprecipitation with direct drying method featured hard-agglomerated morphology, high bulk density, low surface area and low electrical resistivity, probably due to the direct liquid evaporation during drying, the fast shrinkage of the precipitate, the poor removal efficiency of liquid molecules and the hard agglomerate formation after calcination. Very differently, the ATO product obtained by the packing and drying method featured free-agglomerated morphology, low bulk density, high surface area and high electrical resistivity ascribed probably to the formed vapor cyclone environment and liquid evaporation-resistance, avoiding fast liquid removal and improving the removal efficiency of liquid molecules. The intrinsic formation mechanism of ATO nanoparticles from different drying methods was illustrated based on the dehydration process of ATO precipitates. Additionally, the packing and drying time played key roles in determining the bulk density, morphology and electrical conductivity of ATO nanoparticles.

  1. Oxalate co-precipitation synthesis of calcium zirconate and calcium titanate powders.

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Sanchez, Bernadette A.; Tuttle, Bruce Andrew

    2009-06-01

    Fine powders of calcium zirconate (CaZrO{sub 3}, CZ) and calcium titanate (CaTiO{sub 3}, CT) were synthesized using a nonaqueous oxalate co-precipitation route from Ca(NO{sub 3}){sub 2}{center_dot}4 H{sub 2}O and group(IV) n-butoxides (Ti(OBu{sup n}){sub 4} or Zr(OBu{sup n}){sub 4}). Several reaction conditions and batch sizes (2-35 g) were explored to determine their influence on final particle size, morphology, and phase. Characterization of the as-prepared oxalate precursors, oven dried oxalate precursors (60-90 C), and calcined powders (635-900 C) were analyzed with TGA/DTA, XRD, TEM, and SEM. Densification and sintering studies on pressed CZ pellets at 1375 and 1400 C were also performed. Through the developed oxalate co-precipitation route, densification temperatures for CZ were lowered by 125 C from the 1500 C firing temperature required for conventional mixed oxide powders. Low field electrical tests of the CZ pellets indicated excellent dielectric properties with dielectric constants of {approx}30 and a dissipation factor of 0.0004 were measured at 1 kHz.

  2. Coprecipitation synthesis and negative thermal expansion of NbVO5.

    Science.gov (United States)

    Wang, Jinrui; Deng, Jinxia; Yu, Ranbo; Chen, Jun; Xing, Xianran

    2011-04-07

    We develop a coprecipitation synthesis route to prepare NbVO(5) with simple oxide Nb(2)O(5) and NH(4)VO(3) as starting materials. No metal alkoxide or organometallic substance was used in the process. Nano-crystal NbVO(5) was obtained by calcination of the coprecipitates at 550 °C for 2 h. DSC/TG and XRD investigations indicate that the target compound NbVO(5) is completely formed up to 504.5 °C and is thermally stable below 658 °C. Rietveld XRD refinements give an orthorhombic structure with space group Pnma and lattice parameters, a=11.8453(2), b=5.5126(3) and c=6.9212(2) Å, respectively. In particular, HTXRD determinations show a negative thermal expansion in NbVO(5) with a TEC of -6.63 × 10(-6) °C(-1) in the temperature range of RT-600 °C. This fact is ascribed to the tilting of NbO(6) octahedra and VO(4) tetrahedra in the flexible framework structure. The present synthesis route is facile and easy to be extended to prepare analogues such as TaVO(5), etc. © The Royal Society of Chemistry 2011

  3. Gadolinium-doped ceria nanopowders synthesized by urea-based homogeneous co-precipitation (UBHP)

    Energy Technology Data Exchange (ETDEWEB)

    Accardo, G., E-mail: d16605@kist.re.kr [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Spiridigliozzi, L. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy); Cioffi, R.; Ferone, C. [Department of Engineering, INSTM Research Unit, University Parthenope of Naples, Centro Direzionale, Is. C4, 80143 Napoli (Italy); Di Bartolomeo, E. [Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Viale della Ricerca Scientifica, 00133 Rome (Italy); Yoon, Sung Pil [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Dell’Agli, G. [Department of Civil and Mechanical Engineering, INSTM Research Unit, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, FR (Italy)

    2017-02-01

    Gadolinium (10%)-doped ceria was successfully synthesized by using an urea-based co-precipitation method (UBHP). A single fluorite phase was obtained after a low temperature (400 °C) calcination treatment. The resulting powders showed grains of nanometric size with some agglomerations and an overall good sinterability. Pellets were sintered at 1300 and 1500 °C for 3 h. The ionic conductivity was measured by electrochemical impedance spectroscopy measurements and a correlation between electrical properties and microstructure was revealed. The promising conductivity values showed that the synthesized powders are suitable for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. - Highlights: • Urea-based homogeneous co-precipitation is applied to synthesize nanocrystalline GDC. • Dense GDC samples at different sintering temperatures were characterized. • SEM and TEM revealed a well define microstructure and controlled composition. • Correlation between electrochemical properties by EIS and microstructure was discussed. • UBHP method can be used to prepare high performance GDC electrolytes.

  4. Separation and preconcentration of Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) ions with coprecipitation method without carrier element and their determination in food and water samples.

    Science.gov (United States)

    Mendil, Durali; Karatas, Murat; Tuzen, Mustafa

    2015-06-15

    In this study, Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) were determined in some food and water samples after development 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) coprecipitation procedure using flame atomic absorption spectrometry (FAAS). Effects of some analytical parameter including pH, sample volume, reagent amount, centrifuge rate and time, etc. on the presented coprecipitation system were studied for the quantitative recoveries of Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) ions. The influences of matrix ions were examined. The recovery values for analyte ions were calculated ⩾ 95%. The relative standard deviation was found 8.0% and the preconcentration factor was found as 25 for all analyte ions. The detection limits (k=3, N=21) were found to be as 0.80 μg L(-1) Cu(II), 3.08 μg L(-1) Pb(II), 0.28 μg L(-1) Zn(II), 0.91 μg L(-1) Fe(III) and 1.82 μg L(-1) Cr(III). NIST SRM 1515 Apple leaves and GBW-07605 Tea certified reference materials were used to confirm the accuracy of the method. The simultaneous coprecipitation method was applied to various water and microwave digested food samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [School of Materials Science and Technology, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian Distract, Beijing 100083 (China); Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States); Bhushan, Bharat, E-mail: bhushan.2@osu.edu [Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States)

    2016-08-15

    Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  6. Evaluation of Controlled-Release Property and Phytotoxicity Effect of Insect Pheromone Zinc-Layered Hydroxide Nanohybrid Intercalated with Hexenoic Acid.

    Science.gov (United States)

    Ahmad, Rozita; Hussein, Mohd Zobir; Kadir, Wan Rasidah Wan Abdul; Sarijo, Siti Halimah; Hin, Taufiq-Yap Yun

    2015-12-30

    A controlled release formulation for the insect pheromone hexenoic acid (HE) was successfully developed using zinc-layered hydroxide (ZLH) as host material through a simple coprecipitation technique, resulting in the formation of inorganic-organic nanolayered material with sustained release properties. The release of HE from its nanohybrid was found to occur in a controlled manner, governed by a pseudo-second order kinetics model. The maximum amount of HE released from the nanocomposite into solutions at pH 4, 6.5, and 8 was found to be 84, 73, and 83% for 1100 min, respectively. The hexenoate zinc-layered hydroxide nanomaterial (HEN) was found to be nontoxic for plants when green beans and wheat seeds were successfully germinated in all HEN concentrations tested in the experiment, with higher percentage of seed germination and higher radical seed growth as compared to its counter anion, HE. ZLH can be a promising carrier for insect pheromone toward a new generation of environmentally safe pesticide nanomaterial for crop protection.

  7. The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

    Directory of Open Access Journals (Sweden)

    Hadnađev-Kostić Milica S.

    2012-01-01

    Full Text Available Layered double hydroxides (LDHs have been studied to a great extent as environmental-friendly complex materials that can be used as photocatalysts or photocatalyst supports. ZnAl layered double hydroxides and their derived mixed oxides were chosen for the investigation of photocatalytic performances in correlation with the UV intensities measured in the South Pannonia region. Low supersaturation coprecipitation method was used for the ZnAl LDH synthesis. For the characterization of LDH and thermal treated samples powder X-ray diffraction (XRD, scanning electron microscopy (SEM, electron dispersive spectroscopy (EDS, nitrogen adsorption-desorption were used. The decomposition of azodye, methylene blue was chosen as photocatalytic test reaction. The study showed that the ZnAl mixed oxide obtained by thermal decomposition of ZnAl LDH has stable activity in the broader UV light irradiation range characterizing the selected region. Photocatalytic activity could be mainly attributed to the ZnO phase, detected both in LDH and thermally treated samples. The study showed that the ZnAl mixed oxide obtained by the calcination of ZnAl LDH has a stable activity within the measured UV light irradiation range; whereas the parent ZnAl LDH catalyst did not perform satisfactory when low UV irradiation intensity is implied.

  8. Study of 2,4-dichlorophenoxyacetic acid (2,4-D) removal by Cu-Fe-layered double hydroxide from aqueous solution

    Science.gov (United States)

    Nejati, Kamellia; Davary, Soheila; Saati, Marziye

    2013-09-01

    The hydrotalcite-like compound of Cu-Fe-layered double hydroxide was studied as a potential adsorbent of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The nanoparticles of Cu-Fe layered double hydroxide were prepared by Cu/Fe molar ratio of 2:1 using a coprecipitation method at pH 8.5 and characterized by the X-ray powder diffraction (XRD), the Fourier transform infrared spectroscopy (FT-IR), the thermal gravimetric analysis (TGA) and the elemental analysis. The size and morphology of nanoparticles were examined by the transmission electron microscopy (TEM). The adsorption experiments on LDH, on the other hand, were conducted in three different procedures, namely, time-dependent, pH-dependent and temperature-dependent. Characterization of the adsorption products by the XRD method indicates that the intercalation of 2,4-D between the LDH layers has not occurred and the surface adsorption had taken place. The adsorption kinetic was tested for pseudo-first-order, pseudo-second-order, Elovich and Intra-particle diffusion kinetic models and the rate constants were calculated. The equilibrium adsorption data were described by Langmuir and Freundlich equations. It was observed that, the Langmuir isotherm slightly better fitted to the experimental data rather than that of Freundlich. In the adsorption experiments, the Gibbs free energy values, ΔG°, the enthalpy, ΔH°, and the entropy, ΔS° were also determined.

  9. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  10. Conversion coatings prepared or treated with calcium hydroxide solutions

    Science.gov (United States)

    Minevski, Zoran (Inventor); Clarke, Eric (Inventor); Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor)

    2002-01-01

    A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.

  11. Automatized and desktop AC-susceptometer for the in situ and real time monitoring of magnetic nanoparticles' synthesis by coprecipitation.

    Science.gov (United States)

    Fernández-García, M P; Teixeira, J M; Machado, P; Oliveira, M R F F; Maia, J M; Pereira, C; Pereira, A M; Freire, C; Araujo, J P

    2015-04-01

    The main purpose of this work was to design, develop, and construct a simple desktop AC susceptometer to monitor in situ and in real time the coprecipitation synthesis of magnetic nanoparticles. The design incorporates one pair of identical pick-up sensing coils and one pair of Helmholtz coils. The picked up signal is detected by a lock-in SR850 amplifier that measures the in- and out-of-phase signals. The apparatus also includes a stirrer with 45°-angle blades to promote the fast homogenization of the reaction mixture. Our susceptometer has been successfully used to monitor the coprecipitation reaction for the synthesis of iron oxide nanoparticles.

  12. Comparative study on the preparation of Uranium source using a Cerium fluoride Co-precipitation method and an Electrodeposition method

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han-Byeol; Park, Seunghoon; Shin, Jung-Ki; Ahn, Gil Hoon; Chung, Heejun; Kwak, Sung-Woo [Korea Institute of Nonproliferation and control, Daejeon (Korea, Republic of)

    2015-05-15

    This analysis can be used to identify the undeclared nuclear activities of North Korea. The international community has developed a method of collecting and analyzing uranium particles within a limited time in the field to determine whether or not undeclared nuclear activities have taken place. This study shows the U source using CeF{sub 3} coprecipitation has no significant difference. In addition, this CeF{sub 3} coprecipitation method is simple and time saving. It is expected to be useful for rapid on-site detection of undeclared uranium enrichment activities.

  13. Highly transparent cerium doped gadolinium gallium aluminum garnet ceramic prepared with precursors fabricated by ultrasonic enhanced chemical co-precipitation.

    Science.gov (United States)

    Zhang, Ji-Yun; Luo, Zhao-Hua; Jiang, Hao-Chuan; Jiang, Jun; Chen, Chun-Hua; Zhang, Jing-Xian; Gui, Zhen-Zhen; Xiao, Na

    2017-11-01

    Cerium doped gadolinium gallium aluminum garnet (GGAG:Ce) ceramic precursors have been synthesized with an ultrasonic chemical co-precipitation method (UCC) and for comparison with a traditional chemical co-precipitation method (TCC). The effect of ultra-sonication on the morphology of powders and the transmittance of GGAG:Ce ceramics are studied. The results indicate that the UCC method can effectively improve the homogenization and sinterability of GGAG:Ce powders, which contribute to obtain high transparent GGAG ceramic with the highest transmittance of 81%. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Precipitation and aging of magnesium hydroxide before suspension polymerisation

    OpenAIRE

    Skoglund, Therese

    2005-01-01

    A colloid of magnesium hydroxide is used to stabilize droplets of monomers before suspension polymerisation. The characteristics of precipitated magnesium hydroxide changes significantly during the first hours. The viscosity is high and flucctuating at first but decreases and becomes low and stable after a few hours. When the colloid ages the primary particles agglomerate into larger particles which increases in size by time due to, among other things, Oswald ripening and aggregation. This ca...

  15. Real-time tracking of hydrogen peroxide secreted by live cells using MnO{sub 2} nanoparticles intercalated layered doubled hydroxide nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Asif, Muhammad; Aziz, Ayesha [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Dao, Anh Quang [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Hue Industrial College, 70 Nguyen Hue, Hue, Thua Thien Hue, 531081 (Viet Nam); Hakeem, Abdul; Wang, Haitao; Dong, Shuang; Zhang, Guoan [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Xiao, Fei [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Shenzhen Institute of Huazhong University of Science & Technology, Shenzhen, 518000 (China); Liu, Hongfang, E-mail: liuhf@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Shenzhen Institute of Huazhong University of Science & Technology, Shenzhen, 518000 (China)

    2015-10-22

    We report a facile and green method for the fabrication of new type of electrocatalysts based on MnO{sub 2} nanoparticles incorporated on MgAl LDH P-type semiconductive channel and explore its practical applications as high-performance electrode materials for electrochemical biosensor. A series of MgAl layered doubled hydroxide (LDH) nanohybrids with fixed Mg/Al (M{sup 2+}/M{sup 3+} atomic ratio of 3) and varied amount of MnCl{sub 2}.4H{sub 2}O are fabricated by a facile co-precipitation method. This approach demonstrates the combination of distinct properties including excellent intercalation features of LDH for entrapping nanoparticles and high loading of MnO{sub 2} nanoparticles in the host layers of LDH. Among all samples, Mn5–MgAl with 0.04% loaded manganese has a good crystalline morphology. A well-dispersed MnO{sub 2} nanoparticles encapsulated into the host matrix of hydrotalcite exhibit enhanced electrocatalytic activity towards the reduction of H{sub 2}O{sub 2} as well as excellent stability, selectivity and reproducibility due to synergistic effect of good catalytic ability of MnO{sub 2} and conductive MgAl LDH. Glass carbon electrode (GCE) modified with Mn5–MgAl possesses a wide linear range of 0.05–78 mM, lowest detection limit 5 μM (S/N = 3) and detection sensitivity of 0.9352 μAmM{sup −1}. This outstanding performance enables it to be used for real-time tracking of H{sub 2}O{sub 2} secreted by live HeLa cells. This work may provide new insight in clinical diagnosis, on-site environmental analysis and point of care testing devices. - Highlights: • MnO{sub 2}MgAl nanohybrids have been fabricated by a facile and robust co-precipitation approach. • MgAl layered doubled hydroxide can be used for the intercalation of MnO{sub 2} nanoparticles. • MgAl layered doubled hydroxide nanohybrid serves as p-type semiconductive channel for efficient electrocatalysis. • The nanohybrid electrode demonstrates excellent electrochemical performance

  16. Efficacy of NiTi rotary instruments in removing calcium hydroxide dressing residues from root canal walls

    Directory of Open Access Journals (Sweden)

    Milton Carlos Kuga

    2012-02-01

    Full Text Available The aim of this study was to evaluate the efficacy of three rotary instrument systems (K3, ProTaper and Twisted File in removing calcium hydroxide residues from root canal walls. Thirty-four human mandibular incisors were instrumented with the ProTaper System up to the F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA, and filled with a calcium hydroxide intracanal dressing. After 7 days, the calcium hydroxide dressing was removed using the following rotary instruments: G1 - NiTi size 25, 0.06 taper, of the K3 System; G2 - NiTi F2, of the ProTaper System; or G3 - NiTi size 25, 0.06 taper, of the Twisted File System. The teeth were longitudinally grooved on the buccal and lingual root surfaces, split along their long axis, and their apical and cervical canal thirds were evaluated by SEM (×1000. The images were scored and the data were statistically analyzed using the Kruskall Wallis test. None of the instruments removed the calcium hydroxide dressing completely, either in the apical or cervical thirds, and no significant differences were observed among the rotary instruments tested (p > 0.05.

  17. Sono-assisted preparation of magnetic magnesium-aluminum layered double hydroxides and their application for removing fluoride.

    Science.gov (United States)

    Chang, Qing; Zhu, Lihua; Luo, Zhihong; Lei, Min; Zhang, Suicheng; Tang, Heqing

    2011-03-01

    A simple ultrasound-assisted co-precipitation method in combination with a calcination treatment was developed to prepare magnetic Mg-Al layered double hydroxides composite as an adsorbent material to remove fluoride ions from aqueous solutions. The application of ultrasound in the preparation process promoted the formation of the hydrotalcite-like phase and drastically shortened the time being required for preparation of the crystalline composite. It was found that the ultrasound irradiation assistance decreased the size of the composite particles and increased the specific surface area, being favorable to the improvement of the adsorption capacity. The composite prepared under the ultrasound irradiation exhibited fairly high maximum adsorption capacity of fluoride (47.7 mg g(-1)), which was 60% higher than that of the composite prepared without the ultrasound irradiation assistance with the same aging time. The thermodynamic and kinetic studies demonstrated that the adsorption of fluoride ions involved the reconstruction of the layered structure in the composite. In addition, the magnetic composite can be effectively and simply separated by using an external magnetic field, and then regenerated by desorption and calcination. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Effect of rare Earth ions on the properties of composites composed of ethylene vinyl acetate copolymer and layered double hydroxides.

    Directory of Open Access Journals (Sweden)

    Lili Wang

    Full Text Available BACKGROUND: The study on the rare earth (RE-doped layered double hydroxides (LDHs has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. METHODOLOGY/PRINCIPAL FINDINGS: The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA/LDHs composites were also explored in detail. CONCLUSIONS/SIGNIFICANCE: S-Ni₀.₁MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni₀.₁MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites.

  19. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    Science.gov (United States)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  20. Synthesis and Characteristics of Valeric Acid-Zinc Layered Hydroxide Intercalation Material for Insect Pheromone Controlled Release Formulation

    Directory of Open Access Journals (Sweden)

    Rozita Ahmad

    2016-01-01

    Full Text Available A new intercalation compound of insect pheromone, valeric acid (VA, based on zinc layered hydroxide (ZLH as host release material, was successfully prepared through coprecipitation method. The as-produced organic-inorganic nanolayered material, valerate nanohybrid, VAN, shows the formation of a new peak at lower 2θ angle with basal spacing of 19.8 Å with no ZnO reflections, which indicate that the intercalation of anion between the inorganic ZLH interlamellae was accomplished. The elemental, FTIR, and ATR analyses of the nanohybrid supported the fact that the intercalation with the percentage anion loading was calculated to be 23.0% (w/w. The thermal stability property of the resulting nanohybrid was enhanced compared to the unbound anion. Field emission scanning electron micrograph of the ZnO has a nonuniform granular structure but transforms into flake-like structure with various sizes after the intercalation process. Release kinetics of anion from the interlayer of intercalated compound exhibited a slow release behavior governed by the pseudo-second-order kinetic model at different pHs of aqueous media. The valerate anion was released from VAN with the highest release rate at pH 4. These findings provide the basis to further development of controlled release formulation for insect pheromone based on ZLH intercalation.

  1. Synthesis and characterization of novel Co/Bi-layered double hydroxides and their adsorption performance for lead in aqueous solution

    Directory of Open Access Journals (Sweden)

    Amita Jaiswal

    2017-05-01

    Full Text Available The Co/Bi-layered double hydroxides (Co/Bi-LDH were synthesized by co-precipitation method and used for the removal of lead from aqueous solutions. The Co/Bi-LDH was characterized using X-ray diffraction (XRD, Fourier Transform Infrared spectroscopy (FTIR, Transmission Electron Microscopy (TEM, Selected Area Electron Diffraction (SAED and BET for textural properties. Adsorption of lead solution by Co/Bi-LDH was carried out using batch experiment by mixing the lead solution and the adsorbent. The effects of various parameters such as contact time, pH, adsorbent dosage and initial concentration were investigated. The optimum pH for lead removal was found to be 4 and the optimum time of lead removal was found to be 120 min. The isotherm data were analyzed using Freundlich and Langmuir. The adsorption isotherms can be well described by the Langmuir model with R2 > 0.99. Its adsorption kinetics followed the pseudo-second-order kinetic model. Thermodynamic parameters were also studied. It was found that the synthesized Co/Bi-LDH can reduce the lead concentration and makes it a potential material for the decontamination of lead polluted water.

  2. Tribological performance of Mg/Al/Ce layered double hydroxides nanoparticles and intercalated products as lubricant additives

    Science.gov (United States)

    Li, Shuo; Qin, Haojing; Zuo, Ranfang; Bai, Zhimin

    2015-10-01

    Mg/Al/Ce ternary layered double hydroxides (LDHs) were synthesized via coprecipitation and intercalated by succinic acid and lauric acid through ion exchange method respectively. The LDHs products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). Tribological properties of LDHs as lubricant additives were evaluated by four-ball friction and air compressor test. The results indicated that Mg/Al/Ce LDHs were prepared successfully with Ce/Al molar ratio of 0.05 and crystallization temperature of 140 °C. The interlayer spacing of LDHs precursor was expanded by succinic acid and lauric acid to 8.838 and 17.519 Å respectively. All the three LDHs products can reduce friction and wear of engine lubricating oil in the tests. LDHs intercalated with lauric acid showed best tribological performance among them which was attributed to sliding each other between laminates, good dispersibility in oil medium and a protective tribofilm formed on the worn surface.

  3. Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.

    Science.gov (United States)

    Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

    2014-01-01

    The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts.

  4. High performance NiFe layered double hydroxide for methyl orange dye and Cr(VI) adsorption.

    Science.gov (United States)

    Lu, Yi; Jiang, Bin; Fang, Liang; Ling, Faling; Gao, Jiemei; Wu, Fang; Zhang, Xihua

    2016-06-01

    The NiFe layered double hydroxides (LDHs) with different mole ratio of Ni/Fe (4:1, 3:1, 7:3 and 1:1) were prepared by a simple coprecipitation method. The adsorption performance were evaluated by the removal of methyl orange (MO) dye and hexavalent chromium(VI) heavy metal ion. It is found that Ni4Fe1-LDH can remove more than 92% of MO in 10 min at the 10 mg/L MO initial concentration, and 97% of Cr(VI) in 1 h at 4 mg/L Cr2O7(2-) initial concentration. The saturated adsorption capacity of Ni4Fe1-LDH is found to be as large as 205.76 mg/g for MO and 26.78 mg/g for Cr(VI). The adsorption behavior of this new adsorbent is fitted well with Langmuir isotherm and the pseudo-second-order kinetic model, indicative of a monolayer and chemical adsorption that synergistically originates from exchangeable anions mechanism and layer charge density. Due to the excellent removal capacity of MO and Cr(VI), the NiFe-LDHs could be a promising adsorbent for wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Speciation analysis of 129I in seawater by carrier-free AgI-AgCl coprecipitation and accelerator mass spectrometric measurement

    DEFF Research Database (Denmark)

    Luo, Maoyi; Hou, Xiaolin; He, Chaohui

    2013-01-01

    A rapid and simple method was developed for speciation analysis of 129I in seawater by selective coprecipitation of carrier-free iodide and accelerator mass spectrometry (AMS) measurement of 129I. Iodide was separated from seawater and other species of iodine by coprecipitation of AgI with Ag2SO3...

  6. Low temperature synthesis of nanocrystalline lanthanum monoaluminate powders by chemical coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C.-L. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Wang, C.-L. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Chen, T.-Y. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Chen, G.-J. [Department of Materials Science and Engineering, I-Shou University, 1 Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung 840, Taiwan (China); Hung, I-M. [Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan (China); Shih, C.-J. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China)]. E-mail: CJShih@kmu.edu.tw; Fung, K.-Z. [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China)

    2007-08-16

    Nanocrystalline lanthanum monoaluminate (LaAlO{sub 3}) powders were prepared by chemical coprecipitation using 25 vol.% of NH{sub 4}OH, 0.05 M La(NO{sub 3}){sub 3}.6H{sub 2}O and 0.05 M Al(NO{sub 3}){sub 3}.9H{sub 2}O aqueous solutions as the starting materials. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analyses (TGA/DTA), X-ray diffraction (XRD), Raman spectrometry, specific surface area (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized to characterize the LaAlO{sub 3} powders prepared by chemical coprecipitation. The crystallization temperature of the LaAlO{sub 3} precursor gels precipitated at pH 9 is estimated as 810 deg. C by TG/DTA. The XRD pattern of the LaAlO{sub 3} precursor gels precipitated at pH 8-12 and calcined at 700 deg. C for 6 h shows a broad arciform continuum exist between 24{sup o} and 32{sup o} and sharp peaks of LaAlO{sub 3} except the precursor gels precipitated at pH 9. For the LaAlO{sub 3} precursor gels precipitated at pH 9 and calcined at 700 deg. C for 6 h, the formation of the perovskite LaAlO{sub 3} phase occurs and the presence of crystalline impurities is not found. The crystallite size of LaAlO{sub 3} slightly increases from 37.8 to 41.5 nm with calcination temperature increasing from 700 to 900 deg. C for 6 h. The LaAlO{sub 3} powders prepared by chemical coprecipitation have a considerably large specific surface of 30 m{sup 2}/g. The relative density greater than 97% is obtained when these nanocrystalline LaAlO{sub 3} powders are sintered at 1550 deg. C for 2 h.

  7. Selective Aerobic Oxidation of 5-Hydroxymethylfurfural in Water Over Solid Ruthenium Hydroxide Catalysts with Magnesium-Based Supports

    DEFF Research Database (Denmark)

    Gorbanev, Yury; Kegnæs, Søren; Riisager, Anders

    2011-01-01

    Solid catalyst systems comprised of ruthenium hydroxide supported on magnesium-based carrier materials (spinel, magnesium oxide and hydrotalcite) were investigated for the selective, aqueous aerobic oxidation of the biomass-derived chemical 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid...

  8. Layered zinc hydroxide salts: delamination, preferred orientation of hydroxide lamellae, and formation of ZnO nanodiscs.

    Science.gov (United States)

    Demel, Jan; Pleštil, Josef; Bezdička, Petr; Janda, Pavel; Klementová, Mariana; Lang, Kamil

    2011-08-15

    Delamination of layered zinc hydroxide salts (LZH) into hydroxide layers provides nanobuilding blocs of a two-dimensional anisotropy. The methodology, extent of delamination, the size and stability of hydroxide lamellae are described in detail. The ability of lamellae to restack to form oriented hydroxide films depends on the solvent, original LZH salt, and conditions used for delamination. The most interesting results were obtained using LZH intercalated with dodecyl sulfate anions and LZH nitrate delaminated in butanol at 60 °C and in formamide at room temperature, respectively. The former method produces hydroxide lamellae of a lateral size of ca. 10-20 nm. The inner structure of the hydroxide layers is conserved and separated lamellae restack to the original layered structure of LZH dodecyl sulfate. The latter method yields lamellae with a size decreasing from 73.3 nm to 10 nm after a 2-week aging, while their thickness is nearly constant (2.6-3.8 nm). However, the use of formamide is complicated by the formation of Zn(II) formate. The major part of LZH intercalated with dodecyl sulfate anions is transformed during the delamination procedure to anisotropic ZnO nanoparticles, either needle-like particles prolonged in the [0 0 1] direction or disc-like particles flattened along the (0 0 1) plane. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. The Effects of Aluminium Hydroxide and Magnesium Hydroxide on the Mechanical Properties of Thermoplastic Polyurethane Materials

    Directory of Open Access Journals (Sweden)

    Erkin Akdoğan

    2015-12-01

    Full Text Available Thermoplastic polyurethane materials are widely used in automotive, clothing, electrical and electronics, medical, construction, machine industry due to excellent physical and chemical properties. Thermoplastic polyurethane materials combustion and resistance to high temperature characteristics are poor. Additives and fillers are added into the polyurethane matrix to improve those properties. Particularly adding these agents as a flame retardant are affect mechanical properties of polyurethane materials. Therefore, it is important to determinate the mechanical properties of these materials. In this study, 5% by weight of the thermoplastic polyurethane material, aluminium tri hydroxide (ATH, (Al2O3 3H2O and magnesium hydroxide (MgOH, (Mg(OH2 were added. Ammonium polyphosphate (APP as an intumescent flame retardant with inorganic flame retardants were added to increase the flame resistance of produced composite structure. Tensile test, tear test, hardness and Izod impact tests were made and compared of those produced composites. As a result of experiments the addition of ATH has lowered the tensile strength and tear strength contrast to this the addition of MgOH has improved those properties. Hardness and Izod impact test results were showed that both of the additives have no negative effect.

  10. Thermodynamic stability of CoOOH and its coprecipitation with manganese

    Science.gov (United States)

    Hem, J.D.; Roberson, C.E.; Lind, Carol J.

    1985-01-01

    A precipitate of cobalt oxyhydroxides formed by bubbling oxygen through a dilute solution of Co(NO3)2 held at pH 9.0 and 25??C was aged for 23 months in contact with the original solution, with access to atmospheric oxygen. Co3O4 and CoOOH were identified in the precipitate by X-ray diffraction. Chemical equilibria involving these solids were evaluated by measurements of solution pH and Co2+ activities and by redox potential measurements and gave a ??GcoOOH0 of -92.3 ?? 0.5 kcal/mole. This value and other thermodynamic data show relative feasibility of hypothetical reaction steps and changes in reaction paths during automated coprecipitation titrations and subsequent aging of a precipitate that finally contained ??MnOOH, MnO2 (birnessite) and CoOOH. ?? 1985.

  11. Synthesis of cerium oxide (CeO{sub 2}) nanoparticles using simple CO-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Farahmandjou, M.; Zarinkamar, M.; Firoozabadi, T. P., E-mail: farahamndjou@iauvaramin.ac.ir [Islamis Azad University, Varamin-Phisva Branch, Department of Physics, Varamin (Iran, Islamic Republic of)

    2016-11-01

    Synthesis of cerium oxide (CeO{sub 2}) nanoparticles was studied by new and simple co-precipitation method. The cerium oxide nanoparticles were synthesized using cerium nitrate and potassium carbonate precursors. Their physicochemical properties were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (Sem), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (Ftir) and UV-Vis spectrophotometer. XRD pattern showed the cubic structure of the cerium oxide nanoparticles. The average particle size of CeO{sub 2} was around 20 nm as estimated by XRD technique and direct HRTEM observations. The surface morphological studies from Sem and Tem depicted spherical particles with formation of clusters. The sharp peaks in Ftir spectrum determined the existence of CeO{sub 2} stretching mode and the absorbance peak of UV-Vis spectrum showed the bandgap energy of 3.26 eV. (Author)

  12. TRANSPARENT CONDUCTING OXIDE SYNTHESIS OF ALUMINIUM DOPED ZINC OXIDES BY CHEMICAL COPRECIPITATION

    Directory of Open Access Journals (Sweden)

    Silvia Maioco

    2013-03-01

    Full Text Available Aluminium doped zinc oxides (AZO are promising replacements for tin doped indium oxides (ITO but thin films show a wide range of physical properties strongly dependent on deposition process conditions. Submicrometric 1% aluminum doped zinc oxide ceramics (AZO are examined, prepared by coprecipitation, from Zn(NO32 and Al(NO33 aqueous solutions, sintered at 1200°C and subsequently annealed in 10-16 atm controlled oxygen fugacity atmospheres, at 1000°C. Electrical resistivity diminishes by two orders of magnitude after two hours of annealing and the Seebeck coefficient gradually changes from -140 to -50 µV/K within 8 h. It is concluded that increased mobility is dominant over the increased carrier density, induced by changes in metal-oxygen stoichiometry

  13. Temperature Effect on Hydroxyapatite Preparation by Co-precipitation Method under Carbamide Influence

    Directory of Open Access Journals (Sweden)

    Luo Jing

    2015-01-01

    Full Text Available Hydroxyapatite crystal was prepared by homogeneous co-precipitation method using a mixture of Calcium nitrate and diammonium phosphate as raw materials and carbamide as the buffering agent. To analyzed the influence of temperature on hydroxyapatite crystal morphology, the phase composition, crystal morphology and growth orientation were characterized by X-ray diffraction, scanning electron microscope and infrared spectrum respectively. The results show that when the reaction temperature increase from 70 °C to 95 °C, the phases composition of crystal transform from the two phases of tricalcium phosphate and eight calcium phosphate to hydroxyapatite single crystal; the morphology of the hydroxyapatite crystals transforms from nodular whisker to perfectly and compactly acicular whisker.

  14. Influence of various surfactants on magnetic property of cobalt ferrite prepared by Co-precipitation technique

    Science.gov (United States)

    Solanki, Neha; Khatri, Hemal; Jotania, R. B.

    2016-05-01

    Cobalt Ferrite (CoFe2O4) particles were synthesised using a Co-precipitation method. Influence of three different surfactants i.e. (1) Cationic - CTAB (Cetyl Tri-Methyl Ammonium Bromide), (2) Anionic - SDBS (Sodium Dodecyl Benzene Sulphonate) and (3) Nonionic - Triton X-100, on magnetic property of Cobalt Ferrite were investigated. Magnetic property of Cobalt ferrite powder was studied at room temperature using Vibrating Sample Measurements (VSM) technique under an applied magnetic field of 15kOe. The results show maximum value of saturation magnetization - Ms (81.87 emu/g) for the sample synthesised without surfactant and Coercivity value found maximum (2086 kOe) for the sample synthesized in presence of surfactant SDBS.

  15. Preparation of YAG:Nd nano-sized powder by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Li Xia; Liu Hong; Wang Jiyang; Cui Hongmei; Zhang Xudong; Han Feng

    2004-08-15

    Nd{sup 3+} doped yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12} (YAG) nano-sized powders were prepared by a co-precipitation method using hydroxypropyl cellulose (HPC) as dispersant. The formation process and structure of the as-prepared sample were investigated by means of TG-DTA, XRD, IR, and TEM. It has been found that the YAG powders were amorphous up to 700 deg. C and transformed into pure phase YAG crystallite at 900 deg. C for 2 h, because of the uniformly distribution of Al and Y elements. The size of YAG powder is about 30 nm in diameter and mono-disperse in the presence of HPC. Optical absorption and emission spectra of nano-crystallites versus Nd{sup 3+} concentration and sintering temperature were also studied.

  16. Synthesis and Antibacterial and Antibiofilm Activity of Iron Oxide Glycerol Nanoparticles Obtained by Coprecipitation Method

    Directory of Open Access Journals (Sweden)

    Simona Liliana Iconaru

    2013-01-01

    Full Text Available The glycerol iron oxide nanoparticles (GIO-NPs were obtained by an adapted coprecipitation method. The X-ray diffraction (XRD studies demonstrate that GIO-NPs were indexed into the spinel cubic lattice with a lattice parameter of 0.835 nm. The refinement of XRD spectra indicated that no other phases except maghemite were detected. The adsorption of glycerol on iron oxide nanoparticles was investigated by Fourier transform infrared (FTIR spectroscopy. On the other hand, this work implicated the use of GIO-NPs in antibacterial studies. The results indicate that, in the case of P. aeruginosa  1397 biofilms, at concentrations from 0.01 mg/mL to 0.625 mg/mL, the glycerol iron oxide inhibits the ability of this strain to develop biofilms on the inert substratum.

  17. Arsenic control in process tailings: continuous coprecipitation of As(V) with iron sulphate media

    Energy Technology Data Exchange (ETDEWEB)

    Daenzer, R.; De Klerk, R.J.; Demopoulos, G.P., E-mail: george.demopoulos@mcgill.ca [McGill Univ., Dept. of Mining and Materials Engineering, Montreal, QC (Canada)

    2010-07-01

    Arsenic constitutes a serious environmental problem for the mineral processing industries. The removal of high concentrations of arsenic in the case of uranium milling process effluents is done by adjusting the iron to arsenic molar ratio to four (MFe{sub tot}/MAs=4) and subsequently neutralizing with slaked lime in a continuous coprecipitation (CCPTN) circuit. This paper investigates the production of arsenic-bearing phases though CCPTN from simulated waste process effluents and their long term stability at accelerated conditions. In particular, special attention is given to a two stage continuous reactor set-up. Moreover, the effect of a fraction of total iron as ferrous iron and the presence of co-ions such as nickel and aluminum on the stability of the products was investigated. (author)

  18. Ubbelohde viscometer measurement of water-based Fe3O4 magnetic fluid prepared by coprecipitation

    Science.gov (United States)

    Gu, H.; Tang, X.; Hong, R. Y.; Feng, W. G.; Xie, H. D.; Chen, D. X.; Badami, D.

    2013-12-01

    Fe3O4 nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid.

  19. Speciation analysis of 129I in seawater using coprecipitation and accelerator mass spectrometry and its applications

    DEFF Research Database (Denmark)

    Xing, Shan; Hou, Xiaolin; Aldahan, Ala

    2017-01-01

    Speciation analysis of long-lived 129I in seawater can provide useful information on the source of water masses. This paper presents an improved method for speciation analysis of 129I based on coprecipitation of iodide as AgI with Ag2SO3 and AgCl. By adding a small amount of 127I carrier, the sep...

  20. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    Science.gov (United States)

    Rau, Gregory Hudson [Castro Valley, CA

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  1. Comparison of the Penetration Depth of Conventional and Nano-Particle Calcium Hydroxide into Dentinal Tubules.

    Science.gov (United States)

    Zand, Vahid; Mokhtari, Hadi; Hasani, Aila; Jabbari, Golchin

    2017-01-01

    The aim of this in vitro study was to evaluate and compare the penetration depth of conventional (CH) and nano-particle calcium hydroxide (NCH) into dentinal tubules. Ninety human single-rooted teeth were instrumented by RaCe rotary system and after chemomechanical preparation were randomly divided in two equal groups (n=45). In the first group conventional CH and in the other NCH was used as intracanal medicament. After 2 weeks of incubation all roots were intentionally split at longitudinal axis and prepared for scanning electron microscope (SEM) observation. Three zones of each root, coronal, middle and apical were examined under SEM and the maximum penetration depth of the dressing material into dentinal tubules was recorded for each zone. Data were analyzed using the independent sample t test and the level of significance was set at 0.05. In all of the three zones, NCH group had greater penetration depth than CH (Ppenetration depth increased from the apical section to the coronal. The depth of penetration of nano-particle calcium hydroxide into the dentinal tubules was significantly higher than that of conventional calcium hydroxide. The lowest penetration depth was observed in apical zone in both groups.

  2. Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative.

    Science.gov (United States)

    Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal; Soylak, Mustafa

    2009-01-19

    A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H(2)SO(4) and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N=10) was found 0.7 microg L(-1). The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

  3. The influence of crystallised Fe3O4 on the magnetic properties of coprecipitation-derived ferrimagnetic glass-ceramics.

    Science.gov (United States)

    Bretcanu, O; Spriano, S; Verné, E; Cöisson, M; Tiberto, P; Allia, P

    2005-07-01

    Ferrimagnetic glass-ceramics are potential candidates for magnetic induction hyperthermia, which is one form of inducing deep-regional hyperthermia, by using a magnetic field. The aim of this work was to analyse the influence of the amount of crystallised magnetite on the magnetic properties of glass-ceramic samples. Thus, two different ferrimagnetic glass-ceramics with the composition of the system Na(2)O-CaO-SiO(2)-P(2)O(5)-FeO-Fe(2)O(3) were prepared by melting at 1500 degrees C for 30 min of the coprecipitation-derived starting products. The X-ray diffraction patterns show the presence of nanometric magnetite crystals in a glassy matrix after cooling from melting temperature. The estimated amount of crystallised magnetite varies between 20 and 45 wt.%, as a function of the chemical composition. The morphology of the crystals was studied by scanning electron micrography and transmission electron micrography. Glass transition temperature and thermal stability were investigated by differential thermal analysis. Magnetic hysteresis cycles were analysed using a vibrating sample magnetometer with a maximum applied field of 17 kOe, at room temperature, in quasi-static conditions. Calorimetric measurements were carried out using a magnetic induction furnace. The power losses estimated from calorimetric measurements under a magnetic field of 40 kA/m and 440 kHz are 65 W/g for the glass-ceramic with lower iron oxides content and 25 W/g for the glass-ceramic with higher iron oxide content.

  4. EFFICACY OF DIFFERENT ENDODONTIC IRRIGATION PROTOCOLS IN CALCIUM HYDROXIDE REMOVAL

    Directory of Open Access Journals (Sweden)

    Elka N. Radeva

    2016-10-01

    Full Text Available Introduction: Calcium hydroxide is widely used in the field of endodontics as a temporary root canal filling. This medicament significantly increases pH and optimizes the treatment outcome. Its total removal before final obturation is very important. Otherwise it could affect the hermetic filling and respectively the endodontic success. Aim: To evaluate the most effective irrigation protocol of calcium hydroxide removal from root canals. Materials and methods: In this study 36 single root canal teeth were observed. They were randomly divided into three groups (n=10 each group according to the technique applied for calcium hydroxide removal - manual irrigation, irrigation and Revo-S rotary instrumentation; and passive ultrasonic irrigation, and a control group (n=6 – irrigation with distilled water only. After calcium hydroxide removals following the procedures above, teeth were separated longitudinally in a buccal-lingual direction and remnants of medicaments were observed in the apical, middle and coronal part of each tooth. Then all of the specimens were observed using scanning electron microscopy and evaluated by a specified scale. The results have undergone statistical analysis. Results: In the case of calcium hydroxide in the apex and in the middle with highest average is Revo-S, followed by Ultrasonic and irrigation. In the coronal part the highest average belongs to Revo-S, irrigation and Ultrasonic. In all groups the highest average is represented by control group. Conclusion: There is not a universal technique for removal of intracanal medicaments and applying more than one protocol is required.

  5. Preparation of aluminum hydroxide by recycling of aluminum dross

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyung-Kyu; Lee, Hoo-In; Kim, Joon-Soo [Korea Institute of Geoscience and Mineral Resources, Taejeon(Korea)

    2001-10-31

    Aluminum dross should be recycled in consideration of characteristics of the dross and its reutilization after processing. In this study, aluminum dross generated in the domestic secondary aluminum industry was processed to use it as raw material for producing aluminum hydroxide. Sample dross was classified according to its size. The dross smaller than 850 {mu}m was leached with sodium hydroxide solution to extract the remaining aluminum from the dross into the solution, and then aluminum hydroxide precipitate was recovered from the leach liquor. Purity of the obtained aluminum hydroxide was above 98%, and size of the sample was in range of 3-39 {mu}m. Recovery of aluminum hydroxide precipitate was highest on condition that A/C ratio of the solution was 0.5 and pulp density was 14-16% at the leaching step. From the result, it was suggested that this process could be applicable to recycling of aluminum dross. (author). 8 refs., 5 tabs., 9 figs.

  6. Use of calcium hydroxide in deep cavities of primary teeth.

    Science.gov (United States)

    Fernandes, Jocianelle Maria; Massoni, Andreza Cristina; Ferreira, Jainara Maria; Menezes, Valdenice Aparecida

    2013-01-01

    To perform a literature review on the clinical and/or laboratory performance of the use of calcium hydroxide in deep cavities of primary teeth. Literature in professional journals and summaries of BBO, LILACS, and MEDLINE databases (2000 to 2010) linked to the Virtual Health Library and PUBMED were searched. The search strategies used included the following descriptors: "dental caries" and "dental cavity lining" and "primary tooth", "dental cavity lining" and "primary tooth" and "calcium hydroxide", "dental caries" and "dental cavity lining" and "primary tooth" and "calcium hydroxide". The abstracts were selected according to the following inclusion criteria: published between 2000 and 2010, English language, trial and/or laboratory studies or literature review, regarding the use of calcium hydroxide in deep cavities of primary teeth. The abstracts analysis was performed by two reviewers separately. Potentially relevant studies available in full were analyzed based on criteria for quality assessment and displayed on an evidence-based table. After reading the abstracts (N = 39), six were selected as a basis for developing the study. Analysis suggests that calcium hydroxide is an interesting alternative in the control of caries lesions of primary teeth with the possibility of significantly increasing the success of indirect pulp capping; however, it should not be considered a determining factor in the success of a restorative procedure.

  7. The citotoxicity of calcium hydroxide intracanal dressing by MTT assay

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2007-12-01

    Full Text Available Calcium hydroxide had been used as the intracanal dressing in endodontic treatment due to its high alkaline and high antimicrobial capacity. It also be able to dissolve the necrotic tissue, prevent the root resorbtion and regenerate a new hard tissue. The aim of this study is to identify the concentration of calcium hydroxide that has the lowest citotoxicity. There are 5 groups, each group had 8 samples with different concentration of calcium hydroxide. Group I: 50%, Group II: 55%, Group III: 60%, Group IV: 65% and Group V: 70%. The citotoxicity test by using enzymatic assay of MTT [3-(4.5- dimethylthiazol-2yl ]-2.5 diphenyl tetrazolium bromide, against fibroblast cell (BHK-21. The result of susceptibility test was showed by the citotoxicity detection of the survive cell of fibroblast that was measured spectrophotometrically using 595 nm beam. The data was analyzed using One-Way ANOVA test with significant difference α = 0.05 and subsequently LSD test. The result showed that in concentration 50%, 55%, 60%, 65%, and 70% calcium hydroxide had low toxicity, but calcium hydroxide 60%, had the lowest toxicity.

  8. Photo-oxidation of EPDM/layered double hydroxides composites: Influence of layered hydroxides and stabilizers

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The photo-oxidation of ethylene propylene diene monomer (EPDM/ layered double hydroxide (LDH composites as well as EPDM/LDH with stabilizers is studied under accelerated UV irradiation (λ≥290 nm at 60°C for different time intervals. The development of functional groups during oxidation was monitored by FT-IR spectroscopy. The photodegradation of the pristine polymer and composites take place and the increase in hydroxyl and carbonyl groups with irradiation times, was estimated. EPDM filled LDH showed higher degradation rate than pristine EPDM, while in acidic medium EPDM/LDH showed almost equal degradation as in isolated conditions. These results show the advantages of LDHs as a filler as well as an acid killer. The effect of stabilizers is very less because of their concentration in comparison of LDH.

  9. Comparison of nanomilling and coprecipitation on the enhancement of in vitro dissolution rate of poorly water-soluble model drug aripiprazole.

    Science.gov (United States)

    Abdelbary, Aly A; Li, Xiaoling; El-Nabarawi, Mohamed; Elassasy, Abdelhalim; Jasti, Bhaskara

    2014-06-01

    The aim of this study was to evaluate the effect of coprecipitation and nanomilling on the crystallinity of a model drug, aripiprazole and evaluate the in vitro dissolution rate (IDR). Aripiprazole compositions were prepared by physical mixing, coprecipitation and nanomilling using hydroxypropylcellulose (HPC), polyvinylpyrrolidone (PVP) K17 and pluronic F127. The particle size, solubility, IDR and drug crystallinity were studied. Aripiprazole pluronic compositions were compressed into tablets and dissolution rate was evaluated. The particle size of nanomilled compositions was significantly smaller than that of the other compositions. The saturation solubility of aripiprazole from nanoparticle (NP) and coprecipitate (CP) from PVP and Pluronic was comparable, however, NP of HPC containing composition showed higher solubility when compared to its CP compositions. The crystallinity of aripiprazole decreased from physical mixtures to coprecipitates and further in NPs. The increased aripiprazole IDR was due to decreased crystallinity from coprecipitate compositions and disruption of crystallinity from nanomilled compositions. Aripiprazole tablets prepared from nanomilled powder dissolved >75% within 10 min compared with 17% and 20% for tablets prepared from physical mixture and coprecipitate powders, respectively. The increase in IDR due to nanomilling was more significant than coprecipitation and NPs retained the IDR after compression into tablets.

  10. Magnesium hydroxide nanoparticles synthesized in water-in-oil microemulsions.

    Science.gov (United States)

    Wu, Jianming; Yan, Hong; Zhang, Xuehu; Wei, Liqiao; Liu, Xuguang; Xu, Bingshe

    2008-08-01

    Well-dispersed magnesium hydroxide nanoplatelets were synthesized by a simple water-in-oil (w/o) microemulsion process, blowing gaseous ammonia (NH(3)) into microemulsion zones solubilized by magnesium chloride solution (MgCl(2)). Typical quaternary microemulsions of Triton X-100/cyclohexane/n-hexanol/water were used as space-confining microreactors for the nucleation, growth, and crystallization of magnesium hydroxide nanoparticles. The obtained magnesium hydroxide was characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission election microscopy (HRTEM), X-ray powder diffraction (XRD), laser light scattering, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC). The mole ratio of water to surfactant (omega(0)) played an important role in the sizes of micelles and nanoparticles, increasing with the increase of omega(0). The compatibility and dispersibility of nanoparticles obtained from reverse micelles were improved in the organic phase.

  11. Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles.

    Science.gov (United States)

    Pidchenko, Ivan; Kvashnina, Kristina O; Yokosawa, Tadahiro; Finck, Nicolas; Bahl, Sebastian; Schild, Dieter; Polly, Robert; Bohnert, Elke; Rossberg, André; Göttlicher, Jörg; Dardenne, Kathy; Rothe, Jörg; Schäfer, Thorsten; Geckeis, Horst; Vitova, Tonya

    2017-02-21

    Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M4 high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U(IV), U(V), and U(VI) existing simultaneously in the same sample. The contributions of the three different uranium redox states are quantified with the iterative transformation factor analysis (ITFA) method. U L3 XAS and transmission electron microscopy (TEM) reveal that initially sorbed U(VI) species recrystallize to nonstoichiometric UO2+x nanoparticles within 147 days when stored under anoxic conditions. These U(IV) species oxidize again when exposed to air. U M4 HR-XANES data demonstrate strong contribution of U(V) at day 10 and that U(V) remains stable over 142 days under ambient conditions as shown for magnetite nanoparticles containing 1000 ppm U. U L3 XAS indicates that this U(V) species is protected from oxidation likely incorporated into octahedral magnetite sites. XAS results are supported by density functional theory (DFT) calculations. Further characterization of the samples include powder X-ray diffraction (pXRD), scanning electron microscopy (SEM) and Fe 2p X-ray photoelectron spectroscopy (XPS).

  12. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties.

    Science.gov (United States)

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T; Gallagher, William M; Kiely, Patrick; Redmond, Gareth

    2016-07-29

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

  13. Synthesis of mono and multidomain YIG particles by chemical coprecipitation or ceramic procedure

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Garcia, L. [Departamento de Materiales Nanoestructurados, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Suarez, M., E-mail: m.suarez@cinn.e [Departamento de Materiales Nanoestructurados, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Menendez, J.L. [Departamento de Materiales Nanoestructurados, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo -UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2010-04-09

    Yttrium iron garnet powders have been synthesized by chemical coprecipitation using two different precursors, nitrates and chlorides, and by an oxides mixture route. It is shown that depending on the precursors and synthesis conditions used pure yttrium iron garnet powders can be obtained with a mono or multidomain magnetic behaviour. The yttrium iron garnet crystalline structure, as studied by Raman spectroscopy, was already formed after calcination at temperatures as low as 800 {sup o}C when the nitrate precursors were used. However, calcination temperatures of up to 1100 {sup o}C were required to obtain yttrium iron garnet powders when the precursors were chlorides or when the oxides mixture route was chosen. The saturation magnetization of the powders correlates well with the structural characterization: when nitrate precursors were used, the saturation magnetization was already close to the bulk value, 26.8 emu/cm{sup 3}, after calcination at 800 {sup o}C. However, the saturation magnetization of the powders obtained by the chlorides and oxides mixture routes was close to zero up to calcination temperatures of 1100 {sup o}C. Finally, both the chlorides and the oxides mixture routes yield multidomain micron sized yttrium iron garnet powders, whereas the nitrates route led to monodomain submicron sized powders.

  14. Effect of Calcination at Synthesis of Mg-Al Hydrotalcite Using co-Precipitation Method

    Directory of Open Access Journals (Sweden)

    Niar Kurnia Julianti

    2017-01-01

    Full Text Available The use of hydrotalcite in catalysis has wide attention in academic research and industrial parties. Based on its utilization, hydrotalcite can be active catalyst or support. This research is focused on the investigation of characteristic like spesific surface area of Mg-Al hydrotalcite which is prepared with different temperature of calcination. Synthesis of Mg-Al hydrotalcites with Mg/Al molar ratio 3:1 were prepared by co-precipitation method. Mg(NO33.6H2O and Al(NO33.9H2O as precursors of Mg-Al hydrotalcite. Na2CO3 was used as precipitant agent and NaOH was used as buffer solution. The solution was mixed and aging for 5 hours at 650oC. The dried precipitate was calcined at 2500oC, 3500oC, 4500oC, 5500oC and 6500oC. The characterization of functional group was determined by Fourier Transform Infra Red (FT-IR. The Identical peaks diffractogram were analyzed by X-Ray Diffraction (XRD. The spesific surface area was determined by adsorption-desorption of nitrogen. The largest surface area that obtained from the calcination temperature of 650oC is 156.252 m2/g.

  15. Cerium and neodymium co-precipitation in molten chloride by wet argon sparging

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, J.F. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Renard, C., E-mail: catherine.renard@ensc-lille.fr [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Laplace, A. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Lacquement, J. [CEA, Nuclear Energy Division, DTEC/DIR, F-30207 Bagnols sur Ceze (France); Abraham, F. [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2013-01-15

    Co-precipitations of cerium (III) and neodymium (III) at 10 wt.% in LiCl-CaCl{sub 2} (30-70 mol%) molten salt at 705 Degree-Sign C have been achieved using an original way of precipitation, wet argon sparging. Several CeCl{sub 3}/NdCl{sub 3} ratios have been studied, and the isolated powders were analyzed using different characterization methods including XRD investigations. The lanthanides precipitation yields have been determined around 99.9% using ICP-AES analysis. XRD demonstrated that the precipitates mainly contained mixed oxychloride (Ce{sub 1-x}Nd{sub x})OCl and a small amount of the mixed oxide Ce{sub 1-y}Nd{sub y}O{sub 2-0.5y}. Calcination of these precipitates has resulted in the cerium and neodymium mixed oxides. For the precipitation with a Ce/Nd = 50/50 ratio, an hydroxychloride Ln(OH){sub 2}Cl and the oxychloride Ce{sup IV}(Nd{sub 0.7}Ce{sub 0.3}){sup III}O{sub 3}Cl have been identified as unexpected intermediate compounds.

  16. Heating ability and hemolysis test of magnetite nanoparticles obtained by a simple co-precipitation method

    Directory of Open Access Journals (Sweden)

    B.I. Macías-Martínez

    2016-08-01

    Full Text Available The present paper reports the heating ability and hemolysis test of magnetite nanoparticles (MNPs for biomedical applications, obtained by a novel and easy co-precipitation method, in which it is not necessary the use of controlled atmospheres and high stirring rates. Different molar proportions of FeCl2:FeCl3 (2:1 and 3:2 respectively were used and the obtained MNPs were analyzed by X-ray diffraction, vibrating sample magnetometry and transmission electron microscopy. The heating ability was evaluated under a magnetic field using a solid state induction heating equipment at two different frequencies (362 and 200 kHz. Additionally, a hemolysis test was performed according to the ASTM method. The obtained ferrites showed a particle size in the range of 8–12 nm and superparamagnetic behavior. The MNPs increased the temperature up to 43.1 °C in 5 min under a low magnetic field and showed non hemolytic effect up to 3 mg/ml. The MNPs obtained are highly potential materials for hyperthermia cancer treatment.

  17. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties

    Science.gov (United States)

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T.; Gallagher, William M.; Kiely, Patrick; Redmond, Gareth

    2016-07-01

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

  18. Fabrication of Tb3Al5O12 transparent ceramics using co-precipitated nanopowders

    Science.gov (United States)

    Dai, Jiawei; Pan, Yubai; Wang, Wei; Luo, Wei; Xie, Tengfei; Kou, Huamin; Li, Jiang

    2017-11-01

    Terbium aluminum garnet (TAG) precursor was synthesized by a co-precipitation method from a mixed solution of terbium and aluminum nitrates using ammonium hydrogen carbonate (AHC) as the precipitant. The powders calcined at different temperatures were investigated by XRD, FTIR and FESEM in order to choose the optimal calcination temperature. Fine and low-agglomerated TAG powders with average particle size of 88 nm were obtained by calcining the precursor at 1100 °C for 4 h. Using this powder as starting material, TAG transparent ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) sintering. For the sample pre-sintered at 1700 °C for 20 h with HIP post-treated at 1700 °C for 3 h, the average grain size is about 3.9 μm and the in-line transmittance is beyond 55% in the region of 500-1600 nm, reaching a maximum transmittance of 64.2% at the wavelength of 1450 nm. The Verdet constant at 633 nm is measured to be -178.9 rad T-1 m-1, which is 33% larger than that of the commercial TGG single crystal (-134 rad T-1 m-1).

  19. Co-precipitation synthesis of lutetium aluminum garnet (LuAG) powders: The influence of ethanol

    Science.gov (United States)

    Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Zhang, Pande; Mao, Xiaojian; Zhang, Long

    2017-09-01

    Aluminum Garnet (LuAG) precursors were co-precipitated by using ethanol-water as the precipitant solvent. The effect of different volume ratios of ethanol to water (R) on the preparation of pure-phase LuAG powders has been mainly studied. The evolution of phase, composition and micro-structure of the as-synthesized LuAG powders were characterized by TG/DTA, FTIR, XRD, BET, and SEM. The BET-equivalent diameter of LuAG nano particles increased with R. The ethanol-water solvent does not change the main composition of the LuAG precursors, but has great influence on the morphology of the final LuAG nano particles. Uniformly dispersed LuAG powders calcined at 1200 °C for 3 h with a particle size of approximately 120 nm were obtained by using ethanol-water solvent with proper R = 1. The mechanism of ethanol in the preparation process was discussed.

  20. Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avvaru Praveen; Kumar, B. Prem; Kumar, A.B.V. Kiran; Huy, Bui The [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Facile synthesis of palladium nanoparticles on alumina surface. Black-Right-Pointing-Pointer The surface morphology and properties of the nanocrystalline powders were characterized. Black-Right-Pointing-Pointer The catalytic activities of palladium nanoparticles were investigated. - Abstract: The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600 Degree-Sign C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG-DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd{sup 0} while in the atmospheric air indicates the existence pure Pd{sup 0} along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

  1. Biomimetic Coprecipitation of Silk Fibrin and Calcium Phosphate: Influence of Selenite Ions.

    Science.gov (United States)

    Wang, Yanhua; Hao, Hang; Zhang, Shengmin

    2017-08-01

    Large bone defect creates an urgent need for osteogenic biomaterials. However, bone nonunion and infection are choke points in the therapy of this disease. How to recruit the mesenchymal stem cells to defect sites and increase the cell viability are the critical processes. One effective method was the fabrication of biomimetic silk fibrin/selenium-doped hydroxyapatite (SF/HASe) material, which could create a niche for cell proliferation. So, the aim of the present study was to seek a facile route to prepare this biocomposites and investigate the osteogenic capability. Results showed that the biomimetic coprecipitation was a successful route to prepare SF/HASe biocomposites, which presented higher cell proliferation activity and better modulation of the selenite release during incubation in biological medium. Besides, the biocomposites exhibited weird and porous pot morphology. Such features could provide large surface area for the cells and proteins to attach. Silk fibrin, adhered onto the surface of hydroxyapatite (HA) crystals, plays a crucial impact on the release profile of selenite ions. The release behavior of the selenite ions exhibited stably slow release fashion. Therefore, it is feasible to employ SF/HASe biocomposites to repair bone defects and apply into the therapy of osteosarcoma postoperatively.

  2. Synthesis of Magnetite Nano-Particles by Reverse CO-PRECIPITATION

    Science.gov (United States)

    Kazemzadeh, Hamid; Ataie, Abolghasem; Rashchi, Fereshteh

    Magnetite nano-particles have been synthesized by reverse co-precipitation method using iron salts in alkaline medium in the presence of diethylene glycol (DEG). Effect of DEG on the nano-particle characteristics was investigated by XRD, FE-SEM, FTIR and VSM techniques. From XRD results it was concluded that in the presence of DEG the composition of magnetite did not change, however the mean crystallite size reduced from 10 to 5 nm. SEM micrograph showed that DEG decreased the size of spherical magnetite nano-particles from 50 to 20 nm. Fourier transform infrared spectra (FTIR) indicated that the DEG molecules chemisorbed on the magnetite nano-particles. Under the given experimental conditions, the rate of crystallization and growth reduced, which is probably due to the capping of DEG to the magnetite nano-particles. The agglomeration was also decreased which is attributed to the coating of magnetite nano-particles by DEG which prevents the formation of hydrogen bonding between magnetite and water molecules.

  3. Structural Characterization of Polymer-Clay Nanocomposites Prepared by Co-Precipitation Using EPR Techniques

    Directory of Open Access Journals (Sweden)

    Udo Kielmann

    2014-02-01

    Full Text Available Polymer-clay nanocomposites (PCNCs containing either a rubber or an acrylate polymer were prepared by drying or co-precipitating polymer latex and nanolayered clay (synthetic and natural suspensions. The interface between the polymer and the clay nanoparticles was studied by electron paramagnetic resonance (EPR techniques by selectively addressing spin probes either to the surfactant layer (labeled stearic acid or the clay surface (labeled catamine. Continuous-wave (CW EPR studies of the surfactant dynamics allow to define a transition temperature T* which was tentatively assigned to the order-disorder transition of the surfactant layer. CW EPR studies of PCNC showed that completely exfoliated nanoparticles coexist with agglomerates. HYSCORE spectroscopy in PCNCs showed couplings within the probe −assigned with DFT computations− and couplings with nuclei of the environment, 1H and 23Na for the surfactant layer probe, and 29Si, 7Li, 19F and 23Na for the clay surface probe. Analysis of these couplings indicates that the integrity of the surfactant layer is conserved and that there are sizeable ionic regions containing sodium ions directly beyond the surfactant layer. Simulations of the very weak couplings demonstrated that the HYSCORE spectra are sensitive to the composition of the clay and whether or not clay platelets stack.

  4. Characterization of nanosized spinel ferrite powders synthesized by coprecipitation and autocombustion method

    Energy Technology Data Exchange (ETDEWEB)

    Aphesteguy, Juan Carlos, E-mail: caphestegu@fi.uba.a [LAFMACEL, Fac. de Ingenieria, UBA, Paseo Colon 850, C1063EHA Buenos Aires (Argentina); Jacobo, Silvia E., E-mail: sjacobo@fi.uba.a [LAFMACEL, Fac. de Ingenieria, UBA, Paseo Colon 850, C1063EHA Buenos Aires (Argentina); Schegoleva, N.N., E-mail: vlasova@imp.uran.r [Ural State University, Dept. Magnetism and Magnetic Nanomaterials, Lenin Ave, 51, 620083 Ekaterinburg (Russian Federation); Institute of Metal Physics UD RAS, Kovalevskaya , 18, 620041, Ekaterinburg (Russian Federation); Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.e [Universidad del Pais Vasco UPV-EHU, Dept. Electricidad y Electronica, 48940 Leioa (Spain)

    2010-04-16

    Magnetic nanoparticles of magnetite (Fe{sub 3}O{sub 4}) and NiCuZn-doped magnetite (Ni{sub 0.35}Cu{sub 0.15}Zn{sub 0.5}Fe{sub 2}O{sub 4}) were prepared by coprecipitation and by sol-gel combustion methods accordingly. The average size, d, of magnetite nanoparticles (d = 12 nm) and the NiCuZn ferrite nanoparticles ignited at about 250 {sup o}C (d = 30 nm) was estimated from X-ray diffraction patterns. The Moessbauer spectroscopy revealed the existence of the paramagnetic doublet in both samples. For magnetite, coercive force of about 400 Oe was found at 5 K. Likewise, the coercive field of the NiCuZn-doped magnetite nanoparticles decreases with Fe{sup 2+} substitution at low temperature (260 Oe). This behavior can be explained taking into account the fact that the magnetocrystalline anisotropy constant of Fe{sub 3}O{sub 4} is higher than that of NiCuZn ferrite.

  5. Preparation, characterization and thermodynamic properties of Zr-containing Cl-bearing layered double hydroxides (LDHs)

    Energy Technology Data Exchange (ETDEWEB)

    Rozov, Konstantin; Curtius, Hilde; Bosbach, Dirk [Forschungszentrum Juelich GmbH (Germany). Inst. of Energy and Climate Research (IEK-6) Nuclear Waste Management and Reactor Safety

    2015-07-01

    Zr-containing layered double hydroxides (LDHs) with variable xZr{sub solid} = Zr/(Zr + Al) mole fractions were synthesized by a co-precipitation method at ambient conditions. The chemical compositions of samples and corresponding aqueous solutions after syntheses were analyzed by ICP-OES, EDX (Mg, Al, Zr) and ion chromatography (Cl{sup -}). Results of PXRD technique demonstrated that solids with 0 ≤ x Zr{sub solid} ≤ 0.5 show only X-ray reflexes typical for pure LDH compositions, while products of syntheses with xZr{sub solid} > 0.5 display additional patterns attributed to brucite. ICP-OES and EDX techniques shown that in pure Zr-containing LDHs the Mg/(Al + Zr) ratio is reducing with increase of xZr{sub solid} and the stoichiometry of brucite-like layers corresponds to [Mg{sub 3-2x}Al{sub 1-x}Zr{sub x}]. This fact may indicate that the incorporation of 1 Zr-containing specie results in the removal of 1 Al- and 2 Mg-containing species from the pure Mg-Al-composition. Such mechanism may be confirmed by the observation that measured a{sub 0} = b{sub 0} distances are generally consistent with theoretical estimates obtained from [Mg{sub 3-2x}Al{sub 1-x}Zr{sub x}]-stoichiometry. The presence of predominant Mg{sup 2+}, Al(OH){sub 4}{sup -} and Zr(OH){sub 5}{sup -} complexes in aqueous solutions after syntheses was established in thermodynamic calculations by applying GEMS-Selektor v.3. code and, therefore, the reaction: Mg{sub 3}Al{sub 1}(OH){sub 8}Cl{sub 1} + Zr(OH){sub 5}{sup -} = Mg{sub 1}Zr{sub 1}(OH){sub 5}Cl{sub 1} + Al(OH){sub 4}{sup -} + 2Mg{sup 2+} + 4OH{sup -} can describe a mechanism of Zr-substitution. Estimates of the molar Gibbs free energies of Zr-containing LDHs with 0 ≤ = xZr{sub solid} ≤ 0.5 show that the incorporation of Zr into the LDH increasing significantly their aqueous solubility. Thus, it is not possible to neglect that Zr can be partly localized as Zr(OH){sub 5}{sup -}-ligands in the interlayer space of the LDH structure.

  6. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis

    OpenAIRE

    Muhammad Faizan Shareef; Muhammad Arslan; Naseem Iqbal; Nisar Ahmad; Tayyaba Noor

    2017-01-01

    This paper presents the effect of a synthesis method for cobalt catalyst supported on hydrotalcite material for Fischer-Tropsch synthesis. The hydrotalcite supported cobalt (HT-Co) catalysts were synthesized by co-precipitation and hydrothermal method. The prepared catalysts were characterized by using various techniques like BET (Brunauer–Emmett–Teller), SEM (Scanning Electron Microscopy), TGA (Thermal Gravimetric Analysis), XRD (X-ray diffraction spectroscopy), and FTIR (Fourier Transform I...

  7. DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    OGDEN DM; KIRCH NW

    2007-10-31

    This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.

  8. Interaction of pristine hydrotalcite-like layered double hydroxides ...

    Indian Academy of Sciences (India)

    Metal oxides in general have surface acidic sites, but for exceptional circumstances, are not expected to mineralize CO2. Given their intrinsic basicity and an expandable interlayer gallery, the hydrotalcite-like layered double hydroxides (LDHs) are expected to be superior candidate materials for CO2 mineralization.

  9. The digestibility and intake of sodium hydroxide or local alkali ...

    African Journals Online (AJOL)

    The digestibility and intake of sodium hydroxide or local alkali-treated straw by goats. JA Ibeawuchi, AM Tula. Abstract. No Abstract. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Article Metrics. Metrics Loading ... Metrics powered by PLOS ALM.

  10. Interaction of pristine hydrotalcite-like layered double hydroxides ...

    Indian Academy of Sciences (India)

    Abstract. Metal oxides in general have surface acidic sites, but for exceptional circumstances, are not expected to mineralize CO2. Given their intrinsic basicity and an expandable interlayer gallery, the hydrotalcite-like layered double hydroxides (LDHs) are expected to be superior candidate materials for CO2 mineralization.

  11. Antimicrobial effectiveness of different preparations of calcium hydroxide

    Directory of Open Access Journals (Sweden)

    Anshul Gangwar

    2011-01-01

    Results and Conclusions: It was seen that calcium hydroxide and CMCP combination showed the maximum zone of inhibition, and maximum inhibitory effect was seen at 24 hours. The bacteria most susceptible was found to be S. aureus and the least susceptible was E. faecalis. Further clinical studies are required to substantiate these results.

  12. A comparison between sodium hydroxide treated and untreated bird ...

    African Journals Online (AJOL)

    A digestion and a growth trial was conducted, (i)to determine the effect of sodium hydroxide (NaOH)treatment of bird-proof sorghum (BPS) on nitrogen and energy digestibility, and (ii)to compare treated with untreated BPS as grain components in a pig growth diet. The polyphenol content of BPS was reduced from 1,33 to 0 ...

  13. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal ...

  14. Oxidative leaching of chromium from layered double hydroxides ...

    Indian Academy of Sciences (India)

    The layered double hydroxide (LDH) of Zn with Cr on treatment with a hypochlorite solution releases chromate ions as a result of oxidative leaching by a dissolution–reprecipitation mechanism. The residue is found to be -Zn(OH)2. The LDH of Mg with Cr on the other hand is resistant to oxidative leaching. In contrast, a ...

  15. Page 1 Solubility of Rare Earth Hydroxides in Aqueous Sodium ...

    Indian Academy of Sciences (India)

    Solubility of Rare Earth Hydroxides in Aqueous Sodium Potassium Tartrate 317 undissolved after treatment with Rochelle Salt solution. The quantity measured was the weight of oxide in the filtrate. This was done by igniting the precipitated oxalate and also by titrating its sulphuric acid solution against standard potassium ...

  16. Praseodymium(III sulfate hydroxide, Pr(SO4(OH

    Directory of Open Access Journals (Sweden)

    Xiao-Juan Wang

    2011-02-01

    Full Text Available The title compound, Pr(SO4(OH, obtained under hydrothermal conditions, consists of PrIII ions coordinated by nine O atoms from six sulfate groups and three hydroxide anions. The bridging mode of the O atoms results in the formation of a three-dimensional framework, stabilized by two O—H...O hydrogen-bonding interactions.

  17. Line broadening in the PXRD patterns of layered hydroxides: The ...

    Indian Academy of Sciences (India)

    Unknown

    reflections and turbostratic disorder broadens the 0k´ reflections. The line broadening caused by struc- tural disorder has to be discounted before estimates of particle size are made by applying the Scherrer formula. Keywords. Layered double hydroxides; pyroaurite; structural disorder; stacking faults; turbostraticity;.

  18. Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

    Science.gov (United States)

    Shelton, Timothy L.; Bensema, Bronwyn L.; Brune, Nicholas K.; Wong, Christopher; Yeh, Max; Osterloh, Frank E.

    2017-01-01

    Hematite has attracted considerable interest as a photoanode material for water oxidation under visible illumination. Here, we explore the limits of photocatalytic water oxidation activity with iron (III) oxide hydroxide nanocrystals and NaIO4 as a sacrificial electron acceptor (E=1.63 V NHE at pH=0.5). The sol was prepared by hydrolysis of FeCl3 in boiling 0.002-M HCl solution and confirmed to mainly consist of ß-FeO(OH) (akaganéite) particles with 5 to 15 nm diameter. From a 0.01 M aqueous NaIO4 solution, the sol evolves between 4.5 and 35.2 μmol O2 h-1, depending on pH, light intensity (>400 nm, 290 to 700 mW cm-2), ß-FeO(OH), and NaIO4 concentration. The activity increases with pH, and depends linearly on light intensity and photocatalyst amount, and it varies with sacrificial electron donor concentration. Under optimized conditions, the apparent quantum efficiency is 0.19% (at 400 nm and 460 mW cm-2), and the turnover number is 2.58 based on total ß-FeO(OH). Overall, the efficiency of the ß-FeO(OH)/NaIO4 photocatalytic system is limited by electron hole recombination and by particle aggregation over longer irradiation times (24 h). Lastly, surface photovoltage measurements on ß-FeO(OH) films on fluorine doped tin oxide substrate confirm a 2.15 eV effective band gap for the material.

  19. Sorption and coprecipitation of trace concentrations of thorium with various minerals under conditions simulating an acid uranium mill effluent environment

    Science.gov (United States)

    Landa, Edward R.; Le, Anh H.; Luck, Rudy L.; Yeich, Philip J.

    1995-01-01

    Sorption of thorium by pre-existing crystals of anglesite (PbSO4), apatite (Ca5(PO4)3(HO)), barite (BaSO4), bentonite (Na0.7Al3.3Mg0.7Si8O20(OH)4), celestite (SrSO4), fluorite (CaF2), galena (PbS), gypsum (CaSO4·2H2O), hematite (Fe2O3), jarosite (KFe3(SO4)2(OH)6), kaolinite (Al2O3·2SiO2·2H2O), quartz (SiO2) and sodium feldspar (NaAlSi3O8) was studied under conditions that simulate an acidic uranium mill effluent environment. Up to 100% removal of trace quantitiees of thorim (approx. 1.00 ppm in 0.01 N H2SO4) from solution occurred within 3 h with fluorite and within 48 h in the case of bentonite. Quartz, jarosite, hematite, sodium feldspar, gypsum and galena removed less than 15% of the thorium from solution. In the coprecipitation studies, barite, anglesite, gypsum and celestite were formed in the presence of thorium (approx. 1.00 ppm). Approximately all of the thorium present in solution coprecipitated with barite and celestite; 95% coprecipitated with anglesite and less than 5% with gypsum under similar conditions. When jarosite was precipitated in the presence of thorium, a significant amount of thorium (78%) was incorporated in the precipitate.

  20. Sample pretreatment in the determination of specific alpha emitters in drinking water using [Ba+Fe]-coprecipitation method.

    Science.gov (United States)

    Suarez-Navarro, J A; Pujol, Ll; Suarez-Navarro, M J

    2015-02-01

    The [Ba+Fe]-coprecipitation method is applied to measure gross alpha activity for radiological examination of drinking water in the laboratory. This method collects all the alpha-emitting radionuclides of interest (natural alpha emitters and transuranium elements) in a precipitate on a filter. This paper describes an investigation of sample pretreatment of the precipitate collected by the [Ba+Fe]-coprecipitation method for gross alpha activity determination. The aim of this preliminary work is to be a starting point to develop simple and rapid radiochemical procedures for specific alpha emitters (polonium, radium, thorium, uranium, plutonium and americium), in contrast to the sophisticated, expensive and time-consuming alpha spectrometry method. The sample pretreatment aspects considered include quantitative [Ba+Fe]-coprecipitation, two methods for precipitate treatment (leaching and complete destruction of the filter), and the determination of the alpha-emitting proportions present in the barium sulfate precipitate and acid solution obtained after precipitate treatment. Furthermore, a radiochemical procedure for (226)Ra determination was performed and finally, the sample pretreatment proposed in this work was summarized. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Application of Ozone Related Processes to Mineralize Tetramethyl Ammonium Hydroxide in Aqueous Solution

    OpenAIRE

    Chyow-San Chiou; Kai-Jen Chuang; Ya-Fen Lin; Hua-Wei Chen; Chih-Ming Ma

    2013-01-01

    Tetramethyl ammonium hydroxide (TMAH) is an anisotropic etchant used in the wet etching process of the semiconductor industry and is hard to degrade by biotreatments when it exists in wastewater. This study evaluated the performance of a system combined with ultraviolet, magnetic catalyst (SiO2/Fe3O4) and O3, denoted as UV/O3, to TMAH in an aqueous solution. The mineralization efficiency of TMAH under various conditions follows the sequence: UV/O3 > UV/H2O2/O3 > H2O2/SiO2/Fe3O4/O3 > H2O2/O3 >...

  2. Development of polymer nanocomposites based on layered double hydroxides

    Directory of Open Access Journals (Sweden)

    Sipusic, J.

    2009-05-01

    Full Text Available Polymeric nanocomposites are commonly considered as systems composed of a polymeric matrix and - usually inorganic - filler. The types of nanofillers are indicated in Fig. 1. Beside wellknown layered silicate fillers, recent attention is attracted to layered double hydroxide fillers (LDH, mainly of synthetic origin. The structure of LDH is based on brucite, or magnesium hydroxide, Mg(OH2 and is illustrated in Fig. 2. The modification of LDHs is commonly done by organic anions, to increase the original interlayer distance and to improve the organophilicity of the filler, keeping in mind their final application as fillers for, usually hydrophobic, polymer matrices. We have used the modified rehydration procedure for preparing organically modified LDH. The stoichiometric quantities of Ca33Al2O6, CaO and benzoic (B (or undecenoic (U acid were mixed with water and some acetone. After long and vigorous shaking, the precipitated fillers were washed, dried and characterized. X-ray diffraction method (XRD has shown the increase of the original interlayer distance for unmodified LDH (OH–-saturated of 0.76 nm to the 1.6 nm in LDH-B or LDH-U fillers (Fig. 3. Infrared spectroscopy method (FTIR has confirmed the incorporation of benzoic anion within the filler layers (Fig. 4. For the preparation of LDH-B and LDH-U composites with polystyrene (PS, poly(methyl methacrylate (PMMA and copolymer (SMMA matrices, a two-step in situ bulk radical polymerization was selected (Table 1 for recipes, azobisisobutyronitrile as initiator, using conventional stirred tank reactor in the first step, and heated mold with the movable wall (Fig. 6 in the second step of polymerization. All the prepared composites with LDH-U fillers were macroscopically phase-separated, as was the PMMA/LDH-B composite.PS/LDH-B and SMMA/LDH-B samples were found to be transparent and were further examined for deduction of their structure (Fig. 5 and thermal properties. FTIR measurements showed that

  3. Diode Laser and Calcium Hydroxide for Elimination of Enterococcus Faecalis in Root Canal

    Directory of Open Access Journals (Sweden)

    Neda Naghavi

    2014-06-01

    Full Text Available Introduction: The ultimate goal of endodontic treatment is to eliminate the bacterial infection in the root canal system. While mechanical debridement combined with chemical irrigation removes the bulk of microorganisms, residual bacteria are readily detectable in approximately one-half of teeth just prior to obturation. Laser light can be used to destroy bacteria. This in vitro study was performed to evaluate the effect of diode laser and calcium hydroxide on mono-infected dental canals.Methods: Fifty five single-rooted human premolars were prepared and contaminated with Enterococcus faecalis. After three weeks of incubation, the samples were divided into three experimental groups (n = 15 and two control groups (n = 5. In the first and second groups, the teeth were rinsed for 5 min with either sterile saline or 5.25% NaOCl and irradiated with a 810-nm diode laser at 1.5 W output for 5 × 4s. In the third group, the teeth were rinsed with 5.25% NaOCl and then Ca(OH2 paste was inserted in the canals for 1 week. Intracanal bacterial sampling was done and the samples were plated to determine the CFU count. Results: 5.25% NaOCl plus laser was as effective as calcium hydroxide and significantly more effective than sterile saline (P>0.05 in elimination of E. faecalis. Complete elimination of E. faecalis was seen only for the one week calcium hydroxide treatment. Conclusion: Combination therapy with NaOCl irrigation and diode laser irradiation can be recommended as an effective treatment option for elimination of E. faecalis from the root canal system.

  4. Physicochemical fabrication of antibacterial calcium phosphate submicrospheres with dispersed silver nanoparticles via coprecipitation and photoreduction under laser irradiation.

    Science.gov (United States)

    Nakamura, Maki; Oyane, Ayako; Shimizu, Yoshiki; Miyata, Saori; Saeki, Ayumi; Miyaji, Hirofumi

    2016-12-01

    We achieved rapid, surfactant-free, and one-pot fabrication of antibacterial calcium phosphate (CaP) submicrospheres containing silver nanoparticles by combining physical laser and chemical coprecipitation processes. In this physicochemical process, weak pulsed laser irradiation (20min) was performed on a labile CaP reaction mixture supplemented with silver ions as a light-absorbing agent. The silver content in the submicrospheres was controlled for a wide range (Ag/P elemental ratio varied from 0.60 to 62.0) by tuning the initial concentration of silver ions (from 5 to 20mM) in the CaP reaction mixture. At the silver concentration of 5mM, we obtained unique nanocomposite particles: CaP submicrospheres (average diameter of approximately 500nm) containing metallic silver nanoparticles dispersed throughout, as a result of CaP and silver coprecipitation with simultaneous photoreduction of silver ions and spheroidization of the coprecipitates. These CaP submicrospheres containing silver nanoparticles (ca. 0.3mg silver per 1mg submicrospheres) exhibited antibacterial activity against major pathogenic oral bacteria, i.e., Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. Moreover, the CaP submicrospheres dissolved and neutralized the acidic environment generated by Streptococcus mutans, demonstrating their potential as acid-neutralizing and remineralizing agents. The present process and resulting antibacterial CaP-based submicrospheres are expected to be useful in dental healthcare and infection control. Nano- and microsized spheres of calcium phosphate (CaP) containing silver nanoparticles have great potential in dental applications. Conventional fabrication processes were time-consuming or weak regarding the size/shape control of the spheres. In this study, we achieved a simple (one-pot), rapid (20-min irradiation), and surfactant-free fabrication of CaP submicrospheres containing silver nanoparticles by pulsed laser irradiation

  5. In situ oligomerization of 2-(thiophen-3-yl)acetate intercalated into Zn{sub 2}Al layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Tronto, Jairo, E-mail: jairotronto@ufv.br [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Pinto, Frederico G.; Costa, Liovando M. da [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Leroux, Fabrice; Dubois, Marc [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, BP 80026, F-6317 Clermont-Ferrand (France); Valim, João B. [Universidade de São Paulo, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química, Av. dos Bandeirantes 3900, CEP 14.040-901, Ribeirão Preto, SP (Brazil)

    2015-01-15

    A layered double hydroxide (LDH) with cation composition Zn{sub 2}Al was intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers. To achieve in situ polymerization and/or oligomerization of the intercalated monomers, soft thermal treatments were carried out, and subsequent hybrid LDH materials were analyzed by means of several characterization techniques using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), {sup 13}C CP–MAS nuclear magnetic resonance (NMR), electron spin resonance (EPR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP–OES), and elemental analysis. PXRD analysis suggested that the intercalated monomers formed a bilayer. Thermal treatment of the hybrid LDH assembly above 120 °C provokes partially the breakdown of the layered structure, generating the phase zincite. EPR results indicated that vicinal monomers (oligomerization) were bound to each other after hydrothermal or thermal treatment, leading to a polaron response characteristic of electron conductivity localized on a restricted number of thiophene-based monomer segments. Localized unpaired electrons exist in the material and interact with the {sup 27}Al nuclei of the LDH layers by superhyperfine coupling. These unpaired electrons also interact with the surface of ZnO (O{sup 2−} vacancies), formed during the thermal treatments. - Graphical abstract: We synthesized a layered double hydroxide (LDH) with cation composition Zn{sub 2}Al, intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers, by coprecipitation at constant pH. We thermally treated the material, to achieve in situ polymerization and/or oligomerization of the intercalated monomers. - Highlights: • A Zn{sub 2}Al–LDH was intercalated with 2-(thiophen-3-yl)acetate monomers. • To achieve in situ oligomerization of the monomers, thermal treatments were made.

  6. Effect of rotary instrumentation and of the association of calcium hydroxide and chlorhexidine on the antisepsis of the root canal system in dogs Efeito da instrumentação automatizada e da associação hidróxido de cálcio e clorexidina na anti-sepsia de canais radiculares de cães

    Directory of Open Access Journals (Sweden)

    Janir Alves Soares

    2006-04-01

    Full Text Available This study aimed at evaluating the antisepsis of the root canal system (RCS and periapical region (PR provided by rotary instrumentation associated with chlorhexidine + calcium hydroxide as intracanal medicament. Chronic periapical lesions were induced in 26 pre-molar roots in two dogs. After microbiological sampling, automatic instrumentation using the Profile system and irrigation with 5.25% sodium hypochlorite solution, with a final rinse of 14.3% EDTA followed by profuse irrigation with physiological saline were carried out in 18 root canals. After drying the canals, a paste based on calcium hydroxide associated with a 2% chlorhexidine digluconate solution was placed inside them. After 21 days, the medication was removed, leaving the root canals empty and coronally sealed. After 96 hours, a final microbiological sample was obtained, followed by histomicrobiological processing by the Brown & Brenn method. Eight untreated root canals represented the control group (C-G. Based on the Mann-Whitney test at a confidence level of 5% (p Este estudo objetivou avaliar a anti-sepsia do sistema de canais radiculares (SCR e da região periapical (RP proporcionada pela instrumentação automatizada associada a medicação intracanal à base de hidróxido de cálcio + clorexidina. Lesões periapicais crônicas foram induzidas em 26 raízes de pré-molares de dois cães. Após amostragem microbiológica, procedeu-se à instrumentação automatizada de 18 canais radiculares (CR utilizando-se o sistema Profile e a solução de hipoclorito de sódio a 5,25%, com irrigação final com EDTA a 14,3%, seguida de irrigação profusa com soro fisiológico. Após se secarem os canais, foi colocada em seu interior uma pasta à base de hidróxido de cálcio P.A. associada à solução de digluconato de clorexidina a 2%. Transcorridos 21 dias, removeu-se a medicação, deixando-se os CR vazios e selados coronariamente. Após 96 horas, obteve-se a amostra microbiol

  7. Effect of biomechanical preparation and calcium hydroxide pastes on the antisepsis of root canal systems in dogs Ação do preparo biomecânico e de pastas à base de hidróxido de cálcio na anti-sepsia do sistema de canais radiculares de cães

    Directory of Open Access Journals (Sweden)

    Janir Alves Soares

    2005-03-01

    Full Text Available In the endodontic treatment of root canals with necrotic pulps associated with periapical radiolucent areas, one of the main objectives of treatment consists in eliminating the microorganisms spread throughout the ramifications of the root canal system. The scope of this study was to evaluate the antiseptic efficacy of biomechanical preparation and two calcium hydroxide-based pastes, in dogs' teeth with experimentally induced chronic periapical lesions. After initial microbiological sampling, instrumentation of the root canals was undertaken using the conventional technique, using K type files used in conjunction with a solution of 5.25% sodium hypochlorite. After ninety-six hours, further microbiological sampling was undertaken and Calen/CPMC or Calasept pastes were applied for 15 and 30 days. Ninety six hours after the removal of the medication, the third microbiological sampling was undertaken and finally histomicrobiological analysis followed using Brown & Brenn staining. The results were analyzed using the Kruskall-Wallis test, with a level of significance established at 5% (p0.05, characterized by an elevated incidence of cocci, bacilli and filaments, predominantly gram-positive, in root canals, secondary canals and accessories, apical cementoplasts and dentinal tubules, but with a low incidence of microorganisms in areas of cementum resorption and the periapical lesion. The biomechanical preparation and intracanal dressing based on calcium hydroxide were important in the antisepsis of the root canal; however, both procedures did not produce significant changes in the microbiological aspects of the root canal system.No tratamento endodôntico dos canais radiculares com polpa necrótica associados à áreas radiolúcidas periapicais, um dos principais objetivos consiste em eliminar os microrganismos situados em todo o sistema de ramificações. Por conseguinte, o objetivo deste estudo foi avaliar a eficácia anti-séptica do preparo

  8. Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulphate ions: Synthesis, characterisation and dye removal properties

    Directory of Open Access Journals (Sweden)

    Fatima Zahra Mahjoubi

    2017-01-01

    Full Text Available In this work, Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulphate ions were synthesised via a co-precipitation method at a constant solution pH. The as-synthesised samples were characterised by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM and simultaneous thermogravimetric/differential thermal analysis (TGA-DTA. The XRD patterns showed that Zn-Al-SO4 had the greatest interlayer spacing, followed by Zn-Al-Cl, Zn-Al-NO3 and Zn-Al-CO3. The FTIR spectra clearly confirmed the presence of intercalated anions in the structure of the LDHs. Batch experiments for methyl orange (MO adsorption onto synthesised samples were investigated under various conditions such as contact time, initial dye concentration and solution pH. The experimental results show that pH is the most influencing factor. The effective pH range for the MO removal was found to be 3.5–4.5. The kinetics data can be described accurately by a pseudo-second-order kinetic model instead of a pseudo-first-order model. The equilibrium data were analysed using the Langmuir, Freundlich and Dubinin–Radushkevich models. The results showed that the Langmuir and Dubinin–Radushkevich isotherm models fit well to the experimental data. The Zn-Al-LDH samples exhibited exceptional Langmuir maximum adsorption capacities of 2758, 2455, 2270 and 1684 mg/g for Zn-Al-SO4, Zn-Al-Cl, Zn-Al-NO3 and Zn-Al-CO3, respectively.

  9. Adsorption properties of aluminum magnesium mixed hydroxide for the model anionic dye Reactive Brilliant Red K-2BP.

    Science.gov (United States)

    Li, Yujiang; Gao, Baoyu; Wu, Tao; Wang, Biao; Li, Xia

    2009-05-30

    The use of aluminum magnesium mixed metal hydroxide (MMH) as adsorbent to remove Reactive Brilliant Red K-2BP (RBR K-2BP), as a model anionic dye, from aqueous solution was investigated. MMH was prepared by coprecipitation and was characterized by XRD, TEM and average particle diameter. Adsorption experiments were carried out as a function of pH, contact time, concentration of dye, adsorbent dosage, and temperature. The results showed that MMH was particularly effective to remove RBR K-2BP, and that the effective pH range for the dye removal was between 4.0 and 11.0, but at pHs lower than 4, dissolution of MMH took place. A significant decline of dye adsorption occurred at pHs above the isoelectric point (IEP). The adsorption of RBR K-2BP on MMH reached equilibrium within 4h. The appropriate adsorbent dosage was 1000 mg/L. The interaction between the surface sites of MMH and the dye ions may be a combination of both anion exchange and surface complexation. Three kinetic models have been evaluated to fit the experimental data. It was shown that the pseudo-second-order model best described the adsorption kinetics of RBR K-2BP on MMH. The equilibrium isotherm showed that the adsorption of RBR K-2BP onto MMH was consistent with the Langmuir and Freundlich equations. And the saturated adsorption capacity of MMH for RBR K-2BP was 657.5mg/g. The adsorption process was endothermic in nature. MMH displayed superior treatment efficiency to the industrial dye effluents from a printing and dyeing plant with a removal efficiency of 93.8-96.7% for colored materials and 77.9-83.6% for COD.

  10. Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite.

    Science.gov (United States)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Hussein-Al-Ali, Samer Hasan; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2013-01-01

    In the study reported here, magnesium/aluminum (Mg/Al)-layered double hydroxide (LDH) was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: "PANE" (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method) and "PAND" (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method), respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w), respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells, with a half maximal inhibitory concentration of 35.6 μg/mL for PANE and 36.0 μg/mL for PAND for MCF-7 cells, and 19.8 μg/mL for PANE and 30.3 μg/mL for PAND for HeLa cells. No half maximal inhibitory concentration for either nanocomposite was found for 3T3 cells.

  11. The Effect of Sodium Hydroxide on Drag Reduction using a Biopolymer.

    Directory of Open Access Journals (Sweden)

    Singh Harvin Kaur A/P Gurchran

    2014-07-01

    Full Text Available Drag reduction is observed as reduced frictional pressure losses under turbulent flow conditions and hence, substantially increases the flowrate of the fluid. Practical application includes water flooding system, pipeline transport and drainage system. Drag reduction agent, such as polymers, can be introduced to increase the flowrate of water flowing, reducing the water accumulation in the system and subsequently lesser possibility of heavy flooding. Currently used polymer as drag reduction agents is carboxymethylcellulose, to name one. This is a synthetic polymer which will seep into the ground and further harm our environment in excessive use of accumulation. A more environmentally-friendly drag reduction agent, such as the polymer derived from natural sources or biopolymer, is then required for such purpose. As opposed to the synthetic polymers, the potential of biopolymers as drag reduction agents, especially those derived from a local plant source, are not extensively explored. The drag reduction of a polymer produced from a local plant source within the turbulent regime will be explored and assessed in this study using a rheometer where a reduced a torque produced can be perceived as a reduction of drag. The cellulose powder was converted to carboxymethylcellulose (CMC by etherification process using sodium monochloroacetate and sodium hydroxide. The carboxymethylation reaction then was optimized against concentration of NaOH. The research is structured to focus on producing the biopolymer and also assess the drag reduction ability of the biopolymer produced against concentration of sodium hydroxide.

  12. Removal of arsenate with hydrous ferric oxide coprecipitation: effect of humic acid.

    Science.gov (United States)

    Du, Jingjing; Jing, Chuanyong; Duan, Jinming; Zhang, Yongli; Hu, Shan

    2014-02-01

    Insights from the adverse effect of humic acid (HA) on arsenate removal with hydrous ferric oxide (HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering (SERS), extended X-ray absorption fine structure (EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurement, and charge distribution multisite complexation (CD-MUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26-3.31 angstroms. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.

  13. Magnetism in Mn-doped ZnO nanoparticles prepared by a co-precipitation method

    Science.gov (United States)

    Jayakumar, O. D.; Salunke, H. G.; Kadam, R. M.; Mohapatra, Manoj; Yaswant, G.; Kulshreshtha, S. K.

    2006-03-01

    We report the synthesis of nominal 2 and 5 at.% Mn-doped ZnO nanocrystalline particles by a co-precipitation method. Rietveld refinement of x-ray diffraction data revealed that Mn-doped ZnO crystallizes in the monophasic wurtzite structure and the unit cell volume increases with increasing Mn concentration. DC magnetization measurements showed ferromagnetic ordering above room temperature with Hc~150 Oe for nominal 2 at.% Mn-doped ZnO nanoparticles annealed at 675 K. A distinct ferromagnetic resonance (FMR) signal was observed in the EPR spectra of the 2 at.% Mn-doped ZnO nanoparticles annealed at 675 K. EPR measurements were used to estimate the number of spins participating in ferromagnetic ordering. Of the total Mn present in the 2 at.% Mn ZnO lattice, 25% of the Mn2+ ions were responsible for ferromagnetic ordering, whereas nearly 5% of the Mn2+ ions remained uncoupled (isolated spins). A well resolved EPR spectrum of 5% Mn-doped ZnO samples annealed at 875-1275 K (g = 2.007, A = 80 G, D = 210 G and E = 15 G) confirmed that Mn was substitutionally incorporated into the ZnO lattice as Mn2+. On increasing the temperature of annealing beyond 1075 K an impurity phase emerges in both the 2 and 5 at.% Mn-doped ZnO samples, which has been identified as a variant of (Zn1-XMn(II)X)Mn(III)2O4 with Tc~15 K. Our results indicate that the observed room temperature ferromagnetism in Mn-doped ZnO can be attributed to the substitutional incorporation of Mn at Zn-sites rather than due to the formation of any metastable secondary phases.

  14. Preparation of ZnO-SnO2 ceramic materials by a coprecipitation method

    Directory of Open Access Journals (Sweden)

    Caballero, A. C.

    2006-06-01

    Full Text Available Tin (IV-doped zinc oxide ceramics find its main application as specific gas sensor devices. The sensor ability of the mixture and its particular affinity for a particular gas (selectivity depends both on the crystalline phases in the microstructure of the sintered semiconductor and on the degree of tin incorporation into ZnO lattice. By means of a highly reactive coprecipitation method it is revealed that the range of solid solution of tin in zinc oxide stays below 0.1 mol % of SnO2 since higher concentrations lead to segregation of a secondary Zn2SnO4 spinel type-phase.Los materiales cerámicos basados en óxido de cinc dopado con estaño (IV encuentran su principal aplicación como dispositivos sensores específicos de gases. La capacidad sensora de la mezcla de óxidos y su particular afinidad por un determinado gas específico (selectividad es función directa de cuáles sean las fases cristalinas presentes en la microestructura del semiconductor sinterizado, así como del grado de incorporación del estaño en la red del ZnO. La obtención del polvo cerámico de partida por un método de coprecipitación altamente reactivo revela que el rango de solución sólida del estaño en el óxido de cinc se encuentra por debajo del 0.1 % en moles de SnO2; concentraciones superiores llevan a la segregación de una fase secundaria, Zn2SnO4, con estructura de tipo espinela.

  15. Sequestration of uranium on fabricated aluminum co-precipitated with goethite (Al-FeOOH)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yubing; Yang, Shubin; Wang, Qi; Wang, Xiangke [Chinese Academy of Science, Hefei (China). Key Laboratory of Novel Thin Film Solar Cells; Alsaedi, Ahmad [King Abdulaziz Univ., Jeddah (Saudi Arabia). Nonlinear Analysis and Applied Mathematics (NAAM) Research Group

    2014-11-01

    Aluminum co-precipitated with goethites (Al-FeOOHs) are ubiquitous within (sub)-surface environments, which are considered one of the most important sinks for radionuclide pollution management. Accordingly, various mole ratios Al-FeOOH were synthesized and characterized by XRD, FT-IR, TEM, specific surface area and potentiometric acid-base titration. According to XRD and TEM images, the morphology of Al-FeOOH was transformed from acicular-like goethite to cotton-like gibbsite with increasing Al content. The adsorption and sequential desorption of U(VI) on Al-FeOOHs were conducted by batch techniques under N{sub 2} conditions. The batch adsorption results showed that the adsorption of U(VI) on Al-FeOOHs slightly increased at pH < 4.0, then the significant increase of U(VI) adsorption was observed at pH from 4.0 to 7.0, whereas the suppressed adsorption at pH > 8.0 was due to the electrostatic repulsion between negative charge surface and negative carbonato-complexes. The adsorption of U(VI) on Al-FeOOHs was independent of ionic strength at pH > 5.0, indicating that the inner-sphere surface complexation predominated their adsorption behaviors, whereas U(VI) adsorption on Al-FeOOH could be the outer-sphere surface/cation exchange reaction. The sequential extraction texts showed that the desorption of U(VI) from Al-FeOOHs decreased with increasing Al content. These findings highlighted the effect of Al content on the sequestration and immobilization of U(VI) onto Al-FeOOHs from (sub)-surface environments in pollution management.

  16. Determination of 1-naphthol and 2-naphthol from environmental waters by magnetic solid phase extraction with Fe@MgAl-layered double hydroxides nanoparticles as the adsorbents prior to high performance liquid chromatography.

    Science.gov (United States)

    Zhou, Qingxiang; Lei, Man; Li, Jing; Zhao, Kuifu; Liu, Yongli

    2016-04-08

    Magnetic Fe@MgAl-layered double hydroxides (MgAl-LDHs) composite was firstly synthesized by coating MgAl-layered double hydroxides on the surface of the dispersed nanoscale zero valent irons with co-precipitation method and characterized by transmission electron microscopy and X-ray diffraction techniques. The synthesized Fe@MgAl-LDHs nanoparticles were investigated for magnetic solid phase extraction (MSPE) of 1-naphthol and 2-naphthol from the water samples. The elutent containing 1-naphthol and 2-naphthol was analyzed by high performance liquid chromatography with variable wavelength detection (HPLC-UV). Under optimal conditions, there is good linear relationship between the concentration and the peak area in the range of 0.5-200 μgL(-1) with the correlation coefficients (r(2)) above 0.998 for 1-naphthol and 2-naphthol. The limits of detection were 0.22 μgL(-1) and 0.19 μgL(-1) for 1-naphthol and 2-naphthol, respectively, and precisions were both below 2.5% (n=6). The real water analysis demonstrated that the spiked recoveries were in the range of 79.2-80.9% (n=3). All these results indicated that the developed MSPE-HPLC-UV method was proved to be an efficient tool for the analysis of naphthols. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Impact of Intracanal Calcium Hydroxide or Triple Antibiotic Paste on Bond Strength of Root Canal Sealers: An In Vitro Study

    OpenAIRE

    Gündoğar, Mustafa

    2017-01-01

    Objectives:Theaim of this study is to compare the effects of intracanal treatments withcalcium hydroxide (CH) or triple antibiotic paste (TAP) on bond strength of acalcium silicate-based sealer (MTA Fillapex) and an epoxy resin- based sealer(MM Seal). Materials and Methods: Sixty extracted maxillary central incisors were preparedwith a rotary system to size 40. The specimens were randomly divided into twogroups, which received either intracanal CH or TAP. After rinsing, the teeth ineach group...

  18. A Case of Recurrent Renal Aluminum Hydroxide Stone

    Science.gov (United States)

    Cakıroglu, Basri; Dogan, Akif Nuri; Tas, Tuncay; Gozukucuk, Ramazan; Uyanik, Bekir Sami

    2014-01-01

    Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca). The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics. PMID:25013740

  19. Surface Properties of Metal Hydroxide Microparticles in the Ambient Air

    Directory of Open Access Journals (Sweden)

    Zakharenko Valery

    2017-01-01

    Full Text Available The adsorption and photoadsorption properties of Mg(OH2 and Ca(OH2 microparticles in the ambient air were investigated. The compositional analysis of an adsorption layer of microparticles was carried out. The kinetics of photodesorption of molecules from microcrystal surfaces and the interaction of HCFC-22 (CHF2Cl in the dark and under light were studied. Quantum yields and their spectral dependencies were determined for CO2 photodesorption, O2 and CO photoadsorption. The effect of weakly bound CO displacement from the surface of microparticles was revealed during dark adsorption of HCFC-22. It is supposed that adsorbed CO is formed as a result of atmospheric CO2 reduction after the break of Mg—OH bonds. In case of calcium hydroxide, CO is generated during the interaction of calcium hydroxide with carbon dioxide in the presence of water.

  20. Leaching kinetics of gibbsitic bauxite with sodium hydroxide

    Directory of Open Access Journals (Sweden)

    Abdel-Aal El-Sayed A.

    2016-01-01

    Full Text Available In this paper the results of a leaching kinetics study of bauxite ore with sodium hydroxide are presented. The effect of ore particle size, sodium hydroxide concentration and reaction temperature on the Al2O3 extraction rate was determined. The results obtained showed that 99% of Al2O3 was leached out using −200+270 mesh ore particle size at a reaction temperature of 105 °C for 60 min reaction time with 250 g/L NaOH. The solid-to-liquid ratio was maintained constant at 1:20. The results indicated that leaching of bauxite is the rate controlling process. The activation energy was determined to be 46.04 kJ/mole, which was characteristic for a chemically controlled process.

  1. Immobilization of laccase on hybrid layered double hydroxide

    Directory of Open Access Journals (Sweden)

    David Isidoro Camacho Córdova

    2009-01-01

    Full Text Available Crystals of Mg/Al layered double hydroxide were synthesized by alkaline precipitation and treated in an aqueous solution of glutamic acid. The glutamate ions were not intercalated into the interlayer space, but were detected in the material by Fourier transform infrared spectroscopy, suggesting that only the external surfaces of crystals were modified with glutamate ions. The resulting hybrid material was tested as a support for immobilization of the enzyme laccase (Myceliophthora thermophila. The immobilized enzyme preparation was characterized by electronic paramagnetic resonance spectroscopy and by assays of catalytic activity. The activity of the immobilized laccase was 97% of the activity in the free enzyme. Layered double hydroxide is a suitable support for use in remediation of soil studies.

  2. Ultrasound-assisted synthesis of magnesium hydroxide nanoparticles from magnesium.

    Science.gov (United States)

    Baidukova, Olga; Skorb, Ekaterina V

    2016-07-01

    Acoustic cavitation in water provides special kinetic and thermodynamic conditions for chemical synthesis and nanostructuring of solids. Using cavitation phenomenon, we obtained magnesium hydroxide from pure magnesium. This approach allows magnesium hydroxide to be synthesized without the requirement of any additives and non-aqueous solvents. Variation of sonochemical parameters enabled a total transformation of the metal to nanosized brucite with distinct morphology. Special attention is given to the obtaining of platelet-shaped, nanometric and de-agglomerated powders. The products of the synthesis were characterized by transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Copyright © 2016 Elsevier B.V. All rights reserved.

  3. A Case of Recurrent Renal Aluminum Hydroxide Stone

    Directory of Open Access Journals (Sweden)

    Basri Cakıroglu

    2014-01-01

    Full Text Available Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca. The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics.

  4. Nickel hydroxide positive electrode for alkaline rechargeable battery

    Energy Technology Data Exchange (ETDEWEB)

    Young, Kwo; Wang, Lixin; Mays, William; Reichman, Benjamin; Chao-Ian, Hu; Wong, Diana; Nei, Jean

    2018-02-20

    Certain nickel hydroxide active cathode materials for use in alkaline rechargeable batteries are capable of transferring >1.3 electrons per Ni atom under reversible electrochemical conditions. The specific capacity of the nickel hydroxide active materials is for example .gtoreq.325 mAh/g. The cathode active materials exhibit an additional discharge plateau near 0.8 V vs. a metal hydride (MH) anode. Ni in an oxidation state of less than 2, such as Ni.sup.1+, is able to participate in electrochemical reactions when using the present cathode active materials. It is possible that up to 2.3 electrons, up to 2.5 electrons or more may be transferred per Ni atom under electrochemical conditions.

  5. Synthesis and Characterization of Magnesium Hydroxide Nanoparticles via Hydrothermal Method

    OpenAIRE

    Sierra-Fernandez, A.; Flores-Carrasco, Gregorio; Gómez-Villalba, Luz Stella; Milošević, Olivera; Fort, R.; Rabanal, Maria Eugenia

    2014-01-01

    The interest in the nanostructured magnesium hydroxide (Mg(OH)2) is rapidly growing due to the fact that its physical and chemical properties makes it appropriate for multiple applications. So far, it has been used in medicine, industry, or more recently, in the conservation of cultural heritage. The current research is based on the synthesis and the characterization of functional and nanocrystalline Mg(OH)2 with different particle sizes, morphologies and high purity. The synthesis was carrie...

  6. Recent progress in the synthesis of nanostructured magnesium hydroxide

    OpenAIRE

    Balducci, Giulia; Bravo Diaz, Laura; Gregory, Duncan H.

    2017-01-01

    This review highlights synthetic routes for producing nanostructured magnesium hydroxide and focuses on how these various preparative approaches can produce Mg(OH)2 nanoparticles with controlled size and morphology. Mg(OH)2 nanocrystals with rod-, needle-, hollow tube- or platelet-like morphology can be synthesised by the modification of chemical and physical experimental parameters such as the selection of magnesium precursor, solvent and temperature or by employing surface modifiers and tem...

  7. Surface modification of magnesium hydroxide using vinyltriethoxysilane by dry process

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Shengjie [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Lijuan, E-mail: lilj@isl.ac.cn [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008 (China); Xu, Defang; Zhu, Donghai; Liu, Zhiqi; Nie, Feng [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008 (China)

    2016-09-30

    Highlights: • A modification mechanism for magnesium hydroxide using silane by dry process was proposed. • Si−O−Mg bonds were formed directly by the reaction between Si-OC{sub 2}H{sub 5} and hydroxyl groups of magnesium hydroxide. • Dispersibility and compatibility of modified magnesium hydroxide improved in organic phase. - Abstract: In order to improve the compatibility between magnesium hydroxide (MH) and polymer matrix, the surface of MH was modified using vinyltriethoxysilane (VTES) by dry process and the interfacial interaction between MH and VTES was also studied. Zeta potential measurements implied that the MH particles had better dispersion and less aggregation after modification. Sedimentation tests showed that the surface of MH was transformed from hydrophilic to hydrophobic, and the dispersibility and the compatibility of MH particles significantly improved in the organic phase. Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses showed that a thin layer had formed on the surface of the modified MH, but did not alter the material’s crystalline phase. Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectra (XPS) and Thermogravimetric analysis (TGA) showed that the VTES molecules bound strongly to the surface of MH after modification. Chemical bonds (Si−O−Mg) formed by the reaction between Si-OC{sub 2}H{sub 5} and hydroxyl group of MH, also there have physical adsorption effect in the interface simultaneously. A modification mechanism of VTES on the MH surface by dry process was proposed, which different from the modification mechanism by wet process.

  8. Structural and magnetic characterization of co-precipitated Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Tirupanyam, B.V. [Department of Physics, Government College (Autonomous), Rajamahendravaram 533103 (India); Meena, S.S.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Babu, Ch. Seshu [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Ramakrishna, K.S. [Department of Physics, Srinivasa Institute of Engineering and Technology, Amalapuram 533222 (India); Potukuchi, D.M. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University, Kakinada 533003 (India); Sastry, D.L., E-mail: dl_sastry@rediffmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India)

    2016-06-01

    A series of Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni{sup 2+} ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core–shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe{sup 3+} ions and absence of Fe{sup 2+} ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core–shell interactions. - Highlights: • Thermodynamic solubility of Ni{sup 2+} in zinc ferrite influences the crystallite sizes. • At room temperature the ferrite systems exhibit superparamagnetism. • Core–shell model was exactly suited to explain magnetic behavior. • Core–shell interactions decrease with increase in Ni{sup 2+} ion concentration.

  9. A situ co-precipitation method to prepare magnetic PMDA modified sugarcane bagasse and its application for competitive adsorption of methylene blue and basic magenta.

    Science.gov (United States)

    Yu, Jun-Xia; Chi, Ru-An; Zhang, Yue-Fei; Xu, Zhi-Gao; Xiao, Chun-Qiao; Guo, Jia

    2012-04-01

    Magnetic pyromellitic dianhydride (PMDA) modified sugarcane bagasse (SCB) was prepared by a situ co-precipitation method. Results showed that the magnetic modified SCB could be recycled easily by an applied magnetic field. Adsorption capacities of the magnetic sorbent for cationic dyes: methylene blue and basic magenta were 315.5 and 304.9mgg(-1), respectively. Competitive adsorption in the binary system showed that concentration percentages (C(P)) and initial concentration (C(0)) both had good linear relationship with adsorption capacities of the magnetic sorbent (q(e)(')) in the investigated range. The linear equations between C(P) and q(e)(') almost did not affect by the variation of total initial concentration of the dyes (C(T)), whereas that between C(0) and q(e)(') changed greatly with it. C(P) was the main factor that impacted q(e)(') in the binary competitive adsorption system. Similar linear equations between C(P) and q(e)(') demonstrated that the magnetic sorbent had similar adsorption affinity toward the two dyes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Structure and thermodynamics of Cr-Fe hydroxide solid solutions

    Science.gov (United States)

    Guo, X.; Daemen, L.; Liu, N.; Wu, D.; Boukhalfa, H.; Migdissov, A. A.; Sun, C.; Navrotsky, A.; Roback, R. C.; Reimus, P. W.; Xu, H.

    2016-12-01

    Cr(VI) in the form of CrO42- is a pollutant species in soils and groundwater that poses health and environmental issues. Natural remediation processes include reduction of Cr(VI) to Cr(III). Via electron exchange with naturally abundant Fe-bearing minerals, which leads to the formation of Cr(III)-Fe(III) hydroxides. Because these phases are largely X-ray amorphous, their structural characteristics have not been well determined. In this work, we synthesized five samples with different Fe/Cr ratios, and we used synchrotron X-rays to obtain high-resolution diffraction (XRD) and absorption spectroscopy (XAS) data to study both their long range and local structural characteristics. In addition, infrared spectroscopy was conducted to obtain OH bonding information. Our results indicate that the crystallinity of these samples decreases systematically with increasing Fe/Cr ratio and that the Fe-rich samples may contain oxyhydroxides. Thermogravimetry (TG) and differential scanning calorimetry (DSC) coupled with mass spectrometry (MS) data indicate that these oxyhydrides contain about 15 - 33 wt. % water/OH- and a water contents decrease with increasing Fe/Cr ratio. Finally, the enthalpies of formation of this solid solution are all endothermic, suggesting the instability of these hydroxides relative to their corresponding oxides. These comprehensive structural and thermodynamic analyses yield fundamental parameters for understanding the behavior of Cr-Fe hydroxides/oxyhydroxides in the environment.

  11. Cuprous hydroxide in a solid form: does it exist?

    Science.gov (United States)

    Soroka, Inna L; Shchukarev, Andrey; Jonsson, Mats; Tarakina, Nadezda V; Korzhavyi, Pavel A

    2013-07-14

    Experimental studies have been performed to obtain the unknown cuprous hydroxide compound, which has recently been predicted theoretically (P. A. Korzhavyi et. al., Proc. Natl. Acad. Sci. U. S. A., 2012, 109, 686-689) to be metastable in a solid form. The reduction of Cu(2+) with ferrous ethylenediamine tetraacetate (EDTA) results in the formation of a yellow powder precipitate whose composition corresponds to CuOH × H2O as probed by Fourier Transform Infrared Spectroscopy (FTIR) and cryogenic X-ray Photoelectron Spectroscopy (XPS). A similar compound has been found on the surface of Cu-CuH powder stored in water, as detected by XPS. The reduction of Cu(2+) to Cu(+) with free radicals in aqueous solutions results in a Cu2O precipitate as the final product, while the formation of the yellow cuprous hydroxide colloids may be an intermediate step. Our studies reveal that cuprous hydroxide does exist in a solid form and most likely has a hydrated form, CuOH × H2O.

  12. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model.

    Science.gov (United States)

    Choi, Goeun; Piao, Huiyan; Alothman, Zeid A; Vinu, Ajayan; Yun, Chae-Ok; Choy, Jin-Ho

    2016-01-01

    Methotrexate (MTX), an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection.

  13. Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

    Science.gov (United States)

    de Almeida, Marciano Fabiano; Bellato, Carlos Roberto; Mounteer, Ann Honor; Ferreira, Sukarno Olavo; Milagres, Jaderson Lopes; Miranda, Liany Divina Lima

    2015-12-01

    A series of TiO2/MgZnAl photocatalysts were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO2 nanoparticles by the co-precipitation method at variable pH with different Zn2+/Mg2+ molar ratios. The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO2 lead to significant enhancement of TiO2/MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N2 adsorption-desorption, XRD, SEM, EDS, IR and UV-vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evaluation of UV-vis (filter cut-off for λ > 300 nm) photocatalytic activity. The most efficient photocatalyst composite was obtained at a 5% Zn2+/Mg2+ molar ratio, in the catalyst identified as TiO2/MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min. The TiO2/MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

  14. Synthesis and characterization of chitosan/Mg-Al layered double hydroxide composite for the removal of oil particles from oil-in-water emulsion.

    Science.gov (United States)

    Elanchezhiyan, S Sd; Meenakshi, Sankaran

    2017-11-01

    The recovery of oil from oil-in-water emulsion has been investigated using chitosan/magnesium-aluminium layered double hydroxide hybrid composite (CS-LDHCs) by a single co-precipitation method. Resulting better adsorption efficiency of CS-LDHCs could be observed, indicating the synthesized material was effective to adsorb oil particles from oil-in-water emulsion at acidic pH (pH 3.0) than as-prepared LDH and raw chitosan. The enhancement of adsorption properties by CS-LDHCs material were attributed to the high content of LDH in chitosan, which makes the material more effective towards immobilization of oily particles. Batch experiment study has been elucidated by varying different physicochemical parameters such as time, pH, dose, initial oil concentration and temperature. The as-synthesized CS-LDHCs was characterized by various spectro analytical techniques viz., FTIR, SEM with EDAX, XRD, TGA and DSC analysis. To find out the best fit for the sorption process, the obtained adsorption equilibrium data was explained with Freundlich, Langmuir, Dubinin-Radushkevich and Tempkin isotherm models. The mechanism of adsorption process was demonstrated by calculating ΔG°, ΔH° and ΔS° values from thermodynamic parameters in order to understand the nature of sorption process. The schematic representation of oil removal using CS-LDHCs was explored in detail. This work provides an apparent proposal for the growth of oil removal technology. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Removal of Evans Blue and Yellow thiazole dyes from aqueous solution by Mg-Al-CO3 Layered Double Hydroxides as anion-exchanger

    Directory of Open Access Journals (Sweden)

    Mohamed Bouraada

    2014-06-01

    Full Text Available Mg-Al-CO3 Layered double hydroxide (LDH was prepared by co-precipitation method at constant pH, and subsequently used to remove Evans Blue (EB and Yellow thiazole (YT dyes from aqueous solutions. The obtained material was characterized by powder X-ray diffraction (PXRD, Fourier transform infrared spectroscopy (FTIR, thermal analysis and BET. The kinetic and equilibrium aspects of sorption of the anionic dyes from aqueous solution by Mg-Al-CO3 were investigated in batch mode. The sorption kinetic data were found to be consistent with the pseudo-second-order model. Data for YT and EB sorption by Mg-Al-CO3 were fitted better by the Langmuir equation than by the Freundlich equation based on the determination coefficient values R2 . The maximum adsorption capacities of 222.2 mgg-1 for Yellow thiazole and 107.5 mgg-1 for Evans blue. The thermodynamic parameters including Gibbs free energy (G°, standard enthalpy change (H°, and standard entropy change (S° for the process were calculated. The negative G° value indicates the spontaneity of the removal process.

  16. ZnO-Layered Double Hydroxide@Graphitic Carbon Nitride Composite for Consecutive Adsorption and Photodegradation of Dyes under UV and Visible Lights

    Science.gov (United States)

    Zhang, Luhong; Li, Li; Sun, Xiaoming; Liu, Peng; Yang, Dongfang; Zhao, Xiusong

    2016-01-01

    In this work, a ZnO-layered double hydroxide@graphitic carbon nitride composite (ZnO-LDH@C3N4) was synthesized via co-precipitation method with solvothermal treatment. The structure and morphology of ZnO-LDH@C3N4 composite were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopes/transmission electron microscopes (SEM/TEM), N2 adsorption/desorption, ultraviolet visible diffuse reflectance spectroscopy (UV-Vis-DRS), photoluminescence spectrometer (PL) and electrochemical impedance spectroscopy (EIS). The adsorption and photocatalytic properties of ZnO-LDH@C3N4 composite towards the organic dyes: Orange II sodium salt (OrgII, an anionic azo dye) and methylene blue (MB, a cationic azo dye) were investigated. Compared to ZnO-LDH and g-C3N4, the ZnO-LDH@C3N4 composite displayed an excellent performance in both adsorption and photocatalytic degradation of the organic dyes. Moreover, a combination of ZnO-LDH and g-C3N4 significantly improved the photocatalytic performance of ZnO-LDH and g-C3N4 under visible-light irradiation. The adsorption and photocatalytic mechanism were also investigated. PMID:28774047

  17. Ni/Fe and Mg/Fe layered double hydroxides and their calcined derivatives: preparation, characterization and application on textile dyes removal

    Directory of Open Access Journals (Sweden)

    Rachid Elmoubarki

    2017-07-01

    Full Text Available In this study, Mg/Fe and Ni/Fe layered double hydroxides (LDHs with molar ratio (M2+/Fe3+ of 3 and intercalated with carbonate ions were synthesized by co-precipitation method. The as-synthesized materials and their calcined products (CLDHs were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, thermo-gravimetric and differential thermal analyses (TGA–DTA, transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM-EDX, inductively coupled plasma (ICP and elemental chemical analysis CHNSO. The materials were used as adsorbents for the removal availability of textile dyes from aqueous solution. Methylene blue (MB and malachite green (MG, representative of cationic dyes, and methyl orange (MO representative of anionic dyes were used as model molecules. Adsorption experiments were carried out under different parameters such as contact time, temperature, initial dyes concentration and solution pH. Experimental results indicate that CLDHs had much higher adsorption capacities compared to LDHs. Adsorption kinetic data fitted well the pseudo-second order kinetic model. The process was spontaneous, endothermic for cationic dyes and exothermic for the anionic dye. Equilibrium sorption data fitted the Langmuir model instead of Freundlich model.

  18. High Active Zn/Mg-Modified Ni–P/Al2O3 Catalysts Derived from ZnMgNiAl Layered Double Hydroxides for Hydrodesulfurization of Dibenzothiophene

    Directory of Open Access Journals (Sweden)

    Feng Li

    2017-07-01

    Full Text Available A series of ZnMgNiAl layered double hydroxides (LDHs containing 20 wt.% Ni and different Zn/Mg molar ratios were prepared by a coprecipitation method, and then were introduced with H2PO4− via a microwave-hydrothermal method. With the resulting mixtures as the precursors, Zn/Mg-modified ZnMgNi–P/Al2O3 catalysts were prepared. The Zn/Mg molar ratio affected the formation of Ni2P and Ni12P5 in nickel phosphides. The ZnMgNi–P/Al2O3 catalyst with a Zn/Mg molar ratio of 3:1 exhibits the best dibenzothiophene hydrodesulfurization (HDS activity. Compared with the Ni–P/Al2O3 catalyst prepared from the impregnation method, the ZnMgNi–P/Al2O3 catalyst shows a higher HDS activity (81.6% vs. 54.3% and promotes the direct desulfurization of dibenzothiophene.

  19. Synthesis and characterization of graphene quantum dots/CoNiAl-layered double-hydroxide nanocomposite: Application as a glucose sensor.

    Science.gov (United States)

    Samuei, Sara; Fakkar, Jila; Rezvani, Zolfaghar; Shomali, Ashkan; Habibi, Biuck

    2017-03-15

    In the present work, a novel nanocomposite based on the graphene quantum dots and CoNiAl-layered double-hydroxide was successfully synthesized by co-precipitation method. To achieve the morphological, structural and compositional information, the resulted nanocomposite was characterized by scanning electron microscopy X-ray diffraction, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and photoluminescence. Then, the nanocomposite was used as a modifier to fabricate a modified carbon paste electrode as a non-enzymatic sensor for glucose determination. Electrochemical behavior and determination of glucose at the nanocomposite modified carbon paste electrode were investigated by cyclic voltammetry and chronoamperometry methods, respectively. The prepared sensor offered good electrocatalytic properties, fast response time, high reproducibility and stability. At the optimum conditions, the constructed sensor exhibits wide linear range; 0.01-14.0 mM with a detection limit of 6 μM (S/N = 3) and high sensitivity of 48.717 μAmM-1. Finally, the sensor was successfully applied to determine the glucose in real samples which demonstrated its applicability. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Studies of the magnetic field intensity on the synthesis of chitosan-coated magnetite nanocomposites by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wei; Jia Shaoyi; Wu Qian; Wu Songhai; Ran Jingyu [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Liu Yong, E-mail: che_824@126.com [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Hou Jingwei [Petrochemical Research Institute of PetroChina, Beijing, 100195 (China)

    2012-02-01

    Chitosan-coated magnetite nanocomposites (Fe{sub 3}O{sub 4}/CS) were prepared under different external magnetic field by co-precipitation method. The effects of the magnetic field intensity on phase composition, morphology and magnetic properties of the Fe{sub 3}O{sub 4}/CS nanocomposites were investigated by X-ray diffractometer (XRD), Fourier transform infrared analysis (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that the intensity of the magnetic field in the co-precipitation reaction process did not result in the phase composition change of the magnetic chitosan but improved the crystallinity of magnetite. The morphology of Fe{sub 3}O{sub 4}/CS nanocomposites was greatly changed by the magnetic field. It was varied from random spherical particles to chain-like cluster structure and rod-like cluster structure with the magnetic field intensity increased in the synthetic process. The VSM results indicated that all the products had excellent superparamagnetic properties regardless of the presence or the absence of the magnetic field, and the saturation magnetization values of the Fe{sub 3}O{sub 4}/CS nanocomposites were significantly improved by the magnetic field. - Highlights: Black-Right-Pointing-Pointer Fe{sub 3}O{sub 4}/chitosan nanocomposites were synthesized under the different external magnetic fields. Black-Right-Pointing-Pointer Magnetite assembled along the direction of lines of magnetic force in the co-precipitation process. Black-Right-Pointing-Pointer Fe{sub 3}O{sub 4}/chitosan presented chain-like cluster structures at 0.25 T and rod-like cluster structures at 0.35 T.

  1. Assessment of the Pozzolanic Activity of a Spent Catalyst by Conductivity Measurement of Aqueous Suspensions with Calcium Hydroxide.

    Science.gov (United States)

    Velázquez, Sergio; Monzó, José M; Borrachero, María V; Payá, Jordi

    2014-03-28

    The pozzolanic activity of the spent catalyst produced by fluid catalytic cracking (FCC) has been studied by various methods in recent years. However, no quick and easy method has been reported for this activity based on the associated studies. In this work, the pozzolanic activity of a spent catalyst was investigated by measuring its electrical conductivity in aqueous suspensions of pozzolan/calcium hydroxide. The behavior of the FCC catalyst residue was compared to that of reactive and inert materials of similar chemical compositions. Further, the influence of temperature on the suspension was studied, and also, a new method was proposed in which the pozzolan/calcium hydroxide ratio was varied (with the initial presence of solid Ca(OH)₂ in the system). It was concluded that the method is effective, fast and simple for evaluating the high reactivity of the catalyst. Therefore, this method is an alternative for the evaluation of the reactivity of pozzolanic materials.

  2. Assessment of the Pozzolanic Activity of a Spent Catalyst by Conductivity Measurement of Aqueous Suspensions with Calcium Hydroxide

    Science.gov (United States)

    Velázquez, Sergio; Monzó, José M.; Borrachero, María V.; Payá, Jordi

    2014-01-01

    The pozzolanic activity of the spent catalyst produced by fluid catalytic cracking (FCC) has been studied by various methods in recent years. However, no quick and easy method has been reported for this activity based on the associated studies. In this work, the pozzolanic activity of a spent catalyst was investigated by measuring its electrical conductivity in aqueous suspensions of pozzolan/calcium hydroxide. The behavior of the FCC catalyst residue was compared to that of reactive and inert materials of similar chemical compositions. Further, the influence of temperature on the suspension was studied, and also, a new method was proposed in which the pozzolan/calcium hydroxide ratio was varied (with the initial presence of solid Ca(OH)2 in the system). It was concluded that the method is effective, fast and simple for evaluating the high reactivity of the catalyst. Therefore, this method is an alternative for the evaluation of the reactivity of pozzolanic materials. PMID:28788583

  3. Assessment of the Pozzolanic Activity of a Spent Catalyst by Conductivity Measurement of Aqueous Suspensions with Calcium Hydroxide

    Directory of Open Access Journals (Sweden)

    Sergio Velázquez

    2014-03-01

    Full Text Available The pozzolanic activity of the spent catalyst produced by fluid catalytic cracking (FCC has been studied by various methods in recent years. However, no quick and easy method has been reported for this activity based on the associated studies. In this work, the pozzolanic activity of a spent catalyst was investigated by measuring its electrical conductivity in aqueous suspensions of pozzolan/calcium hydroxide. The behavior of the FCC catalyst residue was compared to that of reactive and inert materials of similar chemical compositions. Further, the influence of temperature on the suspension was studied, and also, a new method was proposed in which the pozzolan/calcium hydroxide ratio was varied (with the initial presence of solid Ca(OH2 in the system. It was concluded that the method is effective, fast and simple for evaluating the high reactivity of the catalyst. Therefore, this method is an alternative for the evaluation of the reactivity of pozzolanic materials.

  4. Comparison of sodium hydroxide and calcium hydroxide pretreatments on the enzymatic hydrolysis and lignin recovery of sugarcane bagasse.

    Science.gov (United States)

    Chang, Menglei; Li, Denian; Wang, Wen; Chen, Dongchu; Zhang, Yuyuan; Hu, Huawen; Ye, Xiufang

    2017-11-01

    Sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) respectively dissolved in water and 70% glycerol were applied to treat sugarcane bagasse (SCB) under the condition of 80°C for 2h. NaOH solutions could remove more lignin and obtain higher enzymatic hydrolysis efficiency of SCB than Ca(OH)2 solutions. Compared with the alkali-water solutions, the enzymatic hydrolysis of SCB treated in NaOH-glycerol solution decreased, while that in Ca(OH)2-glycerol solution increased. The lignin in NaOH-water pretreatment liquor could be easily recovered by calcium chloride (CaCl2) at room temperature, but that in Ca(OH)2-water pretreatment liquor couldn't. NaOH pretreatment is more suitable for facilitating enzymatic hydrolysis and lignin recovery of SCB than Ca(OH)2 pretreatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Coprecipitated, copper-based, alumina-stabilized materials for carbon dioxide capture by chemical looping combustion.

    Science.gov (United States)

    Imtiaz, Qasim; Kierzkowska, Agnieszka Marta; Müller, Christoph Rüdiger

    2012-08-01

    Chemical looping combustion (CLC) has emerged as a carbon dioxide capture and storage (CCS) process to produce a pure stream of CO(2) at very low costs when compared with alternative CCS technologies, such as scrubbing with amines. From a thermodynamic point of view, copper oxide is arguably the most promising candidate for the oxygen carrier owing to its exothermic reduction and oxidation reactions and high oxygen-carrying capacity. However, the low melting point of pure copper of only 1085 °C has so far prohibited the synthesis of copper-rich oxygen carriers. This paper is concerned with the development of copper-based and Al(2)O(3)-stabilized oxygen carriers that contain a high mass fraction of CuO, namely, 82.4 wt %. The oxygen carriers were synthesized by using a coprecipitation technique. The synthesized oxygen carriers were characterized in detail with regards to their morphological properties, chemical composition, and surface topography. It was found that both the precipitating agent and the pH at which the precipitation was performed strongly influenced the structure and chemical composition of the oxygen carriers. In addition, XRD analysis confirmed that, for the majority of the precipitation conditions investigated, CuO reacted with Al(2)O(3) to form fully reducible CuAl(2)O(4). The redox characteristics of the synthesized materials were evaluated at 800 °C by using methane as the fuel and air for reoxidation. It was found that the oxygen-carrying capacity of the synthesized oxygen carriers was strongly influenced by both the precipitating agent and the pH at which the precipitation was performed; however, all oxygen carriers tested showed a stable cyclic oxygen-carrying capacity. The oxygen carriers synthesized at pH 5.5 using NaOH or Na(2)CO(3) as the precipitating agents were the best oxygen carriers synthesized owing to their high and stable oxygen transfer and uncoupling capacities. The excellent redox characteristics of the best oxygen carrier

  6. Optical, magnetic and electrical investigation of cobalt ferrite nanoparticles synthesized by co-precipitation route

    Energy Technology Data Exchange (ETDEWEB)

    Gul, I.H., E-mail: iftikhar_qau@yahoo.co [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Maqsood, A. [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Naeem, M. [Department of Applied Physics, Federal Urdu University, Islamabad (Pakistan); Ashiq, M. Naeem [Department of Chemistry, Bahauddin Zakariya University, Multan (Pakistan)

    2010-09-24

    Research highlights: {yields} Particle size reduces to less than 50 nm. {yields} DC electrical resistivity increases with substitution of Al. {yields} Dielectric constant decreases. {yields} Dielectric loss factor also decreases with substitution of Al. {yields} High dielectric constants decrease the penetration depth of the electromagnetic waves by increasing the skin effect. Hence, the much lower dielectric constants obtained for the ferrites warrant their application at high frequencies. - Abstract: Aluminum substituted cobalt ferrite nanoparticles CoFe{sub 2-x}Al{sub x}O{sub 4} (for x = 0.00, 0.25, 0.50) have been synthesized by the chemical co-precipitation route. The average crystallite size was calculated using the Scherrer formula and found within 17-27 nm range. The optical absorption spectra of all the samples showed two clear electronic transitions, first is around 0.75 eV while the second at about 0.84 eV. The later is identified by means of {sup 4}A{sub 2} {yields} {sup 4}T{sub 1} ({sup 4}F) transition while the former is attributed to the overlapping of the {sup 4}A{sub 2} {yields} {sup 4}T{sub 1} ({sup 4}F) transition of the tetrahedral Co{sup 2+} ions and the Co{sup 2+} + Fe{sup 3+} {yields} Co{sup 3+} + Fe{sup 2+} metal-metal charge transfer transition. The saturation magnetization at room temperatures was found to be 61.50 emu/g for pure CoFe{sub 2}O{sub 4} nanoparticles, while it decreased with increasing Al{sup 3+} concentration up to 52.00 emu/g (for x = 0.50). The Curie temperature was determined from AC magnetic susceptibility measurement. It was observed that Curie temperature decreased with Al{sup 3+} concentration (x) and DC electrical resistivity decreased with increase in temperature. Activation energy and drift mobility have been calculated from the temperature dependent DC electrical resistivity measurements for all the samples. The variation of dielectric constant, dielectric loss and tangent loss factor for all the samples have been

  7. Magnetite nanoparticles prepared by co-precipitation method in different conditions

    Energy Technology Data Exchange (ETDEWEB)

    Aphesteguy, J.C., E-mail: caphestegu@fi.uba.ar [LAFMACEL-INTECIN, Facultad de Ingeniería, UBA, Paseo Colón 850, C1063EHA Buenos Aires (Argentina); Kurlyandskaya, G.V. [Universidad del País Vasco UPV-EHU, Dept. Electricidad y Electronica, 48940 Leioa (Spain); Ural Federal University, Dept. Magnetism and Magnetic Nanomaterials, 620000 Ekaterinburg (Russian Federation); Celis, J.P. de [National Technology University (UTN), Facultad Regional Avellaneda, Department of Chemistry (Argentina); Safronov, A.P. [Ural Federal University, Dept. Magnetism and Magnetic Nanomaterials, 620000 Ekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Ekaterinburg 620016 (Russian Federation); Schegoleva, N.N. [Institute of Metal Physics UD RAS, Ekaterinburg 620044 (Russian Federation)

    2015-07-01

    Magnetic nanoparticles (MNPs) of pure magnetite (Fe{sub 3}O{sub 4}) were prepared in an aqueous solution (sample M−I) and in a water-ethyl alcohol mixture (sample M−II) by the co-precipitation method. The structure and magnetic properties of both samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic (M−H) and microwave measurements (FMR). The mean average particle diameter and particle size distribution was evaluated by the Dynamic Light Scattering (DLS) and Brunauer- Emmett-Teller techniques (BET). The Quantitative chemical analysis of iron was performed by Inductively Coupled Plasma (ICP)- Atomic Emission Spectroscopy (AES) technique. The MNPs prepared in aqueous solution show a higher grain than those prepared in the water-ethyl alcohol mixture. The type of phase structure in both cases can be defined as “defective spinel”. The shape of the majority of M−I MNPs is octahedral. The shape of the majority of M−II MNPs is cubic. The specific surface area of MNPs was as high as 14.4 m{sup 2}/g for M−I sample and 77.8 m{sup 2}/g for sample M–II. The obtained saturation magnetization values of 75 emu/g (M−I) and 68 emu/g (M−II) are consistent with expected values for magnetite MNPs of observed sizes. Ferromagnetic resonance (FMR) measurements confirmed that MNPs of both types are magnetically homogeneous materials. FMR lines' position and line widths can be understood by invoking the local dipolar fields, deviations from sphericity, magnetocrystalline anisotropy and stresses. M−I sample shows sizeable zero field microwave absorption which is absent in the M−II case. The differences in microwave behaviour of M−I and M−II MNPs can be used in the design of microwave radiation absorbing multilayers. - Highlights: • Magnetite nanoparticles were prepared in two different conditions. • Specific surface area of sample prepared in water- ethanol mix is

  8. Influence of Impregnation and Coprecipitation Method in Preparation of Cu/ZnO Catalyst for Methanol Synthesis

    OpenAIRE

    Prasetyaningsih, Yusi; Hendriyana, Hendriyana; Susanto, Herri

    2016-01-01

    Cu/ZnO catalyst was succesfully prepared using a coprecipitation method. The mixing procedure of the Cu(NO3)2, Zn(NO3)2 and Na2CO3 solutions had an important influence on the characteristics of the catalyst. The best catalyst obtained was the one prepared with slow mixing of the salt solutions and a CuO/ZnO molar ratio of 50:50. This raw catalyst had a maximum surface area of about 61.6 m2/g. Increasing the CuO/ZnO molar ratio caused an agglomeration of precipitated particles, reducing the su...

  9. Mechanistic study of inhibition of levofloxacin absorption by aluminum hydroxide.

    Science.gov (United States)

    Tanaka, M; Kurata, T; Fujisawa, C; Ohshima, Y; Aoki, H; Okazaki, O; Hakusui, H

    1993-01-01

    The mechanisms of reduction in absorption of levofloxacin (LVFX) by coadministration of aluminum hydroxide were studied. The partition coefficient of LVFX (0.1 mM) between chloroform and phosphate buffer (pH 5.0) was reduced by 60 to 70% with the addition of metal ions such as Cu2+, Al3+, and Fe2+ (0.8 mM), which indicated the formation of LVFX-metal ion chelates. However, there was no significant difference in absorption from rat intestine between the synthetic LVFX-Al3+ (1:1) chelate (6.75 mM) and LVFX (6.75 mM) in an in situ recirculation experiment. On the other hand, Al(NO3)3 (1.5 mM) significantly inhibited the absorption of LVFX (1.5 mM) by 20% of the control in the in situ ligated loop experiment, in which partial precipitation of aluminum hydroxide was observed in the dosing solution. Data for adsorption of LVFX and ofloxacin (OFLX) from aqueous solution by aluminum hydroxide were shown to fit Langmuir plots, and the adsorptive capacities (rmax) and the K values were 7.0 mg/g and 1.77 x 10(4) M-1 for LVFX and 7.4 mg/g and 1.42 x 10(4) M-1 for OFLX, respectively. The rate of adsorption of several quinolones (50 microM) onto aluminum hydroxide (2.5 mg/ml) followed the order norfloxacin (NFLX) (72.0%) > enoxacin (ENX) (61.0%) > OFLX (47.2%) approximately LVFX (48.1%). The elution rate of adsorbed quinolones with water followed the rank order LVFX (17.9%) approximately OFLX (20.9%) approximately ENX (18.3%) > NFLX (11.9%). These results strongly suggest that adsorption of quinolones by aluminum hydroxide reprecipitated in the small intestine would play an important role in the reduced bioavailability of quinolones after coadministration with aluminum-containing antacids. Images PMID:8257141

  10. Effect of Polyvinyl alcohol on Burning Rate for Flexible PVC with Addition of Magnesium hydroxide and Aluminum tri-hydroxide

    OpenAIRE

    Zuhair Jabbar Abdul Ameer; Diyar Hussein Habbeb

    2017-01-01

    In this research study the effect each of Polyvinyl alcohol, magnesium hydroxide, Aluminum trihydroxide on Polyvinyl chloride combustion speed used in the manufacture of electrical cables. Several composite samples were manufactured using the twin screw extruder. Combustion speed measured by the specification (ASTM D 635-03) as been studying composite samples surfaces using scanning electron microscope technology. The results that the parent used three additives reduce the combustion speed an...

  11. Effect of Polyvinyl alcohol on Burning Rate for Flexible PVC with Addition of Magnesium hydroxide and Aluminum tri-hydroxide

    Directory of Open Access Journals (Sweden)

    Zuhair Jabbar Abdul Ameer

    2017-05-01

    Full Text Available In this research study the effect each of Polyvinyl alcohol, magnesium hydroxide, Aluminum trihydroxide on Polyvinyl chloride combustion speed used in the manufacture of electrical cables. Several composite samples were manufactured using the twin screw extruder. Combustion speed measured by the specification (ASTM D 635-03 as been studying composite samples surfaces using scanning electron microscope technology. The results that the parent used three additives reduce the combustion speed and turning the surface of fine to coarse

  12. Toxicity and Metabolism of Layered Double Hydroxide Intercalated with Levodopa in a Parkinson’s Disease Model

    Directory of Open Access Journals (Sweden)

    Aminu Umar Kura

    2014-04-01

    Full Text Available Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 µg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment.

  13. Effects of dissimilatory sulfate reduction on FeIII (hydr)oxide reduction and microbial community development

    Science.gov (United States)

    Kwon, Man Jae; Boyanov, Maxim I.; Antonopoulos, Dionysios A.; Brulc, Jennifer M.; Johnston, Eric R.; Skinner, Kelly A.; Kemner, Kenneth M.; O'Loughlin, Edward J.

    2014-03-01

    Although dissimilatory iron and sulfate reduction (DIR and DSR) profoundly affect the biogeochemical cycling of C, Fe, and S in subsurface systems, the dynamics of DIR and DSR in the presence of both FeIII (hydr)oxides and sulfate have not been well-studied with mixed microbial populations. This study examined the response of native microbial communities in subsurface sediment from the U.S. Department of Energy’s Integrated Field Research Challenge site in Rifle, CO to the availability of sulfate and specific FeIII (hydr)oxide minerals in experimental systems containing lactate as the electron donor, with ferrihydrite, goethite, or lepidocrocite and high (10.2 mM) or low (0.2 mM) sulfate as electron acceptors. We observed rapid fermentation of lactate to acetate and propionate. FeIII reduction was slow and limited in the presence of low-sulfate, but the extent of FeIII reduction increased more than 10 times with high-sulfate amendments. Furthermore, the extent of FeIII reduction was higher in ferrihydrite or lepidocrocite incubations than in goethite incubations. Propionate produced during fermentation of lactate was used as the electron donor for DSR. The concurrence of sulfate reduction and FeII production suggests that FeII production was driven primarily by reduction of FeIII by biogenic sulfide. X-ray absorption fine-structure analysis confirmed the formation of ferrous sulfide and the presence of O-coordinated ferrous species. 16S rRNA-based microbial community analysis revealed the development of distinct communities with different FeIII (hydr)oxides. These results highlight the highly coupled nature of C, Fe, and S biogeochemical cycles during DIR and DSR and provide new insight into the effects of electron donor utilization, sulfate concentration, and the presence of specific FeIII (hydr)oxide phases on microbial community development.

  14. Cobalt hydroxide nanoflakes and their application as supercapacitors and oxygen evolution catalysts

    Science.gov (United States)

    Rovetta, A. A. S.; Browne, M. P.; Harvey, A.; Godwin, I. J.; Coleman, J. N.; Lyons, M. E. G.

    2017-09-01

    Finding alternative routes to access and store energy has become a major issue recently. Transition metal oxides have shown promising behaviour as catalysts and supercapacitors. Recently, liquid exfoliation of bulk metal oxides appears to be an effective route which provides access to two-dimensional (2D) nano-flakes, the size of which can be easily selected. These 2D materials exhibit excellent electrochemical charge storage and catalytic activity for the oxygen evolution reaction. In this study, various sized selected cobalt hydroxide nano-flake materials are fabricated by this time efficient and highly reproducible process. Subsquently, the electrochemical properties of the standard size Co(OH)2 nanoflakes were investigated. The oxide modified electrodes were prepared by spraying the metal oxide flake suspension onto a porous conductive support electrode foam, either glassy carbon or nickel. The cobalt hydroxide/nickel foam system was found to have an overpotential value at 10 mA cm-2 in 1 M NaOH as low as 280 mV and an associated redox capacitance exhibiting numerical values up to 1500 F g-1, thereby making it a viable dual use electrode.

  15. A study of thermally activated Mg–Fe layered double hydroxides as potential environmental catalysts

    Directory of Open Access Journals (Sweden)

    MILICA S. HADNAĐEV-KOSTIĆ

    2010-09-01

    Full Text Available Layered double hydroxides (LDHs and mixed oxides derived after thermal decomposition of LDHs with different Mg–Fe contents were investigated. These materials were chosen because of the possibility to tailor their various properties, such as ion-exchange capability, redox and acid–base and surface area. Layered double hydroxides, [Mg1-xFex(OH2](CO3x/2×mH2O (where x presents the content of trivalent ions, x = M(III/(M(II + M(III were synthesized using the low supersaturation precipitation method. The influence of different Mg/Fe ratios on the structure and surface properties of the LDH and derived mixed oxides was investigated in correlation to their catalytic properties in the chosen test reaction (Fischer–Tropsch synthesis. It was determined that the presence of active sites in the mixed oxides is influenced by the structural properties of the initial LDH and by the presence of additional Fe phases. Furthermore, a synthesis outside the optimal range for the synthesis of single phase LDHs leads to the formation of metastable, multiphase systems with specific characteristics and active sites.

  16. Accidental contamination of a German town's drinking water with sodium hydroxide.

    Science.gov (United States)

    Lendowski, Luba; Färber, Harald; Holy, Andreas; Darius, Anke; Ehrich, Bernd; Wippermann, Christine; Küfner, Bernd; Exner, Martin

    2015-05-01

    Case report of a very serious drinking water incident putting up to 50,000 inhabitants of a town near Bonn in North Rhine-Westphalia, Germany at risk. A concentrated solution of highly alkaline water by sodium hydroxide was accidentally washed into the town's drinking water at a pumping station and increased the pH-value of the water to 12. Residents who came into contact with the contaminated water immediately had a toxic reaction. The incident was detected by complaints from customers and after that was stopped within several hours. The pipes were flushed and the customers were warned not to use the water till the all clear. After this immediate management there was an investigation and the cause of the incident was detected as an accidental release of accumulated sodium hydroxide (NaOH) solution. The lack of a network alarm system and the automatic cut-off mechanisms as deficiencies in the design of the station were rectified by the water company immediately after the incident. Copyright © 2015 Elsevier GmbH. All rights reserved.

  17. Quality-by-design: an integrated process analytical technology approach to determine the nucleation and growth mechanisms during a dynamic pharmaceutical coprecipitation process.

    Science.gov (United States)

    Wu, Huiquan; Khan, Mansoor A

    2011-05-01

    The objective of this study was to demonstrate the feasibility of using an integrated process analytical technology (PAT) approach to determine nucleation and growth mechanisms of a dynamic naproxen (drug)-Eudragit L100 (polymer) coprecipitation process. The influence of several thermodynamically important formulation and process variables (drug/polymer ratio, alcohol, and water usages) on coprecipitation process characteristics was investigated via real-time in situ focused beam reflectance measurement (FBRM) monitoring and near real-time particle vision microscopy measurement. The final products were characterized by near-infrared (NIR) spectroscopy and NIR chemical imaging microscopy. The coprecipitation nucleation induction time (t(ind) ) was measured by both FBRM trend statistics and process trajectory method, respectively. Furthermore, nucleation kinetics was evaluated based on t(ind) measurement and corresponding supersaturation ratio (S) estimated. It was found that plots of ln(t(ind) ) versus (ln(2) S)(-1) consist of two linear segments and are consistent with classical primary nucleation mechanisms. Apparently, the coprecipitation process is governed by heterogeneous primary nucleation mechanism at low S (14 ≤ S ≤ 503) and by homogeneous primary nucleation mechanism at high S (1216 ≤ S ≤ 3649). Off-line characterizations collectively supported this statement. Therefore, it demonstrated that integration real-time PAT process monitoring with first-principles modeling and off-line product characterization could enhance understanding to coprecipitation process dynamics and nucleation/growth mechanisms, which is impossible via off-line techniques alone. Copyright © 2010 Wiley-Liss, Inc.

  18. Comparison of arsenic co-precipitation and adsorption by iron minerals and the mechanism of arsenic natural attenuation in a mine stream.

    Science.gov (United States)

    Park, Jin Hee; Han, Young-Soo; Ahn, Joo Sung

    2016-12-01

    Mine stream precipitate collected from Ilkwang mine, Korea, contained high concentrations of arsenic (As), while water collected from the same site had negligible As concentrations, indicating natural attenuation of As occurred in the mine stream. The mechanism of attenuation was explained by comparison of X-ray absorption near edge structure (XANES) of As(V) co-precipitated with or adsorbed to iron (Fe) minerals in mine precipitates. Arsenic in the mine precipitate was present as As(V) and schwertmannite was the main Fe mineral. Arsenic co-precipitation with schwertmannite was the major mechanism of As removal in the mine stream, followed by As adsorption by goethite and As co-precipitation with ferrihydrite. Schwertmannite and ferrihydrite were formed in acid mine drainage and As was incorporated in their structure during formation. Additionally, schwertmannite and ferrihydrite may transform to goethite with As adsorbed onto the goethite surface. Based on the results of batch experiments of As co-precipitation and adsorption, co-precipitation of As with ferrihydrite and schwertmannite was the most effective As sequestration mechanism in the removal of As(V) from acid mine drainage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Comparison of the Antimicrobial Efficacy of Calcium Hydroxide and Photodynamic Therapy Against Enterococcus faecalis and Candida albicans in Teeth With Periapical Lesions; An In Vivo Study

    OpenAIRE

    Ahangari, Zohre; Mojtahed Bidabadi, Maryam; Asnaashari, Mohammad; Rahmati, Afsaneh; Tabatabaei, Fahimeh Sadat

    2017-01-01

    Introduction: Elimination of pathological microflora of root canal systems is a major goal in endodontic treatment. This study aimed to compare the antimicrobial efficacy of calcium hydroxide as an intracanal medication and antibacterial photodynamic therapy (aPDT) against Enterococcus faecalis and Candida albicans in teeth with periapical (PA) lesions.

  20. Advances in aluminum hydroxide-based adjuvant research and its mechanism

    OpenAIRE

    He, Peng; Zou, Yening; Hu, Zhongyu

    2015-01-01

    In the past few decades, hundreds of materials have been tried as adjuvant; however, only aluminum-based adjuvants continue to be used widely in the world. Aluminum hydroxide, aluminum phosphate and alum constitute the main forms of aluminum used as adjuvants. Among these, aluminum hydroxide is the most commonly used chemical as adjuvant. In spite of its wide spread use, surprisingly, the mechanism of how aluminum hydroxide-based adjuvants exert their beneficial effects is still not fully und...

  1. Efficacy of three methods for inserting calcium hydroxide-based paste in root canals

    OpenAIRE

    Galvão, Thales; Camargo, Bernardo; Armada, Luciana; Alves, Flávio

    2017-01-01

    Background To compare the quality of calcium hydroxide paste fillings performed by three different techniques. Material and Methods Sixty extracted maxillary central incisors, with previous root canal treatment, were decoronated and the gutta-percha was completely removed from the root canals. Subsequently, the canals were filled with a calcium hydroxide-based paste composed of calcium hydroxide, bismuth carbonate, and glycerin. The study samples were divided into the following three groups o...

  2. Parametric Effect of Sodium Hydroxide and Sodium Carbonate on the Potency of a Degreaser

    OpenAIRE

    Babatope Abimbola Olufemi

    2016-01-01

    Experimental and statistical analysis was carried out on the comparative effect of sodium hydroxide and sodium carbonate on the potency of a laboratory produced degreaser in this work. The materials used include; octadecyl benzene sulphonic acid, sodium hydroxide, sodium carbonate, sodium metasilicate, carboxyl methyl cellulose (C.M.C), formadelhyde, perfume, colourant and distilled water. Different samples of degreaser were produced with varying composition of sodium hydroxide and sodium car...

  3. The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac.

    OpenAIRE

    Neuvonen, P J

    1991-01-01

    1. The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac was investigated in two randomized cross-over studies, both consisting of two phases. 2. Single doses of magnesium hydroxide (850 mg) or of water (150 ml) only were given to six healthy volunteers immediately after the ingestion of ibuprofen (400 mg, Study 1), ketoprofen (50 mg, Study 2) or diclofenac (50 mg, Study 2). Plasma drug concentrations were measured up to 24 h. 3. Magnesium hydroxide ...

  4. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis

    Directory of Open Access Journals (Sweden)

    Muhammad Faizan Shareef

    2017-10-01

    Full Text Available This paper presents the effect of a synthesis method for cobalt catalyst supported on hydrotalcite material for Fischer-Tropsch synthesis. The hydrotalcite supported cobalt (HT-Co catalysts were synthesized by co-precipitation and hydrothermal method. The prepared catalysts were characterized by using various techniques like BET (Brunauer–Emmett–Teller, SEM (Scanning Electron Microscopy, TGA (Thermal Gravimetric Analysis, XRD (X-ray diffraction spectroscopy, and FTIR (Fourier Transform Infrared Spectroscopy. Fixed bed micro reactor was used to test the catalytic activity of prepared catalysts. The catalytic testing results demonstrated the performance of hydrotalcite based cobalt catalyst in Fischer-Tropsch synthesis with high selectivity for liquid products. The effect of synthesis method on the activity and selectivity of catalyst was also discussed. Copyright © 2017 BCREC Group. All rights reserved Received: 3rd November 2016; Revised: 26th February 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Sharif, M.S., Arslan, M., Iqbal, N., Ahmad, N., Noor, T. (2017. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 357-363 (doi:10.9767/bcrec.12.3.762.357-363

  5. Fe-based soft magnetic composites coated with NiZn ferrite prepared by a co-precipitation method

    Science.gov (United States)

    Peng, Yuandong; Yi, Yi; Li, Liya; Ai, Hengyu; Wang, Xiaoxu; Chen, Lulu

    2017-04-01

    Fe powder was coated with NiZn ferrite by a co-precipitation method using chlorate as the raw material. Soft magnetic composites were manufactured via compaction and heat treatment of the coated powder. The coated powder and heat treated powder were analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy. Their magnetic properties were determined using a Quantum Design-Vibrating Sample Magnetometer (QD-VSM). The composites were analysed with SEM and EDS. The permeability and magnetic loss of the composites were measured with a B-H curve analyzer. The results show that, using the co-precipitation method, the raw precipitate was successfully prepared and coated the pure Fe powder and turned into spinel NiZn ferrite treated at 600 ℃ for 1 h. After heat treatment at 500 ℃ under air, the insulation coating layer of soft magnetic composite (SMC) was not destroyed and containing Fe, Ni, Zn and oxygen. The permeabilities of the SMC are stable at edge of the 2-200 kHz frequency range and the total loss was lower.

  6. Characterization of γ- Al{sub 2}O{sub 3} nanopowders synthesized by Co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Jbara, Ahmed S., E-mail: ahmedsbhe@yahoo.com [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Physics Department, Science College, Al-Muthanna University, Samawah - 66001 (Iraq); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Othaman, Zulkafli [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Ati, Ali A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Saeed, M.A., E-mail: moalsd@gmail.com [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Division of Science and Technology, University of Education, Township, Lahore - 54770 (Pakistan)

    2017-02-15

    Co-precipitation technique has been used to synthesize gamma-Al{sub 2}O{sub 3} (γ-Al{sub 2}O{sub 3}) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m{sup 2}/g. Morphology analysis indicates that γ-Al{sub 2}O{sub 3} nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al{sub 2}O{sub 3} may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al{sub 2}O{sub 3} nanopowders. • Pure gamma- Al{sub 2}O{sub 3} phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

  7. Deproteinization assessment using isotopically enriched compounds to trace the coprecipitation of low-molecular-weight selenium species with proteins.

    Science.gov (United States)

    Godin, Simon; Bouzas-Ramos, Diego; Fontagné-Dicharry, Stéphanie; Bouyssière, Brice; Bueno, Maïté

    2017-08-01

    Studies have shown that information related to the presence of low-molecular-weight metabolites is frequently lost after deproteinization of complex matrices, such as blood and plasma, during sample preparation. Therefore, the effect of several deproteinization reagents on low-molecular-weight selenium species has been compared by species-specific isotope labeling. Two isotopically enriched selenium tracers were used to mimic models of small inorganic anionic ((77)Se-selenite) and organic zwitterionic ((76)Se-selenomethionine) species. The results presented here show that the use of a methanol-acetonitrile-acetone (1:1:1 v/v/v) mixture provided approximately two times less tracer loss from plasma samples in comparison with the classic procedure using acetonitrile, which may not be optimal as it leads to important losses of low-molecular-weight selenium species. In addition, the possible interactions between selenium tracers and proteins were investigated, revealing that both coprecipitation phenomena and association with proteins were potentially responsible for selenite tracer losses during protein precipitation in blood samples. However, coprecipitation phenomena were found to be fully responsible for losses of both tracers observed in plasma samples and of the selenomethionine tracer in blood samples. This successfully applied strategy is anticipated to be useful for more extensive future studies in selenometabolomics. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Gd doping induced weak ferromagnetic ordering in ZnS nanoparticles synthesized by low temperature co-precipitation technique

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Palvinder [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Kumar, Sanjeev, E-mail: sanjeev04101977@gmail.com [Applied Science Department, PEC University of Technology, Chandigarh, 160012 (India); Chen, Chi-Liang, E-mail: chen.cl@nsrrc.org.tw [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Yang, Kai-Siang [National Synchrotron Radiation Research Center (NSRRC), Hsinchu, 30076, Taiwan (China); Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Wei, Da-Hua [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China); Srivastava, C. [Materials Engineering Department, Indian Institute of Science, Bangalore, 560012 (India); Rao, S.M. [Department of Physics, Punjabi University, Patiala, Punjab, 147002 (India); Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan (China)

    2017-01-15

    Zn{sub 1−x}Gd{sub x}S nanoparticles with Gd concentration x = 0.00, 0.02 and 0.04 were synthesized by the chemical co-precipitation technique using thioglycerol as capping agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray absorption near-edge structure (XANES) and vibrating sample magnetometer (VSM) were employed to characterize the as synthesized Gd doped ZnS nanoparticles. XRD and TEM studies show the formation of cubic ZnS nanoparticles with an average size in the range 5–10 nm. The doping did not alter the phase of the ZnS. The PL spectra of doped ZnS nanoparticles showed the presence of sulphur vacancies in the lattice. XANES of Gd doped ZnS nanoparticles depicts spectral changes may arise from charge transfer between host Zn and dopant Gd ions. A VSM study shows that the weak ferromagnetic behaviour increases with increase in Gd doping ZnS nanoparticles. - Highlights: • Gd doped ZnS nanoparticles synthesized using co-precipitation technique. • PL studies depict sulphur and zinc vacancies in Gd doped ZnS nanoparticles. • XANES studies depict the charge transfer between host Zn and dopant Gd ions. • Room temperature weak ferromagnetism is observed in Gd doped ZnS nanoparticles.

  9. Ubbelohde viscometer measurement of water-based Fe{sub 3}O{sub 4} magnetic fluid prepared by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gu, H. [School of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Tang, X. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002 (China); Feng, W.G. [Suzhou Nanocomp Inc., Suzhou New District, Suzhou 215011 (China); Xie, H.D.; Chen, D.X. [Suzhou YouNuo Plastic Industry Co., Ltd., Suzhou 215021 (China); Badami, D. [Department of Chemical Engineering, University of Waterloo, Waterloo, Canada ON N2L 3G1 (Canada)

    2013-12-15

    Fe{sub 3}O{sub 4} nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid. - Highlights: • Fe{sub 3}O{sub 4} nanoparticles were prepared using co-precipitation and coated by sodium dodecyl benzene sulfonate to obtain water-based magnetic fluid. • The viscosity of different magnetic fluids was measured using an Ubbelohde viscometer. • The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity of magnetic fluids were studied.

  10. Structural, magnetic, dielectric and bonding properties of BiMnO3 grown by co-precipitation technique

    Directory of Open Access Journals (Sweden)

    S. Hanif

    Full Text Available In this work, powders of BiMnO3 (BMO are prepared by using co-precipitation method. The effect of sintering temperature on the physical properties is observed. The X-ray diffraction (XRD reveals monoclinic structure, while the surface morphology observed by scanning electron microscopy (SEM indicates sintering temperature dependent grain growth and an increased surface uniformity. The paramagnetic behavior is exhibited by the grown samples at room temperature (RT, which is due to the ordering temperature well below RT. The dielectric constant and the dielectric loss decay with frequency, which is due to the dipole relaxation. Moreover, Mn–O and Bi–O vibrational bands have been observed in the range 800–850 cm−1 and 500–600 cm−1, respectively. The prepared samples find potential application as a multiferroic material, with simultaneous control over both the magnetism and the dielectric characteristics. Keywords: Multiferroics, Paramagnetism, Co-precipitation, Dielectric constant, Surface morphology

  11. Evaluation of Three Chitin Metal Silicate Co-Precipitates as a Potential Multifunctional Single Excipient in Tablet Formulations

    Directory of Open Access Journals (Sweden)

    Rana Al-Shaikh Hamid

    2010-05-01

    Full Text Available The performance of the novel chitin metal silicate (CMS co-precipitates as a single multifunctional excipient in tablet formulation using direct compression and wet granulation methods is evaluated. The neutral, acidic, and basic drugs Spironolactone (SPL, ibuprofen (IBU and metronidazole (MET, respectively, were used as model drugs. Commercial Aldactone®, Fleximex® and Dumazole® tablets containing SPL, IBU and MET, respectively, and tablets made using Avicel® 200, were used in the study for comparison purposes. Tablets of acceptable crushing strength (>40 N were obtained using CMS. The friability values for all tablets were well below the maximum 1% USP tolerance limit. CMS produced superdisintegrating tablets (disintegration time < 1 min with the three model drugs. Regarding the dissolution rate, the sequence was as follow: CMS > Fleximex® > Avicel® 200, CMS > Avicel® 200 > Dumazole® and Aldactone® > Avicel® 200 > CMS for IBU, MET and SPL, respectively. Compressional properties of formulations were analyzed using density measurements and the compression Kawakita equation as assessment parameters. On the basis of DSC results, CMS co precipitates were found to be compatible with the tested drugs. Conclusively, the CMS co-precipitates have the potential to be used as filler, binder, and superdisintegrant, all-in-one, in the design of tablets by the direct compression as well as wet granulation methods.

  12. Effect of different adhesive protocols vs calcium hydroxide on primary tooth pulp with different remaining dentin thicknesses:24-month results.

    Science.gov (United States)

    Büyükgüral, Bülent; Cehreli, Zafer C

    2008-03-01

    The aim of this randomized, controlled, single-blind and prospective study was to evaluate the clinical and radiographic success rates of three different bonding protocols vs calcium hydroxide liner for protection of the dentin-pulp complex of primary molars with different remaining dentin thicknesses. Two hundred forty primary molar teeth with moderate to deep occlusal caries were restored in 97 children who met inclusion criteria. After cavity preparation, the teeth were randomly assigned into four groups (n = 60/group) with respect to the material used for protection of the dentin-pulp complex: (1) total-etching with 36% phosphoric acid followed by an acetone-based adhesive (Prime&Bond NT), (2) a self-etch adhesive system (Xeno III), (3) an acetone-based adhesive (Prime&Bond NT) without prior acid conditioning, and (4) control: calcium hydroxide cement (Dycal). Teeth in groups 1-3 were restored with a polyacid-modified resin-based composite (Dyract AP) and those in group 4 with amalgam. The remaining dentin thickness was calculated using image analysis software (ImageJ). The teeth were evaluated clinically and radiographically for 24 months. The distribution of restored teeth with minimal remaining dentin thickness (restorative treatments was 100%. Protection of the dentin-pulp complex with the tested bonding protocols resulted in similar outcomes in mainly shallow and medium deep cavities as compared to calcium hydroxide amalgam in more deep cavities, when indirect pulp treatment was performed in class I compomer restorations.

  13. Interlayer Structures and Dynamics of Arsenate and Arsenite Intercalated Layered Double Hydroxides: A First Principles Study

    National Research Council Canada - National Science Library

    Yingchun Zhang; Xiandong Liu; Chi Zhang; Mengjia He; Xiancai Lu

    2017-01-01

    In this study, by using first principles simulation techniques, we explored the basal spacings, interlayer structures, and dynamics of arsenite and arsenate intercalated Layered double hydroxides (LDHs...

  14. Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

    Science.gov (United States)

    Waychunas, G. A.; Rea, B. A.; Fuller, C. C.; Davis, J. A.

    1993-05-01

    EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, α (goethite), β (akaganeite), and γ (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface ( 3.28 ±0.01 Å) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces ( 3.25 ± 0.02 Å). Mono-dentate arsenate linkages ( 3.60 ± 0.03 Å) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As/Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ± 0.01 Å. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As/Fe ratio is increased. Coherent crystallite size is probably no more than 10 Å in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As/Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As/Fe) indicates ferrihydrite units consisting mainly of Fe

  15. Evaluation of calcium ion release and change in pH on combining calcium hydroxide with different vehicles

    Directory of Open Access Journals (Sweden)

    Charu Grover

    2014-01-01

    of 99.53, 17.98, 74.93% respectively with a significant difference among all groups. Group 1 reached the highest Ca 2+ level (39.79% at the end of 1 day but showed almost complete release of calcium hydroxide at the end of 15 days. Group 3 showed least calcium ion release (17.98% at 15 days. Group 4 showed a sustained release of Ca +2 ions from 74% at 15 days to 95% at the end of 30 days. After the 1 st h; Group 1 showed the highest pH level (11.8. However, pH reduced to 7.8 at the end of 30 days in this group. Group 2 showed the highest pH value (10.35, followed by Group 4 (10.32 after 30 days. Conclusion: Chitosan can be used as a promising vehicle for calcium hydroxide to maintain an alkaline pH and to allow sustained release of calcium ions in the root canal system.

  16. Catalytic oxidation of sulfide ions over nickel hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A.; Khristov, P. [Institute of Catalysis, Bulgarian Academy of Sciences, Sofia (Bulgaria); Losev, A. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    1996-01-18

    The catalytic sulfide ion oxidation by oxygen to elemental sulfur over {beta}-Ni(OH){sub 2} and LiNiO{sub 2} has been studied. As a result of experimental investigation performed, a reaction mechanism is suggested which involves heterogeneous and homogeneous processes. Dioxygen activation in the heterogeneous process proceeds via a redox Ni{sup 2+} <-> Ni{sup 3+} transition and participation of OH{sup -} groups. The active HO{sup -}{sub 2} species thus formed carries on the reaction in homogeneous phase. Nickel hydroxides are promising catalysts for practical application

  17. Iron oxide hydroxide nanoflower assisted removal of arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Raul, Prasanta Kumar, E-mail: prasanta.drdo@gmail.com [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Devi, Rashmi Rekha; Umlong, Iohborlang M. [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India); Thakur, Ashim Jyoti [Department of Chemical Sciences, Tezpur University, Napaam, Tezpur 784028, Assam (India); Banerjee, Saumen; Veer, Vijay [Defence Research Laboratory, Post Bag No. 2, Tezpur 784001, Assam (India)

    2014-01-01

    Graphical abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. TEM image clearly reveals that the nanoparticle looks flower like morphology with average particle size less than 20 nm. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature and the data fitted to different isotherm models indicate the heterogeneity of the adsorbent surface. The material can be regenerated up to 70% using dilute hydrochloric acid and it would be utilized for de-arsenification purposes. - Highlights: • The work includes synthesis of iron oxide hydroxide nanoflower and its applicability for the removal of arsenic from water. • The nanoparticle was characterized using modern instrumental methods like FESEM, TEM, BET, XRD, etc. • The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic at room temperature. • The sorption is multilayered on the heterogeneous surface of the nano adsorbent. • The mechanism of arsenic removal of IOH nanoflower follows both adsorption and ion-exchange. - Abstract: Non-magnetic polycrystalline iron oxide hydroxide nanoparticle with flower like morphology is found to play as an effective adsorbent media to remove As(III) from 300 μg L{sup −1} to less than 10 μg L{sup −1} from drinking water over wide range of pH. The nanoparticle was characterized by X-ray powder diffraction analysis (XRD), BET surface area, FTIR, FESEM and TEM images. TEM image clearly reveals flower like morphology with average particle size less than 20 nm. The nanoflower morphology is also supported by FESEM images. The maximum sorption capacity of the sorbent is found to be 475 μg g{sup −1} for arsenic and the data fitted to different isotherm models indicate the

  18. LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

    Directory of Open Access Journals (Sweden)

    Luíz Paulo Figueredo Benício

    2015-02-01

    Full Text Available The current research aims to introduce Layered Double Hydroxides (LDH as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy.

  19. Bonding by Hydroxide-Catalyzed Hydration and Dehydration

    Science.gov (United States)

    Gwo, Dz-Hung

    2008-01-01

    A simple, inexpensive method for bonding solid objects exploits hydroxide-catalyzed hydration and dehydration to form silicate-like networks in thin surface and interfacial layers between the objects. The method can be practiced at room temperature or over a wide range of temperatures. The method was developed especially to enable the formation of precise, reliable bonds between precise optical components. The bonds thus formed exhibit the precision and transparency of bonds formed by the conventional optical-contact method and the strength and reliability of high-temperature frit bonds. The method also lends itself to numerous non-optical applications in which there are requirements for precise bonds and/or requirements for bonds, whether precise or imprecise, that can reliably withstand severe environmental conditions. Categories of such non-optical applications include forming composite materials, coating substrates, forming laminate structures, and preparing objects of defined geometry and composition. The method is applicable to materials that either (1) can form silicate-like networks in the sense that they have silicate-like molecular structures that are extensible into silicate-like networks or (2) can be chemically linked to silicate-like networks by means of hydroxide-catalyzed hydration and dehydration. When hydrated, a material of either type features surface hydroxyl (-OH) groups. In this method, a silicate-like network that bonds two substrates can be formed either by a bonding material alone or by the bonding material together with material from either or both of the substrates. Typically, an aqueous hydroxide bonding solution is dispensed and allowed to flow between the mating surfaces by capillary action. If the surface figures of the substrates do not match precisely, bonding could be improved by including a filling material in the bonding solution. Preferably, the filling material should include at least one ingredient that can be hydrated to

  20. Coprecipitation: An excellent tool for the synthesis of supported metal catalysts – From the understanding of the well known recipes to new materials

    OpenAIRE

    Behrens, M.

    2015-01-01

    Constant-pH co-precipitation is a standard synthesis technique for catalyst precursors. The general steps of this synthesis route are described in this work using the successfully applied industrial synthesis of the Cu/ZnO/(Al2O3) catalyst for methanol synthesis as an example. Therein, co-precipitation leads to well-defined and crystalline precursor compound with a mixed cationic lattice that contains all metal species of the final catalyst. The anions are thermally decomposed to give the mix...

  1. Thermoluminescence and photoluminescence properties of NaCl:Mn, NaCL:Cu nano-particles produced using co-precipitation and sono-chemistry methods

    Energy Technology Data Exchange (ETDEWEB)

    Mehrabi, M. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Zahedifar, M. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Saeidi-Sogh, Z. [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Ramazani-Moghaddam-Arani, A., E-mail: ramazmo@kashanu.ac.ir [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Sadeghi, E. [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Harooni, S. [Institute of Nanosince and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of)

    2017-02-21

    The NaCl: Cu and NaCl: Mn nanoparticles (NPs) were produced by co-precipitation and sono-chemistry methods and their thermoluminescence (TL) and photoluminescence (PL) properties were studied. By decreasing the particles size a considerable increase in sensitivity of the samples to high dose gamma radiation was observed. The NPs produced by sono-chemistry method have smaller size, homogeneous structure, more sensitivity to high gamma radiation and less fading than of those produced by co-precipitation method.

  2. Atomically thin layered NiFe double hydroxides assembled 3D microspheres with promoted electrochemical performances

    Science.gov (United States)

    Li, Xiaomin; Zai, Jiantao; Liu, Yuanyuan; He, Xiaobo; Xiang, Shijie; Ma, Zifeng; Qian, Xuefeng

    2016-09-01

    LDHs in atomic thickness (mono-/bi-layers) usually exhibit novel physicochemical properties, especially in surface-dependent energy storage and catalysis areas. However, the thickness of the commonly reported 2D LDHs is in nanoscale and the bottom-up synthesis of atomically thin LDHs is rarely reported. Herein, high-quality atomically thin layered NiFe-LDHs assembled 3D microspheres were synthesized via a rational designed reaction system, where the formation of atomically thin building blocks was controlled by the synergetic effects of released carbonate anions and butanol. Furthermore, the complexant and solvents played important effects on the process of coprecipitation and the assembling of LDHs. Due to the nature of atomically thin LDHs nanosheets and unique 3D hierarchical structures, the obtained microspheres exhibited excellent electrocatalytic oxygen evolution reaction (OER) activity in alkaline medium with an onset overpotential (0.435 V, which is lower than that of common LDHs) and good durability. The as-prepared 3D NiFe-LDHs microspheres were also firstly used as supercapacitor materials and displayed a high specific capacitance of 1061 F g-1 at the current density of 1 A g-1.

  3. A coprecipitation technique to prepare Sr0⋅ 5Ba0⋅ 5Nb2O6

    Indian Academy of Sciences (India)

    ... and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr0.5Ba0.5Nb2O6 phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr0.5Ba0.5Nb2O6 (SBN). Transmission electron microscopic (TEM) ...

  4. Removal of oxyanions from synthetic wastewater via carbonation process of calcium hydroxide: Applied and fundamental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Montes-Hernandez, G., E-mail: German.MONTES-HERNANDEZ@obs.ujf-grenoble.fr [LGCA, University Joseph Fourier, Observatoire des Sciences de l' Univers de Grenoble and CNRS, BP 53 X, 38042 Grenoble Cedex 9 (France); LPG, University Joseph Fourier, Observatoire des Sciences de l' Univers de Grenoble and CNRS, BP 53 X, 38042 Grenoble Cedex 9 (France); Concha-Lozano, N. [LGCA, University Joseph Fourier, Observatoire des Sciences de l' Univers de Grenoble and CNRS, BP 53 X, 38042 Grenoble Cedex 9 (France); Renard, F. [LGCA, University Joseph Fourier, Observatoire des Sciences de l' Univers de Grenoble and CNRS, BP 53 X, 38042 Grenoble Cedex 9 (France); Physics of Geological Processes, University of Oslo (Norway); Quirico, E. [LPG, University Joseph Fourier, Observatoire des Sciences de l' Univers de Grenoble and CNRS, BP 53 X, 38042 Grenoble Cedex 9 (France)

    2009-07-30

    Removal of oxyanions (selenite, selenate, arsenate, phosphate and nitrate) during calcite formation was experimentally studied using aqueous carbonation of calcium hydroxide under moderate pressure (P{sub CO2} {approx_equal} 20 bar) and temperature (30 {sup o}C). The effects of Ca(OH){sub 2} dose (10 and 20 g), Ca(OH){sub 2} source (commercial pure material or alkaline paper mill waste) and oxyanion initial concentration (from 0 to 70 mg atom/L) were investigated for this anisobaric gas-liquid-solid system. The Ca(OH){sub 2} carbonation reaction allowed successfully the removal of selenite (>90%), arsenate (>78%) and phosphate ({approx_equal}100%) from synthetic solutions. Conversely, nitrate and selenate had not any physicochemical affinity/effect during calcite formation. The rate of CO{sub 2} transfer during calcite formation in presence of oxyanions was equal or slower than for an oxyanion-free system, allowing to define a retarding kinetic factor RF that can vary between 0 (no retarding effect) to 1 (total inhibition). For selenite and phosphate RF was quite high, close to 0.3. A small retarding effect was detected for arsenate (RF {approx} 0.05) and no retarding effect was detected for selenate and nitrate (RF {approx} 0). In general, RF depends on the oxyanion initial concentration, oxyanion nature and Ca(OH){sub 2} dose. The presence of oxyanions could also influence the crystal morphology and aggregation/agglomeration process. For example, a c-axis elongation of calcite crystals was clearly observed at the equilibrium, for calcite formation in presence of selenite and phosphate. The oxyanions removal process proposed herein was inspired on the common physicochemical treatment of wastewater using calcium hydroxide (Ca(OH){sub 2}). The particularity, for this novel method is the simultaneous calcium hydroxide carbonation with compressed carbon dioxide in order to stabilise the solid matter. This economical and ecological method could allow the removal of

  5. Pulpal response of dogs primary teeth to an adhesive system or to a calcium hydroxide cement Resposta pulpar de dentes decíduos de cães a um sistema adesivo ou ao cimento de hidróxido de cálcio

    Directory of Open Access Journals (Sweden)

    Rosângela Almeida RIBEIRO

    2000-03-01

    Full Text Available The aim of this study was to evaluate the pulpal response of dogs primary teeth to an adhesive system or to a calcium hidroxide cement after mechanic exposure of the pulp. Three mongrel dogs were used and ten class V cavities were prepared on their teeth. A mechanic pulp exposure was produced with a sterile exploratory probe in the central portion of each cavity and bleeding was controlled with dry sterile cotton pellets. Enamel, dentin and the site of the pulp exposure of five teeth were etched with 35% phosphoric acid followed by the application of an adhesive system (Scotchbond Multi-Purpose - 3M. In the other five teeth, calcium hydroxide cement (Hydro C - Dentsply was applied on the site of the pulp exposition before application of the adhesive system (Scotchbond Multi-Purpose - 3M. All teeth were restored with a resin composite (Z-100 - 3M. After 7, 30 or 45 days the dogs were anesthetized and perfused with saline followed by a solution of neutral buffered formalin. Maxilla and mandible were sectioned into three parts and placed in a solution for demineralization. Following bone demineralization, all teeth were cut, trimmed, embedded in paraffin and longitudinally cut. Then, the teeth were stained with hematoxilin and eosin and observed under a light microscope. The results obtained with the treatments proposed in this study showed the presence and persistence of an inflammatory response of different intensities at the three experimental periods. There was no variation in the inflammatory response regarding the different treatments performed.O objetivo deste estudo foi de avaliar a resposta pulpar de dentes decíduos de cães à um sistema adesivo ou a um cimento de hidróxido de cálcio após exposição mecânica da polpa. Foram utilizados três cães sem raça definida, e nestes foram realizados dez preparos cavitários classe V. Uma exposição pulpar mecânica foi produzida com uma sonda exploradora esterilizada, na porção central

  6. Interaction of Pu(IV,VI) hydroxides/oxides with metal hydroxides/oxides in alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Fedoseev, A.M.; Krot, N.N.; Budantseva, N.A.; Bessonov, A.A.; Nikonov, M.V.; Grigoriev, M.S.; Garnov, A.Y.; Perminov, V.P.; Astafurova, L.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

    1998-08-01

    The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.

  7. New trends on liquid effluent treatments: coprecipitation, adsorption, filtration, photo-catalysis, a complementary association of innovative tools

    Energy Technology Data Exchange (ETDEWEB)

    Barre, Yves [CEA, DEN, MAR, DTCD, SPDE, Laboratoire des Procedes Avances de Decontamination, 30207 Bagnols sur Ceze (France); Pacary, Vincent [CEA, DEN, MAR, DRCP, SCPS, LCSE, 30207 Bagnols sur Ceze (France); Schrive, Luc [CEA, DEN, MAR, DTCD, SPDE, Laboratoire des Fluides Supercritiques et Membranes, 30207 Bagnols sur Ceze (France); Guibal, Eric [Ecole des Mines d' Ales, Centre de Recherche LGEI, 6 avenue de Clavieres, 30319 Ales Cedex (France)

    2009-06-15

    The ever increasing pressure to reduce the release of radioactive and other toxic substances into environment requires constant improvement/upgrading of processes and technologies for treatment and conditioning of liquid radioactive wastes. The extensive research is carried out on various processes including ion exchange, sorption, coprecipitation, membrane separation and photo-catalytic degradation of organics substances. A judicious combination of the processes is being pursued to meet the end objectives of improved decontamination and waste volume reduction. In a previous study, an elaborated model is proposed to predict the radioactive strontium decontamination factor of nuclear waste solutions which can be realized by using a coprecipitation process with barium sulphate. Simulations of the coprecipitation of strontium ions with barium sulphate have been performed in continuous and semibatch reactors. Thanks to these simulations, laws of the treatment efficiency variation as a function of several process parameters (mean residence time, stirring speed, concentration) have been determined and experimentally verified. This study leads to the determination of optimal treatment conditions. Three apparatus (recycling apparatus, fluidized bed and reactor/settling tank) providing these optimal conditions have been successfully tested and offered significant outlooks for the reduction of the residual sludge volume. Since the development of new ceramic membranes with large filtration area and their long term use verification in conventional water purification fields, these membrane processes have been adopted by the nuclear industry as a viable alternative treatment method for liquid radioactive wastes. Ion exchange is one of the most common and effective treatment methods for liquid radioactive. Spent ion exchange resins are considered to be problematic waste that requires precautions during its immobilization to meet the acceptance criteria for disposal. Efforts to

  8. Adsorption kinetic and thermodynamic studies of phosphate onto tantalum hydroxide.

    Science.gov (United States)

    Yu, Shi-Hua; Dong, Xiao-Le; Gong, Hong; Jiang, Heng; Liu, Zhi-Gang

    2012-12-01

    Tantalum hydroxide exhibits the ability for the removal of phosphate from aqueous solution. The kinetic study, adsorption isotherm, thermodynamic study, desorption, and foreign anions effect were examined in batch experiments. The kinetic process was very well described by a pseudo-second-order rate model. The adsorption isotherms showed that phosphate uptake fitted with a Langmuir-type model very well, with an increase of PO4(3-) adsorption capacity from 78.5 to 97.0 mg/g when the temperature increased from 298 to 338 K. The negative values of deltaG(0) and the positive values of deltaH(0) indicated that the phosphate adsorption process was spontaneous and endothermic naturally. While the deltaS(0) values obtained were positive, indicating an increase in randomness at the solid-liquid interface during the adsorption. Foreign anions tests showed that the presence of competitive ions cause minimal interference with the adsorption of phosphate on tantalum hydroxide.

  9. Layered double hydroxide nanoparticles as target-specific delivery carriers: uptake mechanism and toxicity.

    Science.gov (United States)

    Choi, Soo-Jin; Choy, Jin-Ho

    2011-07-01

    Layered double hydroxides (LDHs), also known as anionic nanoclays or hydrotalcite-like compounds, have attracted a great deal of interest for their potential as delivery carriers. In this article, we describe the cellular uptake behaviors and uptake pathway of LDHs in vitro and in vivo, which can not only explain the mechanism by which high efficacy of biomolecules delivered through LDH nanocarriers could be obtained, but also provide novel strategies to enhance their delivery efficiency. Toxicological effects of LDHs in cell lines and in animal models are also present, aiming at providing critical information about their toxicity potential, which should be carefully considered for their biomedical application. Understanding the uptake behaviors, uptake mechanism and toxicity of LDHs in terms of dose-response relationship, diverse physicochemical properties and interaction with different biological systems is important to optimize delivery efficiency as well as biocompatibility.

  10. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    Science.gov (United States)

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems.

  11. Operando formation of an ultra-low friction boundary film from synthetic magnesium silicon hydroxide additive

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Qiuying; Rudenko, Pavlo; Miller, Dean J.; Wen, Jianguo; Berman, Diana; Zhang, Yuepeng; Arey, Bruce; Zhu, Zihua; Erdemir, Ali

    2017-06-01

    The paper reports the operando and self-healing formation of DLC films at sliding contact surfaces by the addition of synthetic magnesium silicon hydroxide (MSH) nanoparticles to base oil. The formation of such films leads to a reduction of the coefficient of friction by nearly an order of magnitude and substantially reduces wear losses. The ultralow friction layer characterized by transmission electron microscope (TEM), electron energy loss spectroscopy (EELS), and Raman spectroscopy consists of amorphous DLC containing SiOx that forms in a continuous and self-repairing manner during operation. This environmentally benign and simple approach offers promise for significant advances in lubrication and reduced energy losses in engines and other mechanical systems.

  12. Layered double hydroxide using hydrothermal treatment: morphology evolution, intercalation and release kinetics of diclofenac sodium

    Science.gov (United States)

    Joy, Mathew; Iyengar, Srividhya J.; Chakraborty, Jui; Ghosh, Swapankumar

    2017-11-01

    The present work demonstrates the possibilities of hydrothermal transformation of Zn-Al layered double hydroxide (LDH) nanostructure by varying the synthetic conditions. The manipulation in washing step before hydrothermal treatment allows control over crystal morphologies, size and stability of their aqueous solutions. We examined the crystal growth process in the presence and the absence of extra ions during hydrothermal treatment and its dependence on the drug (diclofenac sodium (Dic-Na)) loading and release processes. Hexagonal plate-like crystals show sustained release with ˜90% of the drug from the matrix in a week, suggesting the applicability of LDH nanohybrids in sustained drug delivery systems. The fits to the release kinetics data indicated the drug release as a diffusion-controlled release process. LDH with rod-like morphology shows excellent colloidal stability in aqueous suspension, as studied by photon correlation spectroscopy.

  13. Structural perturbation of diphtheria toxoid upon adsorption to aluminium hydroxide adjuvant

    NARCIS (Netherlands)

    Regnier, Marie; Metz, Bernard; Tilstra, Wichard; Hendriksen, Coenraad; Jiskoot, Wim; Norde, Willem; Kersten, Gideon

    2012-01-01

    Aluminium-containing adjuvants are often used to enhance the potency of vaccines. In the present work we studied whether adsorption of diphtheria toxoid to colloidal aluminium hydroxide induces conformational changes of the antigen. Diphtheria toxoid has a high affinity for the aluminium hydroxide

  14. Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin.

    Science.gov (United States)

    Montero, Janaina Corazza; Mori, Graziela Garrido

    2012-01-01

    This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

  15. Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin

    Directory of Open Access Journals (Sweden)

    Janaina Corazza Montero

    2012-08-01

    Full Text Available This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

  16. Determination of Ultra-Trace Amounts of Selenium(IV) by Flow Injection Hydride Generation Atomic Absorption Spectrometry with On-line Preconcentration by Co-precipitation with Lanthanium Hydroxide. Part II. On-line Addition of Coprecipating Agent

    DEFF Research Database (Denmark)

    Nielsen, Steffen; Sloth, Jens Jørgen; Hansen, Elo Harald

    1996-01-01

    with hydrochloric acid, allowing an ensuing determination via hydride generation. At different sample flow rates, i.e., 4.8, 6.4 and 8.8 ml/min, enrichment factors of 30, 40 and 46, respectively, were obtained at a sampling frequency of 33 samples/h. The detection limit (3s) was 0.005 µg/l at a sample flow rate...

  17. Synthesis of nonspherical superparamagnetic particles: in situ coprecipitation of magnetic nanoparticles in microgels prepared by stop-flow lithography.

    Science.gov (United States)

    Suh, Su Kyung; Yuet, Kai; Hwang, Dae Kun; Bong, Ki Wan; Doyle, Patrick S; Hatton, T Alan

    2012-05-02

    We present the synthesis of nonspherical magnetic microparticles with multiple functionalities, shapes, and chemistries. Particle synthesis was performed in two steps: polymeric microparticles functionalized homogenously with carboxyl groups were generated using stop-flow lithography, and then in situ coprecipitation was used to grow magnetic nanoparticles at these carboxyl sites. With successive growth of magnetic nanoparticles, we obtained polymeric particles with saturation magnetizations of up to 42 emu/g microparticle. The growth in the magnetic nanoparticle mean size and polydispersity was determined from the magnetization curves obtained following each growth cycle; nanoparticle sizes were limited by the physical constraint of the effective mesh within the hosting gel microparticle. Particles with spatially segregated domains of varying magnetic properties (e.g., Janus particles, particles with step changes in magnetite concentration, etc.) can be synthesized readily using this approach. © 2012 American Chemical Society

  18. Effect of Co2+ and Ni2+-doped zinc borate nano crystalline powders by co-precipitation method

    Science.gov (United States)

    Shim, Jaesool; Venkata Reddy, Ch.; Sarma, G. V. S. S.; Narayana Murthy, P.; Ravikumar, R. V. S. S. N.

    2015-05-01

    A simple co-precipitation method has been used for the synthesis of Co2+ and Ni2+-doped zinc borate nanopowders. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV/Vis absorption, Scanning electron microscope (SEM) with EDS and photoluminescence (PL) spectroscopies techniques has been employed for their characterization. Powder X-ray diffraction data reveals that the crystal structure belongs to monoclinic for both as-prepared samples. SEM images showed surface morphology of the prepared samples. Optical absorption spectra showed the characteristic bands of doped ions in octahedral site symmetry. From the optical absorption data crystal field and inter-electronic repulsion parameters are evaluated. The FT-IR spectra showed the characteristic vibrational bands related to ZnO, BO3 and BO4 molecules. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions.

  19. Effect of Co(2+) and Ni(2+)-doped zinc borate nano crystalline powders by co-precipitation method.

    Science.gov (United States)

    Shim, Jaesool; Venkata Reddy, Ch; Sarma, G V S S; Narayana Murthy, P; Ravikumar, R V S S N

    2015-05-05

    A simple co-precipitation method has been used for the synthesis of Co(2+) and Ni(2+)-doped zinc borate nanopowders. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV/Vis absorption, Scanning electron microscope (SEM) with EDS and photoluminescence (PL) spectroscopies techniques has been employed for their characterization. Powder X-ray diffraction data reveals that the crystal structure belongs to monoclinic for both as-prepared samples. SEM images showed surface morphology of the prepared samples. Optical absorption spectra showed the characteristic bands of doped ions in octahedral site symmetry. From the optical absorption data crystal field and inter-electronic repulsion parameters are evaluated. The FT-IR spectra showed the characteristic vibrational bands related to ZnO, BO3 and BO4 molecules. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Room temperature ferromagnetism and luminescent behavior of Ni doped ZnO nanoparticles prepared by coprecipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Deepawali; Mahajan, Aman; Kaur, Parvinder; Singh, Gurinder Pal; Kumar, Sunil; Singh, D. P., E-mail: dpsinghdr@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Ashokan, K., E-mail: email-ashokaniuac@gmail.com [Material Science Division, Inter University Accelerator Centre, New Delhi-110067 (India)

    2016-05-23

    The samples of Zn{sub 1-x}Ni{sub x}O (x= 0.00 and 0.05) were prepared using coprecipitation method and annealed at different temperatures. The effect of Ni ion substitution on the structural and optical properties has been studied using X-ray Diffraction, UV-Visible, Photoluminescence and Magnetic measurements. XRD measurements demonstrate that all the prepared samples are wurtzite polycrystalline single phase in nature, ruling out the presence of any secondary phase formation. Ultraviolet visible measurements showed a decrease in band gap with the increase in annealing temperature and doping concentration. The PL data shows the red shift in all the samples and luminescence quenching with Ni doping. Compared to undoped ZnO, Ni doped ZnO showed room temperature ferromagnetism.