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Sample records for long-life microwave-assisted h

  1. Microwave-assisted one step synthesis of 8-arylmethyl-9H-purin-6-amines.

    Science.gov (United States)

    Tao, Hui; Kang, Yanlong; Taldone, Tony; Chiosis, Gabriela

    2009-01-15

    Molecular chaperone heat shock protein 90 (Hsp90) is an important target in cancer and neurodegenerative diseases, and has rapidly become the focus of several drug discovery efforts. Among small molecule Hsp90 inhibitors with clinical applicability are derivatives of 8-arylmethyl-9H-purin-6-amine class. Here we report the use of microwave-assisted chemistry for the successful one-pot delivery of 8-arylmethyl-9H-purin-6-amines. We discuss the applicability as well as the limitations of this method towards the creation of a large chemical diversity in the 8-arylmethyl-9H-purin-6-amine series.

  2. Microwave-assisted one step synthesis of 8-arylmethyl-9H-purin-6-amines

    OpenAIRE

    2008-01-01

    Molecular chaperone heat shock protein 90 (Hsp90) is an important target in cancer and neurodegenerative diseases, and has rapidly become the focus of several drug discovery efforts. Among small molecule Hsp90 inhibitors with clinical applicability are derivatives of 8-arylmethyl-9H-purin-6-amine class. Here we report the use of microwave-assisted chemistry for the successful one-pot delivery of 8-arylmethyl-9H-purin-6-amines. We discuss the applicability as well as the limitations of this me...

  3. A microwave-assisted and heteropolyacids-catalysed cyclocondensation reaction for the synthesis of 4(3H)-quinazolinones.

    Science.gov (United States)

    Ighilahriz, Karima; Boutemeur, Baya; Chami, Fariza; Rabia, Cherifa; Hamdi, Maâmar; Hamdi, Safouane M

    2008-04-03

    We have investigated a microwave-assisted synthesis of 4(3H)-quinazolinones by condensation of anthranilic acid, orthoesters (or formic acid) and substituted anilines,using Keggin-type heteropolyacids (H(3)PW(12)O(40).13H(2)O, H(4)SiW(12)O(40).13H(2)O,H(4)SiMo(12)O(40).13H(2)O or H(3)PMo(12)O(40).13H(2)O) as catalysts. We found that the the use of H(3)PW(12)O(40).13H(2)O acid coupled to microwave irradiation allows a solvent-free, rapid (approximately 13min) and high-yielding reaction.

  4. Microwave-assisted synthesis of novel 2H-chromene derivatives bearing phenylthiazolidinones and their biological activity assessment.

    Science.gov (United States)

    El Azab, Islam H; Youssef, Mohamed M; Amin, Mahmoud A

    2014-11-26

    6-Hydroxy-2-oxo-2H-chromene-4-carbaldehyde (2), 6-chloro-2-oxo-2H-chromene-4-carbaldehyde (3) and 6-hydrazinyl-4-methyl-2H-chromen-2-one (5) were prepared as single-pharmacophore motif key intermediates. Compounds 2, 3 and 5 were incorporated in a series of multicomponent reactions (MCRs), under microwave assistance as well as conventional chemical synthesis processes, to afford a series of three and/or four-pharmacophoric-motif conjugates 8a,b, 11, 13, 16, 17, 19 and 20 in good yields. The newly synthesized compounds were characterized by IR, NMR, 13C-NMR, MS and elemental analyses. Finally the synthesized compounds have been screened for their biological activity whereupon they exhibited remarkable antimicrobial activity on different classes of bacteria and the fungus.

  5. One-pot Microwave-Assisted Synthesis of 1H-Phenanthro[9,10- d][1,2,3]triazole

    Directory of Open Access Journals (Sweden)

    Mehrak Faraji

    2008-09-01

    Full Text Available In this study, a fast and good yield one-pot microwave-assisted synthesis (45 seconds of 1H-phenanthro[9,10-d][1,2,3]triazole by a 1,3-dipolar cycloaddition reaction of sodium azide and 9-bromophenanthrene in the presence of potassium tert-butoxide in DMSO as solvent is reported.

  6. High yield and facile microwave-assisted synthesis of conductive H{sub 2}SO{sub 4} doped polyanilines

    Energy Technology Data Exchange (ETDEWEB)

    Gizdavic-Nikolaidis, Marija R., E-mail: m.gizdavic@auckland.ac.nz [School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland, 1142 (New Zealand); Faculty of Physical Chemistry, Studentski Trg 12-16, PO Box 137, 11001, Belgrade (Serbia); Jevremovic, Milutin M. [Public Company Nuclear Facilities of Serbia, 12-14 Mike Petrovica Alasa, Vinca, 11351, Belgrade (Serbia); Milenkovic, Maja [Faculty of Physical Chemistry, Studentski Trg 12-16, PO Box 137, 11001, Belgrade (Serbia); Allison, Morgan C. [School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland, 1142 (New Zealand); Stanisavljev, Dragomir R. [Faculty of Physical Chemistry, Studentski Trg 12-16, PO Box 137, 11001, Belgrade (Serbia); Bowmaker, Graham A. [School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland, 1142 (New Zealand); Zujovic, Zoran D. [School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland, 1142 (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington, 6140 (New Zealand); Institute of General and Physical Chemistry, Studentski Trg 12-16, 11001, Belgrade (Serbia)

    2016-04-15

    The microwave-assisted synthesis of polyaniline (PANI) was performed using ammonium persulphate (APS) as oxidizing agent in 0.5 M–2.5 M concentration range of aqueous sulphuric acid (H{sub 2}SO{sub 4}) at 93 W applied microwave power of 10 min duration. The microwave (MW) synthesized PANIs had 3 times higher yield in comparison to PANI samples prepared using a classical method, CS (0 W MW power) at the same temperature for 10 min synthesis duration period. Fourier Transform Infrared (FTIR) and UV–Vis spectroscopies confirmed the formation of PANI structure in all products. The influence of H{sub 2}SO{sub 4} acid dopant on the spin concentration of MW and CS H{sub 2}SO{sub 4} doped PANI samples were examined by EPR spectroscopy, while the morphological characteristics were investigated by using scanning electron microscopy (SEM). XRD results showed amorphous phases in both MW and CS H{sub 2}SO{sub 4} doped PANI samples. Conductivity measurements revealed ∼1.5 times higher conductivity values for MW H{sub 2}SO{sub 4} doped PANI samples in comparison with PANI samples prepared by the CS method under same condition. The influence of sulfate anion in comparison to chloride anion as a dopant on morphological, dopant levels and conductivity properties of MW PANI samples were also investigated. - Highlights: • Nanoporous microwave synthesized doped polyanilines as chemical sensor material. • Morphology and physical properties of polyanilines depend on acid concentration. • Spin concentration is determined by the nature of the polyaniline synthesis.

  7. MICROWAVE-ASSISTED SYNTHESIS OF SOME 5(6)-NITRO-1H ...

    African Journals Online (AJOL)

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    reagents for the synthesis of 2-substitued benzimidazoles [5-9]. ... study, we wish to report the synthesis of 5-nitro-1H-benzimidazoles and their ... Diethyl Ether ... iminoester hydrochloride 1(a-d) (0.013 mol) in methanol (30 mL) were stirred at ...

  8. Plasma and Beam Production Experiments with HYBRIS, aMicrowave-assisted H- Ion

    Energy Technology Data Exchange (ETDEWEB)

    Keller, R. AUTHOR-Kwan, S.; Hahto, S.; Regis, M.; Wallig, J.

    2006-09-13

    A two-stage ion source concept had been presented a few years ago, consisting of a proven H- ion source and a 2.45-GHz Electron Cyclotron-Resonance (ECR) type ion source, here used as a plasma cathode. This paper describes the experimental development path pursued at Lawrence Berkeley National Laboratory, from the early concept to a working unit that produces plasma in both stages and creates a negative particle beam. Without cesiation applied to the second stage, the H{sup -} fraction of this beam is very low, yielding 75 micro-amperes of extracted ion beam current at best. The apparent limitations of this approach and envisaged improvements are discussed.

  9. Microwave-assisted pretreatment of woody biomass with ammonium molybdate activated by H2O2.

    Science.gov (United States)

    Verma, Pradeep; Watanabe, Takahito; Honda, Yoichi; Watanabe, Takashi

    2011-02-01

    Pretreatments for enzymatic saccharification are crucial for the establishment of lignocellulosic biorefineries. In this study, we focused on ammonium ions and peroxometal complexes as potential delignifying agents. We first examined the pretreatment of beech wood with nine different ammonium salts in the presence of H(2)O(2). Significant pretreatment effects were found only for ammonium molybdate, which is transformed to a peroxometal complex on reacting with H(2)O(2). Since microwave sensitizer effects are expected for (peroxo)molybdate, beech wood was pretreated using external heating and microwave irradiation. As a result, a maximum sugar yield of 59.5% was obtained by microwave irradiation at 140°C for 30 min, while external heating in an autoclave gave a sugar yield of 41.8%. We also found that an ammonium ion is the key counterion accelerating the pretreatment with molybdate. These results highlight the powerful selective delignifying capability of the H(2)O(2)-activated ammonium molybdate system energized by microwave radiation.

  10. Wax: A benign hydrogen-storage material that rapidly releases H2-rich gases through microwave-assisted catalytic decomposition.

    Science.gov (United States)

    Gonzalez-Cortes, S; Slocombe, D R; Xiao, T; Aldawsari, A; Yao, B; Kuznetsov, V L; Liberti, E; Kirkland, A I; Alkinani, M S; Al-Megren, H A; Thomas, J M; Edwards, P P

    2016-10-19

    Hydrogen is often described as the fuel of the future, especially for application in hydrogen powered fuel-cell vehicles (HFCV's). However, its widespread implementation in this role has been thwarted by the lack of a lightweight, safe, on-board hydrogen storage material. Here we show that benign, readily-available hydrocarbon wax is capable of rapidly releasing large amounts of hydrogen through microwave-assisted catalytic decomposition. This discovery offers a new material and system for safe and efficient hydrogen storage and could facilitate its application in a HFCV. Importantly, hydrogen storage materials made of wax can be manufactured through completely sustainable processes utilizing biomass or other renewable feedstocks.

  11. Wax: A benign hydrogen-storage material that rapidly releases H2-rich gases through microwave-assisted catalytic decomposition

    Science.gov (United States)

    Gonzalez-Cortes, S.; Slocombe, D. R.; Xiao, T.; Aldawsari, A.; Yao, B.; Kuznetsov, V. L.; Liberti, E.; Kirkland, A. I.; Alkinani, M. S.; Al-Megren, H. A.; Thomas, J. M.; Edwards, P. P.

    2016-01-01

    Hydrogen is often described as the fuel of the future, especially for application in hydrogen powered fuel-cell vehicles (HFCV’s). However, its widespread implementation in this role has been thwarted by the lack of a lightweight, safe, on-board hydrogen storage material. Here we show that benign, readily-available hydrocarbon wax is capable of rapidly releasing large amounts of hydrogen through microwave-assisted catalytic decomposition. This discovery offers a new material and system for safe and efficient hydrogen storage and could facilitate its application in a HFCV. Importantly, hydrogen storage materials made of wax can be manufactured through completely sustainable processes utilizing biomass or other renewable feedstocks. PMID:27759014

  12. Degradation of H-acid in aqueous solution by microwave assisted wet air oxidation using Ni-loaded GAC as catalyst

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yao-bin; QUAN Xie; ZHAO Hui-min; CHEN Shuo; YANG Feng-lin

    2005-01-01

    A novel process, microwave assisted catalytic wet air oxidation(MW-CWO), was applied for the degradation of H-acid( 1-amino8-naphthol-3, 6-disulfonic acid) in aqueous solution. Ni-loaded granular activated carbon (GAG), prepared by immersion-calcination method, was used as catalyst. The results showed that the MW-CWO process was very effective for the degradation of H-acid in aqueous solution under atmospheric pressure with 87.4% TOC (total organic carbon) reduction in 20 min. Ni on GAC existed in the form of NiO as specified by XRD. Loss of Ni was significant in the initial stage, and then remained almost constant after 20 min reaction. BET surface area results showed that the surface property of GAC after MW-CWO process was superior to that of blank GAC.

  13. Microwave-assisted one-pot synthesis and anti-biofilm activity of 2-amino-1H-imidazole/triazole conjugates.

    Science.gov (United States)

    Steenackers, Hans; Ermolat'ev, Denis; Trang, Tran Thi Thu; Savalia, Bharat; Sharma, Upendra K; De Weerdt, Ami; Shah, Anamik; Vanderleyden, Jozef; Van der Eycken, Erik V

    2014-06-14

    A microwave-assisted protocol was developed for the construction of 2-amino-1H-imidazole/triazole conjugates starting from the previously described 2-hydroxy-2,3-dihydro-1H-imidazo[1,2-a]pyrimidin-4-ium salts. The process involves a one-pot hydrazinolysis/Dimroth-rearrangement of these salts followed by a ligand-free copper nanoparticle-catalyzed azide-alkyne Huisgen cycloaddition. The 2-amino-1H-imidazole/triazole conjugates showed moderate to high preventive activity against biofilms of S. Typhimurium, E. coli, P. aeruginosa and S. aureus. The most active compounds had BIC50 values between 1.3 and 8 μM. A remarkable finding was that introduction of the triazole moiety into the side chain of 2-aminoimidazoles with a long (C8-C13) 2N-alkyl chain did drastically improve their activity. Conclusively, the 2-amino-1H-imidazole/triazole scaffold provides a lead structure for further design and development of novel biofilm inhibitors.

  14. Iodine Catalyzed Microwave-Assisted Synthesis of 14-Aryl(Alkyl)-14H-dibenzo[a,j]xanthenes

    Institute of Scientific and Technical Information of China (English)

    DING,Fei-Qing; AN,Li-Tao; ZOU,Jian-Ping

    2007-01-01

    A straightforward and effective procedure for the synthesis of 14-aryl(alkyl)-14H-dibenzo[a,j]xanthenes was described using a catalytic amount of molecular iodine under microwave irradiation to afford the corresponding xanthenes in good yields.

  15. Microwave-assisted Chemical Transformations

    Science.gov (United States)

    In recent years, there has been a considerable interest in developing sustainable chemistries utilizing green chemistry principles. Since the first published report in 1986 by Gedye and Giguere on microwave assisted synthesis in household microwave ovens, the use of microwaves as...

  16. Microwave assisted synthesis of novel 4h-chromene derivatives bearing phenoxypyrazole and their antimicrobial activity assess

    Directory of Open Access Journals (Sweden)

    Sangani Chetan B.

    2012-01-01

    Full Text Available A new series of 4H-chromene derivatives 4(a-p bearing 5-phenoxypyrazole nucleus has been synthesized under microwave irradiation by reaction of 5-phenoxypyrazole-4-carbaldehyde 1(a-h, malononitrile 2 and compounds (Cyclohexanedione, Dimedon 3(a-b in presence of NaOH as basic catalyst. All the compounds were screened against three Gram positive bacteria (Streptococcus pneumoniae, Clostridium tetani, Bacillus subtilis, three Gram negative bacteria (Salmonella typhi, Vibrio cholerae, Escherichia coli and two fungi (Aspergillus fumigatus, Candida albicans using broth microdilution MIC (Minimum Inhibitory Concentration method. Upon study of antimicrobial screening, it has been observed that, majority of the compounds were found to be active against Clostridium tetani and Bacillus subtilis as well as against Candida albicans as compared to standard drugs.

  17. Crystal structure of 5-butylamino-3-methyl-1-(pyridin-2-yl-1H-pyrazole-4-carbaldehyde obtained from a microwave-assisted reaction using caesium carbonate as catalyst

    Directory of Open Access Journals (Sweden)

    Mario A. Macías

    2016-11-01

    Full Text Available The title compound, C14H18N4O, synthesized from an unconventional microwave-assisted method using caesium carbonate as catalyst, has an approximately planar conformation with the pyridyl and pyrazole rings inclined by a dihedral angle of 7.94 (3°, allowing the formation of an intramolecular N—H...N hydrogen bond. The supramolecular assembly has a three-dimensional arrangement controlled mainly by weak C—H...O and C—H...π interactions.

  18. Microwave-assisted synthesis of bismuth oxide

    Directory of Open Access Journals (Sweden)

    Eva Bartonickova

    2007-12-01

    Full Text Available Single phase and ultrafine bismuth oxide was synthesized via microwave-assisted hydrothermal synthesis. The effect of reaction parameters (temperature/pressure and pH on the product phase composition and morphology was discussed. The transformation of bismuth hydroxide into bismuth oxide was controlled by pH value and it was accelerated by time and temperature. The phase composition of reaction products was strongly dependent on pH value. The amorphous products were obtained at acidic pH conditions and the crystalline single phase product α-Bi2O3 phase was obtained at pH ≥12. The particle size was reduced from micrometric to nanometric size in the presence of a chelating agent. The bismuth hydroxides into bismuth oxides transformation mechanism, consisting in polycondensation ofBi–OH bounds to Bi–O–Bi bridges and crystallization of Bi2O3, was proposed.

  19. Effect of ionic liquid amount (C{sub 8}H{sub 15}BrN{sub 2}) on the morphology of Bi{sub 2}Te{sub 3} nanoplates synthesized via a microwave-assisted heating approach

    Energy Technology Data Exchange (ETDEWEB)

    Ji Guangbin [Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, College of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Shi Yi, E-mail: yshi@nju.edu.cn [Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, College of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Pan Lijia; Zheng Youdou [Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, College of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2011-05-19

    Highlights: > Rapidly synthesis Bi{sub 2}Te{sub 3} nanoplates via a microwave-assisted ionic liquid method. > Ionic liquid plays a key role on the morphologies of the samples. > Single-crystal in nature with the growth direction of <112-bar 0>. > Power factor gets a maximum at about 450 K. - Abstract: Bi{sub 2}Te{sub 3} crystals with plate-like morphology have been successfully synthesized via a microwave-assisted heating approach in room temperature ionic liquid (RTIL) of 1-butyl-3-methylimidazolium bromide (C{sub 8}H{sub 15}BrN{sub 2}). Scanning electronic microscopy (SEM) observation of as-synthesized Bi{sub 2}Te{sub 3} confirmed their morphology of the hexagonal plates. It was observed that the edge and thickness values of as-synthesized Bi{sub 2}Te{sub 3} were in the size of 0.5-2 {mu}m and less than 100 nm, respectively. High-resolution transmission electronic microscopy (HR-TEM) and selected area electron diffraction (SAED) results revealed that the Bi{sub 2}Te{sub 3} plates are of single-crystal in nature with the growth direction of <112-bar 0>. In addition, as increasing the amount of ionic liquid, SEM results showed a novel evolution process of Bi{sub 2}Te{sub 3} morphologies from mixture of Bi{sub 2}Te{sub 3} nanorods and nanoplates to regular hexagonal plates, and then nanoplates with many small flecks. Furthermore, a possible mechanism regarding the formation of Bi{sub 2}Te{sub 3} plates was proposed as well on the basis of the experimental results. The power factor of Bi{sub 2}Te{sub 3} nanoplates is examined to evaluate its thermoelectric property.

  20. Microwave Assisted Synthesis of 1-[5-(Substituted Aryl-1H-Pyrazol-3-yl]-3,5-Diphenyl-1H-1,2,4-Triazole as Antinociceptive and Antimicrobial Agents

    Directory of Open Access Journals (Sweden)

    Shantaram Gajanan Khanage

    2014-05-01

    Full Text Available Purpose: An efficient technique has been developed for microwave assisted synthesis of 1-[5-(substituted aryl-1H-pyrazol-3-yl]-3,5-diphenyl-1H-1,2,4-triazole as antinociceptive and antimicrobial agents. Methods: The desired compounds (S1-S10 were synthesized by the microwave irradiation via cyclization of formerly synthesized chalcones of 3,5-diphenyl-1H-1,2,4-triazole and hydrazine hydrate in mild acidic condition. All newly synthesized compounds were subjected to study their antinociceptive and antimicrobial activity. The analgesic potential of compounds was tested by acetic acid induced writhing response and hot plate method. The MIC values for antimicrobial activity were premeditated by liquid broth method. Results: The compounds S1, S2, S4, S6 and S10 were found to be excellent peripherally acting analgesic agents when tested on mice by acetic acid induced writhing method and compounds S3, S6 and S1 at dose level of 100 mg/kg were exhibited superior centrally acting antinociceptive activity when tested by Eddy’s hot plate method. In antimicrobial activity compound S10 found to be broad spectrum antibacterial agent at MIC value of 15.62 μg/ml and compound S6 was exhibited antifungal potential at 15.62 μg/mL on both fungal strains. Conclusion: Some novel pyrazoles clubbed with 1,2,4-triazole derivatives were synthesized and evaluated as possible antimicrobial, centrally and peripherally acting analgesics.

  1. A facile microwave assisted one-pot synthesis of novel 1-methylhexahydroquinazolin-5(6H-ones and bis-1-methylhexahydroquinazolin-5(6H-ones

    Directory of Open Access Journals (Sweden)

    Madhusudhan Saha

    2011-03-01

    Full Text Available Novel hexahydroquinazolin-5(6H-ones 3a-j have been synthesized in good yields by the reaction of enaminones 2a-b with primary amines and formaldehyde under the influence microwaves. Enaminones 2a-b have also been reacted with diamines and formaldehyde under similar conditions resulting in hitherto unreported bis- hexahydroquinazolin-5(6H-ones 4a-d and 5a-d. The structures of the molecules have been established with the help of spectral and analytical data.

  2. Microwave-assisted Weak Acid Hydrolysis of Proteins

    Directory of Open Access Journals (Sweden)

    Miyeong Seo

    2012-06-01

    Full Text Available Myoglobin was hydrolyzed by microwave-assisted weak acid hydrolysis with 2% formic acid at 37 oC, 50 oC, and100 oC for 1 h. The most effective hydrolysis was observed at 100 oC. Hydrolysis products were investigated using matrixassistedlaser desorption/ionization time-of-flight mass spectrometry. Most cleavages predominantly occurred at the C-termini ofaspartyl residues. For comparison, weak acid hydrolysis was also performed in boiling water for 20, 40, 60, and 120 min. A 60-min weak acid hydrolysis in boiling water yielded similar results as a 60-min microwave-assisted weak acid hydrolysis at100 oC. These results strongly suggest that microwave irradiation has no notable enhancement effect on acid hydrolysis of proteinsand that temperature is the major factor that determines the effectiveness of weak acid hydrolysis.

  3. Microwave assisted template synthesis of silver nanoparticles

    Indian Academy of Sciences (India)

    K J Sreeram; M Nidhin; B U Nair

    2008-12-01

    Easier, less time consuming, green processes, which yield silver nanoparticles of uniform size, shape and morphology are of interest. Various methods for synthesis, such as conventional temperature assisted process, controlled reaction at elevated temperatures, and microwave assisted process have been evaluated for the kind of silver nanoparticles synthesized. Starch has been employed as a template and reducing agent. Electron microscopy, photon correlation spectroscopy and surface plasmon resonance have been employed to characterize the silver nanoparticles synthesized. Compared to conventional methods, microwave assisted synthesis was faster and provided particles with an average particle size of 12 nm. Further, the starch functions as template, preventing the aggregation of silver nanoparticles.

  4. Microwave-assisted extraction of polycyclic aromatic compounds from coal.

    Science.gov (United States)

    Kerst, M; Andersson, J T

    2001-08-01

    Microwave-assisted extraction (MAE) of polycyclic aromatic compounds (PACs) from coal is shown to give the same pattern of compounds as Soxhlet extraction. MAE requires only 10 mL solvent and 10 min extraction time whereas Soxhlet uses 200 mL and takes 24 h. Although the yields were lower, dichloromethane (DCM) was preferred to pyridine, N-methyl-2-pyrrolidone (NMP), and NMP with CS2 because the pattern of the PACs is shown to be independent of solvent and DCM is a much more convenient solvent to work with.

  5. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Ning, Rong [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Ding, E-mail: ma97chen@hotmail.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Qianxia [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Bian, Zhibing; Dai, Haixiong; Zhang, Chi [Jiangsu Jinling Special Paint Co., Ltd., Yangzhou 225212 (China)

    2014-10-15

    Highlights: • TiH{sub 2} was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH{sub 2} with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process.

  6. Microwave-assisted synthesis of novel 5-trichloromethyl-4,5-dihydro-1H-1-pyrazole methyl esters under solvent free conditions

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcos A.P.; Beck, Paulo; Machado, Pablo; Brondani, Sergio; Moura, Sidnei; Zanatta, Nilo; Bonacorso, Helio G.; Flores, Alex F.C. [Universidade Federal de Santa Maria, RS (Brazil). Dept. de Quimica. Nicleo de Quimica de Heterociclos (NUQUIMHE)]. E-mail: mmartins@base.ufsm.br

    2006-03-15

    Twelve novel 5-trichloromethyl-4,5-dihydro-1H-1-pyrazole ethyl esters have been synthesized in good yields (70-98%) by using environmentally benign microwave induced techniques. The compounds were synthesized from the cyclocondensation of 1,1,1-trichloro-4-alkoxy-3-alken-2-ones [CCl3{sub C}(O)C(R{sup 2})=C(R{sup 1} )OR, where R, R{sup 2} = H, alkyl; R{sup 1} = H, alkyl and aryl] with hydrazine methyl carboxylate. The advantages obtained by the using of microwave irradiation under solvent-free conditions, rather than a conventional method, were demonstrated. (author)

  7. Microwave-assisted synthesis of self-assembled BiO{sub 1.84}H{sub 0.08} hierarchical nanostructures as a new photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Pei; Hou, Dongfang; Shi, Hongyu; Chen, Chaoji; Huang, Yunhui; Hu, Xianluo, E-mail: huxl@mail.hust.edu.cn

    2014-11-15

    Highlights: • Hierarchical BiO{sub 1.84}H{sub 0.08} nanostructures were prepared by microwave irradiation. • The microwave-hydrothermal method is rapid, one-pot, and low-temperature. • The morphology of the BiO{sub 1.84}H{sub 0.08} nanostructures can be tailored. • The photocatalytic properties were studied upon UV–visible irradiation. • Self-assembled flower-like BiO{sub 1.84}H{sub 0.08} shows enhanced photocatalytic activity. - Abstract: Self-assembled hierarchical nanostructures of BiO{sub 1.84}H{sub 0.08} spheres have been successfully synthesized by a rapid, one-pot, low-temperature hydrothermal route under microwave irradiation. The as-prepared hierarchically nanostructured BiO{sub 1.84}H{sub 0.08} possesses a high surface area of 113 m{sup 2} g{sup −1}. By adjusting the reaction temperature and reactant concentration, the morphology of the as-formed BiO{sub 1.84}H{sub 0.08} nanostructures can be tailored. As a new photocatalyst, the flower-like spherical BiO{sub 1.84}H{sub 0.08} exhibits enhanced photocatalytic activity for degradation of Rhodamine B (RhB) under UV–visible light. The synthetic procedure is simple, efficient, and scalable for mass production. Therefore, the as-formed BiO{sub 1.84}H{sub 0.08} hierarchical nanostructures may offer great potential applications for decomposition of organic contaminants.

  8. Microwave assisted catalytic wet air oxidation of H-acid in aqueous solution under the atmospheric pressure using activated carbon as catalyst.

    Science.gov (United States)

    Zhang, Yaobin; Quan, Xie; Chen, Shuo; Zhao, Yazhi; Yang, Fenglin

    2006-09-01

    Catalytic wet air oxidation (CWAO) is a promising method for the treatment of heavily contaminated wastewater. However, its application is restricted due to severe operation conditions (high pressure and high temperature). A microwave (MW) assisted oxidation method was investigated aiming to treat heavily contaminated wastewater under milder conditions. H-acid (1-amino-8-naphthol-3, 6-disulfonic acid) was selected as target compound to evaluate the performance of this novel process. The removal of H-acid and TOC (total organic carbon) for H-acid solution of 3000 mg/L reached as high as 92.6% in 20 min and 84.2% in 60 min, respectively under optimal conditions. The existence of activated carbon and oxygen proved to be critical for effective treatment. The activated carbon acted not only as a catalyst for H-acid decomposition, but also as a special material for the absorption of MW energy. Air was supplied to the reactor as an oxygen source at constant flows. The amino group in H-acid was converted ultimately into nitrate, and sulfonic group into sulfate. This observation gave an evidence of H-acid mineralization although other organic intermediates were unable to be determined. The value of BOD(5)/COD (ratio of 5d biochemical oxygen demand to chemical oxygen demand) increased from 0.008 to 0.467 indicating a significant improvement of biodegradability for the solution, which is beneficial for the further biological treatment of the wastewater.

  9. Microwave-Assisted Transesterification of Macroalgae

    Directory of Open Access Journals (Sweden)

    Angel Sanchez

    2012-03-01

    Full Text Available Nowadays microwave radiation is being researched to produce biodiesel from different raw materials due to the many advantages that this technology presents compared to traditional transesterification, such as shorter reaction times and less amount of heat energy to obtain biodiesel. The aim of this research was to explore the possibility of carrying out the microwave-assisted transesterification of macroalgae and compare the results with the traditional transesterification. For that reason, some experiences were conducted using sunflower oil and macroalgae as raw material. Based on the obtained results, the best conditions for microwave-assisted transesterification reaction were macroalgae to methanol ratio of 1:15 (wt/vol, sodium hydroxide concentration of 2 wt % and reaction time of 3 min.

  10. Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation

    Directory of Open Access Journals (Sweden)

    Pradipta Kumar Basu

    2011-01-01

    Full Text Available Two new effective methodologies have been adopted for the preparation of 4-(2′-bromobenzyloxybenzopyran-7-ones 3(a–h. In the first methodology, 4-hydroxy[1]benzopyran-2-ones 1(a–d was alkylated with 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b under phase transfer catalysis condition using lithium hydroxide/tetrabutyl ammonium bromide in N,N-dimethylformamide at 40–50°C and in the second method the microwave irradiation protocol has been exploited by simply mixing of 4-hydroxy[1]benzopyran-2-ones 1(a–d with 25% excess of 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b. A catalytic amount of TBAB and potassium carbonate were added and irradiated in an open Erlenmeyer flask in a microwave oven for 4–10 min. The tributyltin-hydride-mediated radical cyclisation of 3(a–h was carried out under microwave irradiation to generate 12H-benzopyrano[3,2-c][1]benzopyran-5-ones 4(a–h in 78–88% yield and in this technique yields were significantly improved and reaction time was shortened compared to the previously reported conventional radical cyclisation method.

  11. Microwave assisted synthesis of a series of charge-transfer photosensitizers having quinoxaline-2(1H)-one as anchoring group onto TiO2 surface

    Science.gov (United States)

    Caicedo, Mauricio; Echeverry, Carlos A.; Guimarães, Robson R.; Ortiz, Alejandro; Araki, Koiti; Insuasty, Braulio

    2017-04-01

    In this work, we present the synthesis of novel donor-acceptor compounds based on 3-methylquinoxaline-2(1H)one which follow an easy synthetic route, involving Knoevenagel reaction with electron-donor groups such as N,N-dimethylaminobenzene, ferrocene, triphenylamine (TPA) and ((E)-4,4'-(ethene-1,2-diyl) bis (N,N-diphenylaniline). Additionally, the optical properties were measured by means of the absorption and emission spectroscopy suggesting a push-pull behavior which was further confirmed by electrochemical experiments. Finally, the quinoxaline-2(1H)one fragment not only bestow wide absorption, but also can chelate to titanium ions on the TiO2 surface, allowing a strong electron coupling between the excited-state energy level of the dyes and the conduction band of TiO2.

  12. Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.

    Science.gov (United States)

    Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

    2014-01-30

    FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data.

  13. Microwave-assisted Heterogeneous Photocatalytic Oxidation of Ethylene%C2H4的微波场助气相光催化氧化

    Institute of Scientific and Technical Information of China (English)

    郑宜; 付贤智; 李旦振

    2001-01-01

    用溶胶-凝胶法制备了多孔性TiO2和SO2-4/TiO2催化剂, 对其结构进行了表征, 并以C2H4为模型反应物考察了微波对催化剂的光催化氧化反应性能的影响. 在微波场中TiO2和SO2-4/TiO2催化剂的光催化氧化性能得到明显改善, 无微波场时乙烯转化率分别为20%(TiO2)和41%(SO2-4/TiO2), 而在微波辐射和紫外光的同时作用下乙烯转化率分别提高到27%和62%, SO2-4/TiO2催化剂的微波场助效应更为显著.%Porous TiO2 and SO2-4/TiO2 catalysts were prepared by sol-gel method and charaterized by XRD, N2 sorption analysis applying BET method, and microwave absorption spectrum. Photocatalytic oxidation of C2H4 in air stream was studied. The results showed that the photocatalytic activity of both SO2-4/TiO2 and TiO2 catalysts was obviously increased under the reaction condition of ultraviolet combined with microwave. The conversions of ethylene over TiO2 and SO2-4/TiO2 were enhanced from 20% and 41%(UV) to 27% and 62%(UV+MW), respectively. The effect of MW on SO2-4/TiO2 catalyst was more notable. The improvement on photocatalytic activity was attributed to the polarization effect of the highly defected catalysts in microwave field, which increased the transition probability of photon-generated electrons and decreased the electron-hole recombination on semiconductor surface.

  14. Microwave-assisted enzymatic synthesis of beef tallow biodiesel.

    Science.gov (United States)

    Rós, Patrícia C M Da; Castro, Heizir F de; Carvalho, Ana K F; Soares, Cleide M F; Moraes, Flavio F de; Zanin, Gisella M

    2012-04-01

    Optimal conditions for the microwave-assisted enzymatic synthesis of biodiesel have been developed by a full 2² factorial design leading to a set of seven runs with different combinations of molar ratio and temperature. The main goal was to reduce the reaction time preliminarily established by a process of conventional heating. Reactions yielding biodiesel, in which beef tallow and ethanol used as raw materials were catalyzed by lipase from Burkholderia cepacia immobilized on silica-PVA and microwave irradiations within the range of 8-15 W were performed to reach the reaction temperature. Under optimized conditions (1:6 molar ratio of beef tallow to ethanol molar ratio at 50°C) almost total conversion of the fatty acid presented in the original beef tallow was converted into ethyl esters in a reaction that required 8 h, i.e., a productivity of about 92 mg ethyl esters g⁻¹ h⁻¹. This represents an increase of sixfold for the process carried out under conventional heating. In general, the process promises low energy demand and higher biodiesel productivity. The microwave assistance speeds up the enzyme catalyzed reactions, decreases the destructive effects on the enzyme of the operational conditions such as, higher temperature, stability, and specificity to its substrate, and allows the entire reaction medium to be heated uniformly.

  15. Application and research advancement on the microwave-assisted extraction

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; ZHENG Xianzhe

    2007-01-01

    This paper summarized application and research advancement of the microwave-assisted extraction in the agriculture,food industry, environmental analytical chemistry, traditional Chinese medicine industry, and so on. The microwave-assisted extraction was manifested to be a simple device, wide area of application, high extraction efficiency, good reproducibility and low consumption of agent and time as well as low environmental pollution. At present, industrialization question of the microwave-assisted extraction technology has been attached importance, which will impel the microwave-assisted extraction technology to more development in the future.

  16. Microwave assisted synthesis and biological activity of novel coumarinyltriazolothiadiazoles

    Directory of Open Access Journals (Sweden)

    Kumar P

    2010-01-01

    Full Text Available A series of new 3-(4-methylcoumarinyl-7-oxymethyl-6-substitutedphenyl-5,6-dihydro-s-triazolo (3,4-b(1,3,4-thiadiazoles 2(a-j have been synthesized by reacting 5-(4-methyl coumarinyl-7-oxymethyl-4-amino-3-mercapto(4H-1,2,4-triazole with various aromatic aldehydes by microwave assisted organic synthesis. The structure of the compounds 2 (a-j has been confirmed by IR, 1 H NMR and mass spectral data. All the compounds were screened for antimicrobial and antioxidant activity. Among the compounds tested, compounds 2d (4-dimethyl amino phenyl derivative and 2h (3,4-dimethoxy phenyl derivative showed better antimicrobial and antioxidant activity than rest of the compounds in the series.

  17. Microwave-assisted synthesis of arene Ru(Ⅱ) complex [(η6-C6H5) Ru(PIP) Cl]Cl·2H2O%微波辅助合成芳烃钌(Ⅱ)配合物[(η6-C6H5)Ru(PIP)Cl]Cl·2H2O

    Institute of Scientific and Technical Information of China (English)

    陈艾纯; 吴琼; 陈燕华; 梅文杰; 吴韦黎; 胡晓莹; 吴剑; 汪保国

    2013-01-01

    目的 探讨应用微波辅助合成技术制备芳烃钌(Ⅱ)化合物[(η6-C6H6)Ru(PIP) Cl] Cl·2H2O(3).方法 首先以RuCl3·nH2O、1,3-环己二烯和1,10-邻菲哕啉为原料微波辐射下制备得到芳烃钌前体[(η6-C6H6)RuCl2]2(1)和2-苯基-咪唑并[4,5f][1,10]菲哕啉(PIP,2),然后,在二氯甲烷溶液中,微波辐射1与2制备芳烃钌(Ⅱ)配合物3;采用ESI-MS、IR、1H-NMR、13C-NMR对目标配合物进行表征.结果 60℃条件下,化合物1与2在二氯甲烷溶液微波辐射30 min,制备得到了芳烃钌配合物3,反应产率为90.3%;目标产物经ESI-MS、IR、1H-NMR和13C-NMR表征,实验值与理论值基本一致.结论 与传统加热方法相比,微波辅助合成芳烃钌配合物明显缩短了反应时间,提高了反应产率.%Objective To research the preparation of arene Ru( Ⅱ ) complex [η6-C6H6)RU(PIP)Cl]Cl· 2H2O(3) by using microwave-assisted synthesis technology. Methods [ ( η6 -C6H6 ) RuCl2 ]2 (1) was synthesized from RuCl2 · nH2O and 1,3-cyclohexadiene by using microwave-assisted synthesis technology, and 2-phenyl-imidazole[4,5/] [1,10]phenanthroline (PIP,2) also synthesized from 1,10-phenanthroline-5 ,6-dione and benzaldehyde under microwave irradiation, and then 2 and 3 were mixed in CH2Cl2 solution to prepare [ (η6-C6H6)Ru( PIP) Cl] Cl · 2H2O (3) under the irradiation microwave. The target complex 3 was characterized by using ESI-MS, IR,1H-NMR and 13C-NMR spectra. Results Arene Ru( Ⅱ ) complex 3 was prepared from 1 and 2 in CH2Cl2 at 60℃ for 30 min under microwave irradiation with a yield of 90. 3%,and characterized by ESI-MS, IR,1H-NMR and 13C-NMR spectra. Conclusion A novel arene ruthenium ( Ⅱ ) complexes 3 have been synthesized under the irradiation of microwave, and with far more less time and higher yield compared with the conventional method.

  18. Microwave-assisted rapid characterization of lipase selectivities.

    Science.gov (United States)

    Bradoo, Sapna; Rathi, Pooja; Saxena, R K; Gupta, Rani

    2002-04-18

    A rapid screening procedure for characterization of lipase selectivities using microwaves was developed. The rate of reaction of various commercial lipases (porcine pancreas, Mucor miehei, Candida rugosa, Pseudomonas cepacia) as well as lipases from laboratory isolates-Bacillus stearothermophilus and Burkholderia cepacia RGP-10 for triolein hydrolysis was 7- to 12-fold higher in a microwave oven as compared to that by pH stat. The esterification of sucrose/methanol and ascorbic acid with different fatty acids was also achieved within 30 s in a microwave using porcine pancreas, B. stearothermophilus SB-1 and B. cepacia RGP-10 lipases. The relative rates and selectivity of the lipases both for hydrolytic and synthesis reactions remains unaltered. However, the rate of reaction was dynamically enhanced when exposed to microwaves. Microwave-assisted enzyme catalysis can become an attractive procedure for rapid characterization of large number of enzyme samples and substrates, which otherwise is a cumbersome and time-consuming exercise.

  19. Microwave-Assisted Hydrothermal Synthesis of Cellulose/Hydroxyapatite Nanocomposites

    Directory of Open Access Journals (Sweden)

    Lian-Hua Fu

    2016-09-01

    Full Text Available In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH2PO4·2H2O, or organic phosphorus sources (adenosine 5′-triphosphate disodium salt (ATP, creatine phosphate disodium salt tetrahydrate (CP, or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH2PO4·2H2O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

  20. RAPID SOLVENT-FREE MICROWAVE ASSISTED SYNTHESIS OF SOME N’-BENZYLIDENE SALICYLIC ACID HYDRAZIDES

    Directory of Open Access Journals (Sweden)

    Tutuk Budiati

    2012-06-01

    Full Text Available Condensation reaction has been carried out for the synthesis of some N'-benzylidene-2-hydroxybenzohydrazides using microwave assisted solvent-free method. The structures of all the products obtained in the present work are supported by spectral and analytical data (UV, IR, and 1H-NMR spectroscopy. The desired hydrazides are in 62-80% yields under microwave irradiation. The reaction was completed in 8-10 min.

  1. Optimization of microwave assisted extraction of pectin from orange peel.

    Science.gov (United States)

    Prakash Maran, J; Sivakumar, V; Thirugnanasambandham, K; Sridhar, R

    2013-09-12

    In this study, microwave-assisted extraction was applied for pectin extraction from the dried orange peel and Box-Behnken response surface design was used to study and optimize the effects of processing variables (microwave power, irradiation time, pH and solid-liquid ratio) on the yield of pectin. The amount of pectin extracted increased with increasing microwave power, while it reduces as the time, pH and solid-liquid ratio increased. From the results, second order polynomial model was developed and it adequately explained the data variation and significantly represented the actual relationship between independent variables and the response. An optimization study using Derringer's desired function methodology was performed and optimal conditions based on both individual and combinations of all independent variables (microwave power of 422W, irradiation time of 169 s, pH of 1.4 and solid-liquid ratio of 1:16.9 g/ml) were determined with maximum pectin yield of 19.24%, which was confirmed through validation experiments.

  2. A study of thermal properties of sodium titanate nanotubes synthesized by microwave-assisted hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Preda, Silviu, E-mail: predas01@yahoo.co.uk [Institute of Physical Chemistry “Ilie Murgulescu”, 202 Splaiul Independentei, 060021 Bucharest (Romania); Rutar, Melita [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Jožef Stefan International Postgraduate School, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Umek, Polona [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Zaharescu, Maria [Institute of Physical Chemistry “Ilie Murgulescu”, 202 Splaiul Independentei, 060021 Bucharest (Romania)

    2015-11-15

    Highlights: • The microwave-assisted hydrothermal route was used for titanate nanotubes synthesis. • Conversion to single-phase nanotube morphology completes after 8 h reaction time. • The nanotube morphology is stable up to 600 °C, as determined by in-situ XRD and SEM. • Sodium ions migrate to the surface due to thermal motion and structure condensation. - Abstract: Sodium titanate nanotubes (NaTiNTs) were synthesized by microwave-assisted hydrothermal treatment of commercial TiO{sub 2}, at constant temperature (135 °C) and different irradiation times (15 min, 1, 4, 8 and 16 h). The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry and specific surface area measurements. The irradiation time turned out to be the key parameter for morphological control of the material. Nanotubes were observed already after 15 min of microwave irradiation. The analyses of the products irradiated for 8 and 16 h confirm the complete transformation of the starting TiO{sub 2} powder to NaTiNTs. The nanotubes are open ended with multi-wall structures, with the average outer diameter of 8 nm and specific surface area up to 210 m{sup 2}/g. The morphology, surface area and crystal structure of the sodium titanate nanotubes synthesized by microwave-assisted hydrothermal method were similar to those obtained by conventional hydrothermal method.

  3. Comparison of Microwave-Assisted and Hydrodistillation Methods for Extraction of Essential Oil from Achillea millefolium

    Directory of Open Access Journals (Sweden)

    S. Mollasalehi

    2013-08-01

    Full Text Available Microwave-assisted hydrodistillation (MAHD method has been compared with hydrodistillation (HD conventional technique for extraction of essential oil from Achillea millefolium. Microwave-assisted hydrodistillation were examined at three levels of microwave powers (300, 500, and 700 W. Obtained results show that MAHD offers important advantages over HD in terms of energy savings and extraction time (20 min against 2.5 h. Also, the essential oils were analyzed by GC-MS. The amount of oxygenated compounds and monoterpene, such as 1,8 -Cineole, Lavandulyl acetate,Caryophylla-dien, Aromadendrene were increased in the microwave method. All these results suggest that MAHD represents an excellent alternative method for extraction of essential oils from plant materials.

  4. Microwave-assisted Synthesis of Arene Ru(Ⅱ) Complex [(η6-C6H6) Ru(H2iiP) Cl] Cl in SiC Vessel%SiC管中微波辅助芳烃钌(Ⅱ)化合物[(η6-C6H6)Ru(H2iiP)Cl]Cl的合成

    Institute of Scientific and Technical Information of China (English)

    吴琼; 梅文杰; 吴韦黎; 陈燕华; 曾玲莉; 郑文杰

    2013-01-01

    使用SiC管为反应容器,在微波辐射条件下以[(6-C6H6)RuCl2]2为原料与2-(吲哚基)咪唑[4,5-f]-[1,10]菲啰啉(H2iiP)反应,制得芳烃钌(Ⅱ)化合物[(η6-C6H6)Ru(H2iiP) C1]Cl(1),并对其进行了表征.采用正交实验法确定反应的最佳合成条件为:投料比n([(η6-C6 H6)RuCl2]2)∶n(H2iiP)=1∶2.2,反应温度90℃,微波辐射时间30 min.该反应的平均产率达到96.0%,反应产率的相对标准偏差(RSD)为1.28%,说明微波辐射条件下,在SiC管中能够高产率地制备芳烃钌化合物,并且反应具有良好的重现性.进一步采用MTT方法研究发现,芳烃钌(Ⅱ)化合物1能够选择性抑制MCF-7乳腺癌的生长.%Arene Ru(Ⅱ) complex [(η6-C6H6) Ru(H2iiP) Cl] Cl(1) was synthesized using [(η6-C6H6)·RuCl2] 2 and 2-indole-3-imidazole [4,5-f] [1,10] phenanthroline (H2 iiP) as raw material under microwave irradiation.The target compound was characterized by means of elemental analysis,ESI-MS,IR and NMR.The best craft condition determined by orthogonal test is that reactant molar ratio of 1.0 ∶ 2.2,the reaction temperature of 90 ℃ and the microwave irradiation time of 30 min.Then the average yield of 96.0% and RSD of 1.28% confirmed that microwave-assisted synthesis of arene Ru(Ⅱ) complex in SiC vessel gives a good stability and reiteration.The antitumor activity of arene Ru (Ⅱ) complex 1 was determined by MTT assay and the results showed that complex 1 could selectively inhibit the growth of MCF-7,indicating its potential utility in chemotherapy.

  5. Microwave-Assisted Synthesis of Cinnamyl Long Chain Aroma Esters.

    Science.gov (United States)

    Worzakowska, Marta

    2015-06-08

    Cinnamyl long chain aroma esters were prepared by using the conventional and microwave-assisted methods. The esterification reaction of naturally occurring 3-phenyl-prop-2-en-1-ol and different chain lengths acidic and diol reagents was carried out at the temperature of 140 °C under solvent free conditions. As acidic reagents, oxolane-2,5-dione, oxane-2,6-dione, hexanedioic acid and decanedioic acid were applied. Ethane-1,2-diol and 2,2'-[oxybis(2,1-ethandiyloxy)]diethanol were used as diol reagents. The synthesis of high molecular mass cinnamyl esters under conventional method conditions requires a long time to obtain high yields. The studies confirm that by using microwave irradiation, it is possible to reduce the reaction times to only 10-20 min. The structures of prepared esters were confirmed on the basis of FTIR, 1H-NMR and 13C-NMR. In addition, the newly obtained cinnamyl long chain esters were tested for their thermal properties. The TG studies proved the high thermal resistance of the obtained esters under inert and oxidative conditions.

  6. Preliminary study: kinetics of oil extraction from sandalwood by microwave-assisted hydrodistillation

    Science.gov (United States)

    Kusuma, H. S.; Mahfud, M.

    2016-04-01

    Sandalwood and its oil, is one of the oldest known perfume materials and has a long history (more than 4000 years) of use as mentioned in Sanskrit manuscripts. Sandalwood oil plays an important role as an export commodity in many countries and its widely used in the food, perfumery and pharmaceuticals industries. The aim of this study is to know and verify the kinetics and mechanism of microwave-assisted hydrodistillation of sandalwood based on a second-order model. In this study, microwave-assisted hydrodistillation is used to extract essential oils from sandalwood. The extraction was carried out in ten extraction cycles of 15 min to 2.5 hours. The initial extraction rate, the extraction capacity and the second-order extraction rate constant were calculated using the model. Kinetics of oil extraction from sandalwood by microwave-assisted hydrodistillation proved that the extraction process was based on the second-order extraction model as the experimentally done in three different steps. The initial extraction rate, h, was 0.0232 g L-1 min-1, the extraction capacity, C S, was 0.6015 g L-1, the second-order extraction rate constant, k, was 0.0642 L g-1 min-1 and coefficient of determination, R 2, was 0.9597.

  7. Microwave-assisted organic acid extraction of lignin from bamboo: structure and antioxidant activity investigation.

    Science.gov (United States)

    Li, Ming-Fei; Sun, Shao-Ni; Xu, Feng; Sun, Run-Cang

    2012-10-01

    Microwave-assisted extraction in organic acid aqueous solution (formic acid/acetic acid/water, 3/5/2, v/v/v) was applied to isolate lignin from bamboo. Additionally, the structural features of the extracted lignins were thoroughly investigated in terms of C₉ formula, molecular weight distribution, FT-IR, (1)H NMR and HSQC spectroscopy. It was found that with an increase in the severity of microwave-assisted extraction, there was an increase of phenolic hydroxyl content in the lignin. In addition, an increase of the severity resulted in a decrease of the bound carbohydrate content as well as molecular weight of the lignin. Antioxidant activity investigation indicated that the radical scavenging index of the extracted lignins (0.35-1.15) was higher than that of BHT (0.29) but lower than that of BHA (3.85). The results suggested that microwave-assisted organic acid extraction provides a promising way to prepare lignin from bamboo with good antioxidant activity for potential application in the food industry. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Microwave-assisted pyrolysis of biomass for liquid biofuels production

    DEFF Research Database (Denmark)

    Yin, Chungen

    2012-01-01

    Production of 2nd-generation biofuels from biomass residues and waste feedstock is gaining great concerns worldwide. Pyrolysis, a thermochemical conversion process involving rapid heating of feedstock under oxygen-absent condition to moderate temperature and rapid quenching of intermediate products......, is an attractive way for bio-oil production. Various efforts have been made to improve pyrolysis process towards higher yield and quality of liquid biofuels and better energy efficiency. Microwave-assisted pyrolysis is one of the promising attempts, mainly due to efficient heating of feedstock by ‘‘microwave...... dielectric heating’’ effects. This paper presents a state-of-the-art review of microwave-assisted pyrolysis of biomass. First, conventional fast pyrolysis and microwave dielectric heating is briefly introduced. Then microwave-assisted pyrolysis process is thoroughly discussed stepwise from biomass...

  9. Microwave-assisted extraction of polysaccharides from solanum nigrum

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-qing; LIU-qin; JIANG xin-yu; ZENG fan

    2005-01-01

    The microwave-assisted method was used to extract polysaccharides from solanum nigrum. The optimum experimental parameters, mechanism of the extraction and the effect of microwave-assisted extraction process on the structures of polysaccharides were investigated. The extract was analyzed by the modified phenol-sulfuric acid method at 490 nm. The optimum experimental parameters were obtained by orthogonal experiments as follows: extraction time 15 min, microwave radiation power 455 W and the process ratio of materials mass to solvent volume 1∶20. The results show that compared with the conventional reflux extraction, the microwave-assisted extraction has a higher yield in shorter time, with no effect on the finally obtained polysaccharides as seen from the FT-IR spectra. The scanning electron microscopy images reveal that the mechanism of the extraction is related to the structural changes of the plant cells in different extracting conditions.

  10. Microwave-assisted 1T to 2H phase reversion of MoS2 in solution: a fast route to processable dispersions of 2H-MoS2 nanosheets and nanocomposites

    Science.gov (United States)

    Xu, Danyun; Zhu, Yuanzhi; Liu, Jiapeng; Li, Yang; Peng, Wenchao; Zhang, Guoliang; Zhang, Fengbao; Fan, Xiaobin

    2016-09-01

    Exfoliated molybdenum disulfide (MoS2) has unique 2H phase and semiconductor properties and potential applications across a wide range of fields. However, the chemically exfoliated MoS2 nanosheets from Li x MoS2 have a 1T phase, and searching for a fast route to get processable 2H-MoS2 nanosheets and its nanocomposites is still an urgent task. This study reports on a simple, fast and efficient microwave strategy to achieve the 1T to 2H phase conversion of MoS2 and the successful preparation of processable 2H-MoS2 nanosheets and their nanocomposites. The method here may be easily changed to achieve the phase change of other exfoliated TMDs.

  11. Microwave-assisted synthesis of new aryliminothiazolylidene-2-thiazolidin-4-ones and their azarhodacyanines analogues

    Directory of Open Access Journals (Sweden)

    Souad Kasmi-Mir

    2014-07-01

    Full Text Available We here report an efficient microwave-assisted protocol for the synthesis of new arylimino-thiazolylidene-2-thiazolidin-4-ones 6 and their azarhodacyanines derivatives 7 with quantitative yield from 2'-(methylthio-4'-oxo-3H,4'H-[2,5-bithiazolylidene]-3'-ium tosylates 5 and 2-arylimino-5-(thiazol-2(3H-ylidene thiazolidin-4-ones 6, respectively, using as starting material the 4-thiazoline-2-thiones 1 and 3-methyl-2-thioxo-1,3-thiazolidin-4-one 3. The transformation of the tosylate salts 5 into their arylimino derivatives 6 has not been reported to date.

  12. Microwave-assisted extraction kinetics of terpenes from caraway seeds

    NARCIS (Netherlands)

    Chemat, S.; Ait-Amar, H.; Lagha, A.; Esveld, D.C.

    2005-01-01

    The process conditions during the extraction of carvone and limonene from caraway seed (Carum carvi L.) with microwave-assisted extraction have been studied with respect to microwave power, radiation dose and extraction time in order to obtain the secondary metabolites selectively. Using classical s

  13. Microwave-Assisted Synthesis of "N"-Phenylsuccinimide

    Science.gov (United States)

    Shell, Thomas A.; Shell, Jennifer R.; Poole, Kathleen A.; Guetzloff, Thomas F.

    2011-01-01

    A microwave-assisted synthesis of "N"-phenylsuccinimide has been developed for the second-semester organic teaching laboratory. Utilizing this procedure, "N"-phenylsuccinimide can be synthesized in moderate yields (40-60%) by heating a mixture of aniline and succinic anhydride in a domestic microwave oven for four minutes. This technique reduces…

  14. Efficient Microwave-Assisted Synthesis of 5-Deazaflavine Derivatives

    Directory of Open Access Journals (Sweden)

    Justo Cobo

    2010-10-01

    Full Text Available A series of pyrimido[4,5-b]quinolines  (5-deazaflavines, were synthesized by microwave assisted intramolecular cyclization. The N4-substituted-2,4-diamino-6-chloro-pyrimidine-5-carbaldehydes, were prepared by selective monoamination of 2-amino-4,6-dichloropyrimidine-5-carbaldehyde with aliphatic and aromatic amines.

  15. Design of guanidinium ionic liquid based microwave-assisted extraction for the efficient extraction of Praeruptorin A from Radix peucedani.

    Science.gov (United States)

    Ding, Xueqin; Li, Li; Wang, Yuzhi; Chen, Jing; Huang, Yanhua; Xu, Kaijia

    2014-12-01

    A series of novel tetramethylguanidinium ionic liquids and hexaalkylguanidinium ionic liquids have been synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids were confirmed by (1)H NMR spectroscopy and mass spectrometry. A green guanidinium ionic liquid based microwave-assisted extraction method has been developed with these guanidinium ionic liquids for the effective extraction of Praeruptorin A from Radix peucedani. After extraction, reversed-phase high-performance liquid chromatography with UV detection was employed for the analysis of Praeruptorin A. Several significant operating parameters were systematically optimized by single-factor and L9 (3(4)) orthogonal array experiments. The amount of Praeruptorin A extracted by [1,1,3,3-tetramethylguanidine]CH2CH(OH)COOH is the highest, reaching 11.05 ± 0.13 mg/g. Guanidinium ionic liquid based microwave-assisted extraction presents unique advantages in Praeruptorin A extraction compared with guanidinium ionic liquid based maceration extraction, guanidinium ionic liquid based heat reflux extraction and guanidinium ionic liquid based ultrasound-assisted extraction. The precision, stability, and repeatability of the process were investigated. The mechanisms of guanidinium ionic liquid based microwave-assisted extraction were researched by scanning electron microscopy and IR spectroscopy. All the results show that guanidinium ionic liquid based microwave-assisted extraction has a huge potential in the extraction of bioactive compounds from complex samples.

  16. Perlite-SO3H nanoparticles as an efficient and reusable catalyst for one-pot three-component synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives under both microwave-assisted and thermal solvent-free conditions: Single crystal X-ray structure analysis and theoretical study

    Directory of Open Access Journals (Sweden)

    Ali Ramazani

    2016-01-01

    Full Text Available A general synthetic route for the synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives has been developed using perlite-SO3H nanoparticles as efficient catalyst under both microwave-assisted and thermal solvent-free conditions. The combination of 2-naphthol, aldehyde and urea enabled the synthesis of 1,2-dihydro-1-aryl-naphtho[1,2-e][1,3]oxazine-3-one derivatives in the presence of perlite-SO3H nanoparticles in good to excellent yields. This method provides several advantages like simple work-up, environmentally benign, and shorter reaction times along with high yields. In order to explore the recyclability of the catalyst, the perlite-SO3H nanoparticles in solvent-free conditions were used as catalyst for the same reaction repeatedly and the change in their catalytic activity was studied. It was found that perlite-SO3H nanoparticles could be reused for four cycles with negligible loss of their activity. Single crystal X-ray structure analysis and theoretical studies also were investigated for 4i product. The electronic properties of the compound have been analyzed using DFT calculations (B3LYP/6-311+G*. The FMO analysis suggests that charge transfer takes place within the molecule and the HOMO is localized mainly on naphthalene and oxazinone rings whereas the LUMO resides on the naphthalene ring.

  17. Synthesis of nanostructured and microstructured ZnO and Zn(OH)2 on activated carbon cloth by hydrothermal and microwave-assisted chemical bath deposition methods

    Science.gov (United States)

    Mosayebi, Elham; Azizian, Saeid; Hajian, Ali

    2015-05-01

    Nanostructured and microstructured ZnO and Zn(OH)2 loaded on activated carbon cloth were synthesized by microwave-assisted chemical bath deposition and hydrothermal methods. By hydrothermal method the deposited sample on carbon fiber is pure ZnO with dandelion-like nanostructures. By microwave-assisted chemical bath method the structure and composition of deposited sample depends on solution pH. At pH = 9.8 the deposited sample on carbon fiber is pure ZnO with flower-like microstructure; but at pH = 10.8 the sample is a mixture of ZnO and Zn(OH)2 with flower-like and rhombic microstructures, respectively. The mechanism of crystal grow by microwave-assisted chemical bath method was investigated by SEM method at both pH.

  18. The preparation of nano-composite Ag-H6P2W18062/Ti02 and microwave assisted photocatalytic degradation of methyl orange%纳米复合材料Ag-H6P2W18O62/TiO2的制备与微波辅助光催化甲基橙

    Institute of Scientific and Technical Information of China (English)

    蒋新德; 邢北平; 计远; 张文治; 李莉

    2012-01-01

    The nano-composite material Ag-H6P2W18O62/TiO2 in this study was prepared by sol-gel method combined with temperature-programmed hydrothermal treatment. The phase structures, chemical composition, opticalabsorption properties and surface physicochemical properties were characterized via FTIR, ICP-AES, XRD, nitrogen adsorption/desorption and TEM. The results showed the basic structure of polyoxometaltes in the composites has been basicly matained. The composites Ag-H6P2W18O62/TiO2 are periodical mesoporous materials, and the silver species existing in the nano-composite Ag-H6P2W18O62/TiO2 was metallic Ag. The photocatalytic activities of the as-prepared material were studied by the microwave assisted photodegradation of methyl orange. The results showed that the photocatalytic activitiy of Ag-H6P2W18O62/TiO2 for methyl orange was higher.%采用溶胶一凝胶再结合程序升温溶剂热一步法制备了纳米复合光催化材料Ag-HeP2WtsOJTiO2,并采用傅立叶一红外光谱(FT-IR)、等离子原子反射光谱(ICP-AES)、氮气吸附一脱附测定和透射电子显微镜(TEM)等测试方法Ag-H6P2W18O62/TiO2合成材料的物理化学性质进行了表征。结果表明,复合材料中母体多酸的基本结构未发生明显变化,其Agl)J单质形式存在,且显示为介孔材料。在微波场作用下,复合材料Ag-H6P2W18O62/TiO2对甲基橙的降解表现了较高的催化活性。

  19. Fast, microwave-assisted synthesis of monodisperse HfO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roo, Jonathan De; Keukeleere, Katrien De; Feys, Jonas; Lommens, Petra [Ghent University, Sol-Gel Centre for Research on Inorganic Powders and Thin Films Synthesis (SCRiPTS) (Belgium); Hens, Zeger [Ghent University, Physics and Chemistry of Nanostructures (PCN) (Belgium); Driessche, Isabel Van, E-mail: Isabel.VanDriessche@ugent.be [Ghent University, Sol-Gel Centre for Research on Inorganic Powders and Thin Films Synthesis (SCRiPTS) (Belgium)

    2013-07-15

    A conventional solvothermal synthesis was compared to a microwave-assisted method for the synthesis of HfO{sub 2} nanoparticles. In a microwave, the reaction could be completed in 3 h, compared to 3 days in an autoclave. In the microwave synthesis, the ensemble of particles was found to have a better size dispersion and a smaller average size (4 nm). The reaction mechanism was investigated and proof for an ether elimination process was provided. Post-synthetic modification with dopamine or dodecanoic acid permitted the suspension of the synthesized particles in both polar and apolar solvents, which is an advantage for further processing.

  20. Rapid synthesis of tantalum oxide dielectric films by microwave microwave-assisted atmospheric chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ndiege, Nicholas [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801 (United States)], E-mail: ndiege@uiuc.edu; Subramanian, Vaidyanathan [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801 (United States)], E-mail: ravisv@unr.edu; Shannon, Mark A. [Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green street, Urbana, IL 61801 (United States)], E-mail: mshannon@uiuc.edu; Masel, Richard I. [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801 (United States)], E-mail: r-masel@uiuc.edu

    2008-10-01

    Microwave-assisted chemical vapor deposition has been used to generate high quality, high-k dielectric films on silicon at high deposition rates with film thicknesses varying from 50 nm to 110 {mu}m using inexpensive equipment. Characterization of the post deposition products was performed by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy and Raman spectroscopy. Film growth was determined to occur via rapid formation and accumulation of tantalum oxide clusters from tantalum (v) ethoxide (Ta(OC{sub 2}H{sub 5}){sub 5}) vapor on the deposition surface.

  1. Microwave assisted extraction of phenolic compounds from four different spices.

    Science.gov (United States)

    Gallo, Monica; Ferracane, Rosalia; Graziani, Giulia; Ritieni, Alberto; Fogliano, Vincenzo

    2010-09-09

    Spices and herbs are known not only for their taste, aroma and flavour, but also for their medical properties and value. Both spices and herbs have been used for centuries in traditional medical systems to cure various kinds of illnesses such as common cold, diabetes, cough and cancers. The aim of this work was the comparison between two different extractive techniques in order to get qualitative and quantitative data regarding bioactive compounds of four different spices (Cinnamomum zeylanicum, Coriandrum sativum, Cuminum cyminum, Crocus sativus). The plants were extracted employing ultrasonication and microwave-assisted extractions. The efficiency of extraction of bioactive compounds obtained with the microwave extraction process was in general about four times higher than that resulting from sonication extraction. The various extracts obtained were analyzed for their antioxidant activity using ABTS, DPPH and FRAP assays and for their total polyphenolic content. It can be concluded that microwave-assisted extractions provide significant advantages in terms of extraction efficiency and time savings.

  2. Microwave assisted wet oxidation of p-nitrophenol

    Institute of Scientific and Technical Information of China (English)

    BO; Longli; CHEN; Shuo; QUAN; Xie; LIU; Xitao; ZHAO; Huimin

    2005-01-01

    Aqueous solution of p-nitrophenol (PNP) was treated continuously by microwave assisted wet oxidation while flowing through a granular activated carbon (GAC) fixed bed. PNP was pre-adsorbed onto GAC prior to being put into the reactor so as to prevent PNP adsorption on GAC during microwave irradiation. PNP solutions with different initial concentration (218.6 mg/L and 1200 mg/L) were treated under conditions of microwave power 500 W, liquid flow 6.4 mL/min and air flow 40 mL/min or 60 mL/min. The results indicated that the removal of PNP was higher than 90% and more than 65% PNP was mineralized. Phenol, nitrobenzene, hydroquinone and benzoquinone occurred as course products during the operation process, which were degraded further. The biodegradability of the outflow was improved greatly by microwave assisted wet oxidation.

  3. Dynamic Microwave-assisted Extraction of Flavonoids from Radix Scutellariae

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Dynamic microwave-assisted extraction(DMAE) of flavonoids from Radix Scutellarie was described in this article. A TM010 microwave resonant cavity was used as the energy coupler. Several parameters of DMAE, including concentration, flow rate, volume of the extraction solvent, and irradiation power, were optimized. The extraction was performed under the optimum conditions for the extraction of total flavonoids. The total flavonoids were determined by UV-Vis spectrophotometry. The main bioactive components, including baicalin, baicalein, and wogonin, were determined by HPLC. The extraction yields of the flavonoids obtained by DMAE were compared with those obtained by pressurized microwave assisted extraction( PMAE), ultrasonic extraction ( UE ), soxhlet extraction ( SE ), and reflux extraction( RE), and these results indicate that DMAE is a good alternative method for the extraction of flavonoids from Radix Scutellarie.

  4. Study on microwave-assisted extraction of coal

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; LU Jun-qing; GE Ling-mei; Li Jian-wei

    2007-01-01

    The effect of different factors on coal extraction yield-temperature,solvent,coal type and irradiation time were investigated for different China coals under microwave-assisted extraction(MAE).The results show that the optimum temperature for ethanol,acetone and THF are 393,373 and 373 K respectively and the extraction yield of THF is higher than that of other two solvents under MAE.Extraction with several single organic solvents were conducted for the 5 typical China coals-Shenfu,Tongchuan,Panzhihua,Yitai and Huating coal under microwave-assisted extraction and Soxhlet extraction.Resuits indicat that extraction yield of ethylenediamine,ethanol,acetone,tetrahydrofuran under MAE are are higher than that of Soxhlet extraction and MAE required less time.Tonqchuan coal extracts of ethanol and acetone which were extracted by MAE and Soxhlet extraction were analyzed by GC/MS.

  5. A Rapid Microwave-Assisted Thermolysis Route to Highly Crystalline Carbon Nitrides for Efficient Hydrogen Generation.

    Science.gov (United States)

    Guo, Yufei; Li, Jing; Yuan, Yupeng; Li, Lu; Zhang, Mingyi; Zhou, Chenyan; Lin, Zhiqun

    2016-11-14

    Highly crystalline graphitic carbon nitride (g-C3 N4 ) with decreased structural imperfections benefits from the suppression of electron-hole recombination, which enhances its hydrogen generation activity. However, producing such g-C3 N4 materials by conventional heating in an electric furnace has proven challenging. Herein, we report on the synthesis of high-quality g-C3 N4 with reduced structural defects by judiciously combining the implementation of melamine-cyanuric acid (MCA) supramolecular aggregates and microwave-assisted thermolysis. The g-C3 N4 material produced after optimizing the microwave reaction time can effectively generate H2 under visible-light irradiation. The highest H2 evolution rate achieved was 40.5 μmol h(-1) , which is two times higher than that of a g-C3 N4 sample prepared by thermal polycondensation of the same supramolecular aggregates in an electric furnace. The microwave-assisted thermolysis strategy is simple, rapid, and robust, thereby providing a promising route for the synthesis of high-efficiency g-C3 N4 photocatalysts. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. MICROWAVE-ASSISTED SURFACE MODIFICATION OF CALCIUM BICARBONATE

    Institute of Scientific and Technical Information of China (English)

    Jing Ye; Xiaofei Zhang

    2004-01-01

    Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious superiority to those of powder samples treated by traditional surface modification method and of untreated calcium bicarbonate - in suspension turbidity, suction potential, contact angle with water, and mechanical properties of their composites with PVC resin.

  7. Microwave assisted synthesis of 6-Substituted aminopurine analogs in water

    OpenAIRE

    Qu, Guirong; Han,Suhui; Zhang,Zhiguang; Geng,Mingwei; Xue, Feng

    2006-01-01

    Microwave assisted amination of 6-chloropurine derivatives with various amines in water resulted in a "green chemistry" protocol for the preparation of 6-substituted aminopurine analogs in very good yields. Using a simply modified microwave oven with the refluxing apparatus, the amination of the 6-chloro in the purine structure occurred smoothly. 19 known and 16 unknown 6-substituted aminopurine analogs were prepared through nucleophilic aromatic substitution with simple filtration or column ...

  8. Microwave-Assisted Solid Phase Organic Synthesis.Application to Indole Library Construction

    Institute of Scientific and Technical Information of China (English)

    DAI Wei-Min; SUN Li-Ping; GUO Dian-Shun; HUANG Xiang-Hong

    2004-01-01

    Microwave-assisted organic synthesis (MAOS) has attained increasing popularity due to recent advancement in the instrumentation of microwave technology. Now, MAOS can be performed under controlled temperature and pressure to yield reproducible results. For combinatorial chemistry,the dramatically increased reaction rate under microwave irradiation at high temperature provides an ideal solution to those sluggish reactions, in particular the combinatorial reactions carried out on solid supports. In this presentation, we describe our results on microwave-assisted solid-phase organic synthesis (MASPOS) applied to the construction of indole libraries such as 5. Compounds 4 were synthesized on the Rink amide resins using IRORI MicroKanTM reactors encoded with a radio-frequency (Rf) tag. The resin-bound terminal alkynes 2, prepared via the amide bond, were cross-coupled with the nitroaryl triflate under the conditions adopted from the solution reactions developed by us1,2. The nitro group of 3 was then reduced and sulfonylated to give 4. Ring closure reactions within 4 with Cu(OAc)2 were examined initially in refluxing DCE for 24 h, but no indole product was detected after cleavage from the resin. Therefore, the same reactions were carried out under microwave irradiation at 200 ℃ for 10 min on a Personal Chemistry Emrys Creator, the desired indoles 5 were obtained in 60-95% overall yields calculated from 1 and in >90% purities in most cases3. It is necessary to mention that the IRORI microreactors cannot tolerate the high temperature and the resin-bound 4 must be transferred to the reaction vials for the microwave-assisted ring closure reactions. A traceless synthesis of an indole library via MASPOS will be discussed as well.4

  9. Microwave-assisted extraction in toxicological screening of skeletal tissues.

    Science.gov (United States)

    Desrosiers, Nathalie A; Betit, Caroline C; Watterson, James H

    2009-07-01

    The use of microwave-assisted extraction (MAE) in screening of decomposed bone tissue for model drugs of abuse is described. Rats received 50 mg/kg (i.p.) pentobarbital (n=2), 75 mg/kg (i.p.) ketamine (n=2) or 16 mg/kg (i.p.) diazepam (n=1), or remained drug-free (control). Drug-positive animals were euthanized within 20 min of drug administration. Animal remains were allowed to decompose in a secure outdoor environment to the point of complete skeletonization. Bones (tibiae, femora, vertebrae, ribs, pelvi, humeri and scapulae) were collected and pooled (according to drug) in order to minimize effects due to inter-bone differences in drug distribution. Bones were crushed and cleaned of marrow and residual soft tissue in alkaline solution or phosphate buffer with ultrasonication. Cleaned bones were then ground and underwent MAE in phosphate buffer (pH 6), methanol or a methanol:water mixture (1:1, v/v) at atmospheric pressure in a domestic microwave oven, or passive extraction in methanol. Bone extracts (control and drug-exposed) containing methanol were evaporated to dryness before reconstitution in phosphate buffer (pH 6) and subsequent analysis by ELISA, while bone extracts containing only phosphate buffer were assayed directly by the same ELISA protocol. Measured absorbance values were expressed as the decrease in absorbance, measured as a percentage, relative to the corresponding drug-free control bone extract. The semi-quantitative nature of the ELISA assay allowed examination of the effects of extraction solvent and bone sample mass on the assay response for each drug examined, and subsequent comparison to assays of extracts obtained through passive methanolic extraction of various bone tissues. Overall, the time required for maximal extraction varied with extraction solvent and bone mass for each drug investigated, with significant extraction occurring with all solvent systems examined. MAE may represent a substantially faster extraction system than passive

  10. Determination of Pt from coke samples by ICP-MS after microwave assisted digestion and microwave assisted cloud point extraction

    Energy Technology Data Exchange (ETDEWEB)

    Niemela, M.; Huttunen, S.M.; Gornostayev, S.S.; Peramaki, P. [University of Oulu, Oulu (Finland). Dept. of Chemistry

    2009-09-15

    Platinum in coke samples was determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted sample digestion and temperature controlled microwave assisted cloud point extraction (MW-CPE). Interferences due to hafnium were successfully eliminated using MW-CPE with 2-MBT prior to the determination of platinum by ICP-MS. The validity of the method was studied by spike recovery tests and by analyzing certified reference material (BCR-723 street dust). The results obtained for platinum in the BCR-723 were generally in good agreement with the certified values. Furthermore, the preliminary platinum results obtained for coke sample by ICP-MS after MW-CPE were compared to those obtained by a reference method (NiS-Fire Assay preconcentration/Te coprecipitation and ICP-MS determination).

  11. Antioxidative Peptides Derived from Enzyme Hydrolysis of Bone Collagen after Microwave Assisted Acid Pre-Treatment and Nitrogen Protection

    Directory of Open Access Journals (Sweden)

    Jin Sun

    2010-11-01

    Full Text Available This study focused on the preparation method of antioxidant peptides by enzymatic hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection. Phosphoric acid showed the highest ability of hydrolysis among the four other acids tested (hydrochloric acid, sulfuric acid and/or citric acid. The highest degree of hydrolysis (DH was 9.5% using 4 mol/L phosphoric acid with a ratio of 1:6 under a microwave intensity of 510 W for 240 s. Neutral proteinase gave higher DH among the four protease tested (Acid protease, neutral protease, Alcalase and papain, with an optimum condition of: (1 ratio of enzyme and substrate, 4760 U/g; (2 concentration of substrate, 4%; (3 reaction temperature, 55 °C and (4 pH 7.0. At 4 h, DH increased significantly (P < 0.01 under nitrogen protection compared with normal microwave assisted acid pre-treatment hydrolysis conditions. The antioxidant ability of the hydrolysate increased and reached its maximum value at 3 h; however DH decreased dramatically after 3 h. Microwave assisted acid pre-treatment and nitrogen protection could be a quick preparatory method for hydrolyzing bone collagen.

  12. Microwave assisted synthesis of 2-(2-(tetrazolo[1,5-a]quinolin-4-yl-2,3-dihydro-1h-benzo[b][1,4]diazepin-4-yl substituted phenols and evaluation of their antimicrobial activity

    Directory of Open Access Journals (Sweden)

    Ashok Dongamanti

    2016-01-01

    Full Text Available A series of new benzodiazepines 4a-h have been synthesized by Michael addition of chalcones 3a-h with o-phenylenediamine (OPDA in presence of sodium acetate under conventional heating and microwave irradiation. Structures of the newly synthesized benzodiazepines 4a-h have been established on the basis of IR, 1H & 13C NMR and mass spectral data and tested for antimicrobial activity.

  13. An efficient, microwave-assisted, one-pot synthesis of novel 5,6,7,8-tetrahydroquinoline-3-carbonitriles

    Directory of Open Access Journals (Sweden)

    VIRESH H. SHAH

    2011-06-01

    Full Text Available An efficient, microwave-assisted synthesis of novel 2-alkoxy-5,6,7,8--tetrahydroquinoline-3-carbonitriles, which have not hitherto been reported, via reactions of cyclohexanone and arylidene malononitriles in the corresponding alcohols in presence of sodium is described. All the newly synthesized compounds were characterized by the IR, 1H-NMR, 13C-NMR and mass spectrescopic techniques and by elemental analyses. The newly synthesized compounds were evaluated for their antibacterial and antifungal activities.

  14. SINTESIS PATI JAGUNG TERFOSFORILASI MELALUI TEKNIK GELOMBANG MIKRO [Microwave-Assisted Synthesis of Phosphorylated Corn Starch

    Directory of Open Access Journals (Sweden)

    Atep Dian Supardan*

    2014-06-01

    Full Text Available Phosphorylated starch is a type of modified starches which is mostly imported. Commonly, starch to be modified must contain more than 25% of amylose. This study aimed to synthesize phosphorylated starch and evaluate its potency as a heavy metal adsorbent. Corn starch was subjected to phosphorylation through microwave-assisted reaction with a mixture of sodium dihydrogen orthophosphate and disodium hydrogen phosphate. The experiment was designed to optimize the pH, microwave radiation power, and phosphorylation time. The results showed that the maximum phosphate subtitution degree was obtained at pH of 6, microwave radiation of 500 W, and a reaction time of 10 minutes. The degree of subtitution ranged from 0.567 to 0.787. The physicochemical properties of the product i.e. swelling capacity, solubility, water binding capacity, and paste clarity were significantly different than that of the unmodified corn starch. The infrared spectrum showed a high peak absorption at the wavelength of 1651 cm-1, indicating hydrogen bond formation of phosphoric group-water- phosphoric group. In the fingerprint area, there were two new absorption peaks at 1200 and 990 cm-1, which were assigned for the P=O and C-O-P vibrations, respectively. The phosphorylated corn starch adsorbed methylene blue up to 73.3% and mercury up to 73.6%, suggesting the prospect of the microwave-assisted synthetic phosphorylated corn starch as an effective adsorbent for heavy metals.

  15. Sequential ultrasound-microwave assisted acid extraction (UMAE) of pectin from pomelo peels.

    Science.gov (United States)

    Liew, Shan Qin; Ngoh, Gek Cheng; Yusoff, Rozita; Teoh, Wen Hui

    2016-12-01

    This study aims to optimize sequential ultrasound-microwave assisted extraction (UMAE) on pomelo peel using citric acid. The effects of pH, sonication time, microwave power and irradiation time on the yield and the degree of esterification (DE) of pectin were investigated. Under optimized conditions of pH 1.80, 27.52min sonication followed by 6.40min microwave irradiation at 643.44W, the yield and the DE value of pectin obtained was respectively at 38.00% and 56.88%. Based upon optimized UMAE condition, the pectin from microwave-ultrasound assisted extraction (MUAE), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) were studied. The yield of pectin adopting the UMAE was higher than all other techniques in the order of UMAE>MUAE>MAE>UAE. The pectin's galacturonic acid content obtained from combined extraction technique is higher than that obtained from sole extraction technique and the pectin gel produced from various techniques exhibited a pseudoplastic behaviour. The morphological structures of pectin extracted from MUAE and MAE closely resemble each other. The extracted pectin from UMAE with smaller and more regular surface differs greatly from that of UAE. This has substantiated the highest pectin yield of 36.33% from UMAE and further signified their compatibility and potentiality in pectin extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Microwave-assisted extraction of pectic polysaccharide from waste mango peel.

    Science.gov (United States)

    Maran, J Prakash; Swathi, K; Jeevitha, P; Jayalakshmi, J; Ashvini, G

    2015-06-05

    This present study investigates the extraction characteristics and optimal parameters of the microwave-assisted extraction of pectin from waste mango peel (WMP). Microwave power, pH, time and solid-liquid ratio were selected as the extraction parameters and was studied by using Box-Behnken response surface design. The experimental data was analyzed by least square regression analysis method and a second order polynomial model was constructed for response from the experimental data. The constructed model was adequate to explain the relationships between independent variables and response. All studied factors had great influence on the yield of pectin by individually and interactively. The optimum microwave assisted extraction conditions for the highest pectin yield (28.86%) from WMP was found to be: microwave power of 413W, pH of 2.7, time of 134s and solid-liquid ratio of 1:18g/ml. The experimental value was well correlated with predicted value at the optimal condition.

  17. Synthesis of Nano Crystalline MgAl2O4Spinel Powder by Microwave Assisted Combustion%Synthesis of Nano Crystalline MgAl2O4 Spinel Powder by Microwave Assisted Combustion

    Institute of Scientific and Technical Information of China (English)

    Leila Torkian; Mostafa M Amini; Zohreh Bahrami

    2011-01-01

    Stoichiometric MgAl2O4 spinel nanoparticles were synthesized by microwave assisted combustion reaction from aluminium nitrate nanohydrate (Al(NO3)3.9H2O) and Sol-Gel prepared magnesium hydroxide (Mg(OH)2) in the presence of urea ((NH2)2CO) as a fuel, in about 20 min of irradiation. X-ray diffraction (XRD) studies reveal that microwave assisted combustion synthesis route yields single-phase spinel nanoparticles with larger crystalline size (around 75 nm) than other conventional heating methods. Scanning electronic microscope (SEM) images show nanoparticles with spherical shape and homogenous morphology. The surface area measurements (SBET) show crystals with 2.11 m2/g and 0.0033 mL/g pore volume.

  18. Oyster and Pyramidella Shells as Heterogeneous Catalysts for the Microwave-Assisted Biodiesel Production from Jatropha curcas Oil

    Directory of Open Access Journals (Sweden)

    Achanai Buasri

    2015-01-01

    Full Text Available Microwave-assisted biodiesel production via transesterification of Jatropha curcas oil with methanol using solid oxide catalyst derived from waste shells of oyster and Pyramidella was studied. The shells were calcined at 900°C for 2 h and calcium oxide (CaO catalyst characterizations were carried out by X-ray diffraction (XRD, X-ray fluorescence (XRF, scanning electron microscope (SEM, and the Brunauer-Emmett-Teller (BET surface area measurements. The effects of reaction variables such as reaction time, microwave power, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the economic and environmentally friendly catalysts derived from oyster and Pyramidella shells showed good reusability and had high potential to be used as biodiesel production catalysts under microwave-assisted transesterification of Jatropha curcas oil with methanol.

  19. Experimentos didáticos envolvendo radiação microondas Microwave-assisted experiments for undergraduate courses

    Directory of Open Access Journals (Sweden)

    Fabiana Rosini

    2004-12-01

    Full Text Available Theoretical and practical aspects of the use of microwave-assisted strategies in chemistry are introduced for students using simple and safe experiments employing a domestic oven. Three procedures are proposed for evaluating the distribution of microwave radiation inside the microwave oven cavity: (1 variation of the volume of marshmallows; (2 drying of filter paper wetted with Co(II solution, and (3 variation of water temperature, after microwave-assisted heating. These experiments establish the position with the highest incidence of microwave radiation in the oven cavity, which was chosen for the synthesis of salicylic acid acetate. This synthesis was performed in 5 min of heating and the yield was around 85%. All experiments can be carried out in a 4 h lab-session using low-cost instrumentation.

  20. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Ken Belmore

    2007-07-01

    Full Text Available The newly synthesized 5,10,15,20-tetra[3-(3-trifluoromethylphenoxy]porphyrin, TTFMPP, has been characterized using mass spectroscopy, 1H-, 13C- and 19F-NMR, MALDI-TOF mass spectrometry, UV-Vis and fluorescence spectrophotometry, andcyclic voltammetry. The NMR confirmed the structure of the compound and the massspectrum was in agreement with the proposed molecular formula. The UV-Vis absorptionspectrum of TTFMPP shows characteristic spectral patterns similar to those of tetraphenylporphryin, with a Soret band at 419 nm and four Q bands at 515, 550, 590, and 648 nm.Protonation of the porphyrin with TFA resulted in the expected red shift of the Soret band.Excitation at 419 nm gave an emission at 650 nm. The quantum yield of the porphyrin wasdetermined to be 0.08. Cyclic voltammetry was used to determine the oxidation andreduction potentials of the new porphyrin. Two quasi-reversible one-electron reductions at–1.00 and –1.32 V and a quasi-reversible oxidation at 1.20 V versus the silver/silverchloride reference electrode with tetrabutylammonium tetrafluoroborate as the supportingelectrolyte in methylene chloride were observed.

  1. Novel microwave assisted chemical synthesis of Nd₂Fe₁₄B hard magnetic nanoparticles.

    Science.gov (United States)

    Swaminathan, Viswanathan; Deheri, Pratap Kumar; Bhame, Shekhar Dnyaneswar; Ramanujan, Raju Vijayaraghavan

    2013-04-07

    The high coercivity and excellent energy product of Nd2Fe14B hard magnets have led to a large number of high value added industrial applications. Chemical synthesis of Nd2Fe14B nanoparticles is challenging due to the large reduction potential of Nd(3+) and the high tendency for Nd2Fe14B oxidation. We report the novel synthesis of Nd2Fe14B nanoparticles by a microwave assisted combustion process. The process consisted of Nd-Fe-B mixed oxide preparation by microwave assisted combustion, followed by the reduction of the mixed oxide by CaH2. This combustion process is fast, energy efficient and offers facile elemental substitution. The coercivity of the resulting powders was ∼8.0 kOe and the saturation magnetization was ∼40 emu g(-1). After removal of CaO by washing, saturation magnetization increased and an energy product of 3.57 MGOe was obtained. A range of magnetic properties was obtained by varying the microwave power, reduction temperature and Nd to Fe ratio. A transition from soft to exchange coupled to hard magnetic properties was obtained by varying the composition of NdxFe1-xB8 (x varies from 7% to 40%). This synthesis procedure offers an inexpensive and facile platform to produce exchange coupled hard magnets.

  2. Comparison of microwave-assisted and conventional extraction of mangiferin from mango (Mangifera indica L.) leaves.

    Science.gov (United States)

    Zou, Tangbin; Wu, Hongfu; Li, Huawen; Jia, Qing; Song, Gang

    2013-10-01

    Mangiferin is the main bioactive component in mango leaves, which possesses anti-inflammatory, antioxidative, antidiabetic, immunomodulatory, and antitumor activities. In the present study, a microwave-assisted extraction method was developed for the extraction of mangiferin from mango leaves. Some parameters such as ethanol concentration, liquid-to-solid ratio, microwave power, and extraction time were optimized by single-factor experiments and response surface methodology. The optimal extraction conditions were 45% ethanol, liquid-to-solid ratio of 30:1 (mL/g), and extraction time of 123 s under microwave irradiation of 474 W. Under optimal conditions, the yield of mangiferin was 36.10 ± 0.72 mg/g, significantly higher than that of conventional extraction. The results obtained are beneficial for the full utilization of mango leaves and also indicate that microwave-assisted extraction is a very useful method for extracting mangiferin from plant materials. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Highly efficient isocyanate-free microwave-assisted synthesis of [6]-oligourea

    KAUST Repository

    Qaroush, Abdussalam K.

    2013-01-01

    A new eco-friendly, isocyanate-free, energy-saving method for the production of [6]-oligourea, utilizing a green carbonylating agent, viz. propylene carbonate, is reported. It comprises an organocatalyzed, microwave-assisted, solvent-free synthesis. Two modes of microwave-assisted synthesis, viz. dynamic and fixed energy modes, were applied. Upon optimization, the dynamic mode gave 79% yields of [6]-oligourea. On the other hand, almost quantitative yields were obtained using the fixed mode, within 20 min, at 10 W and with the same catalyst loading. Combination of both organocatalysis and microwave energy input appears to be a key issue for the efficiency of the reaction, with the fixed energy mode being best suited. It should be noted that all data reported are reproducible (due to the homogeneous microwave technology used by CEM Discover S-Class of microwave reactors). To the best of our knowledge, this is the best eco-friendly synthetic approach for the preparation of the title oligomers. It paves the way for using more of the biorenewable and sustainable chemicals as a feedstock for the production of polyureas. The oligomer produced was analyzed by EA, ATR-FTIR, XRD, 1H and 13CNMR. Furthermore, thermal properties of the resulting [6]-oligourea were analyzed using TGA and DSC. © The Royal Society of Chemistry 2013.

  4. Microwave-assisted rapid synthesis, characterization and application of poly (D,L-lactide)-graft-pullulan.

    Science.gov (United States)

    Tang, Xiao-Jiao; Huang, Jun; Xu, Liang-Yu; Li, Yang; Song, Juan; Ma, Yue; Yang, Li; Yuan, Dan; Wu, Hai-Yang

    2014-07-17

    A novel microwave-assisted method was developed to synthetize amphiphilic copolymer poly (d,l-lactide)-graft-pullulan (PL) in a monomode microwave reactor. The effects of microwave power, ratio of catalyst/lactide, ratio of lactide/hydroxyl group of pullulan (lactide/OH-P) and solvent on the synthesis were further investigated. Three samples (designated as PL 8, 9, and 6), characterized by FT-IR and NMR, were applied to form nanoparticles and microparticles investigated by dynamic light scattering, fluorescence spectroscopy and transmission electron microscopy. PL9 and PL6 were used for loading model drug curcumin. The results indicated that microwave-assisted synthesis shortened the copolymerization of PL, with higher yield and lactide conversion, from 24h to 5 min and showed some specific microwave effects compared with conventional oil heating. PL with a relative higher substitution degree gave nanoparticles with smaller sizes and critical aggregation concentrations. The solubility of curcumin was increased to 1.97 mg mL(-1) as the forms of nanoparticles.

  5. Ionic Liquid-Based Microwave-Assisted Extraction of Flavonoids from Bauhinia championii (Benth. Benth.

    Directory of Open Access Journals (Sweden)

    Wei Xu

    2012-12-01

    Full Text Available An ionic liquids (IL-based microwave-assisted approach for extraction and determination of flavonoids from Bauhinia championii (Benth. Benth. was proposed for the first time. Several ILs with different cations and anions and the microwave-assisted extraction (MAE conditions, including sample particle size, extraction time and liquid-solid ratio, were investigated. Two M 1-butyl-3-methylimidazolium bromide ([bmim] Br solution with 0.80 M HCl was selected as the optimal solvent. Meanwhile the optimized conditions a ratio of liquid to material of 30:1, and the extraction for 10 min at 70 °C. Compared with conventional heat-reflux extraction (CHRE and the regular MAE, IL-MAE exhibited a higher extraction yield and shorter extraction time (from 1.5 h to 10 min. The optimized extraction samples were analysed by LC-MS/MS. IL extracts of Bauhinia championii (Benth.Benth consisted mainly of flavonoids, among which myricetin, quercetin and kaempferol, β-sitosterol, triacontane and hexacontane were identified. The study indicated that IL-MAE was an efficient and rapid method with simple sample preparation. LC-MS/MS was also used to determine the chemical composition of the ethyl acetate/MAE extract of Bauhinia championii (Benth. Benth, and it maybe become a rapid method to determine the composition of new plant extracts.

  6. Microwave assisted extraction of mangiferin from Curcuma amada

    OpenAIRE

    PADMAPRIYA K.; Dutta, Abhishek; Chaudhuri, Surabhi; Debjani DUTTA

    2011-01-01

    Mangiferin present in Curcuma amada was extracted with the help of microwave assisted extraction (MAE). The extraction solvent used was ethanol, which is eco-friendly and reduced the risk of environmental hazard. The mangiferin content was found to increase until 500 W, but decreased as the microwave power was increased further. A similar threshold was also obtained for microwave irradiation time. Following a mathematical analysis, an optimal mangiferin yield of 41 μg/mL was obtained from an ...

  7. Microwave-Assisted Extraction of Brewers' Spent Grain Arabinoxylans

    OpenAIRE

    Rocha, M. A. M.; Saraiva, J.; Coimbra,M. A.

    2011-01-01

    Brewers´ spent grain (BSG) is a by-product from beer industry that can be exploited as a source of arabinoxylo-oligosaccharides (AXOS) with prebiotic activity. In this study, microwave-assisted extractions were performed during 2 min at 140-210°Cin order to evaluate the feasibility of this extraction technology for quantitative extraction of the arabinoxylans (AX) or AXOS from BSG. The AX yield increasedwith the increase of the temperature in the range used. The best condition...

  8. Microwave-assisted hydrothermal synthesis of lead zirconate fine powders

    Directory of Open Access Journals (Sweden)

    Apinpus Rujiwatra

    2011-01-01

    Full Text Available A rapid synthesis of lead zirconate fine powders by microwave-assisted hydrothermal technique is reported. The influences of type of lead precursor, concentration of potassium hydroxide mineraliser, applied microwave power and irradiation time are described. The synthesised powders were characterised by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopic microanalysis and light scattering technique. The merits of the microwave application in reducing reaction time and improving particle mono-dispersion and size uniformity as well as the drawbacks, viz. low purity of the desired phase and increasing demand of mineraliser, are discussed in relation to conventional heating method.

  9. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Peng; TANG Shao-Chun; MENG Xiang-Kang

    2009-01-01

    Silver nanoparticles with an average size of about 2Onto are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method.The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability.

  10. Microwave-assisted synthesis of Mo-doped H1-xSr2Nb3-xMoxO10 (x = 0, 0.05, 0.1, 0.15 and 0.2) with high photocatalytic activity

    Science.gov (United States)

    Jing, Xu; Yuelin, Wei; Yunfang, Huang; Jing, Wang; A'xiang, Chen; Leqing, Fan; Jihuai, Wu

    2014-08-01

    H1-xSr2Nb3-xMoxO10 photocatalysts were synthesized using a microwave-irradiation-assisted ion-exchange reaction. The physicochemical properties of the photocatalysts were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and ultraviolet—visible spectroscopy (UV—vis). The photocatalytic activity of the H1-xSr2Nb3-xMoxO10 was evaluated by degrading methyl orange (MO) dye under light irradiation from a 40-W mercury lamp. The results proved that the Mo doping amount had an important effect on the photocatalytic activity of the catalysts. The highest photocatalytic activity was obtained when the doping amount was 15 mol%. Furthermore, the complex preparation process and lengthy time was simplified and shortened greatly.

  11. A NOVEL HIGH-SPEED METHOD FOR THE GENERATION OF 4-ARYLDIHYDROPYRIMIDINE COMPOUND LIBRARIES USING A MICROWAVE-ASSISTED BIGINELLI CONDENSATION PROTOCOL -

    Science.gov (United States)

    In this presentation we report the application of microwave assisted chemistry to the parallel synthesis of 4-aryl-3,4-dihydropyrimidin-2(1H)-ones employing a solventless Biginelli multicomponent condensation protocol. The novel method employs neat mixtures of B-ketoesters, aryl ...

  12. 微波辅助MgH2固相反应法制备Mg2Si1-xSnx基热电材料及性能%Fabrication of Mg2Si1-xSnx from MgH2 by Microwave-Assisted Solid State Reaction and Its Thermoelectric Performance

    Institute of Scientific and Technical Information of China (English)

    王彦坤; 陈少平; 樊文浩; 张华; 孟庆森; 杨江峰; 崔教林

    2016-01-01

    The Bi doped Mg2Si1-xSnx (0.4≤x≤0.6) solid solution thermoelectric material with high purity was synthesized by microwave-assisted solid state reaction followed by field activated and pressure assisted synthesis (FAPAS),and its microstructure and transport properties were characterized.Results show that the replacement of Mg used in traditional processes by MgH2 powder significantly reduces the temperature of the solid state reaction and further inhibits the oxidation and volatilization of magnesium.Meanwhile,the low-temperature and rapid heating from microwave restrains the grain growth effectively;as a result,the pure product with an average grain size of 200 nm has been obtained.Thermoelectric performance was tested in the temperature range of 300~750 K.It is indicated that the solid solution with fine lamellar structure and the doping of Bi significantly lower the thermal conductivity and improve the electric properties simultaneously.The 1.5 at% Bi doped Mg2Si0.4Sn0.6 gets the maximum ZT of 0.91 at 600 K.%在微波作用下利用MgH2、纳米Si粉、Sn粉和Bi粉进行固相反应,结合电场激活压力辅助合成法(FAPAS)制备了高纯Bi掺杂的Mg2Si1-xSnx(0.4≤x≤0.6)基固溶体热电材料,并对其微观结构和熟电性能进行了表征.结果表明,MgH2替代传统原料Mg粉显著降低了圃相反应温度且防止了M8的挥发和氧化,同时微波快速低温加热有效抑制晶粒长大,可获得平均晶粒尺寸为200 nm的高纯产物.在300~750 K的温度区间对样品热电性能进行测试.结果表明,细小的片层固溶体组织和Bi的掺杂有效降低了样品热导率,同时改善了其电性能,在600 K时,含1.5%Bi(原子分数)的Mg2Si0.4Sn0.6热电材料具有最大ZT值0.91.

  13. Microwave-assisted acid and base hydrolysis of intact proteins containing disulfide bonds for protein sequence analysis by mass spectrometry.

    Science.gov (United States)

    Reiz, Bela; Li, Liang

    2010-09-01

    Controlled hydrolysis of proteins to generate peptide ladders combined with mass spectrometric analysis of the resultant peptides can be used for protein sequencing. In this paper, two methods of improving the microwave-assisted protein hydrolysis process are described to enable rapid sequencing of proteins containing disulfide bonds and increase sequence coverage, respectively. It was demonstrated that proteins containing disulfide bonds could be sequenced by MS analysis by first performing hydrolysis for less than 2 min, followed by 1 h of reduction to release the peptides originally linked by disulfide bonds. It was shown that a strong base could be used as a catalyst for microwave-assisted protein hydrolysis, producing complementary sequence information to that generated by microwave-assisted acid hydrolysis. However, using either acid or base hydrolysis, amide bond breakages in small regions of the polypeptide chains of the model proteins (e.g., cytochrome c and lysozyme) were not detected. Dynamic light scattering measurement of the proteins solubilized in an acid or base indicated that protein-protein interaction or aggregation was not the cause of the failure to hydrolyze certain amide bonds. It was speculated that there were some unknown local structures that might play a role in preventing an acid or base from reacting with the peptide bonds therein.

  14. One-pot microwave assisted synthesis under green chemistry conditions, antioxidant screening, and cytotoxicity assessments of benzimidazole Schiff bases and pyrimido[1,2-a]benzimidazol-3(4H)-ones.

    Science.gov (United States)

    Neochoritis, Constantinos G; Zarganes-Tzitzikas, Tryfon; Tsoleridis, Constantinos A; Stephanidou-Stephanatou, Julia; Kontogiorgis, Christos A; Hadjipavlou-Litina, Dimitra J; Choli-Papadopoulou, Theodora

    2011-01-01

    The synthesis of a number of benzimidazole Schiff bases 3 and 3-oxo-pyrimido[1,2-a]benzimidazoles 4 in excellent yields by a one-step sequence from the reaction of 2-aminobenzimidazole under green chemistry conditions is described. Structural assignments of the new compounds as well as complete assignment of (1)H and (13)C NMR signals have been unambiguously achieved based on the analysis of their (1)H and (13)C NMR (1D and 2D), IR, MS and elemental analysis data. To the synthesized Schiff bases the E-configuration was assigned on the basis of comparison of experimental and calculated (DFT) (13)C NMR chemical shifts. Compounds 3 and 4 were evaluated as inhibitors of lipoxygenase (LOX) and of lipid peroxidation (LPO). All the tested derivatives showed inhibition of lipid peroxidation, whereas most of them were found to have higher activation than the reference compound trolox; The Schiff bases 3e, 3h, and 3i, and the pyrimidobenzimidazoles 4a, 4e and 4f were found to be the most potent. The most potent LOX inhibitor within the subset of Schiff bases was found compound 3i, followed by 3f, whereas compounds 4a and 4g were found the most potent of the 3-oxo-pyrimido[1,2-a]benzimidazole group. Moreover, some cytotoxicity assessments were undertaken, whereupon it was found that Schiff base 3i and pyrimidobenzimidazoles 4e and 4f did not exhibit cytotoxicity at similar concentrations resembling thus the inhibitory activity of lipid peroxidation. The most cytotoxic Schiff base and pyrimidobenzimidazole were found to be 3d and 4c, respectively.

  15. Microwave-assisted synthesis of arene ruthenium(II) complexes [(η⁶-RC₆H₅)Ru(m-MOPIP)Cl]Cl (R = -H and -CH₃) as groove binder to c-myc G4 DNA.

    Science.gov (United States)

    Wu, Qiong; Chen, Tianfeng; Zhang, Zhao; Liao, Siyan; Wu, Xiaohui; Wu, Jian; Mei, Wenjie; Chen, Yanhua; Wu, Weili; Zeng, Lingli; Zheng, Wenjie

    2014-06-28

    Two arene Ru(II) complexes coordinated by 2-(3-methoxyphenyl)imidazole[4,5-f][1,10]phenanthroline, [(η(6)-RC6H5)Ru(m-MOPIP)Cl]Cl (R = H, ; R = CH3, 2), have been prepared under microwave irradiation; the crystal structure of 2 exhibits a typical "piano stool" conformation, with bond angles for N1-Ru1-Cl1 86.02 (14)° and N2-Ru1-Cl1 84.51 (14)°. The Ru-C distance for the Ru atom bound to the benzene ring is about 0.2178(8) nm, and the average Ru-N distance for Ru atom to the two chelating N atoms is about 0.2092(4) nm. The evaluation of in vitro anticancer activities revealed that these synthetic Ru(II) complexes selectively inhibited the growth of HepG2 hepatocellular carcinoma cells, with low cytotoxicity toward LO2 human normal liver cells. The results demonstrated that the complexes exhibited great selectivity between human cancer and normal cells by comparing with the ligand m-MOPIP. Furthermore, complexes 1 and 2 could bind to c-myc G4 DNA in groove binding mode in promising affinity, and the insertion of the methyl groups in the arene ligand contributed to strengthen the binding affinity. This was also confirmed by molecular docking calculation and (1)H NMR analysis which showed that both 1 and 2 can bind in the loop constructed by A6-G9 and G21-A25 base pairs in c-myc G4 DNA to block the replication of c-myc oligomer. Taken together, these results suggest that arene Ru(II) complexes display application potential as small molecule inhibitors of c-myc G4 DNA.

  16. Microwave assisted, solvent-free synthesis and in-vitro antimicrobial screening of some novel pyrazolo[3,4-d]pyrimidin-4(5H-one derivatives

    Directory of Open Access Journals (Sweden)

    Dipen K. Sureja

    2017-03-01

    Full Text Available An efficient and solvent-free synthesis of some novel pyrazolo[3,4-d]pyrimidin-4(5H-one derivatives has been developed under microwave irradiation by the reaction of ortho amino ester of 1-substituted pyrazole with different aromatic nitriles in the presence of potassium tert-butoxide. All the newly synthesized compounds were characterized by various spectroscopic techniques and analytical methods. Furthermore, all the newly synthesized compounds have been screened in-vitro for their antimicrobial activities against S. aureus, B. subtilis, E. coli, P. aeruginosa, A. niger and C. albicans. All the compounds showed weak to good activity against all tested microorganisms.

  17. Intensified Microwave-Assisted N-Acylation Procedure - Synthesis and Activity Evaluation of TRPC3 Channel Agonists with a 1,3-Dihydro-2H-benzo[d]imidazol-2-one Core.

    Science.gov (United States)

    de la Cruz, Gema Guedes; Svobodova, Barbora; Lichtenegger, Michaela; Tiapko, Oleksandra; Groschner, Klaus; Glasnov, Toma

    2017-04-01

    Upon controlled microwave heating and using cyanuric chloride as a coupling reagent, an efficient amidation procedure for the synthesis of 1,3-dihydro-2H-benzo[d]imidazol-2-one-based agonists of TRPC3/6 ion channels has been developed. Compared to the few conventional protocols, a drastic reduction in processing time from ca. 2 days down to 10 minutes was achieved accompanied by significantly improved product yields. The robustness of the method was confirmed by 18 additional examples including aromatic, aliphatic, and heterocyclic amines and acids. The obtained agonists were screened for biological activity at 1 μM concentration and few structure-activity relations have been established.

  18. Intensified Microwave-Assisted N-Acylation Procedure – Synthesis and Activity Evaluation of TRPC3 Channel Agonists with a 1,3-Dihydro-2H-benzo[d]imidazol-2-one Core

    Science.gov (United States)

    de la Cruz, Gema Guedes; Svobodova, Barbora; Lichtenegger, Michaela; Tiapko, Oleksandra; Groschner, Klaus; Glasnov, Toma

    2017-01-01

    Upon controlled microwave heating and using cyanuric chloride as a coupling reagent, an efficient amidation procedure for the synthesis of 1,3-dihydro-2H-benzo[d]imidazol-2-one-based agonists of TRPC3/6 ion channels has been developed. Compared to the few conventional protocols, a drastic reduction in processing time from ca. 2 days down to 10 minutes was achieved accompanied by significantly improved product yields. The robustness of the method was confirmed by 18 additional examples including aromatic, aliphatic, and heterocyclic amines and acids. The obtained agonists were screened for biological activity at 1 μM concentration and few structure–activity relations have been established. PMID:28413263

  19. Microwave Assisted Extraction of Phenolic Compounds from Four Different Spices

    Directory of Open Access Journals (Sweden)

    Alberto Ritieni

    2010-09-01

    Full Text Available Spices and herbs are known not only for their taste, aroma and flavour, but also for their medical properties and value. Both spices and herbs have been used for centuries in traditional medical systems to cure various kinds of illnesses such as common cold, diabetes, cough and cancers. The aim of this work was the comparison between two different extractive techniques in order to get qualitative and quantitative data regarding bioactive compounds of four different spices (Cinnamomum zeylanicum, Coriandrum sativum, Cuminum cyminum, Crocus sativus. The plants were extracted employing ultrasonication and microwave-assisted extractions. The efficiency of extraction of bioactive compounds obtained with the microwave extraction process was in general about four times higher than that resulting from sonication extraction. The various extracts obtained were analyzed for their antioxidant activity using ABTS, DPPH and FRAP assays and for their total polyphenolic content. It can be concluded that microwave-assisted extractions provide significant advantages in terms of extraction efficiency and time savings.

  20. Magnetic gold nanotriangles by microwave-assisted polyol synthesis

    Science.gov (United States)

    Yu, Siming; Hachtel, Jordan A.; Chisholm, Matthew F.; Pantelides, Sokrates T.; Laromaine, Anna; Roig, Anna

    2015-08-01

    Simple approaches to synthesize hybrid nanoparticles with magnetic and plasmonic functionalities, with high control of their shape and avoiding cytotoxic reactants, to target biomedical applications remain a huge challenge. Here, we report a facile, fast and bio-friendly microwave-assisted polyol route for the synthesis of a complex multi-material consisting of monodisperse gold nanotriangles around 280 nm in size uniformly decorated by superparamagnetic iron oxide nanoparticles of 5 nm. These nanotriangles are readily dispersible in water, display a strong magnetic response (10 wt% magnetic fraction) and exhibit a localized surface plasmon resonance band in the NIR region (800 nm). Moreover, these hybrid particles can be easily self-assembled at the liquid-air interfaces.Simple approaches to synthesize hybrid nanoparticles with magnetic and plasmonic functionalities, with high control of their shape and avoiding cytotoxic reactants, to target biomedical applications remain a huge challenge. Here, we report a facile, fast and bio-friendly microwave-assisted polyol route for the synthesis of a complex multi-material consisting of monodisperse gold nanotriangles around 280 nm in size uniformly decorated by superparamagnetic iron oxide nanoparticles of 5 nm. These nanotriangles are readily dispersible in water, display a strong magnetic response (10 wt% magnetic fraction) and exhibit a localized surface plasmon resonance band in the NIR region (800 nm). Moreover, these hybrid particles can be easily self-assembled at the liquid-air interfaces. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03113c

  1. Microwave assisted acid and alkali pretreatment of Miscanthus biomass for biorefineries

    Directory of Open Access Journals (Sweden)

    Zongyuan Zhu

    2015-10-01

    Full Text Available Miscanthus is a major bioenergy crop in Europe and a potential feedstock for second generation biofuels. Thermochemical pretreatment is a significant step in the process of converting lignocellulosic biomass into fermentable sugars. In this work, microwave energy was applied to facilitate NaOH and H2SO4 pretreatments of Miscanthus. This was carried out at 180 ℃ in a monomode microwave cavity at 300 W. Our results show that H2SO4 pretreatment contributes to the breakdown of hemicelluloses and cellulose, leading to a high glucose yield. The maximum sugar yield from available carbohydrates during pretreatment is 75.3% (0.2 M H2SO4 20 Min, and glucose yield is 46.7% under these conditions. NaOH and water pretreatments tend to break down only hemicellulose in preference to cellulose, contributing to high xylose yield. Compared to conventional heating NaOH/H2SO4 pretreatment, 12 times higher sugar yield was obtained by using microwave assisted pretreatment within half the time. NaOH pretreatments lead to a significantly enhanced digestibility of the residue, because the effective removal of lignin and hemicellulose makes cellulose fibres more accessible to cellulases. Morphological study of biomass shows that the tightly packed fibres in the Miscanthus were dismantled and exposed under NaOH condition. We studied sugar degradation under microwave assisted H2SO4 conditions. The results shows that 6-8% biomass was converted into levulinic acid (LA during pretreatment, showing the possibility of using microwave technology to produce LA from biomass. The outcome of this work shows great potential for using microwave in the thermo-chemical pretreatment for biomass and also selective production of LA from biomass.

  2. Microwave-assisted synthesis and characterization of hierarchically structured calcium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhenxing [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Wang, Guangjian, E-mail: wgj2260@chnu.edu.cn [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China); Guo, Yajie; Kang, Fangfang; Huang, Yanhong; Bo, Dongsheng [School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000 (China)

    2012-12-15

    Graphical abstract: CaF{sub 2} with different morphologies and hierarchical structure such as dendrites, spherical and cube was prepared under microwave-assisted condition by a simple solvothermal synthesis route using CaCl{sub 2} and [BMIM]BF{sub 4} as initial reagents, respectively. It was found that the species of precursor was of vital importance for the formation of CaF{sub 2} crystals. That is, precursors itself also acted as structure directing agent. The outstanding features of the approach to obtain hierarchical structure CaF{sub 2} were its simplicity, effectiveness and ease of assembly. On the basis of the experimental results, a possible growth mechanism of the CaF{sub 2} crystals was proposed. Display Omitted Highlights: ► CaF{sub 2} with hierarchical structure was synthesized under microwave-assisted conditions. ► Characteristic morphologies with cube, dendrite, hierarchical sphere, etc. were observed. ► Thin cubes assembled into a spherical structure. ► Ionic liquid of [BMIM]BF{sub 4} was fluorine source. ► Possible growth mechanisms of CaF{sub 2} crystals were discussed. -- Abstract: CaF{sub 2} with different morphologies and hierarchical structures was prepared under microwave-assisted condition by a simple hydrothermal route using CaCl{sub 2} and ionic liquid [BMIM]BF{sub 4} as initial reagents, respectively. It was found that both the precursor and pH values played an important role in the formation of CaF{sub 2} crystals with different morphologies. The results suggested that the CaF{sub 2} with cube and spherical structures was obtained at different pH values (4, 8, 11), while the CaF{sub 2} with dendrite shape was formed through an oriented self-assembly growth using (NH{sub 4}){sub 2}HPO{sub 4} as a structure directing agent. Scanning electron microscope observation showed that the as-prepared CaF{sub 2} was of three-dimensional eight-horn-shaped dendritic structure. The influence of the pH values for the reaction solution and

  3. Microwave-assisted Syntheses and Crystal Structures of Benzimidazole Thiazolinone Derivatives

    Institute of Scientific and Technical Information of China (English)

    HU Jun; WANG Peng; WANG Ji-Kui; XU Yan-Hua

    2012-01-01

    A rapid and efficient microwave-assisted synthesis method for the preparation of 3-(lH-benzo[d]imidazol-2-yl)-2-substituted phenyl thiazolidin-4-one (4a, 4b) was described. The structures of 4a and 4b were determined by elemental analyses, IR, 1H NMR and X-ray diffraction. In the crystals of compounds 4a and 4b, the imidazole ring and two benzene rings are planar. Interestingly, the dihedral angle between two benzene rings is 71.5° in 4a, while it is almost perpendicular in 4b due to the different benzene substituents. Meanwhile, the thiazolidinone ring is planar in 4a while slightly distorted with an r.m.s deviation of 0.1494(2) A in 4b. The hydrogen bonding interactions observed link the molecules to form a dimeric unit, which may be effective in the stabilization of the structure.

  4. Microwave assisted-semi bionic extraction of lignan compounds from Fructus Forsythiae by orthogonal design

    Institute of Scientific and Technical Information of China (English)

    TU Qiu-yun; ZHOU Chun-shan; TANG Jian-ping

    2008-01-01

    Microwave assisted-semi bionic extraction (MASBE) process for lignans from Fructus Forsythiae was studied. The influences of solvent pH value, microwave power, dosage of solvent and irradiation time were investigated. Optimum extracting parameters were determined by orthogonal experiments as follows: pH value of solvent at first extraction is 5.5-6.0, that at the second extraction is 7-8; microwave power is 700 W; mass ratio of Fructus Forsythiae to water is 1:12; irradiation time is 10 min, and extracting times is two. Under these optimal conditions, the yield of lignans reaches 0.364%. Compared with the conventionalextraction methods, the MASBE process has the advantages of high extraction rate, high extraction selectivity.

  5. Microwave-assisted synthesis of carbon-supported carbides catalysts for hydrous hydrazine decomposition

    Science.gov (United States)

    Mnatsakanyan, Raman; Zhurnachyan, Alina R.; Matyshak, Valery A.; Manukyan, Khachatur V.; Mukasyan, Alexander S.

    2016-09-01

    Microwave-assisted synthesis of carbon-supported Mo2C and WC nanomaterials was studied. Two different routes were utilized to prepare MoO3 (WO3) - C precursors that were then subjected to microwave irradiation in an inert atmosphere. The effect of synthesis conditions, such as irradiation time and gas environment, was investigated. The structure and formation mechanism of the carbide phases were explored. As-synthesized nanomaterials exhibited catalytic activity for hydrous hydrazine (N2HH2O) decomposition at 30-70 °C. It was shown that the catalyst activity significantly increases if microwave irradiation is applied during the decomposition process. Such conditions permit complete conversion of hydrazine to ammonia and nitrogen within minutes. This effect can be attributed to the unique nanostructure of the catalysts that includes microwave absorbing carbon and active carbide constituents.

  6. Microwave-assisted hydrothermal synthesis and gas sensitivity of nanostructured SnO2

    Institute of Scientific and Technical Information of China (English)

    Liying Man; Jun Zhang; Jieqiang wang; Hongyan Xu; Bingqiang Cao

    2013-01-01

    Precursors for nanostructured SnO2 were synthesized via a microwave-assisted hydrothermal method under different conditions,using SnCl2·2H2O,urea and citric acid as reactants.After calcination of the precursors at 700 ℃ for 2 h.nanostructured SnO2 with different morphologies were obtained,and were then characterized using X-ray powder diffraction (XRD),and field-emission scanning electron microscopy (FESEM).The results show that synthesis temperature and time play an important role in the formation of the 3D hierarchical morphology of the nanostructured SnO2.Gas sensing experiments demonstrate that the synthesized SnO2 materials,especially those with a 3D network structure,exhibit superb sensitivity to alcohol vapors at 240 ℃.

  7. One step microwaved-assisted hydrothermal synthesis of nitrogen doped graphene for high performance of supercapacitor

    Science.gov (United States)

    Sari, Fitri Nur Indah; Ting, Jyh-Ming

    2015-11-01

    Nitrogen doped graphene (NDG) has been synthesized using a microwave-assisted hydrothermal (MHT) method within only several minute. In the method, homemade graphene oxide was reduced using ethylene glycol (EG) to obtain the graphene while ammonia liquid was used as the nitrogen source. However, it was found that the reduction and doping simultaneously occurred and the addition of ammonia further enhanced the reduction. The reduction and doping were examined through various analysis and the mechanisms were proposed. The effects of the hydrothermal temperature and time on the reduction and doping were discussed. It was also shown that the doping leads to enhanced specific capacitance by as much as 54%, a high specific energy density of 42.8 W h kg-1 at a power density of 4330 W kg-1, and excellent long term stability up to 98% retention after 1000 cycles at wide working voltage of 1.6 V in 2 M H2SO4.

  8. A Microwave-Assisted Reduction of Cyclohexanone Using Solid-State-Supported Sodium Borohydride

    Science.gov (United States)

    White, Lori L.; Kittredge, Kevin W.

    2005-01-01

    The reduction of carbonyl groups by sodium borohydride though is a well-known reaction in most organic lab texts, a difficulty for an instructor adopting this reaction in a student lab is that it is too long. Using a microwave assisted organic synthesis solves this difficulty and one such reaction, which is the microwave-assisted reduction of…

  9. Degradation of atrazine by microwave-assisted electrodeless discharge mercury lamp in aqueous solution.

    Science.gov (United States)

    Ta, Na; Hong, Jun; Liu, Tingfeng; Sun, Cheng

    2006-11-02

    The present study investigates the degradation of atrazine (2-chloro-4-(ethyl amino)-6-isopropyl amino-s-triazine) in aqueous solution by a developed new method, namely by means of a microwave-assisted electrodeless discharge mercury lamp (MW-EDML). An experimental design was conducted to assess the influence of various parameters: pH value, initial concentration, amount of EDML, initial volume and coexisted solvent. Atrazine was degraded completely by EDML in a relatively short time (i.e. t(1/2)=1.2 min for 10 mg/l). Additionally, the identification of main degradation products during atrazine degradation process was conducted by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This study proposes the degradation mechanism including four possible pathways for atrazine degradation according to the degradation products.

  10. Microwave-assisted synthesis of WS2 nanowires through tetrathiotungstate precursors

    Directory of Open Access Journals (Sweden)

    Pravas Kumar Panigrahi and Amita Pathak

    2008-01-01

    Full Text Available Tungsten disulfide (WS2 nanowires have been synthesized through a microwave-assisted chemical route that uses tungstic acid, elemental sulfur and monoethanolamine as starting reagents for obtaining a precursor solution of tetrathiotungstate ions. Acidification of the precursor solution yields amorphous precipitates, which lead to the formation of nanowires of WS2 with thickness of about 5–10 nm when heated at 750 °C under argon atmosphere for 1.5 h. Phase and the microstructure of the prepared powders have been investigated through x-ray powder diffraction and high-resolution transmission electron microscopy, respectively. Optical absorption of the WS2 powders reveals a red shift of the exciton bands compared to bulk WS2.

  11. Microwave Assisted Synthesis, Modification With Platinum And Photocatalytical Properties of TiO2 Nanofibers

    Directory of Open Access Journals (Sweden)

    Reinis DRUNKA

    2016-05-01

    Full Text Available In the present work formation of active TiO2 nanoparticles in microwave synthesis and their modification with platinum were studied. Anatase nanopowder and 10 M KOH solution were used as raw materials. Microwave assisted synthesis method permited to obtain TiO2 nanofibres and nanowires with a diameter of 10 nm and a specific surface area in the range of 70 – 150 m2/g. In order to modify TiO2 nanofibers with platinum it was stirred in H2PtCl6 solution under UV irradiation. Photocatalytic activity was determined by degradation of the methylene blue (MB solution under UV and visible light irradiation. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds as well as for hydrogen production by water splitting.

  12. Preparation Of KF-Modified Kaolinite As Green And Reusable Catalyst For Microwave Assisted Biodiesel Conversion

    Science.gov (United States)

    Fatimah, I.; Andiena, R. Z.; Yudha, S. P.

    2017-02-01

    Preparation of KF-modified kaolinite catalyst for microwave-assisted biodiesel conversion has been investigated. Kaolinite modification was conducted by solid-solid reaction between naturally occurring kaolinite mineral and KF salt followed by heating at 200oC for 2h. Prepared catalyst was characterized by using XRD, BET surface area analyzer, and SEM-EDX analysis and for catalytic activity tests, biodiesel conversion of jatropha oil was simulated. The comparison between microwave utilization and conventional method of biodiesel conversion were studied, moreover study on the catalyst reusability was performed. The results show that prepared catalyst gives the better physicochemical character of kaolinite as heterogeneous catalysts application as shown by the higher conversion and also reusability. Furthermore, the use of microwave irradiation exhibits the more time effectiveness. In general, the greener biodiesel conversion using presented methods is promising technique to be developed.

  13. Microwave-assisted synthesis of narcis-like zinc oxide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Kajbafvala, Amir, E-mail: akajbaf@ncsu.ed [Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Raleigh, NC 27695-7907 (United States); Department of Materials Science and Engineering, Center of Excellence for Production of Advanced Materials, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of); Zanganeh, Saeid [Department of Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Way, U-2157 Storrs, CT 06269-2157 (United States); Kajbafvala, Ehsan; Zargar, H.R.; Bayati, M.R. [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, P.O. Box 16845-161, Tehran (Iran, Islamic Republic of); Sadrnezhaad, S.K., E-mail: sadrnezh@sharif.ed [Department of Materials Science and Engineering, Center of Excellence for Production of Advanced Materials, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)

    2010-05-14

    Through a fast, simple, low cost, surfactant-free and convenient microwave-assisted route, narcis-like ZnO nanostructures (10-15 nm size) with flower diameters in the range of 1-2.5 {mu}m were synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and room temperature photoluminescence (PL) measurements were used to characterize the produced ZnO nanostructures. The principle raw materials - ammonium hydroxide (NH{sub 4}OH) and zinc acetate dihydrate [Zn(CH{sub 3}COO){sub 2}.2H{sub 2}O] - were both inexpensive. The method was fast, simple and surfactant-free capable of producing larger quantities of zinc oxide nanostructures. Formation mechanism of narcis ZnO nanostructures has been studied due to the self-assembly of small form ZnO clusters in microwave treated precursor.

  14. Microwave-assisted formation of organic monolayers from 1-alkenes on silicon carbide.

    Science.gov (United States)

    van den Berg, Sebastiaan A; Alonso, Jose Maria; Wadhwa, Kuldeep; Franssen, Maurice C R; Wennekes, Tom; Zuilhof, Han

    2014-09-09

    The rate of formation of covalently linked organic monolayers on HF-etched silicon carbide (SiC) is greatly increased by microwave irradiation. Upon microwave treatment for 60 min at 100 °C (60 W), 1-alkenes yield densely packed, covalently attached monolayers on flat SiC surfaces, a process that typically takes 16 h at 130 °C under thermal conditions. This approach was extended to SiC microparticles. The monolayers were characterized by X-ray photoelectron spectroscopy and static water contact angle measurements. The microwave-assisted reaction is compatible with terminal functionalities such as alkenes that enable subsequent versatile "click" chemistry reactions, further broadening the range and applicability of chemically modified SiC surfaces.

  15. Timesaving microwave assisted synthesis of insulin amyloid fibrils with enhanced nanofiber aspect ratio.

    Science.gov (United States)

    Carvalho, Tiago; Pinto, Ricardo J B; Martins, Manuel A; Silvestre, Armando J D; Freire, Carmen S R

    2016-11-01

    Insulin amyloid fibrils with enhanced aspect ratio, were prepared using a timesaving microwave assisted (MW) methodology, reducing the incubation time from 13 to 2h. The fibrillation process was followed indirectly by Thioflavin T Fluorescence and UV-vis analysis, by measuring the amount of β-sheets formed and the insulin present in solution, respectively. TEM and AFM analysis revealed that the insulin fibrils obtained through the MW method, have very similar lengths but are much thinner than the ones obtained using the conventional method (CM). Additionally, it was verified that the nature of the peptides present in the final insulin fibrils was not affected by microwave irradiation. These morphological differences might reflect on noticeably enhanced mechanical and optical properties that can exploited on the development of advanced bionanomaterials.

  16. Microwave-Assisted Rapid Enzymatic Synthesis of Nucleic Acids.

    Science.gov (United States)

    Hari Das, Rakha; Ahirwar, Rajesh; Kumar, Saroj; Nahar, Pradip

    2016-07-02

    Herein we report microwave-induced enhancement of the reactions catalyzed by Escherichia coli DNA polymerase I and avian myeloblastosis virus-reverse transcriptase. The reactions induced by microwaves result in a highly selective synthesis of nucleic acids in 10-50 seconds. In contrast, same reactions failed to give desired reaction products when carried out in the same time periods, but without microwave irradiation. Each of the reactions was carried out for different duration of microwave exposure time to find the optimum reaction time. The products produced by the respective enzyme upon microwave irradiation of the reaction mixtures were identical to that produced by the conventional procedures. As the microwave-assisted reactions are rapid, microwave could be a useful alternative to the conventional and time consuming procedures of enzymatic synthesis of nucleic acids.

  17. Microwave-assisted synthesis and characterization of nickel ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, Gopal; Sen, Ravindra; Gupta, Nitish, E-mail: nitish.nidhi75@gmail.com [Department of Applied Chemistry, Shri G. S. Institute of Technology and Science, Indore Madhyapradesh (India); Malviya, Nitin [Department of Applied Physics, Shri G. S. Institute of Technology and Science, Indore Madhyapradesh (India)

    2015-08-28

    Nickel ferrite nanoparticles (NiFe{sub 2}O{sub 4}) were successfully prepared by microwave-assisted combustion method (MWAC) using citric Electron acid as a chelating agent. NiFe{sub 2}O{sub 4} nanoparticles were characterized by X-ray diffraction (XRD) pattern, Scanning Microscopy (SEM), Fourier transform infrared (FTIR) and UV-Visible techniques. XRD analysis revealed that NiFe{sub 2}O{sub 4} nanoparticles have spinel cubic structure with the average crystalline size of 26.38 nm. SEM analysis revealed random and porous structural morphology of particles and FTIR showed absorption bands related to octahedral and tetrahedral sites, in the range 400–600cm{sup −1} which strongly favor the formation of NiFe{sub 2}O{sub 4} nanoparticles. The optical band gap is determined by UV Visible method and found to be 5.4 eV.

  18. Microwave-Assisted Preparation of High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Paolo Veronesi

    2015-10-01

    Full Text Available Microwaves at the ISM (Industrial, Scientific and Medical, reserved internationally frequency of 2450 or 5800 MHz have been used to prepare FeCoNiCuAl, FeCrNiTiAl and FeCoCrNiAl2.5 high entropy alloys by direct heating of pressed mixtures of metal powders. The aim of this work is to explore a new microwave-assisted near-net-shape technology, using a powder metallurgy approach for the preparation of high entropy alloys, able to overcome the limits of current melting technologies (defects formation or solid state ones (time demanding. High entropy alloy compositions have been selected so as to comprise at least one ferromagnetic element and one highly reactive couple, like Ni-Al, Ti-Al, Co-Al or Fe-Al. Results show that direct microwave heating of the powder precursors occurs, and further heating generation is favored by the ignition of exothermal reactions in the load. Microwaves have been applied both for the ignition and sustaining of such reactions, showing that by the proposed technique, it is possible to control the cooling rate of the newly-synthesized high entropy alloys. Results showed also that microwave heating in predominant magnetic field regions of the microwave applicator is more effective at controlling the cooling rate. The herein proposed microwave-assisted powder metallurgy approach is suitable to retain the shape of the load imparted during forming by uniaxial pressing. The homogeneity of the prepared high entropy alloys in all cases was good, without the dendritic segregation typical of arc melting, even if some partially-unreacted powders were detected in the samples.

  19. Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

    Science.gov (United States)

    Tajti, Ádám; Dzielak, Anna; Hägele, Gerhard

    2016-01-01

    Summary A practical method was elaborated for the synthesis of (aminomethylene)bisphosphine oxides comprising the catalyst- and solvent-free microwave-assisted three-component condensation of primary amines, triethyl orthoformate and two equivalents of diphenylphosphine oxide. The method is also suitable for the preparation of (aminomethylene)bisphosphonates using (MeO)2P(O)H/(MeO)3CH or (EtO)2P(O)H/(EtO)3CH reactant pairs and even secondary amines. Several intermediates referring to the reaction mechanism together with a few by-products could also be identified. PMID:27559402

  20. Ethanol production from cashew apple bagasse: improvement of enzymatic hydrolysis by microwave-assisted alkali pretreatment.

    Science.gov (United States)

    Rodrigues, Tigressa Helena Soares; Rocha, Maria Valderez Ponte; de Macedo, Gorete Ribeiro; Gonçalves, Luciana R B

    2011-07-01

    In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses, and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L(-1) of NaOH (372 ± 12 and 355 ± 37 mg g(glucan)(-1) ) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment time (15-30 min) and microwave power (600-900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step, improvement on solid percentage (16% w/v) and enzyme load (30 FPU g (CAB-M) (-1) ) increased glucose concentration to 15 g L(-1). The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L(-1) and 1.41 g L(-1) h(-1), respectively.

  1. Covalent immobilization of Candida antarctica lipase B on nanopolystyrene and its application to microwave-assisted esterification

    Institute of Scientific and Technical Information of China (English)

    Attaullah Bukhari; Ani Idris; Madiha Atta; Teo Chee Loong

    2014-01-01

    Nanopolystyrene was used as a solid support for the covalent immobilization of Candida antarctica lipase B (CalB) using the photoreactive reagent 1-fluoro-2-nitro-4-azido benzene (FNAB) as a cou-pling reagent. The obtained derivative was then used as a biocatalyst in a microwave assisted ester-ification experiment. Factors such as contact time, pH, and enzyme concentration were investigated during immobilization. The hydrolytic activity, thermal, and operational stability of immobi-lized-CalB were determined. The maximum immobilized yield (218 µg/mg support) obtained at pH 6.8 exhibited optimum hydrolytic activity (4.42 × 103 mU p-nitrophenol/min). The thermal stability of CalB improved significantly when it was immobilized at pH 10, however, the immobilized yield was very low (93.6 µg/mg support). The immobilized-CalB prepared at pH 6.8 and pH 10 retained 50%of its initial activity after incubation periods of 14 and 16 h, respectively, at 60 °C. The opera-tional stability was investigated for the microwave assisted esterification of oleic acid with metha-nol. Immobilized-CalB retained 50% of its initial activity after 15 batch cycles in the micro-wave-assisted esterification. The esterification time was notably reduced under microwave irradia-tion. The combined use of a biocatalyst and microwave heating is thus an alternative total green synthesis process.

  2. Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption

    Directory of Open Access Journals (Sweden)

    Zhu-Yun Cai

    2015-07-01

    Full Text Available Synthetic calcium phosphate (CaP-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP nanostructure was prepared under weak acidic conditions (pH 5, while the HAP nanorod was prepared under neutral (pH 7 and weak alkali (pH 9 condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

  3. Microwave-assisted rapid synthesis of methyl 2,4,5-trimethoxyphenylpropionate, a metabolite of Cordia alliodora.

    Science.gov (United States)

    Sinha, A K; Joshi, B P; Sharma, A; Kumar, J K; Kaul, V K

    2003-12-01

    Microwave assisted condensation of asaronaldehyde (2) with malonic acid in piperidine-AcOH provides 2,4,5-trimethoxycinnamic acid (3) in 87% yield within 4 min, which upon further reduction with PdCl2- HCOOH-aq. NaOH gives 3-(2,4,5-trimethoxy)phenyl propionic acid (4) in 88% yield within 3 min. Esterification of 4 with MeOH-H+ gives methyl 2,4,5-trimethoxyphenylpropionate (1), a metabolite of Cordia alliodora, in 94% yield within 3 min (overall 69% yield).

  4. Pd(OAc)2/DPPF-catalysed microwave-assisted cyanide-free synthesis of aryl nitriles

    Indian Academy of Sciences (India)

    Dinesh N Sawant; Bhalchandra M Bhanage

    2014-03-01

    This study reports microwave-assisted cyanide-free synthesis of aryl nitriles from aryl halides using palladium acetate/1,1-bis(diphenylphosphino)ferrocene as a new catalyst system. Reported protocol is a rapid, cyanide-free, single step reaction, wherein formamide acts as a solvent as well as a source of cyanide. The use of microwave increases the rate of reaction substantially and it was observed that aryl nitriles can be synthesised in 50 min of microwave irradiation compared to conventional thermal heating protocol which requires 48 h.

  5. Microwave-Assisted Resolution of α-Lipoic Acid Catalyzed by an Ionic Liquid Co-Lyophilized Lipase

    Directory of Open Access Journals (Sweden)

    Ning Liu

    2015-05-01

    Full Text Available The combination of the ionic liquid co-lyophilized lipase and microwave irradiation was used to improve enzyme performance in enantioselective esterification of α-lipoic acid. Effects of various reaction conditions on enzyme activity and enantioselectivity were investigated. Under optimal condition, the highest enantioselectivity (E = 41.2 was observed with a high enzyme activity (178.1 μmol/h/mg when using the ionic liquid co-lyophilized lipase with microwave assistance. Furthermore, the ionic liquid co-lyophilized lipase exhibited excellent reusability under low power microwave.

  6. A heterogeneous-catalyst-based, microwave-assisted protocol for the synthesis of 2,2'-bipyridines.

    Science.gov (United States)

    Moore, Lucas R; Vicic, David A

    2008-06-02

    A new method of preparing 2,2'-bipyridines with short reaction times by using microwave assistance and heterogeneous catalysts has been developed. With a Negishi-like protocol, it was found that Ni/Al(2)O(3)-SiO(2) afforded 2,2'-bipyridine products in up to 86% yield in 1 h. Palladium supported on alumina also provided yields of 2,2'-bipyridines comparable to those seen for homogeneous PEPPSI (1,3-diisopropylimidazol-2-ylidene)(3-chloropyridyl)palladium(II)dichloride) and tetrakis(triphenylphosphanyl)palladium complexes.

  7. Optimization of microwave-assisted extraction for six inorganic and organic arsenic species in chicken tissues using response surface methodology.

    Science.gov (United States)

    Zhang, Wenfeng; Hu, Yuanan; Cheng, Hefa

    2015-09-01

    Response surface methodology was applied to optimize the parameters for microwave-assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high-performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid-to-solid ratio, and the temperature and time of microwave-assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave-assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH4 )2 HPO4 , and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively.

  8. Microwave Assisted Solid State Reaction Synthesis of CdS Nanoparticles%微波固相反应制备CdS纳米粒子

    Institute of Scientific and Technical Information of China (English)

    曹洁明; 房宝青; 刘劲松; 常树全; 张防

    2005-01-01

    CdS nanoparticles with different sizes have been successfully synthesized by microwave-assisted solid state reaction between Cd(CH3COO)2·2H2O and Na2S·9H2O at the presence of suffactant PEG400. The process of heating has influence on the crystallinity of CdS. The products were characterized by XRD, SEM, TEM, and the formation mechanism of CdS nanoparticles has also been discussed.

  9. Conventional wet impregnation versus microwave-assisted synthesis of SnO2/CNT composites

    CSIR Research Space (South Africa)

    Motshekga, S

    2011-03-01

    Full Text Available Carbon nanotubes decorated with SnO2 nanoparticles were prepared by conventional and microwave-assisted wet impregnation. The composites were thoroughly characterized by X-ray diffraction, Raman spectroscopy, BET-surface area measurement, Scanning...

  10. Effects of feedstock characteristics on microwave-assisted pyrolysis - A review.

    Science.gov (United States)

    Zhang, Yaning; Chen, Paul; Liu, Shiyu; Peng, Peng; Min, Min; Cheng, Yanling; Anderson, Erik; Zhou, Nan; Fan, Liangliang; Liu, Chenghui; Chen, Guo; Liu, Yuhuan; Lei, Hanwu; Li, Bingxi; Ruan, Roger

    2017-04-01

    Microwave-assisted pyrolysis is an important approach to obtain bio-oil from biomass. Similar to conventional electrical heating pyrolysis, microwave-assisted pyrolysis is significantly affected by feedstock characteristics. However, microwave heating has its unique features which strongly depend on the physical and chemical properties of biomass feedstock. In this review, the relationships among heating, bio-oil yield, and feedstock particle size, moisture content, inorganics, and organics in microwave-assisted pyrolysis are discussed and compared with those in conventional electrical heating pyrolysis. The quantitative analysis of data reported in the literature showed a strong contrast between the conventional processes and microwave based processes. Microwave-assisted pyrolysis is a relatively new process with limited research compared with conventional electrical heating pyrolysis. The lack of understanding of some observed results warrant more and in-depth fundamental research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Comparative study on conventional, ultrasonication and microwave assisted extraction of γ-oryzanol from rice bran

    National Research Council Canada - National Science Library

    Kumar, Pramod; Yadav, Devbrat; Kumar, Pradyuman; Panesar, Paramjeet Singh; Bunkar, Durga Shankar; Mishra, Diwaker; Chopra, H K

    2016-01-01

    In present study, conventional, ultrasonic and microwave assisted extraction methods were compared with the aim of optimizing best fitting solvent and method, solvent concentration and digestion time for high yield of γ...

  12. An easy two-step microwave assisted synthesis of SnO2/CNT hybrids

    CSIR Research Space (South Africa)

    Motshekga, SC

    2011-11-01

    Full Text Available -ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, BET surface area analysis and DC conductivity measurement. The results showed that the microwave assisted synthesis is a very efficient method in producing CNTs that are heavily...

  13. Application of Ionic Liquids in the Microwave-Assisted Extraction of Proanthocyanidins from Larix gmelini Bark

    OpenAIRE

    Yuangang Zu; Chunjian Zhao; Lin Zhang,; Fengjian Yang; Xiaowei Sun; Lei Yang

    2012-01-01

    Ionic liquid based, microwave-assisted extraction (ILMAE) was successfully applied to the extraction of proanthocyanidins from Larix gmelini bark. In this work, in order to evaluate the performance of ionic liquids in the microwave-assisted extraction process, a series of 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were evaluated for extraction yield, and 1-butyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, ...

  14. Microwave-Assisted Drying for the Conservation of Honeybee Pollen

    Directory of Open Access Journals (Sweden)

    Angelo Canale

    2016-05-01

    Full Text Available Bee pollen is becoming an important product thanks to its nutritional properties, including a high content of bioactive compounds such as essential amino acids, antioxidants, and vitamins. Fresh bee pollen has a high water content (15%–30% wt %, thus it is a good substrate for microorganisms. Traditional conservation methods include drying in a hot air chamber and/or freezing. These techniques may significantly affect the pollen organoleptic properties and its content of bioactive compounds. Here, a new conservation method, microwave drying, is introduced and investigated. The method implies irradiating the fresh pollen with microwaves under vacuum, in order to reduce the water content without reaching temperatures capable of thermally deteriorating important bioactive compounds. The method was evaluated by taking into account the nutritional properties after the treatment. The analyzed parameters were phenols, flavonoids, with special reference to rutin content, and amino acids. Results showed that microwave drying offers important advantages for the conservation of bee pollen. Irrespective of microwave power and treatment time, phenol and flavonoid content did not vary over untreated fresh pollen. Similarly, rutin content was unaffected by the microwave drying, suggesting that the microwave-assisted drying could be a powerful technology to preserve bioprotective compounds in fresh pollen.

  15. Fast microwave assisted pyrolysis of biomass using microwave absorbent.

    Science.gov (United States)

    Borges, Fernanda Cabral; Du, Zhenyi; Xie, Qinglong; Trierweiler, Jorge Otávio; Cheng, Yanling; Wan, Yiqin; Liu, Yuhuan; Zhu, Rongbi; Lin, Xiangyang; Chen, Paul; Ruan, Roger

    2014-03-01

    A novel concept of fast microwave assisted pyrolysis (fMAP) in the presence of microwave absorbents was presented and examined. Wood sawdust and corn stover were pyrolyzed by means of microwave heating and silicon carbide (SiC) as microwave absorbent. The bio-oil was characterized, and the effects of temperature, feedstock loading, particle sizes, and vacuum degree were analyzed. For wood sawdust, a temperature of 480°C, 50 grit SiC, with 2g/min of biomass feeding, were the optimal conditions, with a maximum bio-oil yield of 65 wt.%. For corn stover, temperatures ranging from 490°C to 560°C, biomass particle sizes from 0.9mm to 1.9mm, and vacuum degree lower than 100mmHg obtained a maximum bio-oil yield of 64 wt.%. This study shows that the use of microwave absorbents for fMAP is feasible and a promising technology to improve the practical values and commercial application outlook of microwave based pyrolysis.

  16. Microwave assisted solid-state synthesis, crystal structure and properties of the dialkyltin 2-Naphthyl benzoate%微波固相合成二正丁基锡2-萘甲酸酯配合物{[n-Bu2Sn(O2CC10H9)]2O}2及其结构与性质研究

    Institute of Scientific and Technical Information of China (English)

    张复兴; 王剑秋; 邝代治; 冯泳兰; 张志坚; 李俊华; 张可

    2011-01-01

    二正丁基氧化锡和2-萘甲酸按物质的量比1∶1,通过微波固相合成法合成了二正丁基锡2-萘甲酸酯配合物{[n-Bu2Sn(O2CC10H9)]2O}2.经X-射线衍射方法测定了其晶体结构,配合物属三斜晶系,空间群为π,晶体学参数a=1.19564(7)nm,b=1.26634(7)nm,c=1.42679(9)nm,α=79.7120(10),β=69.0330(10)°,γ=72.1050(10)°,V=1.9146(2)nm3,Z=1,Dc=1.430 g/cra3,μ(MoKa)=13.42 cm-1,F(000)=836,R1=0.0426,wR2=0.1189.配合物是以Sn2O2构成的平面四元环为中心环的二聚体结构,锡原子均为五配位的畸变三角双锥构型.对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及一些前沿分子轨道的组成特征.通过循环伏安法研究了其电化学性质.%The dialkyltin 2-Naphthyl benzoate Compound {[n-Bu2Sn(O2CC10H9)]2I}2 was synthesized by Microwave assisted solid-state synthesis. Its structure has been determined by X-ray single crystal diffraction. The crystal belongs to triclinic with space groupPI-, a = 1.19564(7) nm, b =1.26634(7) nm, c =1. 42679(9) nm, α = 79.7120(10),βi = 69.0330(10)°, γ=72.1050(10)°, V= 1.9146(2) nm3, Z=1, Dc = 1.430 g/cm3, μ(UoKa)=l3A2 cm-1, F(000)=836, R1=0.0426, wR2=0.1189. In the complex, the tin atoms are rendered five-coordination in a distorted tigonal bipyram idalstructure, and the dimer structure is shaped by one Sn2O2 planar. The study on title complex has been performed, with quantum chemistry calculation by means of G98W package and taking Lanl2dz basis set. The stabilities of the complex, the orbital energies and composition characteristics of some frontier molecular orbitals have been investigated. The electrochemistry propertieswere studied by cyclic voltammetry.

  17. Physicochemical characterization of microwave assisted synthesis of silver nanoparticles using Aloe Vera (Aloe barbadensis)

    Science.gov (United States)

    Kuponiyi, Abiola John

    Biosynthesis of silver nanoparticles (AgNP) using different biological extracts is gaining recognition for its numerous applications in different disciplines. Although different approaches (physical and chemical) have been used for the synthesis of AgNP, the green chemistry method is most preferable because of its high efficacy, cost effectiveness, and environmental benignity. Aloe Vera (AV) contains chemical compounds (anthraquinones) that are known to possess antibacterial, antivirus and anticancer properties and the extract is a good chemical reduction agent for AgNP. Hence, it was hypothesized that a microwave assisted synthesis will produce highly concentrated, homogeneous, stable and biologically active AgNP. Thus, the main objective of the study was to evaluate the effect of microwave assisted synthesis of AgNP, the effect of pulse laser treatment on size reduction of a microwave synthesized AgNP, and the physicochemical characterization of AgNP synthesized with Aloe Vera water and ethanol extract. The experiment was conducted in two phases. Phase 1 was first conducted to optimize the experimental variables, thus establishing the optimum variables to apply in the second phase. The experiment in Phase 1 was conducted using three-factor factorial experimental design comprised of the following factors: 1) Extraction Solvent, 2) Heating Methods, 3) pH; and their corresponding levels were water and ethanol, conventional and microwave, pH (7, 8, 10 and 12), respectively. All synthesis was conducted at constant temperature of 80°C. Phase II experimental treatments were Laser ablation (0, 5, and 10 min) and Storage time (Week 1, 2 & 3). The Phase I of the results showed that increased AgNP concentrations were significantly (p 0.05) impact the particle size distribution. Hence, the Zeta potential of the particles has values typically ranging between +100 mV to -100 mV, hence indicative of colloidal stability matrix. Furthermore, the Polydispersity indexes of Week 1

  18. Polarization reversal in BaTiO{sub 3} nanostructures synthesized by microwave-assisted hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Velasco-Davalos, Ivan; Ambriz-Vargas, Fabian [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Gómez-Yáñez, Carlos [Departamento de Ingeniería en Metalurgia y Materiales, ESIQIE, Instituto Politécnico Nacional, UPALM, Zacatenco, CP 07738 DF, México (Mexico); Thomas, Reji, E-mail: reji.thomas@emt.inrs.ca [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada)

    2016-05-15

    Ferroelectric BaTiO{sub 3} nanostructures and thin films were deposited by a microwave assisted hydrothermal process at low temperatures (<250 °C) on metallic Pt/Al{sub 2}O{sub 3}/SiO{sub 2}/Si and Nb:SrTiO{sub 3} (100) substrates. TiO{sub 2} nanoparticles dispersed in the Ba(OH){sub 2} alkaline solution are used as the precursors without any mineralizers. The incorporation of H{sub 2}O{sub 2} into precursor solution served as a strong oxidant and catalyst for the uniform nucleation of BaTiO{sub 3} on the substrate surface. The polycrystalline and epitaxial nature of the films were confirmed by atomic force microscopy and x-ray diffraction studies. We report the ferroelectric behavior of BaTiO{sub 3} films on Nb:SrTiO{sub 3} (100) substrates by piezoresponse force microscopy. - Highlights: • Microwave assisted hydrothermal deposition of highly ordered BaTiO{sub 3} thin films on single crystal substrates. • Fast growth without the needof any mineralizers. • Moderate addition of H{sub 2}O{sub 2} significantly improves the surface coverage. • H{sub 2}O{sub 2} substantially reduces hydrogen incorporation into the film and the associated leakage current. • Out-of-plane polarization reversal demonstrated locally.

  19. Microwave-assisted synthesis, characterization and biological activities of organotin (IV) complexes with some thio Schiff bases.

    Science.gov (United States)

    Singh, Ran Vir; Chaudhary, Pratibha; Chauhan, Shikha; Swami, Monika

    2009-03-01

    Microwave-assisted synthesis and characterization of the organotin (IV) complexes are reported. Trigonal bipyramidal and octahedral complexes of tin (IV) have been synthesized by the reaction of dimethyltin (IV) dichloride with 4-nitrobenzanilide-S-benzyldithiocarbazate (L(1)H), 4-chlorobenzanilide-S-benzyldithiocarbazate (L(2)H), 4-nitrobenzanilidebenzothiazoline (L(3)H) and 4-chlorobenzanilidebenzothiazoline (L(4)H). The complexes so formed were characterized by elemental analysis, conductance measurements, molecular weight determinations and spectral data viz. IR, UV-Visible, (1)H and (13)C NMR. The anti-microbial activities of the ligands and their corresponding organotin (IV) complexes have been screened against various strains of bacteria and fungi. Antifertility activity against male albino rats has also been reported.

  20. Ionic liquid-based ultrasonic/microwave-assisted extraction combined with UPLC-MS-MS for the determination of tannins in Galla chinensis.

    Science.gov (United States)

    Lu, Chunxia; Wang, Hongxin; Lv, Wenping; Ma, Chaoyang; Lou, Zaixiang; Xie, Jun; Liu, Bo

    2012-01-01

    Ionic liquid was used as extraction solvents and applied to the extraction of tannins from Galla chinensis in the simultaneous ultrasonic- and microwave-assisted extraction (UMAE) technique. Several parameters of UMAE were optimised, and the results were compared with of the conventional extraction techniques. Under optimal conditions, the content of tannins was 630.2 ± 12.1 mg g⁻¹. Compared with the conventional heat-reflux extraction, maceration extraction, regular ultrasound- and microwave-assisted extraction, the proposed approach exhibited higher efficiency (11.7-22.0% enhanced) and shorter extraction time (from 6 h to 1 min). The tannins were then identified by ultraperformance liquid chromatography tandem mass spectrometry. This study suggests that ionic liquid-based UMAE is an efficient, rapid, simple and green sample preparation technique.

  1. Microwave assisted extraction of pectin from waste Citrullus lanatus fruit rinds.

    Science.gov (United States)

    Prakash Maran, J; Sivakumar, V; Thirugnanasambandham, K; Sridhar, R

    2014-01-30

    In this present study, microwave-assisted extraction (MAE) was applied to extraction of pectin from waste Citrullus Lanatus fruit rinds. Extraction parameters which are employed in this study are microwave power (160-480 W), irradiation time (60-180s), pH (1-2) and solid-liquid ratio (1:10-1: 30 g/ml) and they were optimized using a four factor three levels Box-Behnken response surface design (BBD) coupled with desirability function methodology. The results showed that, all the process variables have significant effect on the extraction yield of pectin. Optimum MAE conditions for the highest pectin yield from waste C. Lanatus fruit rinds (25.79%) were obtained with microwave power of 477 W, irradiation time of 128 s, pH of 1.52, solid-liquid ratio of 1:20.3g/ml respectively. Validation experiment results were well agreed with predicted value. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Optimization of microwave-assisted enzymatic extraction of polysaccharides from the fruit of Schisandra chinensis Baill.

    Science.gov (United States)

    Cheng, Zhenyu; Song, Haiyan; Yang, Yingjie; Liu, Yan; Liu, Zhigang; Hu, Haobin; Zhang, Yang

    2015-05-01

    A microwave-assisted enzymatic extraction (MAEE) method had been developed, which was optimized by response surface methodology (RSM) and orthogonal test design, to enhance the extraction of crude polysaccharides (CPS) from the fruit of Schisandra chinensis Baill. The optimum conditions were as follows: microwave irradiation time of 10 min, extraction pH of 4.21, extraction temperature of 47.58°C, extraction time of 3h and enzyme concentration of 1.5% (wt% of S. chinensis powder) for cellulase, papain and pectinase, respectively. Under these conditions, the extraction yield of CPS was 7.38 ± 0.21%, which was well in close agreement with the value predicted by the model. The three methods including heat-refluxing extraction (HRE), ultrasonic-assisted extraction (UAE) and enzyme-assisted extraction (EAE) for extracting CPS by RSM were further compared. Results indicated MAEE method had the highest extraction yields of CPS at lower temperature. It was indicated that the proposed approach in this study was a simple and efficient technique for extraction of CPS in S. chinensis Baill.

  3. Optimization of microwave assisted extraction of pectin from sour orange peel and its physicochemical properties.

    Science.gov (United States)

    Hosseini, Seyed Saeid; Khodaiyan, Faramarz; Yarmand, Mohammad Saeid

    2016-04-20

    Microwave assisted extraction technique was used to extract pectin from sour orange peel. Box-Behnken design was used to study the effect of irradiation time, microwave power and pH on the yield and degree of esterification (DE) of pectin. The results showed that the optimum conditions for the highest yield of pectin (29.1%) were obtained at pH of 1.50, microwave power of 700W, and irradiation time of 3min. DE values of pectin ranged from 1.7% to 37.5%, indicating that the obtained pectin was low in methoxyl. Under optimal conditions, the galacturonic acid content and emulsifying activity were 71.0±0.8% and 40.7%, respectively. In addition, the emulsion stability value ranged from 72.1% to 83.4%. Viscosity measurement revealed that the solutions of pectin at low concentrations showed nearly Newtonian flow behavior, and as the concentration increased, pseudoplastic flow became dominant.

  4. The Formation of Nanocrystalline Diamond Coating on WC Deposited by Microwave Assisted Plasma CVD

    Science.gov (United States)

    Toff, M. R. M.; Hamzah, E.; Purniawan, A.

    2010-03-01

    Diamond is one form of carbon structure. The extreme hardness and high chemical resistant of diamond coatings determined that many works on this area relate to coated materials for tribological applications in biomedicine, as mechanical seals or cutting tools for hard machining operations. In the work, nanocrystalline diamond (NCD) coated tungsten carbide (WC) have been deposited by microwave assisted plasma chemical vapor deposition (MAPCVD) from CH4/H2 mixtures. Morphology of NCD was investigated by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quality of NCD is defined as ratio between diamond and non diamond and also full width at half maximum (FWHM) was determined using Raman spectra. The result found that the NCD structure can be deposited on WC surface using CH4/H2 gas mixture with grain size ˜20 nm to 100 nm. Increase %CH4 concentration due to increase the nucleation of NCD whereas decrease the quality of diamond. Based on Raman spectra, the quality of NCD is in the range ˜98.82-99.01% and 99.56-99.75% for NCD and microcrystalline (MCD), respectively. In addition, FWHM of NCD is high than MCD in the range of 8.664-62.24 cm-1 and 4.24-5.05 cm-1 for NCD and MCD respectively that indicate the crystallineity of NCD is smaller than MCD.

  5. Effect of deposition parameters on the structural properties of ZnO nanopowders prepared by microwave-assisted hydrothermal synthesis.

    Science.gov (United States)

    Caglar, Yasemin; Gorgun, Kamuran; Aksoy, Seval

    2015-03-05

    ZnO nanopowders were synthesized via microwave-assisted hydrothermal method at different deposition (microwave irradiation) times and pH values. The effects of pH and deposition (microwave irradiation) time on the crystalline structure and orientation of the ZnO nanopowders have been investigated by X-ray diffraction (XRD) study. XRD observations showed that the crystalline quality of ZnO nanopowders increased with increasing pH value. The crystallite size and texture coefficient values of ZnO nanopowders were calculated. The structural quality of ZnO nanopowder was improved by deposition parameters. Field emission scanning electron microscope (FESEM) was used to analyze the surface morphology of the ZnO nanopowders. Microwave irradiation time and pH value showed a significant effect on the surface morphology.

  6. Microwave assisted novel MoBi2S5 nanoflowers: Synthesis, characterization, photoelectrochemical performance

    Science.gov (United States)

    Pawar, Nita B.; Mali, Sawanta S.; Kharade, Suvarta D.; Kondalkar, Vijay V.; Ghanwat, Vishvanath B.; Khot, Kishorkumar V.; Patil, Pramod S.; Bhosale, Popatrao N.

    2016-11-01

    In the present article, we have studied the effect of post annealing treatment on microstructural, optical and photoelectrochemical (PEC) properties of MoBi2S5 thin films synthesized by microwave assisted technique. The synthesized thin films are vacuum annealed for 4 h at 473 K temperature. The X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV-Vis-NIR spectrophotometer techniques were used for characterization of the as deposited and annealed MoBi2S5 thin films. The XRD patterns confirm the synthesized and annealed thin films have nanocrystalline nature with rhombohedral-orthorhombic crystal structure. SEM micrographs indicate that, nanoflowers exhibit sharper end after annealing. The optical absorption study illustrates that the optical band gap energy has been decrease from 2.0 eV to 1.75 eV with annealing. Finally, applicability of synthesized thin films has been checked for PEC property. The J-V curves revealed that synthesized thin film photoanodes are suitable for PEC cell application. As well, used simple, economical method has great potential for synthesis of various thin film materials.

  7. Empirical modeling of drying kinetics and microwave assisted extraction of bioactive compounds from Adathoda vasica

    Directory of Open Access Journals (Sweden)

    Prithvi Simha

    2016-03-01

    Full Text Available To highlight the shortcomings in conventional methods of extraction, this study investigates the efficacy of Microwave Assisted Extraction (MAE toward bioactive compound recovery from pharmaceutically-significant medicinal plants, Adathoda vasica and Cymbopogon citratus. Initially, the microwave (MW drying behavior of the plant leaves was investigated at different sample loadings, MW power and drying time. Kinetics was analyzed through empirical modeling of drying data against 10 conventional thin-layer drying equations that were further improvised through the incorporation of Arrhenius, exponential and linear-type expressions. 81 semi-empirical Midilli equations were derived and subjected to non-linear regression to arrive at the characteristic drying equations. Bioactive compounds recovery from the leaves was examined under various parameters through a comparative approach that studied MAE against Soxhlet extraction. MAE of A. vasica reported similar yields although drastic reduction in extraction time (210 s as against the average time of 10 h in the Soxhlet apparatus. Extract yield for MAE of C. citratus was higher than the conventional process with optimal parameters determined to be 20 g sample load, 1:20 sample/solvent ratio, extraction time of 150 s and 300 W output power. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were performed to depict changes in internal leaf morphology.

  8. Application of ionic liquid-based microwave-assisted extraction of flavonoids from Scutellaria baicalensis Georgi.

    Science.gov (United States)

    Zhang, Qin; Zhao, San-Hu; Chen, Jue; Zhang, Li-Wei

    2015-10-01

    In the present work, a rapid ionic liquid-based microwave-assisted extraction (ILMAE) method was successfully applied to simultaneous extraction of baicalin, wogonoside, baicalein and wogonin from Scutellaria baicalensis Georgi. A series of 1-alkyl-3-methylirnidazolium ionic liquids with different anions and cations were assessed for extraction efficiency, and 1-octyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, the parameters of ILMAE procedure for the four flavonoids were optimized, and the optimal ILMAE method was validated in the linearity, stability, precision and recovery. Meanwhile, the microstructures of S. baicalensis powders were observed before and after extraction with the help of a scanning electron microscope (SEM) in order to explore the extraction mechanism, and the activity of the crude enzyme solution from S. baicalensis was determined through the hydrolysis of baicalin. Finally, the extraction yields and extraction time of WaterHRE, WaterMAE, ILHRE and Chp were 5.18% (30min), 8.77% (90s), 16.94% (30min) and 18.58% (3h), respectively. The results indicated that compared with the conventional extraction approaches, ILMAE possessed great advantages in extracting flavonoids, such as the highest extraction yield (22.28%), the shortest extraction time (90s), etc.

  9. Dissolution of fluoride complexes following microwave-assisted hydrofluoric acid digestion of marine sediments.

    Science.gov (United States)

    Muratli, Jesse M; McManus, James; Mix, Alan; Chase, Zanna

    2012-01-30

    Microwave-assisted, hydrofluoric acid digestion is an increasingly common tool for the preparation of marine sediment samples for analysis by a variety of spectrometric techniques. Here we report that analysis of terrigenous-dominated sediment samples occasionally results in anomalously low values for several elements, including Al, Ba, Ca, Mg, and Sr. Measured concentrations of these elements increased with time between sample preparation and sample analysis, reaching stable values after 8-29 days. This lag is explained by the formation and subsequent dissolution of poorly soluble fluoride phases during digestion. Other elements, such as Fe, Mn, and Ti, showed little or no lag and were quickly measurable at a stable value. Full re-dissolution of the least soluble fluorides, which incorporate Al and Mg, requires up to four weeks at room temperature, and this duration can vary among sedimentary matrices. This waiting time can be reduced to 6 days (or shorter) if the samples are heated to ≈ 60°C for 24h.

  10. Photocatalytic activity of Eu3+-doped ZnO nanorods synthesized via microwave assisted technique

    Institute of Scientific and Technical Information of China (English)

    P.V. Korake; A.N. Kadam; K.M. Garadkar

    2014-01-01

    The doped ZnO nanorods as a photocatalyst with different Eu contents were prepared by microwave assisted method and they were characterized by means of X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), UV-Vis spectroscopy, surface area Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average crystallite size and band gap energy of Eu-doped ZnO were varied with the Eu content. The XRD pattern of Eu-doped ZnO indicated hexagonal crystal structure with an average crystallite size of 25 nm. The pres-ence of europium with trivalent state and its doping successfully into the crystal lattice of ZnO matrix were confirmed by XPS tech-nique. The photocatalytic activity of Eu-doped ZnO nanorods was evaluated for methyl orange degradation. The photocatalytic experi-ments showed~91%degradation of methyl orange over 0.2 mol.%Eu doped ZnO sample within 3 h under UV light (365 nm).

  11. Ionic liquids based microwave-assisted extraction of lichen compounds with quantitative spectrophotodensitometry analysis.

    Science.gov (United States)

    Bonny, Sarah; Paquin, Ludovic; Carrié, Daniel; Boustie, Joël; Tomasi, Sophie

    2011-11-30

    Ionic liquids based extraction method has been applied to the effective extraction of norstictic acid, a common depsidone isolated from Pertusaria pseudocorallina, a crustose lichen. Five 1-alkyl-3-methylimidazolium ionic liquids (ILs) differing in composition of alkyl chain and anion were investigated for extraction efficiency. The extraction amount of norstictic acid was determined after recovery on HPTLC with a spectrophotodensitometer. The proposed approaches (IL-MAE and IL-heat extraction (IL-HE)) have been evaluated in comparison with usual solvents such as tetrahydrofuran in heat-reflux extraction and microwave-assisted extraction (MAE). The results indicated that both the characteristics of the alkyl chain and anion influenced the extraction of polyphenolic compounds. The sulfate-based ILs [C(1)mim][MSO(4)] and [C(2)mim][ESO(4)] presented the best extraction efficiency of norstictic acid. The reduction of the extraction times between HE and MAE (2 h-5 min) and a non-negligible ratio of norstictic acid in total extract (28%) supports the suitability of the proposed method. This approach was successfully applied to obtain additional compounds from other crustose lichens (Pertusaria amara and Ochrolechia parella).

  12. Ionic liquids based simultaneous ultrasonic and microwave assisted extraction of phenolic compounds from burdock leaves.

    Science.gov (United States)

    Lou, Zaixiang; Wang, Hongxin; Zhu, Song; Chen, Shangwei; Zhang, Ming; Wang, Zhouping

    2012-02-24

    The ionic liquids based simultaneous ultrasonic and microwave assisted extraction (IL-UMAE) technique was first proposed and applied to isolate compounds. The ionic liquids comprising a range of four anions, five 1-alkyl-3-methylimidazolium derivatives were designed and prepared. The results suggested that varying the anion and cation both had apparent effects on the extraction of phenolics. The results also showed that irradiation power, time and solid-liquid ratio significantly affected the yields. The yields of caffeic acid and quercetin obtained by IL-UMAE were higher than those by regular UMAE. Compared with conventional heat-reflux extraction (HRE), the proposed approach exhibited higher efficiency (8-17% enhanced) and shorter extraction time (from 5h to 30s). The results indicated ILUMAE to be a fast and efficient extraction technique. Moreover, the proposed method was validated by the reproducibility and recovery experiments. The ILUMAE method provided good recoveries (from 96.1% to 105.3%) with RSD lower than 5.2%, which indicated that the proposed method was credible. Based on the designable nature of ionic liquids, and the rapid and highly efficient performance of the proposed approach, ILUMAE provided a new alternative for preparation of various useful substances from solid samples.

  13. Phytochemical analysis of Myrtus communis plant: Conventional versus microwave assisted-extraction procedures.

    Science.gov (United States)

    Bouaoudia-Madi, Nadia; Boulekbache-Makhlouf, Lila; Kadri, Nabil; Dahmoune, Farid; Remini, Hocine; Dairi, Sofiane; Oukhmanou-Bensidhoum, Sonia; Madani, Khodir

    2017-06-10

    Background Myrtle (Myrtus communis L) may constitute an interesting dietary source of health protective compounds. Microwave-assisted extraction (MAE) of total phenolic compounds (TPC) from myrtle leaf, stems, pericarp, and seeds was studied and the results were compared with those of the conventional method extraction (CME) in terms of extraction time. Methods Extraction yield/efficiency and antioxidant activity were measured using radical scavenging assay (DPPH•) and reducing power. Results The results show that the MAE was higher in terms of saving energy, extraction time (62 s) and extraction efficiency of bioactive compound compared to CME (2 h). Leaf presented the optimum content of total phenols (250 mg GAE.g-1 DW) and flavonoids (13.65 mg GAE.g-1 DW). However, the anthocyanin content was most important in pericarp extract (176.50±2.17 mg Cyd-3-glu g-1 DW). The antioxidant activity was important in all parts, mainly in leaves. The results indicated that appropriate microwave treatment could be an efficient process to phenolic compounds recovery and thus, better the antioxidant activity of myrtle extract. Conclusions Principal component analysis (PCA) applied to the experimental data shows that the distribution of the myrtle phenolic compounds depended on their plant part localization as well as the extraction method.

  14. Ionic liquids based simultaneous ultrasonic and microwave assisted extraction of phenolic compounds from burdock leaves

    Energy Technology Data Exchange (ETDEWEB)

    Lou Zaixiang, E-mail: louzaixiang@126.com [State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122 (China); Wang Hongxin, E-mail: whx200720082009@yahoo.cn [State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122 (China); Zhu Song; Chen Shangwei; Zhang Ming; Wang Zhouping [State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122 (China)

    2012-02-24

    The ionic liquids based simultaneous ultrasonic and microwave assisted extraction (IL-UMAE) technique was first proposed and applied to isolate compounds. The ionic liquids comprising a range of four anions, five 1-alkyl-3-methylimidazolium derivatives were designed and prepared. The results suggested that varying the anion and cation both had apparent effects on the extraction of phenolics. The results also showed that irradiation power, time and solid-liquid ratio significantly affected the yields. The yields of caffeic acid and quercetin obtained by IL-UMAE were higher than those by regular UMAE. Compared with conventional heat-reflux extraction (HRE), the proposed approach exhibited higher efficiency (8-17% enhanced) and shorter extraction time (from 5 h to 30 s). The results indicated ILUMAE to be a fast and efficient extraction technique. Moreover, the proposed method was validated by the reproducibility and recovery experiments. The ILUMAE method provided good recoveries (from 96.1% to 105.3%) with RSD lower than 5.2%, which indicated that the proposed method was credible. Based on the designable nature of ionic liquids, and the rapid and highly efficient performance of the proposed approach, ILUMAE provided a new alternative for preparation of various useful substances from solid samples.

  15. Pectin from Opuntia ficus indica: Optimization of microwave-assisted extraction and preliminary characterization.

    Science.gov (United States)

    Lefsih, Khalef; Giacomazza, Daniela; Dahmoune, Farid; Mangione, Maria Rosalia; Bulone, Donatella; San Biagio, Pier Luigi; Passantino, Rosa; Costa, Maria Assunta; Guarrasi, Valeria; Madani, Khodir

    2017-04-15

    Optimization of microwave-assisted extraction (MAE) of water-soluble pectin (WSP) from Opuntia ficus indica cladodes was performed using Response Surface Methodology. The effect of extraction time (X1), microwave power (X2), pH (X3) and solid-to-liquid ratio (X4) on the extraction yield was examined. The optimum conditions of MAE were as follows: X1=2.15min; X2=517W; X3=2.26 and X4=2g/30.6mL. The maximum obtained yield of pectin extraction was 12.57%. Total carbohydrate content of WSP is about 95.5% including 34.4% of Galacturonic acid. Pectin-related proteins represent only the 0.66% of WSP mass. HPSEC and light scattering analyses reveal that WSP is mostly constituted of high molecular pectin and FTIR measurements show that the microwave treatment does not alter the chemical structure of WSP, in which Galacturonic acid content and yield are 34.4% and 4.33%, respectively. Overall, application of MAE can give rise to high quality pectin.

  16. The Microwave-Assisted Green Synthesis of TiC Powders

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2016-11-01

    Full Text Available Titanium carbide (TiC is an important engineering material and has found widespread applications. Currently, TiC is typically synthesized through carbothermal reduction, requiring a high temperature (ca. 1700–2300 °C and long reaction time (ca. 10–20 h, which is not eco-friendly. During a conventional reaction path, anatase TiO2 (A-TiO2 was first converted to rutile TiO2 (R-TiO2, which was subsequently reduced to TiC. Herein, we explored the synthesis of TiC powders with the assistance of microwave heating. In particular, we achieved the conversion of A-TiO2, which was more reactive than R-TiO2 for the carbothermal reduction, to TiC, which was directly due to quick microwave heating. As such, the carbothermal reduction started at a much lower temperature of ca. 1200 °C and finished within 30 min when reacting at 1400 °C, leading to significant energy saving. This study shows that microwave-assisted synthesis can be an effective and green process for preparing TiC powders, which is promising for future large-scale production. The influence of the reaction temperature, the reaction duration, and the carbon content on the synthesis of TiC powders was investigated.

  17. Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging

    Science.gov (United States)

    Osborne, Elizabeth A.; Atkins, Tonya M.; Gilbert, Dustin A.; Kauzlarich, Susan M.; Liu, Kai; Louie, Angelique Y.

    2012-06-01

    Currently, magnetic iron oxide nanoparticles are the only nanosized magnetic resonance imaging (MRI) contrast agents approved for clinical use, yet commercial manufacturing of these agents has been limited or discontinued. Though there is still widespread demand for these particles both for clinical use and research, they are difficult to obtain commercially, and complicated syntheses make in-house preparation unfeasible for most biological research labs or clinics. To make commercial production viable and increase accessibility of these products, it is crucial to develop simple, rapid and reproducible preparations of biocompatible iron oxide nanoparticles. Here, we report a rapid, straightforward microwave-assisted synthesis of superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles were produced in two hydrodynamic sizes with differing core morphologies by varying the synthetic method as either a two-step or single-step process. A striking benefit of these methods is the ability to obtain swift and consistent results without the necessity for air-, pH- or temperature-sensitive techniques; therefore, reaction times and complex manufacturing processes are greatly reduced as compared to conventional synthetic methods. This is a great benefit for cost-effective translation to commercial production. The nanoparticles are found to be superparamagnetic and exhibit properties consistent for use in MRI. In addition, the dextran coating imparts the water solubility and biocompatibility necessary for in vivo utilization.

  18. Determination of dieldrin in wool products by gas chromatography with microwave-assisted extraction.

    Science.gov (United States)

    Ohto, Mikiya; Kodama, Shuji; Saito, Yukio; Yamamoto, Atushi

    2006-12-01

    Dieldrin is a moth-proofing agent that was banned by the Stockholm Convention in 2001. The amount of dieldrin in wool products was measured by a microwave-assisted extraction (MAE) method. The optimal conditions were as follows: extraction solvent, acetone/n-hexane (1:1 v/v); extraction temperature, 110 degrees C; extraction time, 10 min; solvent volume, 25 mL. When six samples were used, dieldrin contents determined by GC with the proposed MAE agreed closely with those by the Japanese official method using GC with solvent extraction and cleanup by column chromatography. The proposed MAE has two merits. First, the pretreatment of the MAE needs only 4 h for 11 samples, while that using the Japanese official method needs 2 days for six samples. Second, the volume of organic solvents used for the proposed method was only about one-tenth of that used in the Japanese official method. Our proposed method seems to be easy and useful for daily (routine) tests. Dieldrin contents of 28 used wool products, which were obtained from local clothing shops and ordinary homes, were determined by GC with the proposed MAE, and six products contained dieldrin (0.310-175 ppm). The dry cleaning of the woolen yarn containing 175 ppm dieldrin did not remove a significant amount of dieldrin. Therefore, it seems likely that dieldrin is still distributed slightly but widely throughout the world.

  19. Central composite rotatable design for investigation of microwave-assisted extraction of ginger (Zingiber officinale)

    Science.gov (United States)

    Fadzilah, R. Hanum; Sobhana, B. Arianto; Mahfud, M.

    2015-12-01

    Microwave-assisted extraction technique was employed to extract essential oil from ginger. The optimal condition for microwave assisted extraction of ginger were determined by resposnse surface methodology. A central composite rotatable design was applied to evaluate the effects of three independent variables. The variables is were microwave power 400 - 800W as X1, feed solvent ratio of 0.33 -0.467 as X2 and feed size 1 cm, 0.25 cm and less than 0.2 cm as X3. The correlation analysis of mathematical modelling indicated that quadratic polynomial could be employed to optimize microwave assisted extraction of ginger. The optimal conditions to obtain highest yield of essential oil were : microwave power 597,163 W : feed solvent ratio and size of feed less than 0.2 cm.

  20. Non-polar Solvent Microwave-Assisted Extraction of Volatile Constituents from Dried Zingiber Officinale Rosc.

    Institute of Scientific and Technical Information of China (English)

    YU Yong; WANG Zi-Ming; WANG Yu-Tang; LI Tie-Chun; CHENG Jian-Hua; LIU Zhong-Ying; ZHANG Han-Qi

    2007-01-01

    A new method, non-polar solvent microwave-assisted extraction (NPSMAE), was applied to the extraction of essential oil from Zingiber officinale Rosc. in closed-vessel system. By adding microwave absorption mediumcarbonyl iron powders (CIP) into extraction system, the essential oil was extracted by the non-polar solvent (ether)which can be heated by CIP. The constituents of essential oil obtained by NPSMAE were comparable with those obtained by hydrodistillation (HD) by GC-MS analysis, which indicates that NPSMAE is a feasible way to extract essential oil from dried plant materials. The NPSMAE took much less extraction time (5 min) than HD (180 min),and its extraction efficiency was much higher than that of conventional polar solvent microwave-assisted extraction (PSMAE) and mixed solvent microwave-assisted extraction (MSMAE). It can be a good alternative for the extraction of volatile constituents from dried plant samples.

  1. Microwave-assisted Fenton-like decolorization of methyl orange solution using chromium compounds

    Institute of Scientific and Technical Information of China (English)

    LIU Zuo-hua; TAO Chang-yuan; DU Jun; SUN Da-gui; LI Bai-zhan

    2008-01-01

    Azo dyes discharged in the environment are persistent organic pollutants (POPs), which are very difficult to remove. We developed a microwave-assisted Fenton-like process to degrade methyl orange (MO), an azo dye, with hydrogen peroxide (H2O2) catalyzed by chromium compounds coexisting with MO in the solution. Comparison between the Cr(III)-H2O2 and Cr(VI)-H2O2 systems shows that Cr(VI) has a stronger and more stable catalytical activity than Cr(III), and Cr(III) is more susceptible to a change in the acidity or alkalinity of the reaction system. With a Cr(VI) concentration of 10 mmol L-1 or a Cr(III) concentration of 12 mmol L-1 in the solution under the microwave irradiation of a power larger than 300 W for 3 min, 10 mmol L-1 H2O2 can degrade more than 95% of 1 000 mg L-1 methyl orange; when the microwave power is increased to 700 W, the same amount of H2O2 can degrade all methyl orange in the solution with the same amount of Cr(VI) catalyst. Ultraviolet-visible spectrography indicates the cleavage of the azo bond in methyl orange after treatment, suggesting the potential of this Fenton-like process to degrade azo dye POPs. Reusing waste chromium compounds coexisting with dyestuff in wastewater to catalyze the degradation of azo dyes could be a cost-effective technique for azo dyes and chromate manufacturers and/or users to treat their wastewater and prevent POPs from endangering the environment. This is of particular importance to controlling the water quality of the Three Gorges Reservoir.

  2. Synthesis of benzamides by microwave assisted ring opening of less reactive dimethylaminobenzylidene oxazolone

    Directory of Open Access Journals (Sweden)

    Saurabh C. Khadse

    2017-02-01

    Full Text Available This paper presents the synthesis of some benzamide compounds (B1–B10 by microwave-assisted ring opening of 4-(4-dimethylaminobenzylidene-2-phenyl-5-oxazolone (AZ4. By conventional synthesis involving heating, it was found difficult to obtain ring-opened products, probably due to poor tendency of the carbonyl carbon (C5 of AZ4 to undergo nucleophilic attack by mono/or disubstituted anilines. Microwave assisted reactions were easy to perform, have reduced the reaction time and produced good yields.

  3. Comparative Studies between Conventional and Microwave Assisted Extraction for Rice Bran Oil.

    Science.gov (United States)

    Shukla, Himanshu S; Pratap, Amit

    2017-09-01

    The present work deals with comparison of microwave assisted extraction to that of conventional solvent extraction for the extraction of rice bran oil (RBO); focusing on extraction yield and oil composition. Microwave assisted extraction act as a green process over other method and proved that it is effective method for extraction of oil. The investigation also focuses on the study of functional group and component present in oil. Natural antioxidant component; its activity was confirmed by DPPH assay. The oryzanol content was also determined by measuring the optical density of the sample at 315 nm in n-heptane using UV visible spectrophotometer.

  4. Microwave-assisted shingled magnetic recording simulations on an exchange-coupled composite medium

    Science.gov (United States)

    Tanaka, T.; Kashiwagi, S.; Kanai, Y.; Matsuyama, K.

    2016-10-01

    The potential of microwave-assisted magnetic recording combined with the shingled recording scheme has been studied by simulating read/write processes on exchange-coupled composite media focusing on recording characteristics in the cross-track direction. Microwave fields enhance writability, especially at the track edge, resulting in lower noise and higher signal-to-noise ratio (SNR), which enables higher track density in the shingled recording scheme. Read/write simulations of microwave-assisted shingled recording achieve 1.4 Mtracks/in. while retaining high SNR. Further increases in SNR and track density will require either a narrower reader or track edge noise reduction.

  5. Microwave-assisted Extraction of Rutin and Quercetin from Flos Sophorae

    Institute of Scientific and Technical Information of China (English)

    LI Min-jing; YOU Jing-yan; YAO Shuang; DING Lan; LIU Zhong-ying; ZHANG Han-qi

    2004-01-01

    Three microwave-assisted extraction(MAE) procedures were studied. The first procedure was household microwave oven dynamic extraction(HMODE). The second procedure was special microwave oven bath extraction(SMOBE). The third procedure was microwave resonant cavity dynamic extraction(MRCDE). The results obtained by the three microwave-assisted extraction procedures were compared with those obtained by using traditional Soxhlet extraction. The results indicate that the MAE not only took a shorter time, but also simplified the procedure, and made the extraction a higher yield. At the same time the results obtained by the three MAE procedures were also compared with each other.

  6. Microwave-Assisted Organocatalyzed Rearrangement of Propargyl Vinyl Ethers to Salicylaldehyde Derivatives: An Experimental and Theoretical Study.

    Science.gov (United States)

    Tejedor, David; Cotos, Leandro; Márquez-Arce, Daniel; Odriozola-Gimeno, Mikel; Torrent-Sucarrat, Miquel; Cossío, Fernando P; García-Tellado, Fernando

    2015-12-07

    The microwave-assisted imidazole-catalyzed transformation of propargyl vinyl ethers (PVEs) into multisubstituted salicylaldehydes is described. The reaction is instrumentally simple, scalable, and tolerates a diverse degree of substitution at the propargylic position of the starting PVE. The generated salicylaldehyde motifs incorporate a broad range of topologies, spanning from simple aromatic monocycles to complex fused polycyclic systems. The reaction is highly regioselective and takes place under symmetry-breaking conditions. The preparative power of this reaction was demonstrated in the first total synthesis of morintrifolin B, a benzophenone metabolite isolated from the small tree Morinda citrifolia L. A DFT study of the reaction was performed with full agreement between calculated values and experimental results. The theoretically calculated values support a domino mechanism comprising a propargyl Claisen rearrangement, a [1,3]-H shift, a [1,7]-H shift (enolization), a 6π electrocyclization, and an aromatization reaction.

  7. An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

    KAUST Repository

    Patole, Shashikant P.

    2015-10-21

    It is common for as-prepared carbon nanotube (CNT) and graphene samples to contain remnants of the transition metals used to catalyze their growth; contamination may also leave other trace elemental impurities in the samples. Although a full quantification of impurities in as-prepared samples of carbon nanostructures is difficult, particularly when trace elements are intercalated or encapsulated within a protective layer of graphitic carbon, reliable information is essential for reasons such as quantifying the adulteration of physico-chemical properties of the materials and for evaluating environmental issues. Here, we introduce a microwave-based fusion method to degrade single- and double-walled CNTs and graphene nanoplatelets into a fusion flux thereby thoroughly leaching all metallic impurities. Subsequent dissolution of the fusion product in diluted hydrochloric and nitric acid allowed us to identify their trace elemental impurities using inductively coupled plasma optical emission spectrometry. Comparisons of the results from the proposed microwave-assisted fusion method against those of a more classical microwave-assisted acid digestion approach suggest complementarity between the two that ultimately could lead to a more reliable and less costly determination of trace elemental impurities in carbon nanostructured materials. Graphical abstract A method for the complete digestion of carbon nanostructures has been demonstrated. Photographs (on the left side) show zirconium crucibles containing SWCNTs with flux of Na2CO3 and K2CO3, before and after microwave fusion; (on the right side) the appearance of the final solutions containing dissolved samples, from microwave-assisted fusion and microwave-assisted acid digestion. These solutions were used for determining the trace elemental impurities by ICP‒OES.

  8. Microwave-assisted hydrothermal synthesis of CePO{sub 4} nanostructures: Correlation between the structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Palma-Ramírez, D. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Domínguez-Crespo, M.A., E-mail: mdominguezc@ipn.mx [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Torres-Huerta, A.M. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Dorantes-Rosales, H. [Instituto Politécnico Nacional, ESIQIE, Departamento de Metalurgia, C.P. 07300 México D.F. (Mexico); Ramírez-Meneses, E. [Universidad Iberoamericana, Departamento de Ingeniería y Ciencias Químicas, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, C.P. 01219 México D.F. (Mexico); Rodríguez, E. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico)

    2015-09-15

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO{sub 4} is presented. • Microwave energy can replace the energy by convection for obtaining CePO{sub 4}. • CePO{sub 4} demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO{sub 4} morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO{sub 4}) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO{sub 4} nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO{sub 4} with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO{sub 4} can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic.

  9. Fast microwave-assisted extraction of rotenone for its quantification in seeds of yam bean (Pachyrhizus sp.).

    Science.gov (United States)

    Lautié, Emmanuelle; Rasse, Catherine; Rozet, Eric; Mourgues, Claire; Vanhelleputte, Jean-Paul; Quetin-Leclercq, Joëlle

    2013-02-01

    The aim of this study was to find if fast microwave-assisted extraction could be an alternative to the conventional Soxhlet extraction for the quantification of rotenone in yam bean seeds by SPE and HPLC-UV. For this purpose, an experimental design was used to determine the optimal conditions of the microwave extraction. Then the values of the quantification on three accessions from two different species of yam bean seeds were compared using the two different kinds of extraction. A microwave extraction of 11 min at 55°C using methanol/dichloromethane (50:50) allowed rotenone extraction either equivalently or more efficiently than the 8-h-Soxhlet extraction method and was less sensitive to moisture content. The selectivity, precision, trueness, accuracy, and limit of quantification of the method with microwave extraction were also demonstrated.

  10. Comparison of microwave-assisted hydrodistillation withthe traditional hydrodistillation method in the extractionof essential oils from Thymus vulgaris L.

    Science.gov (United States)

    Golmakani, Mohammad-Taghi; Rezaei, Karamatollah

    2008-08-15

    Microwave-assisted hydrodistillation (MAHD) is an advanced hydrodistillation (HD) technique utilizing a microwave oven in the extraction process. MAHD of essential oils from the aerial parts (tops) of Thymus vulgaris L. (common thyme) was studied and the results were compared with those of the conventional HD in terms of extraction time, extraction yield/efficiency, chemical composition, quality of the essential oils and cost of the operation. MAHD was superior in terms of saving energy and extraction time (75min, compared to 4h in HD). Scanning electron microscopy (SEM) of thyme leaves undergone HD and MAHD provided evidences as to a sudden rupture of essential oil glands with MAHD. Gas chromatography-mass spectrometry analysis of the extracted essential oils indicated that the use of microwave irradiation did not adversely influence the composition of the essential oils. MAHD was found to be a green technology. Copyright © 2008 Elsevier Ltd. All rights reserved.

  11. Microwave assisted synthesis of guar gum grafted sodium acrylate/cloisite superabsorbent nanocomposites: reaction parameters and swelling characteristics.

    Science.gov (United States)

    Likhitha, M; Sailaja, R R N; Priyambika, V S; Ravibabu, M V

    2014-04-01

    In this study, superabsorbent nanocomposites of guar gum grafted sodium acrylate have been synthesized via both microwave and conventional techniques. The reaction parameters of both techniques were optimized and the microwave assisted method was proved to have higher grafting yield with lesser time of reaction as compared to the conventional method. X-ray diffraction and scanning electron microscopy analyses revealed that cloisite was exfoliated and uniformly dispersed in guar gum grafted sodium acrylate matrix. The results show that introducing cloisite into the guar gum grafted sodium acrylate network improved the swelling capability and the swelling rate of the superabsorbent nanocomposite was found to be enhanced at an optimal loading of 10% cloisite. The nanocomposites showed high water absorbency within a wide pH range. Preliminary studies on crystal violet dye removal showed promising results.

  12. Microwave-assisted synthesis, characterization and spectral properties of non-peripherally tetra-substituted phthalocyanines containing eugenol moieties

    Science.gov (United States)

    Kantar, Cihan; Şahin, Zarife Sibel; Büyükgüngör, Orhan; Şaşmaz, Selami

    2015-06-01

    The microwave-assisted synthesis and characterization of novel non-peripherally eugenol substituted metallophthalocyanines (M: Co(II), Ni(II), Cu(II), Zn(II)) have been reported for the first time in this study. All the new compounds were characterized by a combination of FT-IR, 1H NMR, 13C NMR, and UV/vis spectroscopy techniques. The crystal structure of compound (1) was also determined by the single crystal diffraction technique. Newly synthesized eugenol substituted phthalocyanines have more redshift Q bands (about 17-18 nm) than previously reported eugenol substituted phthalocyanines. Zinc(II)phthalocyanine (1d) has an extra absorption band at 746 nm that calling "X band" at UV/vis spectrum.

  13. The effect of microwave-assisted for photo-catalytic reaction in aqueous nano TiO2 particles dispersions.

    Science.gov (United States)

    Chae, Jeong-Seok; Chung, Minchul; Ahn, Ho-Geun; Jung, Sang-Chul

    2010-05-01

    In this study, the photo-catalytic degradation of methylene blue in TiO2 particles-dispersed aqueous solution was carried out by irradiating microwave and UV light simultaneously. The results of photocatalytic degradation of methylene blue showed that the decomposition rate increased with the microwave intensity, UV intensity, TiO2 particle dosages and the circulating fluid velocity. From the result of microwave-assisted photo-catalytic degradation of methylene blue, decomposition rate were shown gradually increased according to the increase of pH. The photo-catalytic degradation rate constant obtained under simultaneous irradiation of microwave and UV light case was about 1.5 times higher than irradiation of UV light only case. This result suggests that there is a synergy effect when the constituent techniques are applied together and that the additional irradiation of microwave can play a very important role in photo-catalysis of organic water pollutants.

  14. A facile microwave assisted one pot synthesis of novel xanthene derivatives as potential anti-inflammatory and analgesic agents

    Directory of Open Access Journals (Sweden)

    Anupam G. Banerjee

    2016-09-01

    Full Text Available Microwave assisted irradiation of resorcinol and substituted aryl aldehydes using sulfamic acid as catalyst afforded novel 9-aryl-9H-xanthene-3,6-diol derivatives (1a–f in good yields. The newly synthesized compounds which were previously selected on the basis of PASS prediction were tested for anti-inflammatory activity using carrageenan-induced rat paw edema and analgesic activity using acetic acid induced writhing and formalin-induced paw edema in mice along with the estimation of gastric ulcerogenicity index. Compounds 1e and 1f exhibited significant anti-inflammatory and analgesic activities as compared to standard drug. The study also revealed that compounds (1a–f showed minimum or no ulcerogenicity in mice as that of the standard drug.

  15. Microwave assisted synthesis of sheet-like Cu/BiVO{sub 4} and its activities of various photocatalytic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); Li, Li, E-mail: qqhrll@163.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); College of Heilongjang Province Key Laboratory of Fine Chemicals, Qiqihar University, Qiqihar 161006 (China); Yi, Tingting [College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); Zhang, WenZhi [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); Zhang, Xiuli; Wang, Lili [College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China)

    2015-09-15

    The Cu/BiVO{sub 4} photocatalyst with visible-light responsivity was prepared by the microwave-assisted hydrothermal method. The phase structures, chemical composition and surface physicochemical properties were well-characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption (UV–vis/DRS), scanning electron microscopy (SEM), and N{sub 2} adsorption–desorption tests. Results indicate that the crystal structure of synthetic composite materials is mainly monoclinic scheelite BiVO{sub 4}, which is not changed with the increasing doping amount of Cu. In addition, the presence of Cu not only enlarges the range of the composite materials under the visible-light response, but also increases the BET value significantly. Compared to pure BiVO{sub 4}, 1% Cu/BiVO{sub 4}-160 performs the highest photocatalytic activity to degrade methylene blue under the irradiation of ultraviolet, visible and simulated sunlight. In addition, the capture experiments prove that the main active species was superoxide radicals during photocatalytic reaction. Moreover, the 1% Cu/BiVO{sub 4}-160 composite shows good photocatalytic stability after three times of recycling. - Graphical abstract: A series of BiVO{sub 4} with different amounts of Cu doping were prepared by the microwave-assisted method, moreover, which performed the high photocatalytic activities to degrade methylene blue under multi-mode. - Highlights: • A series of Cu/BiVO{sub 4} with different amounts of Cu doping were prepared by microwave-assisted synthesis. • The morphologies of as-samples were different with the amount of Cu doping increased. • Compared with pure BiVO{sub 4}, as-Cu/BiVO{sub 4} showed stronger absorption in the visible light region obviously. • 1% Cu/BiVO{sub 4}-160 performed the high photocatalytic activities to degrade methylene blue under multi-mode. • OH{sup •} and h{sup +} both play important roles in the photocatalytic reaction.

  16. Microwave Assisted Bioethanol Production from Sago Starch by Co-Culturing of Ragi Tapai and Saccharomyces Cerevisiae

    Directory of Open Access Journals (Sweden)

    N. Saifuddin

    2011-01-01

    Full Text Available Problem statement: Environmental issues such as global warming and recent events throughout the world, including the shortage of petroleum crude oil, the sharp increase in the cost of oil and the political instability of some crude oil producing countries, have demonstrated the vulnerability of the present sources for liquid fuel. These situations have created great demand for ethanol from fermentation process as green fuel. A main challenge in producing the ethanol is the production cost. A rapid and economical single step fermentation process for reliable production of bioethanol was studied by co-culturing commercialized ragi tapai with Saccharomyces cerevisae using raw sago starch. Approach: Enzymatic hydrolysis of sago starch by various amylolytic enzymes was investigated to reveal the potential coupling mechanism of Microwave Irradiation-Enzyme Coupling Catalysis (MIECC. Results: It was shown that enzymatic hydrolysis of starch using typical enzymes may successfully be carried out at microwave condition. The MIECC resulted in increasing initial reaction rate by about 2 times. The results testify on specific activation of enzymes by microwaves and prove the existence of non-thermal effect in microwave assisted reactions. Low power microwave irradiation (80W does not increase the temperature beyond 40°C and hence denaturation of the enzyme is avoided. The maximum ethanol fermentation efficiency was achieved (97.7% of the theoretical value using 100 g L-1 sago starch concentration. The microwave assisted process improved the yield of ethanol by 45.5% compared to the non-microwave process. Among the other advantages of co-culturing of ragi tapai with S. cerevisiae is the enhancement of ethanol production and prevention of the inhibitory effect of reducing sugars on amylolytic activity and the reaction could be completed within 32±1 h. Conclusion: The present study have demonstrated the ability of using cheaply and readily ragi tapai for

  17. Microwave assisted synthesis and in vitro cytotoxicities of substituted (Z)-2-amino-5-(1-benzyl-1H-indol-3-yl)methylene-1-methyl-1H-imidazol-4(5H)-ones against human tumor cell lines

    Science.gov (United States)

    Penthala, Narsimha Reddy; Yerramreddy, Thirupathi Reddy; Crooks, Peter A

    2015-01-01

    The synthesis of several novel substituted (Z)-2-amino-5-(1-benzyl-1H-indol-3-yl)methylene-1-methyl-1H-imidazol-4(5H)-ones structurally related to aplysinopsin have been carried out under microwave irradiation and conventional heating methods. The analogs 3a, 3b, 3d–3g, and 3k and 3l were evaluated for their in vitro cytotoxic activity against an NCI 60 human tumor cell line panel. Compound 3f exhibited good growth inhibitory properties against all but four of the human cancer cell lines examined, and afforded LC50 values <10 mM for 30% of the cell lines in the panel. Compound 3e was an effective inhibitor of leukemia, CNS, melanoma, and breast cancer cell growth, but generally less effective as a cytotoxic agent. Thus, the aplysinopsin analog 3f was regarded as a useful lead compound for further structural optimization. PMID:20006496

  18. A convenient microwave-assisted synthesis of cinchona alkaloid-derived ligands

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An efficient synthesis of cinchona alkaloid-derived ligands based on solvent-free microwave-assisted reaction was described. The coupling of 1,4-dichlorophthalazine or 3,6-dichloropyridazine with quinine, cinchonine or cinchonidine provide bis- or mono-cinchona alkaloid-derived ligands in moderate to good yields (52-89%) within 15 rain under optimum microwave conditions.

  19. MICROWAVE ASSISTED PREPARATION OF CYCLIC UREAS FROM DIAMINES IN THE PRESENCE OF ZNO

    Science.gov (United States)

    A microwave-assisted facile method for the preparation of various ureas, cyclic ureas, and urethanes has been developed that affords nearly quantitative yield of products at 120 degrees C (150 W), 71 kPa within 10 min using ZnO as a catalyst. The enhanced selectivity in this rea...

  20. Microwave-Assisted Synthesis of Mesoporous Nano-Hydroxyapatite Using Surfactant Templates

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (n-HAP) was expeditiously synthesized using the pseudo sol-gel microwave-assisted protocol (30 min) in the presence of two novel templates, namely sodium lauryl ether sulfate (SLES) and linear alkylbenzenesulfonate (LABS). The cooperative self-assem...

  1. Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents

    Indian Academy of Sciences (India)

    C Praveen; A Nandakumar; P Dheenkumar; D Muralidharan; P T Perumal

    2012-05-01

    Microwave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed moderate to good activity.

  2. Solvent-free microwave-assisted synthesis of oxadiazoles containing imidazole moiety

    Indian Academy of Sciences (India)

    Priya V Frank; K S Girish; Balakrishna Kalluraya

    2007-01-01

    Microwave-assisted as well as conventional synthesis of 5-substituted-2-(2-methyl-4-nitro-1-imidazomethyl)-1,3,4-oxadiazoles containing the nitroimidazole moiety is carried out and their antibacterial, antifungal and anti-inflammatory activity is reported.

  3. Microwave-assisted liquefaction of rape straw for the production of bio-oils

    Science.gov (United States)

    Xing-Yan Huang; Feng Li; Jiu-Long Xie; Cornelis F. De Hoop; Chung-Yun Hse; Jin-Qiu Qi; Hui. Xiao

    2017-01-01

    The acid-catalyzed liquefaction of rape straw in methanol using microwave energy was examined. Conversion yield and energy consumption were evaluated to profile the microwave-assisted liquefaction process. Chemical components of the bio-oils from various liquefaction conditions were identified. A higher reaction temperature was found to be beneficial to obtain higher...

  4. Microwave Assisted Alkali Pretreatment of Rice Straw for Enhancing Enzymatic Digestibility

    Directory of Open Access Journals (Sweden)

    Renu Singh

    2014-01-01

    Full Text Available Rapid industrialization, increasing energy demand, and climate change are the conditions that forced the researchers to develop a clean, efficient, renewable, and sustainable source of energy which has a potential to replace fossil fuels. Ethanol is one of the attractive and suitable renewable energy resources. In present study, effectiveness of microwave pretreatment in combination with sodium hydroxide (NaOH for increasing enzymatic hydrolysis of rice straw has been investigated and under optimum conditions obtained a maximum reducing sugar (1334.79 µg/mL through microwave assisted NaOH pretreatment. Chemical composition analysis and scanning electron microscope (SEM images showed that the removal of lignin, hemicellulose, and silicon content is more in microwave assisted NaOH pretreatment than the blank sample. X-ray diffraction (XRD analysis revealed that the crystallinity index of rice straw treated with microwave assisted alkali (54.55% is significantly high as compared to the blank (49.07%. Hence, the present study proves that microwave assisted alkali pretreatment can effectively enhance enzymatic digestibility of rice straw and it is feasible to convert rice straw for bioethanol production.

  5. Microwave-assisted solid-phase Ugi four-component condensations

    DEFF Research Database (Denmark)

    Nielsen, John

    1999-01-01

    An 18-member library was constructed from 2 isocyanides, 3 aldehydes and 3 carboxylic acids via microwave-assisted solid-phase Ugi reactions on TentaGel S RAM. Products of high purity were obtained in moderate to excellent yields after reaction times of 5 minutes or less (irradiation at 60W). (C...

  6. Microwave-assisted synthesis of geopolymers from fluidised bed gasifier bottom ash

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-09-01

    Full Text Available -1 International Conference of Coal Science and Technology, State College, Pennysylvania, USA, 29 September- 3 October 2013 Microwave-assisted synthesis of geopolymers from fluidised bed gasifier bottom ash B.O. Oboirien1, B.C. North1 and E. R. Sadiku2...

  7. Microwave-Assisted Organic Synthesis in the Organic Teaching Lab: A Simple, Greener Wittig Reaction

    Science.gov (United States)

    Martin, Eric; Kellen-Yuen, Cynthia

    2007-01-01

    A greener, microwave-assisted Wittig reaction has been developed for the second-semester organic teaching laboratory. Utilizing this microwave technique, a variety of styrene derivatives have been successfully synthesized from aromatic aldehydes in good yields (41-68%). The reaction not only occurs under neat reaction conditions, but also employs…

  8. Mathematical Modeling of Microwave-Assisted Convective Heating and Drying of Grapes

    Science.gov (United States)

    This research studied the processing performance and product quality of Thompson seedless grapes dried using microwave-assisted convective hot air drying as well as the effect of blanching and dipping pretreatments. Two pretreatment methods were compared, dipping into 2% ethyl oleate (V/V) and 5% p...

  9. Microwave assisted apatite coating deposition on Ti6Al4V implants.

    Science.gov (United States)

    Zhou, Huan; Nabiyouni, Maryam; Bhaduri, Sarit B

    2013-10-01

    In this work we report a novel microwave assisted technology to deposit a uniform, ultra-thin apatite coating without any cracks on titanium implants in minutes. This method comprises of conventional biomimetic coating in synergism with microwave irradiation to result in alkaline earth phosphate nucleation. The microwave assisted coating process mainly follows the initial stages of biomimetic coating until the step of the Ca-P nuclei formation. After that, due to microwave irradiation more Ca-P nuclei are formed to cover the whole surface of the implant instead of the growth of deposited Ca-P nuclei to Ca-P globules and coatings. It is interesting to note the doping of Mg(2+) to Ca-P apatite coating can significantly change the properties and performances of as-deposited coatings. The hydrophilicity, physical properties, bioactivity, cell adhesion, and growth capability of as-deposited microwave assisted coatings were investigated. The study shows that this coating technology has great potential in biomedical applications. Additionally, since biomimetic coating can be applied to series of implant materials such as polymer, metals and glass, it is expected this microwave assisted coating technology can also be applied to these materials if they can remains stable at 100 °C, the boiling point of water.

  10. Microwave assisted air drying of osmotically treated pineapple with variable power programmes

    CSIR Research Space (South Africa)

    Botha, GE

    2012-01-01

    Full Text Available Variable power programmes for microwave assisted air drying of pineapple were studied. The pineapple pieces were pre-treated by osmotic dehydration in a 55º Brix sucrose solution at 40ºC for 90 minutes. Variable power output programmes were designed...

  11. Microwave-assisted functionalization of carbon nanohorns via [2+1] nitrenes cycloaddition.

    Science.gov (United States)

    Karousis, Nikolaos; Ichihashi, Toshinari; Yudasaka, Masako; Iijima, Sumio; Tagmatarchis, Nikos

    2011-02-07

    The microwave-assisted functionalization of carbon nanohorns (CNHs) via [2+1] nitrenes cycloaddition, providing well dispersible hybrid materials possessing aziridino-rings covalently grafted onto the graphitic network of CNHs, was accomplished, while condensation of hydroxy-functionalized CNHs with thioctic acid, furnishing an endocyclic disulfide bond extended from the aziridino-rings, allowed the stabilization of Au nanoparticles.

  12. Microwave-assisted fast and efficient synthesis of some crown ethers

    Institute of Scientific and Technical Information of China (English)

    Ahmad Ziafati; Hossein Eshghi; Omolbanin Sabzevari

    2009-01-01

    13-Crown-4, 16-crown-5, dibenzo-12-crown-4 and dibenzo-14-crown-4 were synthesized by a one-pot microwave-assisted procedure in good yields. Irradiation of diols and dichlorides in the presence of sodium hydroxide in DMSO gave title crown ethers presumably within a template effect.

  13. Rapid and convenient semi-automated microwave-assisted solid-phase synthesis of arylopeptoids

    DEFF Research Database (Denmark)

    Rasmussen, Jakob Ewald; Boccia, Marcello Massimo; Nielsen, John

    2014-01-01

    A facile and expedient route to the synthesis of arylopeptoid oligomers (N-alkylated aminomethyl benz-amides) using semi-automated microwave-assisted solid-phase synthesis is presented. The synthesis was optimized for the incorporation of side chains derived from sterically hindered or unreactive...

  14. Microwave-assisted chemical insertion: a rapid technique for screening cathodes for Mg-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kaveevivitchai, Watchareeya; Huq, Ashfia; Manthiram, Arumugam

    2016-12-19

    We report an ultrafast microwave-assisted solvothermal method for chemical insertion of Mg2+ ions into host materials using magnesium acetate [Mg(CH3COO)2] as a metal-ion source and diethylene glycol (DEG) as a reducing agent. For instance, up to 3 Mg ions per formula unit of a microporous host framework Mo2.5+yVO9+z could be inserted in as little as 30 min at 170–195 °C in air. This process is superior to the traditional method which involves the use of organometallic reagents, such as di-n-butylmagnesium [(C4H9)2Mg] and magnesium bis(2,6-di-tert-butylphenoxide) [Mg-(O-2,6-But2C6H3)2], and requires an inert atmosphere with extremely long reaction times. Considering the lack of robust electrolytes for Mg-ion batteries, this facile approach can be readily used as a rapid screening technique to identify potential Mg-ion electrode hosts without the necessity of fabricating electrodes and assembling electrochemical cells. Due to the mild reaction conditions, the overall structure and morphology of the Mg-ion inserted products are maintained and the compounds can be used successfully as a cathode in Mg-ion batteries. The combined synchrotron X-ray and neutron diffraction Rietveld analysis reveals the structure of the Mg-inserted compounds and gives an insight into the interactions between the Mg ions and the open-tunnel host framework.

  15. Preparation of alumina-doped yttria-stabilized zirconia nanopowders by microwave-assisted peroxyl-complex coprecipitation

    Institute of Scientific and Technical Information of China (English)

    QI Liang; XU Ming-xia; TIAN Yu-ming; ZHAO Jin-wei

    2006-01-01

    Alumina-doped yttria-stabilized zirconia (ADYSZ) nanopowders were prepared by microwave-assisted peroxyl-complex coprecipitation (MAPCC) using ZrOCl2·8H2O,Y2O3 and AlCl3·6H2O as starting materials,NH3·H2O as precipitant and H2O2 as complexant. The effects of adding H2O2 and microwave drying on the preparation and properties of ADYSZ were investigated. The precursors and nanopowders were studied by EDX,XRD,SEM and TEM techniques. The results show that the uniformity of component distribution within ADYSZ nanopowders is improved by adding appropriate dosage of H2O2. Complexing reaction between H2O2 and Zr4+ ion restrains the hydrolyzation and precipitation of Zr4+ ion. With the addition of H2O2,Al3+,Y3+ and Zr4+ ions can be precipitated synchronously in a relatively narrow range of pH value. H2O2 also improves the filterability of the wet precipitate. The highly hydrophilic precipitates can be quickly and effectively separated from aqueous solution. During microwave drying process,the moisture of wet precursors is selectively heated. Quick expansion of steam vapor within the wet colloidal particles causes the aggregations burst into numerous tiny lumps. Compared with oven drying,microwave drying can not only shorten drying time but also reduce aggregation intensity of the resultant ADYSZ nanopowders.

  16. Microwave assisted synthesis of a novel optical chemosensor for selective Fe{sup 3+} detection

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Muhammad [Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701 (Korea, Republic of); Kang, Sung Kwon [Department of Chemistry Chungnam National University, Daejeon 305-754 (Korea, Republic of); Lee, Ki Hwan, E-mail: khlee@kongju.ac.kr [Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701 (Korea, Republic of)

    2015-06-15

    Recently, there has been significant interest in the design and development of optical chemosensors for recognition of biologically and environmentally important analytes with high selectivity, sensitivity and low detection-limit because of their fundamental role in medical, environmental and biological applications. Herein, a novel fluorogenic signaling probe 6 for the selective detection of ferric ion in mixed aqueous organic media has been developed through microwave assisted Schiff base formation by reacting 4-amino-3-(2-fluorobenzyl)-1H-1,2,4-triazole-5(4H)-thione 5 with thiophene-2-carbaldehyde. The formation of probe 6 was characterized by FT-IR, {sup 1}H NMR, {sup 13}C NMR, mass spectrometric and single crystal X-ray diffraction analysis. The photophysical results of (Z)-3-(2-fluorobenzyl)-4-[(thiophen-2-ylmethylene) amino]-1H-1,2,4-triazole-5(4H)-thione (6) corroborates its applicability as optical sensing platform for selective Fe{sup 3+} detection in pure organic as well as mixed organic-aqueous media. Through fluorescence titration at 478 nm, we were confirmed that the ligand 6 exhibited remarkable decline in the fluorescence intensity by complexation between 6 and Fe{sup 3+} while it appeared negligible fluorescent quenching in case of the competitive ions in MeOH/water (8:2, v/v, pH 7) at ambient temperature. Meanwhile, the emergence of a new characteristic redshifted signal at 357 nm with gradual increment in the absorption intensity on gentle increase in the ferric ion concentration and continuous shifting in the ligand absorption bands after Fe{sup 3+} addition ascribed the conformational changes in the ligand structure upon Fe{sup 3+} binding. Due to simplicity, low cost, fast response time, considerable sensitivity and robustness, the proposed sensing method might be a practical tool for environmental samples analysis and biological studies. - Highlights: • A novel fluorogenic signaling probe for ferric ion has been developed. • The ligand

  17. Microwave-Assisted Conversion of Levulinic Acid to γ-Valerolactone Using Low-Loaded Supported Iron Oxide Nanoparticles on Porous Silicates

    Directory of Open Access Journals (Sweden)

    Alfonso Yepez

    2015-09-01

    Full Text Available The microwave-assisted conversion of levulinic acid (LA has been studied using low-loaded supported Fe-based catalysts on porous silicates. A very simple, productive, and highly reproducible continuous flow method has been used for the homogeneous deposition of metal oxide nanoparticles on the silicate supports. Formic acid was used as a hydrogen donating agent for the hydrogenation of LA to effectively replace high pressure H2 mostly reported for LA conversion. Moderate LA conversion was achieved in the case of non-noble metal-based iron oxide catalysts, with a significant potential for further improvements to compete with noble metal-based catalysts.

  18. Microwave-assisted Facile and Ultrafast Growth of ZnO Nanostructures and Proposition of Alternative Microwave-assisted Methods to Address Growth Stoppage

    Science.gov (United States)

    Rana, Abu Ul Hassan Sarwar; Kang, Mingi; Kim, Hyun-Seok

    2016-04-01

    The time constraint in the growth of ZnO nanostructures when using a hydrothermal method is of paramount importance in contemporary research, where a long fabrication time rots the very essence of the research on ZnO nanostructures. In this study, we present the facile and ultrafast growth of ZnO nanostructures in a domestic microwave oven within a pressurized environment in just a few minutes. This method is preferred for the conventional solution-based method because of the ultrafast supersaturation of zinc salts and the fabrication of high-quality nanostructures. The study of the effect of seed layer density, growth time, and the solution’s molar concentration on the morphology, alignment, density, and aspect ratio of ZnO nanorods (ZNRs) is explored. It is found in a microwave-assisted direct growth method that ~5 mins is the optimum time beyond which homogeneous nucleation supersedes heterogeneous nucleation, which results in the growth stoppage of ZNRs. To deal with this issue, we propound different methods such as microwave-assisted solution-replacement, preheating, and PEI-based growth methods, where growth stoppage is addressed and ZNRs with a high aspect ratio can be grown. Furthermore, high-quality ZnO nanoflowers and ZnO nanowalls are fabricated via ammonium hydroxide treatment in a very short time.

  19. Microwave-assisted pyrolysis of methyl ricinoleate for continuous production of undecylenic acid methyl ester (UAME).

    Science.gov (United States)

    Nie, Yong; Duan, Ying; Gong, Ruchao; Yu, Shangzhi; Lu, Meizhen; Yu, Fengwen; Ji, Jianbing

    2015-06-01

    Undecylenic acid methyl ester (UAME) was continuously produced from methyl ricinoleate using a microwave-assisted pyrolysis system with atomization feeding. The UAME yield of 77 wt.% was obtained at 500°C using SiC as the microwave absorbent and heating medium. The methyl ricinoleate conversion and UAME yield from microwave-assisted pyrolysis process were higher than those from conventional pyrolysis. The effect of temperature on the pyrolysis process was also investigated. The methyl ricinoleate conversion increased but the cracking liquid yield decreased when the temperature increased from 460°C to 560°C. The maximum UAME yield was obtained at the temperature of 500°C.

  20. Optimization of microwave-assisted extraction of polysaccharide from Psidium guajava L. fruits.

    Science.gov (United States)

    Amutha Gnana Arasi, Michael Antony Samy; Gopal Rao, Manchineela; Bagyalakshmi, Janardanan

    2016-10-01

    This study deals with the optimization of microwave assisted extraction of polysaccharide from Psidium guajava L. fruit using Response surface methodology. To evaluate the effect of three independent variables, Water to plant material ratio, microwave power used for extraction and Irradiation time, central composite design has been employed. The yield is considered as dependent variable. The design model estimated the optimum yield of 6.81677% at 200W microwave power level, 3:1 water to plant material ratio and 20min of irradiation time. Three factors three levels Central composite design coupled with RSM was used to model the extraction process. ANOVA was performed to find the significance of the model. The polysaccharide extracted using microwave assisted extraction process was analyzed using FTIR Spectroscopy.

  1. Application of ionic liquids in the microwave-assisted extraction of proanthocyanidins from Larix gmelini bark.

    Science.gov (United States)

    Yang, Lei; Sun, Xiaowei; Yang, Fengjian; Zhao, Chunjian; Zhang, Lin; Zu, Yuangang

    2012-01-01

    Ionic liquid based, microwave-assisted extraction (ILMAE) was successfully applied to the extraction of proanthocyanidins from Larix gmelini bark. In this work, in order to evaluate the performance of ionic liquids in the microwave-assisted extraction process, a series of 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were evaluated for extraction yield, and 1-butyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, the ILMAE procedure for the proanthocyanidins was optimized and compared with other conventional extraction techniques. Under the optimized conditions, satisfactory extraction yield of the proanthocyanidins was obtained. Relative to other methods, the proposed approach provided higher extraction yield and lower energy consumption. The Larix gmelini bark samples before and after extraction were analyzed by Thermal gravimetric analysis, Fourier-transform infrared spectroscopy and characterized by scanning electron microscopy. The results showed that the ILMAE method is a simple and efficient technique for sample preparation.

  2. Microwave-assisted extraction versus Soxhlet extraction to determine triterpene acids in olive skins.

    Science.gov (United States)

    Fernandez-Pastor, Ignacio; Fernandez-Hernandez, Antonia; Perez-Criado, Sergio; Rivas, Francisco; Martinez, Antonio; Garcia-Granados, Andres; Parra, Andres

    2017-03-01

    Microwave-assisted extraction is compared with a more classical technique, Soxhlet extraction, to determine the content of triterpene acids in olive skins. The samples used in their original unmilled state and milled were extracted with ethyl acetate or methanol as solvents. The optimized operating conditions (e.g., amount and type of solvent, and time and temperature of extractions) to attain the better extraction yields have been established. For the identification and quantitation of the target compounds, an ultra high performance liquid chromatography with tandem mass spectrometry method was employed. The best results were achieved using the microwave-assisted extraction technique, which was much faster than the Soxhlet extraction method, and showed higher efficiency in the extraction of the triterpenic acids (oleanolic and maslinic).

  3. Microwave-assisted brazing of alumina ceramics for electron tube applications

    Indian Academy of Sciences (India)

    2016-04-01

    Alumina was joined with alumina using microwave-assisted and conventional brazing methods at 960$^{\\circ}$C for 15 min using TiCuSil (68.8Ag–26.7Cu–4.5Ti in wt.%) as the brazing alloy. The brazed joints were characterizedby X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Vickers microhardness evaluation, brazing strength measurement and helium leak test. X-ray diffraction analysis confirmed the formationof Ti-based compounds at the substrate-filler alloy interfaces of the microwave and conventionally brazed joints. The elemental compositions at the joint cross-section were determined by energy dispersive X-ray analysis. Vickers microhardness measurement indicated reliable joint performance for the microwave-assisted brazed joints during actual application in an electron tube. Brazing strength measurement and helium leak test provided the evidence forgood alumina-alumina joint formation.

  4. Accessing Stereochemically Rich Sultams via Microwave-Assisted, Continuous Flow Organic Synthesis (MACOS) Scale-out

    Science.gov (United States)

    Organ, Michael G.; Hanson, Paul R.; Rolfe, Alan; Samarakoon, Thiwanka B.; Ullah, Farman

    2011-01-01

    The generation of stereochemically-rich benzothiaoxazepine-1,1′-dioxides for enrichment of high-throughput screening collections is reported. Utilizing a microwave-assisted, continuous flow organic synthesis platform (MACOS), scale-out of core benzothiaoxazepine-1,1′-dioxide scaffolds has been achieved on multi-gram scale using an epoxide opening/SNAr cyclization protocol. Diversification of these sultam scaffolds was attained via a microwave-assisted intermolecular SNAr reaction with a variety of amines. Overall, a facile, 2-step protocol generated a collection of benzothiaoxazepine-1,1′-dioxides possessing stereochemical complexity in rapid fashion, where all 8 stereoisomers were accessed from commercially available starting materials. PMID:22116791

  5. Application of ionic liquids in the microwave-assisted extraction of pectin from lemon peels.

    Science.gov (United States)

    Guolin, Huang; Jeffrey, Shi; Kai, Zhang; Xiaolan, Huang

    2012-01-01

    Microwave-assisted extraction of pectin from lemon peels by using ionic liquid as alternative solvent was investigated. The extracted pectin was detected by Fourier transform infrared spectra. The extraction conditions were optimized through the different experiments in conjunction with the response surface methodology. A pectin yield of 24.68 % was obtained under the optimal parameters: the extraction temperature of 88°C, the extraction time of 9.6 min, and a liquid-solid ratio of 22.7 ml · g(-1). The structure of the pretreated lemon peel samples and the samples after microwave-assisted extraction were characterized by a field emission scanning electron microscope.

  6. Application of Ionic Liquids in the Microwave-Assisted Extraction of Pectin from Lemon Peels

    Directory of Open Access Journals (Sweden)

    Huang Guolin

    2012-01-01

    Full Text Available Microwave-assisted extraction of pectin from lemon peels by using ionic liquid as alternative solvent was investigated. The extracted pectin was detected by Fourier transform infrared spectra. The extraction conditions were optimized through the different experiments in conjunction with the response surface methodology. A pectin yield of 24.68 % was obtained under the optimal parameters: the extraction temperature of 88°C, the extraction time of 9.6 min, and a liquid-solid ratio of 22.7 ml⋅g-1. The structure of the pretreated lemon peel samples and the samples after microwave-assisted extraction were characterized by a field emission scanning electron microscope.

  7. Microwave assisted synthesis of 2-pyridone and 2-pyridone based compounds

    Directory of Open Access Journals (Sweden)

    Mijin Dušan Ž.

    2014-01-01

    Full Text Available 2-Pyridones are important heterocyclic compounds that are widely used in medical chemistry, and their various derivatives have significant biological and medical applications. In this paper, the synthesis of 2-pyridones as well as 2-pyridone based compounds such as 2-quinolones using microwave assisted organic chemistry is reviewed. The review is divided in three parts. In the first part, microwave synthesis of 2-pyridones according to the type of condensation is discussed. In the second part, microwave assisted synthesis of 2-quionolones is listed. At the end of the review several examples of microwave synthesis of other 2-pyridone based compounds (ring fused N-substituted 2-pyridones are given. [Projekat Ministarstva nauke Republike Srbije, br. 172013

  8. Response surface optimization of microwave-assisted extraction for HPLC-fluorescence determination of puerarin and daidz

    Institute of Scientific and Technical Information of China (English)

    Ying-Kun Liu; E Yan; Han-Ying Zhan; Zhi-Qi Zhang

    2011-01-01

    Microwave-assisted extraction was optimized with response surface methodology for HPLC-fluorescence determination of puerarin and daidzein in Radix Puerariae thomsonii.The optimized extraction procedure was achieved by soaking the sample with 70% methanol

  9. MICROWAVE-ASSISTED PREPARATION OF 1-BUTYL-3-METHYLIMIDAZOLIUM TETRACHLOROGALLATE AND ITS CATALYTIC USE IN ACETAL FORMATION UNDER MILD CONDITIONS

    Science.gov (United States)

    1-Butyl-3-methylimidazolium tetrachlorogallate, [bmim][GaCl4], prepared via microwave-assisted protocol, is found to be an active catalyst for the efficient acetalization of aldehydes under mild conditions.

  10. Sugarcane Bagasse Pyrolysis in a Carbon Dioxide Atmosphere with Conventional and Microwave-Assisted Heating

    OpenAIRE

    Lin, Bo-Jhih; Chen, Wei-Hsin

    2015-01-01

    Pyrolysis is an important thermochemical method to convert biomass into bio-oil. In this study, the pyrolysis of sugarcane bagasse in a CO2 atmosphere under conventional and microwave-assisted heating is investigated to achieve CO2 utilization. In the microwave pyrolysis, charcoal is used as the microwave absorber to aid in pyrolysis reactions. The results indicate that the yields of pyrolysis products are greatly influenced by the heating modes. In the conventional heating, the prime product...

  11. Sugarcane bagasse pyrolysis in a carbon dioxide atmosphere with conventional and microwave-assisted heating

    OpenAIRE

    Bo-Jhih eLin; Wei-Hsin eChen

    2015-01-01

    Pyrolysis is an important thermochemical method to convert biomass into bio-oil. In this study, the pyrolysis of sugarcane bagasse in a CO2 atmosphere under conventional and microwave-assisted heating is investigated to achieve CO2 utilization. In the microwave pyrolysis, charcoal is used as the microwave absorber to aid in pyrolysis reactions. The results indicate that the yields of pyrolysis products are greatly influenced by the heating modes. In the conventional heating, the prime product...

  12. Experimental and modeling studies on microwave-assisted extraction of mangiferin from Curcuma amada

    OpenAIRE

    Kullu, Jeke; Dutta, Abhishek; Constales, Denis; Chaudhuri, Surabhi; Debjani DUTTA

    2013-01-01

    Mangiferin, a bioactive compound having potent nutraceutical, strong antioxidant and pharmacological significance has been extracted using microwave-assisted extraction (MAE) technique from Curcuma amada, commonly known as mango ginger. The extraction solvent ethanol is eco-friendly, nontoxic and reduces the risk of environmental hazards. The influence of several independent variables such as microwave power, ethanol concentration, extraction (irradiation) time and pre-leaching time has been ...

  13. Microwave-Assisted Synthesis of Boron-Modified TiO2 Nanocrystals

    OpenAIRE

    Claudia Carlucci; Barbara Federica Scremin; Teresa Sibillano; Cinzia Giannini; Emanuela Filippo; Patrizia Perulli; Agostina Lina Capodilupo; Giuseppina Anna Corrente; Giuseppe Ciccarella

    2014-01-01

    An efficient microwave-assisted synthesis of TiO2:(B) nanorods, using titanium tetraisopropoxide (TTIP), benzyl alcohol as the solvent, together with boric acid and oleic acid as the additive reagents, has been developed. Chemical modification of TTIP by oleic acid was demonstrated as a rational strategy to tune the shape of TiO2 nanocrystals toward nanorod formation. The differently-shaped TiO2:(B) nanocrystals were characterized in detail by transmission electron microscopy (TEM), inductive...

  14. Renewable platform chemicals from directional microwave-assisted liquefaction coupling stepwise extraction of waste biomass

    Science.gov (United States)

    Junfeng Feng; Chungyun Hse; Zhongzhi Yang; Kui Wang; Jianchun Jiang; Junming Xu

    2017-01-01

    Directional microwave-assisted liquefaction and stepwise extraction are introduced for producing platform chemicals: aromatics and monosaccharides. When sulfuric acid was used as a catalyst, a 45% monosaccharides yield and a 29% aromatics yield were obtained from bamboo with 0.3 g catalyst per 18 g methanol and 2 g bamboo at 160 °C with 10 min. Approximately 78–86 wt%...

  15. Rapid, Microwave-Assisted Organic Synthesis of Selective V600EBRAF Inhibitors for Preclinical Cancer Research

    Science.gov (United States)

    Buck, Jason R.; Saleh, Sam; Uddin, Md. Imam; Manning, H. Charles

    2012-01-01

    We report a dramatically improved total synthesis of two highly selective V600EBRAF inhibitors, PLX4720 and PLX4032, that leverages microwave-assisted organic synthesis (MAOS). Compared with previously reported approaches, our novel MAOS method significantly reduces overall reaction time without compromising yield. In addition to providing a gram-scale route to these compounds for preclinical oncology research, we anticipate this approach could accelerate the synthesis of azaindoles in high-throughput, library-based formats. PMID:23180892

  16. Portable microwave assisted extraction: An original concept for green analytical chemistry

    OpenAIRE

    Petitcolas, Emmanuel; de la Guardia, Miguel; Chemat, Farid

    2013-01-01

    This paper describes a portable microwave assisted extraction apparatus (PMAE) for extraction of bioactive compounds especially essential oils and aromas directly in a crop or in a forest. The developed procedure, based on the concept of green analytical chemistry, is appropriate to obtain direct in-field information about the level of essential oils in natural samples and to illustrate green chemical lesson and research. The efficiency of this experiment was validated for the extraction of e...

  17. Literature study of microwave-assisted digestion using electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Chakraborty, R; Das, A K; Cervera, M L; De La Guardia, M

    1996-05-01

    The literature on the use of microwave-assisted digestion procedures for subsequent sample analysis by means of electrothermal atomic absorption spectrometry (ETAAS) is reviewed. The literature survey reveals that this digestion technique has been applied mainly for biological materials. The elements most extensively determined by this method are cadmium and lead followed by copper, chromium, nickel and iron. The microwave digestion conditions, ETAAS furnace programmes and analytical details of the developed methodologies have been carefully revised.

  18. Nordihydroguaiaretic acid recovery from Larrea tridentata by microwave-assisted extraction

    OpenAIRE

    Martins, Sílvia; Mussatto, Solange I.; Aguilar, Cristóbal N.; Garza-Rodriguez, I.; Teixeira, J.A.

    2010-01-01

    Nordihydroguaiaretic acid (NDGA) is a powerful antioxidant with biological activities of great interest in several health areas, including antiviral, cancer chemopreventive, and antitumorgenic. Little information is available on extraction methods of NDGA from Larrea tridentata. Hence, the aim of this study was to develop a rapid and effective microwave-assisted extraction (MAE) method for NDGA recovery from Larrea tridentata leaves, and to compare the results ob...

  19. Microwave Assisted Hot Air Convective Dehydration of Fish Slice: Drying Characteristics, Energy Aspects and Colour Assessment

    Directory of Open Access Journals (Sweden)

    Mohd Rozainee Taib

    2011-01-01

    Full Text Available Dried fish is commonly produced by convective hot air drying. Microwave technology was presented in this paper to improve both process and product quality. Catfish (order Siluriformes slices were dehydrated in a microwave assisted hot air convective dehydration (MWHA system to investigate the effects of microwave power and hot air temperature on drying time, dehydration behaviour, energy consumption and colour of dried fish. Three different microwave power outputs namely medium (373 W, medium low (217 W and low (91 W combined with convective hot air temperature of 40°C, 70°C and 130°C accordingly were employed in the drying experiments. Results show that microwave accelerates drying time up to 120 folds faster compared to drying with hot air convective alone. It was also noted that increasing the hot air temperature was not as significant as increasing the microwave power in reducing the drying time. Experiments show that drying time was reduced about 75 % when an increase of microwave power from low (91 W to medium mode (373 W combining with convective hot air. However, drying with microwave alone required longer drying time. Energy consumption analysis shows that microwave assisted drying process requires less energy usage. Drying fish with microwave assisted hot air dehydration treatment make the colour brighter, shifting towards red and yellow.

  20. Microwave assisted rapid and complete degradation of atrazine using TiO(2) nanotube photocatalyst suspensions.

    Science.gov (United States)

    Zhanqi, Gao; Shaogui, Yang; Na, Ta; Cheng, Sun

    2007-07-16

    A technology, microwave-assisted photocatalysis on TiO(2) nanotubes, which can be applied to degrade atrazine rapidly and completely, was investigated. TiO(2) nanotubes were prepared, and confirmed by XRD, TEM and ESR. Microwave-assisted photocatalytic degradation of atrazine in aqueous solution was investigated. The result indicates that atrazine is completely degraded in 5min and the mineralization efficiency is 98.5% in 20min, which is obviously more efficient than that by the traditional photocatalytic degradation methods. It may be attributed to the intense UV radiation generated by electrodeless discharge lamps under microwave irradiation, the increased number of OH, additional defect sites on TiO(2) under the irradiation of microwave and larger specific surface area of TiO(2) nanotubes which could adsorb more organic substances to degrade than TiO(2) nanoparticles. Along with the degradation of atrazine, the concentrations of Cl(-) and NO(3)(-) increase gradually. In 20min [Cl(-)] and [NO(3)(-)] are 3, 27.8mg/L, respectively, which are close to their stoichiometric values. The major intermediates of atrazine were identified by HPLC/MS and possible degradation pathways of atrazine in microwave-assisted photocatalysis on TiO(2) nanotubes were proposed.

  1. The microwave-assisted ionic-liquid method: a promising methodology in nanomaterials.

    Science.gov (United States)

    Ma, Ming-Guo; Zhu, Jie-Fang; Zhu, Ying-Jie; Sun, Run-Cang

    2014-09-01

    In recent years, the microwave-assisted ionic-liquid method has been accepted as a promising methodology for the preparation of nanomaterials and cellulose-based nanocomposites. Applications of this method in the preparation of cellulose-based nanocomposites comply with the major principles of green chemistry, that is, they use an environmentally friendly method in environmentally preferable solvents to make use of renewable materials. This minireview focuses on the recent development of the synthesis of nanomaterials and cellulose-based nanocomposites by means of the microwave-assisted ionic-liquid method. We first discuss the preparation of nanomaterials including noble metals, metal oxides, complex metal oxides, metal sulfides, and other nanomaterials by means of this method. Then we provide an overview of the synthesis of cellulose-based nanocomposites by using this method. The emphasis is on the synthesis, microstructure, and properties of nanostructured materials obtained through this methodology. Our recent research on nanomaterials and cellulose-based nanocomposites by this rapid method is summarized. In addition, the formation mechanisms involved in the microwave-assisted ionic-liquid synthesis of nanostructured materials are discussed briefly. Finally, the future perspectives of this methodology in the synthesis of nanostructured materials are proposed.

  2. Microwave-Assisted Routes for the Synthesis of Complex Functional Oxides

    Directory of Open Access Journals (Sweden)

    Jesús Prado-Gonjal

    2015-05-01

    Full Text Available The synthesis of complex functional inorganic materials, such as oxides, can be successfully performed by using microwave irradiation as the source of heat. To achieve this, different routes and set-ups can be used: microwave-assisted synthesis may proceed in the solid state or in solution, aqueous or not, and the set ups may be as simple and accessible as domestic oven or quite sophisticated laboratory equipment. An obvious advantage of this innovative methodology is the considerable reduction in time—minutes rather than hours or days—and, as a consequence, energy saving. No less important is the fact that the particle growth is inhibited and the broad variety of different microwave or microwave-assisted synthesis techniques opens up opportunities for the preparation of inorganic nanoparticles and nanostructures. In this work, various microwave synthesis techniques have been employed: solid-state microwaves, single-mode microwaves using a TE10p cavity and microwave-assisted hydrothermal synthesis. Relevant examples are presented and discussed.

  3. Microwave assisted synthesis and antimicrobial activity of novel 1-[1/2-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy-naphthalen-2/1-yl]-3-(1-phenyl-3-aryl-1H-pyrazol-4-yl-propenones

    Directory of Open Access Journals (Sweden)

    Dongamanti Ashok

    2015-06-01

    Full Text Available A series of novel 1-[1/2-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy-naphthalen-2/1-yl]-3-(1-phenyl-3-aryl-1H-pyrazol-4-yl-propenones were design and synthesized by Click reaction followed by Claisen-Schmidt condensation under microwave irradiation and conventional heating methods. The structures of newly synthesized compounds have been established on the basis of elemental analysis, IR, 1H & 13C NMR and mass spectral data. All the compounds were screened for their antimicrobial activity.

  4. 微波辅助合成芳烃钌(Ⅱ)配合物[(η6-RC6H5)Ru(m-MOPIP)Cl]Cl%Microwave-Assisted Synthesis of Arene Ru(Ⅱ) Complexes [(η6-RC6H5)Ru(m-MOPIP)Cl]Cl

    Institute of Scientific and Technical Information of China (English)

    吴琼; 吴剑; 梅文杰; 姚骏骅; 吴韦黎; 陈燕华; 陶韵伊

    2013-01-01

    运用微波辅助合成技术,在二氯甲烷溶液中,60℃条件下,Pyrex管中微波辐射30 min制备得到芳烃钌(Ⅱ)化合物[(η6-RC6H5)Ru(m-MOPIP)Cl]Cl (R=H 3a,R=CH3 3b; m-MOPIP=2-(3-甲氧苯基)-咪唑并[4,5f][1,10]菲哕啉),反应产率分别为90%和91%,目标化合物运用1H NMR,13C NMR,IR,ESI-MS以及1H-1H COSY进行表征;在相同条件下SiC管中,屏蔽微波辐射对反应的影响,3a和3b的产率分别为89%和90%,说明微波“非热效应”对芳烃钌(Ⅱ)配合物的合成没有显著影响.

  5. Microwave-assisted addition of azomethines to isatoic anhydride

    Indian Academy of Sciences (India)

    E Dominic Jacob; Lopez Mathew; Baby Thomas

    2007-01-01

    Diels-Alder addition of azomethines to isatoic anhydride in a solvent-free and eco-friendly condition is investigated using a microwave oven. The product is exclusively 2,3-diaryl-2,3-dihydroquinazolin-4(1H)-ones 4a-d. HOMO-LUMO energy of the iminoketene and the dienophiles were calculated using semi-empirical AM1 calculations.

  6. Sample preparation of sewage sludge and soil samples for the determination of polycyclic aromatic hydrocarbons based on one-pot microwave-assisted saponification and extraction.

    Science.gov (United States)

    Pena, M Teresa; Pensado, Luis; Casais, M Carmen; Mejuto, M Carmen; Cela, Rafael

    2007-04-01

    A microwave-assisted sample preparation (MASP) procedure was developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge and soil samples. The procedure involved the simultaneous microwave-assisted extraction of PAHs with n-hexane and the hydrolysis of samples with methanolic potassium hydroxide. Because of the complex nature of the samples, the extracts were submitted to further cleaning with silica and Florisil solid-phase extraction cartridges connected in series. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, were considered in the study. Quantification limits obtained for all of these compounds (between 0.4 and 14.8 microg kg(-1) dry mass) were well below of the limits recommended in the USA and EU. Overall recovery values ranged from 60 to 100%, with most losses being due to evaporation in the solvent exchange stages of the procedure, although excellent extraction recoveries were obtained. Validation of the accuracy was carried out with BCR-088 (sewage sludge) and BCR-524 (contaminated industrial soil) reference materials.

  7. Sample preparation of sewage sludge and soil samples for the determination of polycyclic aromatic hydrocarbons based on one-pot microwave-assisted saponification and extraction

    Energy Technology Data Exchange (ETDEWEB)

    Pena, M.T.; Pensado, Luis; Casais, M.C.; Mejuto, M.C.; Cela, Rafael [Universidad de Santiago de Compostela, Dpto. Quimica Analitica, Nutricion y Bromatologia. Instituto de Investigacion y Analisis Alimentario, Santiago de Compostela (Spain)

    2007-04-15

    A microwave-assisted sample preparation (MASP) procedure was developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge and soil samples. The procedure involved the simultaneous microwave-assisted extraction of PAHs with n-hexane and the hydrolysis of samples with methanolic potassium hydroxide. Because of the complex nature of the samples, the extracts were submitted to further cleaning with silica and Florisil solid-phase extraction cartridges connected in series. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, were considered in the study. Quantification limits obtained for all of these compounds (between 0.4 and 14.8 {mu}g kg{sup -1} dry mass) were well below of the limits recommended in the USA and EU. Overall recovery values ranged from 60 to 100%, with most losses being due to evaporation in the solvent exchange stages of the procedure, although excellent extraction recoveries were obtained. Validation of the accuracy was carried out with BCR-088 (sewage sludge) and BCR-524 (contaminated industrial soil) reference materials. (orig.)

  8. Microwave-assisted preparation of naphthenic acid esters

    Directory of Open Access Journals (Sweden)

    VERA CIRIN-NOVTA

    2006-12-01

    Full Text Available The synthesis of esters of natural petroleum acids of the naphthenic type assisted with microwave irradiation under the conditions of acid catalysis was carried out with various alcohols: methanol, ethanol, n-butanol and tert-butyl alcohol. Microwave dielectric heating of the reaction mixture in an unmodified microwave oven with activation of the naphthenic acids with sulfuric and p-toluenesulfonic acid afforded the esters of the naphthenic acids. Depending on the catalyst and the steric and nucleophilic properties of the alcohols, the yield of naphthenic esters ranged from 31.25 % to 88.90 %. As a consequence of microwave dielectric heating, the esterification time was reduced from 6–10 h to 5 min.

  9. 二正丁基锡二(邻氯苯甲酸)酯配合物{[n-Bu2Sn(O2CC6H4C1)]2O}2的微波固相合成、结构及体外抗癌活性%Microwave Assisted Solid-state Synthesis, Crystal Structure, Quantum Chemistry Calculation and in vitro Inhibition Activity to Cancer Cells of the Di-n-Buyltin Di-o-chlorobenzoate

    Institute of Scientific and Technical Information of China (English)

    张复兴; 王剑秋; 邝代治; 冯泳兰; 许志锋; 庾江喜

    2012-01-01

    二正丁基氧化锡和邻氯苯甲酸按物质的量比1∶2,通过微波固相合成法合成了二正丁基锡邻氯苯甲酸酯配合物{[n-Bu2Sn(O2CC6H4Cl)]2O}2.经X射线衍射方法测定了其晶体结构,配合物属三斜晶系,空间群为P(1),晶体学参数a=1.17653(4) nm,b=1.20672(4) nm,c=2.74090 (9) nm,α=80.493 (2)°,β=83.995 (2)°,γ=64.260(2)°,V=3.4547(2)nm3,Z=2,D(ε)=1.525 g/cm3,μ(MoKα)=16.34 cm-1,F(000)=1592,R1=0.0414,wR2=0.1349.晶体中每一个结构单元包含了2个键参数完全不同的以Sn2O2构成的平面四元环为中心环的二聚体结构分子,锡原子均为五配位的畸变三角双锥构型.对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征.%Di-n-buyltin di-o-chlorobenzoate { [n-Bu2Sn(O2CC10H9) ]2O }2 was synthesized by a microwave assisted solid-state synthesis. Its structure has been determined by X-ray single crystal diffraction. The crystal belongs to the triclinic space group P 1 with a = 1. 17653(4) nm, 6 = 1. 20672(4) nm, c =2. 74090(9) nm, α=80.493(2)°,β = 83. 995 (2)°, γ = 64. 260 (2)°, V = 3. 4547 (2) nm3,Z =2,Dc = 1.525 g/cm3, μ(MoKα) =16.34 cnr',F(000) =1 592,R1 =0.0414,wR2 =0. 1349. In the complex, the tin atoms are five-coordinated in a distorted tigonal bipyram idalstructure, and the dimeric structure constitutes a Sn2O2 planar. Theoretical study on the title complex has been performed using a quantum chemistry calculation by means of G98W package and taking LANL2DZ basis set. The stabilities of the complex, the orbital energies and composition characteristics of some frontier molecular orbitals were presented.

  10. Microwave assisted synthesis of nano sized sulphate doped hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Alshemary, Ammar Z.; Goh, Yi-Fan; Akram, Muhammad; Razali, Ili Rabihah [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Darul Ta’zim (Malaysia); Abdul Kadir, Mohammed Rafiq [Medical Implant Technology Group, Faculty of Biomedical Engineering and Health Science, Universiti Teknologi Malaysia,81310 UTM Skudai, Johor Darul Ta’zim (Malaysia); Hussain, Rafaqat, E-mail: rafaqat@kimia.fs.utm.my [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor DarulTa’zim (Malaysia)

    2013-06-01

    Highlights: ► Phase pure nano-sized sulphur doped hydroxyapatite has been synthesized. ► TEM analysis confirmed formation of needle shaped structure. ► Lattice parameters and cell volume increased with increase in sulphate doping. ► Crystallite size decreased as sulphate content inside the structure increased. ► Degree of crystallinity decreased with increase in sulphate substitution. - Abstract: Inorganic sulphate is required by all mammalian cells to function properly, it is the fourth most abundant anion in the human plasma. Sulphate ions are the major source of sulphur which is considered an important element for sustenance of life as it is present in the essential amino and is required by cells to function properly. In this study we have successfully substituted sulphate ions (SO{sub 4}{sup 2−}) into hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6−x}(SO{sub 4}){sub x}(OH){sub 2−x}) lattice via ion exchange process with phosphate group. Concentration of SO{sub 4}{sup 2−} ions was varied between X = 0.05–0.5, using (Ca (NO{sub 3}){sub 2}·4H{sub 2}O), ((NH{sub 4}){sub 2}HPO{sub 4}) and (Na{sub 2}SO{sub 4}) as starting materials. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), showed that the substitution of SO{sub 4}{sup 2−} ions into the lattice resulted in peak broadening and reduced peak height due to the amorphous nature and reduced crystallinity of the resulting HA powder. Transmission electron microscopy (TEM) and field emission electron microscopy (FESEM) analysis confirmed the formation of needle shaped particles of 41 nm size with homogenous and uniform distribution of element within the HA structure.

  11. Microwave-assisted extraction technology of elavonoids from hawthorn seed%微波辅助提取山楂籽总黄酮的工艺研究

    Institute of Scientific and Technical Information of China (English)

    乔聚林; 朱传合; 潘广彦; 王芳

    2011-01-01

    The microwave- assisted extraction of total Flavonoids from Hawthorn seed was investigated.The optimal conditions for extraction: microwave intensity 1 886.5 MHz, radiation time 7 min, extraction temperature 90℃, extraction time 4.5 h, solid-liquid ratio of 1∶ 20, 60% ethanol. Under this condition,the extraction rate of flavonoids from hawthorn seed 89.5%. Compared with conventional reflux extraction, the Microwave-assisted extraction rate was increased by 20.2%.%实验将微波辅助技术应用于山楂籽黄酮提取中,结果表明,浸提时间4.5 h、微波强度1 886.5 MHz、间歇作用7 min、水浴温度90℃、乙醇浓度60%、料液比1:20.该条件下,黄酮提取率可达89.5%,与传统回流提取法相比,黄酮提取率提高了20.2%.

  12. Microwave-assisted extraction in combination with capillary electrophoresis for rapid determination of isoquinoline alkaloids in Chelidonium majus L.

    Science.gov (United States)

    Zhou, Qiuhong; Liu, Youping; Wang, Xin; Di, Xin

    2012-09-15

    A simple and rapid method based on microwave-assisted extraction (MAE) followed by capillary electrophoresis (CE) was developed for the quantification of eight isoquinoline alkaloids in Chelidonium majus L. (Ch. majus). The key parameters affecting CE separation and MAE extraction were investigated and optimized. Complete separation of eight alkaloids was achieved within only 9 min using a 500 mM Tris-H(3)PO(4) buffer (pH 2.5) containing 50% (v/v) methanol and 2mM HP-β-cyclodextrin. The optimal MAE extraction was performed at 60 °C for 5 min with methanol-water-HCl (90:10:0.5, v/v/v) as the extracting solvent, which gave much higher extraction efficiency in significantly shorter time than conventional heat reflux extraction (HRE) and ultrasonic extraction (USE) methods. Good linearities were obtained for all the alkaloids investigated with correlation coefficients above 0.9994. The repeatability and intermediate precision were less than 4.11% and the recoveries ranged from 98.0% to 103.9%. The developed method was successfully applied to 14 Ch. majus samples obtained from different regions of China. Compared with previously reported methods, the present method offers a dramatic savings in overall analysis time and considerable reduction in solvent consumption. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Novel Microwave-Assisted Synthesis of the Immunomodulator Organotellurium Compound Ammonium Trichloro(dioxoethylene-O,O'tellurate (AS101

    Directory of Open Access Journals (Sweden)

    M. Pilar Vázquez-Tato

    2014-02-01

    Full Text Available Ammonium trichloro[1,2-ethanediolato-O,O']-tellurate (AS101 is the most important synthetic Te compound from the standpoint of its biological activity. It is a potent immunomodulator with a variety of potential therapeutic applications and antitumoral action in several preclinical and clinical studies. An experimental design has been used to develop and optimize a novel microwave-assisted synthesis (MAOS of the AS101. In comparison to the results observed in the literature, refluxing Te(IV chloride and ethylene glycol in acetonitrile (Method A, or by refluxing Te(IV chloride and ammonium chloride in ethylene glycol (Method B, it was found that the developed methods in the present work are an effective alternative, because although performance slightly decreases compared to conventional procedures (75% vs. 79% by Method A, and 45% vs. 51% by Method B, reaction times decreased from 4 h to 30 min and from 4 h to 10 min, by Methods A and B respectively. MAOS is proving to be of value in the rapid synthesis of compounds with new and improved biological activities, specially based on the benefit of its shorter reaction times.

  14. Ionic liquid-based microwave-assisted extraction of essential oil and biphenyl cyclooctene lignans from Schisandra chinensis Baill fruits.

    Science.gov (United States)

    Ma, Chun-hui; Liu, Ting-ting; Yang, Lei; Zu, Yuan-gang; Chen, Xiaoqiang; Zhang, Lin; Zhang, Ying; Zhao, Chunjian

    2011-12-02

    Ionic liquid-based microwave-assisted extraction (ILMAE) has been successfully applied in extracting essential oil and four kinds of biphenyl cyclooctene lignans from Schisandra chinensis Baill. 0.25 M 1-lauryl-3-methylimidazolium bromide ionic liquid is selected as solvent. The optimum parameters of dealing with 25.0 g sample are 385 W irradiation power, 40 min microwave extraction time and 1:12 solid-liquid ratio. The yields of essential oil and lignans are 12.12±0.37 ml/kg and 250.2±38.2 mg/kg under the optimum conditions. The composition of the essential oil extracted by hydro-distillation, steam-distillation and ILMAE is analyzed by GC-MS. With ILMAE method, the energy consumption time has not only been shortened to 40 min (hydro-distillation 3.0 h for extracting essential oil and reflux extraction 4.0 h for extracting lignans, respectively), but also the extraction efficiency has been improved (extraction of lignans and distillation of essential oil at the same time) and reduces the environmental pollution. S. chinensis materials treated by different methods are observed by scanning electronic microscopy. Micrographs provide more evidence to prove that ILMAE is a better and faster method. The experimental results also indicate that ILMAE is a simple and efficient technique for sample preparation.

  15. Determination of X-Ray Diffraction on the Phase Transformation of Microwave-Assisted Titanate Nanotubes during Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Hsin-Hung Ou

    2010-01-01

    Full Text Available Based on the determination of X-ray powder diffraction, this study aims to investigate the thermal effect on the phase transformation of microwave-assisted titanate nanotubes (MTNTs. The phase transformation is highly dependent on the intercalating amount of Na(I within MTNTs and on the heating atmosphere. In other words, the presence of Na(I favors the transformation of TNTs phase into Na2Ti6O13 whereas anatase phase selectively formed in the case of MTNTs with less Na(I amount. Furthermore, H2 versus O2 is able to form anatase phase and establish a newly transformation pathway. The photocatalytic ability of the calcined MTNTs was also evaluated based on the observed rate constant of trichloroethylene degradation. In addition to anatase phase, the newly phase including Na2Ti6O13 and Ti2O3 with calcined MTNTs is able to photocatalyze trichloroethylene. MTNTs calcined with the presence of H2 also exhibit a superior photocatalytic performance to P25 TiO2.

  16. Microwave-assisted one-pot synthesis of polycyclic 4-quinolone derivatives

    OpenAIRE

    2015-01-01

    A microwave-assisted solvent-free one-pot method to afford 1,2,3,4-tetrahydroacridines-9-one derivatives was developed, with shorter reaction time and from easily available starting materials compared to the known methods. Fil: Muscia, Gisela Celeste. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina; Fil: Carnev...

  17. Simultaneous phase and morphology controllable synthesis of copper selenide films by microwave-assisted nonaqueous approach

    Science.gov (United States)

    Li, Jing; Fa, Wenjun; Li, Yasi; Zhao, Hongxiao; Gao, Yuanhao; Zheng, Zhi

    2013-02-01

    Copper selenide films with different phase and morphology were synthesized on copper substrate through controlling reaction solvent by microwave-assisted nonaqueous approach. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that the pure films could be obtained using cyclohexyl alcohol or benzyl alcohol as solvent. The cubic Cu2-xSe dendrites were synthesized in cyclohexyl alcohol reaction system and hexagonal CuSe flaky crystals were obtained with benzyl alcohol as solvent.

  18. Microwave Assisted Hydrolysis of Holocellulose Catalyzed with Sulfonated Char Derived from Lignin-Rich Residue

    Directory of Open Access Journals (Sweden)

    Kui Wang

    2015-01-01

    Full Text Available A microwave assisted green process has been developed for production of sugars through liquefying holocellulose catalyzed with sulfonated char derived from the lignin-rich residue produced during pretreatment of lignocellulose. Various reaction parameters including the hydrolysis temperature, hydrolysis time, catalyst content, and the ratio of water to feedstock were evaluated. The maximum sugars yield of 82.6% (based on the dry mass of holocellulose was obtained under the optimum reaction conditions. The sulfonated char showed superior catalytic performance to that of dilute sulfuric acid in converting holocellulose into sugars under microwave irradiation.

  19. Low temperature microwave-assisted vs conventional pyrolysis of various biomass feedstocks

    Institute of Scientific and Technical Information of China (English)

    Peter Shuttleworth; Vitaliy Budarin; Mark Gronnow; James H. Clark; Rafael Luque

    2012-01-01

    A comparison between conventional pyrolysis and a novel developed low-temperature microwave-assisted pyrolysis methodology has been performed for the valorisation of a range of biomass feedstocks including waste residues.Microwave pyrolysis was found to efficiently deliver comparable evolution of bio-gases in the system as compared with conventional pyrolysis at significantly reduced temperatures (120-180 ℃ vs 250-400 ℃).The gas obtained from microwave-assistet pyrolysis was found to contain CO2,CH4 and CO as major components as well as other related chemicals (e.g.acids,aldehydes,alkanes) which were obtained in different proportions depending on the selected feedstock.

  20. Microwave assisted synthesis of CdS nanoparticles and their size evolution

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, I. A.; Vazquez, A.; Gomez, I., E-mail: idaliagomezmx@yahoo.com.mx [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Laboratorio de Materiales I, Av. Universidad, Cd. Universitaria, 66451 San Nicolas de los Garza, Nuevo Leon (Mexico)

    2013-05-01

    The study of the size evolution of CdS nanoparticles in aqueous dispersion is presented in this paper. The sodium citrate was employed as stabilizer of CdS nanoparticles synthesized by microwave assisted synthesis. Analysis of this study was carried out by UV-Vis spectrophotometry, by comparison of the band gap energy using theoretical and empirical models. Results obtained show that the synthesis conditions produce CdS nanoparticles with diameters below of 6 nm, which remains stabilized by at least 14 days. These characteristics were confirmed by transmission electron microscopy. The X-ray diffraction pattern confirms cubic phase of the CdS nanoparticles. (Author)

  1. Microwave-assisted Synthesis of Hierarchical ZnO Nanostructures and Their Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Ou Ming

    2016-01-01

    Full Text Available Hierarchical ZnO nanostructures were fabricated via a rapid and facile microwave-assisted route with different zinc salts as reactants. The obtained hierarchical ZnO nanostructures have good crystallinity and high purity. Moreover, it was found that various zinc salts have an obvious effect on the morphologies and microstructures of the final products. Additionally, the photocatalytic activity of the obtained ZnO samples under visible-light irradiation was also evaluated by degradation of Rhodamine B (RhB.

  2. Microwave-assisted solid-state synthesis of oxide ion conducting stabilized bismuth vanadate phases

    Energy Technology Data Exchange (ETDEWEB)

    Vaidhyanathan, B.; Balaji, K.; Rao, K.J. [Indian Inst. of Science, Bangalore (India). Solid State and Structural Chemistry Unit

    1998-11-01

    A microwave-assisted method for the preparation of substituted bismuth vanadates has been described. The method consists of starting with the respective oxides mixed in stoichiometric proportions and exposing the mixture to microwaves. Substitution takes place at the vanadium sites and it has been possible to prepare Ag{sup +}-, Mn{sup 4+}-, Ga{sup 3+}-, Y{sup 3+}-, and Ce{sup 4+}-substituted compounds with up to 10% substitution. Mn{sup 4+}- and Ag{sup +}-substituted compounds are found to exhibit better oxygen ion conductivities than any reported so far in the literature.

  3. Portable microwave assisted extraction: An original concept for green analytical chemistry.

    Science.gov (United States)

    Perino, Sandrine; Petitcolas, Emmanuel; de la Guardia, Miguel; Chemat, Farid

    2013-11-08

    This paper describes a portable microwave assisted extraction apparatus (PMAE) for extraction of bioactive compounds especially essential oils and aromas directly in a crop or in a forest. The developed procedure, based on the concept of green analytical chemistry, is appropriate to obtain direct in-field information about the level of essential oils in natural samples and to illustrate green chemical lesson and research. The efficiency of this experiment was validated for the extraction of essential oil of rosemary directly in a crop and allows obtaining a quantitative information on the content of essential oil, which was similar to that obtained by conventional methods in the laboratory.

  4. Parameters Affecting the Microwave-Assisted Polyol Synthesis of Silver Nanorods

    OpenAIRE

    Srichandana Nandikonda; Davis, Edward W.

    2011-01-01

    The effects of salt chemistry and concentration on the morphology and yield of silver nanorods produced by the microwave-assisted polyol synthesis are reported. Compared to NaCl, iron and copper salts reduced nanorod yield and length and increased diameter. This is in stark contrast to expectations based on the slower traditional polyol process. The role of the cation was further explored using MgCl2 and MnCl2 which showed different concentration dependent effects on nanorod diameter. In addi...

  5. Efficient microwave-assisted synthesis of 5-hydroxymethylfurfural from concentrated aqueous fructose

    DEFF Research Database (Denmark)

    Søndergaard Hansen, Thomas; Woodley, John; Riisager, Anders

    2009-01-01

    Studies on the HCl-catalysed microwave-assisted dehydration of highly concentrated aqueous fructose (27 wt %) to 5-hydroxymethylfurfural (HMF) revealed a significant increase in the fructose conversion rate over the conventional heated systems. Water, being the most benign solvent and therefore...... ideal for green and sustainable chemistry, normally is a poor solvent for the dehydration process resulting in low HMF selectivities and yields. However, reaction at 200 °C with microwave irradiation with a short reaction time of only 1 s resulted in good HMF selectivity of 63% and fructose conversion...

  6. Microwave assisted bi-functional activation of -bromo-tert-alcohols

    Indian Academy of Sciences (India)

    Nandini Kannan; Manjunatha Javagal Rangaswamy; Bettadaiah Bheemanakere Kemapaiah

    2015-08-01

    Microwave-assisted dehydration-oxidation of -bromo-tert-alcohols to afford 2,3-unsaturated ketones in good yield is reported. The reaction of substrates with DMSO in 1:1 ratio (w/v) is promoted by ZnS in a solvent-free condition. A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is elucidated. This is a new observation under microwave and applies to -bromo-tert-alcohols derived from 1,4-disubstitued-1-cyclohexenes. It is very useful in the synthesis of 2,3-unsaturated ketones derived from monoterpenes which are valuable flavour compounds.

  7. Microwave-assisted magnetization reversal using transient precession of magnetization in permalloy hexagons

    Science.gov (United States)

    Okano, Genki; Nozaki, Yukio

    2016-06-01

    Microwave-assisted magnetization reversal utilizing a transient precession of magnetization was demonstrated in a permalloy hexagon by applying a 25-ns-wide microwave field and a 500-ps-wide pulsed field with a tunable delay to the microwave field. The switching field in a combination of these two fields becomes smaller than that in only the microwave field, and this additional reduction in switching field oscillates relative to the delay time. From the comparison with the results of micromagnetic simulations, we found that the oscillatory behavior is attributed to the beats in transient precession that occurs in the early stage of microwave-field-induced magnetization excitation.

  8. Efficient synthesis of a fluorescent tripod detection system for pesticides by microwave-assisted click chemistry.

    Science.gov (United States)

    Mallard-Favier, Isabelle; Blach, Philippe; Cazier, Francine; Delattre, François

    2009-01-26

    A new tripod molecule containing an aromatic core bearing three peracetylated cyclodextrins was synthesized via a microwave-assisted Huisgen 1,3-dipolar cycloaddition and was studied by fluorescence spectroscopy. The photoluminescent properties of complexation phenomena with different pesticides were evaluated in acetonitrile. Fluorescence titrations have been performed to calculate binding constants, sensitivity factors, and limit of detection of the resulting complexes. 2D NMR experiments confirmed the inclusion of pesticide in the hydrophobic cavity of the macrocycle and validated the supramolecular association responsible for the quenching of the fluorescence.

  9. Microwave assisted combustion synthesis of nanocrystalline CoFe2O4 for LPG sensing

    Science.gov (United States)

    Chaudhari, Prashant; Acharya, S. A.; Darunkar, S. S.; Gaikwad, V. M.

    2015-08-01

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe2O4. The process takes only a few minutes to obtain as-synthesized CoFe2O4. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe2O4 prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe2O4 thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  10. Microwave-assisted synthesis of α-aryl malonates: Key intermediates for the

    Directory of Open Access Journals (Sweden)

    Mohamed A. Ibrahim

    2016-11-01

    Full Text Available We disclose a new microwave-assisted protocol for the effective α-arylation of diethyl malonate. The coupling of aryl halides with diethyl malonate proceeds smoothly in short reaction time in the presence of a catalytic amount of Cu(OTf2, 2-picolinic acid and Cs2CO3 in toluene using microwave irradiation. The resulting α-aryl malonates are then used as key intermediates for synthesis of variety of heterocyclic compounds, including benzodiazepines, isoquinolines and pyrrolopyridine scaffolds.

  11. Microwave-Assisted Extraction and Purification of Arctiin and Arctigenin from Fructus Arctii by High-Speed Countercurrent Chromatography.

    Science.gov (United States)

    Lü, Haitao; Sun, Zhaoyun; Shan, Hu; Song, Jiying

    2016-03-01

    An efficient method for the rapid extraction, separation and purification of bioactive lignans, arctiin and arctigenin, from Fructus arctii by microwave-assisted extraction coupled with high-speed countercurrent chromatography was developed. The optimal extraction conditions of arctiin and arctigenin were evaluated by orthogonal array. Arctigenin could be converted from arctiin by hydrochloric acid hydrolysis. The separations were performed at a preparative scale with two-phase solvents composed of ethyl acetate-ethanol-water (5 : 1 : 5, v/v/v) for arctiin, and n-hexane-ethyl acetate-ethanol-water (4 : 4 : 3 : 4, v/v/v/v) for arctigenin. From 500 mg of crude extract sample, 122.3 mg of arctiin and 45.7 mg of arctigenin were obtained with the purity of 98.46 and 96.57%, and the recovery of 94.3 and 81.6%, respectively. Their structures were determined by comparison with the high-performance liquid chromatography retention time of standard substance as well as UV, FT-IR, electrospray ion source (ESI)-MS, (1)H-NMR and (13)C-NMR spectrum. According to the antioxidant activity assay, arctigenin had stronger 1,1-diphenyl-2-picrylhydrazyl free radicals scavenging activity.

  12. Sequential microwave-assisted ultra-fast ZnO nanorod growth on optimized sol-gel seedlayers

    Science.gov (United States)

    Soleimanzadeh, Reza; Mousavi, Matin Sadat Saneei; Mehrfar, Amin; Esfahani, Zahra Kolahdouz; Kolahdouz, Mohammadreza; Zhang, Kouchi

    2015-09-01

    Recently, the studies on ZnO nanostructure characteristics and their fabrication methods have been increased significantly in order to be able to use its magnificent properties by reaching the desired optimum features. Very high growth rate and high quality growth have always been the center of attention. In this study, a sequential microwave-assisted ZnO nanorod (NR) growth as an ultra-fast, highly efficient method for vertical growth of high quality ZnO NRs on different substrates is proposed. A NRs' growth rate of 4.2 μm/h was obtained which led to uniformly distributed, high aspect ratio and vertically-aligned NRs. Furthermore, the influences of spinner's speed as an important parameter on the quality of ZnO seed and annealing treatment have been studied. The sol-gel casting approach is optimized for the layer. Different seed layers were used to grow the nanostructures and the optimum spinner speed is found to be 2000 rpm. In order to diminish the dependency of the uniformity of ZnO NRs on the quality of seed layers, a remedy is suggested.

  13. Highly selective NH3 gas sensor based on Au loaded ZnO nanostructures prepared using microwave-assisted method.

    Science.gov (United States)

    Shingange, K; Tshabalala, Z P; Ntwaeaborwa, O M; Motaung, D E; Mhlongo, G H

    2016-10-01

    ZnO nanorods synthesized using microwave-assisted approach were functionalized with gold (Au) nanoparticles. The Au coverage on the surface of the functionalized ZnO was controlled by adjusting the concentration of the Au precursor. According to X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results, it was confirmed that Au form nanoparticles loaded on the surface of ZnO. The small Au loading level of 0.5wt% showed the highest response of 1600-100ppm of NH3 gas at room temperature (RT) whereas further increase of Au loading level resulted in poor detection of NH3. All Au loaded ZnO (Au/ZnO) based sensors exhibited very short recovery and response times compared to unloaded ZnO sensing materials. The responses of ZnO and Au/ZnO based sensors (0.5-2.5wt%) to other flammable gases, including H2, CO and CH4, were considerably less, demonstrating that Au/ZnO based sensors were highly selective to NH3 gas at room temperature. Spill over mechanism which is the main reason for the observed enhanced NH3 response with 0.5 Au loading level is explained in detail.

  14. A simple fast microwave-assisted synthesis of thermoelectric bismuth telluride nanoparticles from homogeneous reaction-mixture

    Science.gov (United States)

    Pradhan, Susmita; Das, Rashmita; Bhar, Radhaballabh; Bandyopadhyay, Rajib; Pramanik, Panchanan

    2017-02-01

    A new simple chemical method for synthesis of nanocrystalline bismuth telluride (Bi2Te3) has been developed by microwave assisted reduction of homogeneous tartrate complexes of bismuth and tellurium metal ions with hydrazine. The reaction is performed at pH 10. The nano-crystallites have rhombohedral phase identified by XRD. The size distribution of nanoparticle is narrow and it ranges between 50 to 70 nm. FESEM shows that the fine powders are composed of small crystallites. The TEM micrographs show mostly deformed spherical particles and the lattice fringes are found to be 0.137 nm. Energy dispersive X-ray spectroscopy (EDX) analysis shows the atomic composition ratio between bismuth and tellurium is 2:3. Thermoelectric properties of the materials are studied after sintering by spark plasma sintering method (SPS). The grain size of the material after sintering is in the nanometer range. The material shows enhanced Seebeck coefficient and electrical conductivity value at 300 K. The figure of merit is found to be 1.18 at 300 K.

  15. Microwave assisted digestion followed by ICP-MS for determination of trace metals in atmospheric and lake ecosystem.

    Science.gov (United States)

    Ahmed, Manan; Chin, Ying Hui; Guo, Xinxin; Zhao, Xing-Min

    2017-05-01

    The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigate the concentration of trace metals in atmospheric and lake water samples during the rainy season (before and after precipitation) between November and December 2015. Typical methods of sample preparation for trace metal determination such as cloud point extraction, solid phase extraction and dispersive liquid-liquid micro-extraction are time-consuming and difficult to perform; therefore, there is a crucial need for development of more effective sample preparation procedure. A convection microwave assisted digestion procedure for extraction of trace metals was developed for use prior to inductively couple plasma-mass spectrometric determination. The result showed that metals like zinc (133.50-419.30μg/m(3)) and aluminum (53.58-378.93μg/m(3)) had higher concentrations in atmospheric samples as compared to lake samples before precipitation. On the other hand, the concentrations of zinc, aluminum, chromium and arsenic were significantly higher in lake samples after precipitation and lower in atmospheric samples. The relationship between physicochemical parameters (pH and turbidity) and heavy metal concentrations was investigated as well. Furthermore, enrichment factor analysis indicated that anthropogenic sources such as soil dust, biomass burning and fuel combustion influenced the metal concentrations in the atmosphere. Copyright © 2016. Published by Elsevier B.V.

  16. Microwave-assisted synthesis and photocatalytic properties of sulphur and platinum modified TiO2 nanofibers

    Science.gov (United States)

    Drunka, R.; Grabis, J.; Jankovica, Dz; Krumina, A.; Rasmane, Dz

    2015-03-01

    In the present work formation of active TiO2 nanofibers in microwave synthesis and their modification with platinum were studied. Mixture of anatase and rutile nanopowder and 10M KOH solution were used as raw materials. Microwave assisted synthesis method permitted to obtain TiO2 nanofibres with a diameter of 10nm and a specific surface area up to 40.2 m2/g. In order to modify TiO2 nanofibers with platinum it was stirred in H2PtCl6 solution and illuminated with UV irradiation or reduced with sodium boronhydride. To modify titania with sulphur and prepare co-doped nanofibers platinum doped samples were extra treated in hydrogen sulphide atmosphere. Photocatalytic activity was determined by degradation of the methylene blue (MB) solution under UV and visible light irradiation. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds.

  17. Microwave-Assisted Synthesis and Antimicrobial Evaluation of Novel Spiroisoquinoline and Spiropyrido[4,3-d]pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Rasha M. Faty

    2015-01-01

    Full Text Available Bromination of N-substituted homophthalimides and tetrahydropyrido[4,3-d]- pyrimidine-5,7-diones produces 4,4-dibromohomophthalimide and 8,8-dibromo-tetrahydropyrido[4,3-d]pyrimidine-5,7-dione derivatives, respectively, that can be used as precursors for spiro derivatives. The dibromo derivatives react with different binucleophilic reagents to produce several spiroisoquinoline and spirotetrahydropyrido[4,3-d]- pyrimidine-5,7-dione derivatives, respectively. Reaction of the dibromo derivatives with malononitrile produces dicyanomethylene derivatives which react with different binucleophiles to produce new spiro derivatives. All new compounds are prepared by using the usual chemical conditions and microwave assisted conditions. The latter conditions improved the reaction yields, reduced reaction times and ameliorated the effects on the surrounding environment as the reactions are carried out in closed systems. Structures of the newly synthesized compounds are proved using spectroscopic methods such as IR, MS, 1H-NMR and 13C-NMR and elemental analyses. Some of the newly synthesized compounds were tested for their antimicrobial activities, whereby four of them showed moderate activities and the rest showed low or no activities towards the investigated species.

  18. The influence of microwave-assisted drying techniques on the rehydration behavior of blueberries (Vaccinium corymbosum L.).

    Science.gov (United States)

    Zielinska, Magdalena; Markowski, Marek

    2016-04-01

    The aim of this study was to determine the effect of: (a) different drying methods, (b) hot air temperature in a convection oven, and (c) the moisture content of fruits dehydrated by multi-stage drying which involves a transition between different stages of drying, on the rehydration kinetics of dry blueberries. Models describing rehydration kinetics were also studied. Blueberries dehydrated by multi-stage microwave-assisted drying, which involved a hot air pre-drying step at 80 °C until the achievement of a moisture content of 1.95 kg H2O kg(-1)DM, were characterized by significantly higher rates of initial and successive rehydration as well as smaller initial loss of soluble solids in comparison with the samples dried by other methods. The highest initial rehydration rate and the smallest loss of soluble solids after 30 min of soaking were determined at 0.46 min(-1) and 0.29 kg DM kg(-1)DM, respectively. The Peleg model and the first-order-kinetic model fit the experimental data well.

  19. Determination of plant growth regulators in pears by microwave-assisted extraction and liquid chromatography with electrospray ionization mass spectrometry.

    Science.gov (United States)

    Mao, Xuejin; Tang, Lijuan; Tan, Ting; Wan, Yiqun

    2014-06-01

    A new method for the determination of six plant growth regulators, 3-indolylacetic acid, 3-indolepropionic acid, 2-naphthoxyacetic acid, 2,4-dicholrophenoxyacetic acid, 1-naphthlcetic acid, and methyl naphthalene-1-acetate, in pears was established by liquid chromatography with electrospray ionization mass spectrometry. In this study, a microwave-assisted extraction technique was first applied for the determination of plant growth regulators in fruit and three cleanup techniques were, respectively, investigated for the purification of pear samples. The chromatographic separation was performed on a Diamonsil C18 column by using 0.01 mol/L formic acid/ammonium formate buffer solution (pH 3.5)/methanol (35:65, v/v) as the mobile phase with a flow rate of 0.7 mL/min in 1:1 split mode. The LODs ranged from 0.3 to 1.9 μg/kg. Under optimized conditions, the average recoveries (five replicates) for six plant growth regulators (spiked at 0.01, 0.05, and 0.5 mg/kg) ranged from 78.9 to 118.0%, and the RSDs were 1.4-10.3%.

  20. From lignocellulosic biomass to lactic- and glycolic-acid oligomers: a gram-scale microwave-assisted protocol.

    Science.gov (United States)

    Carnaroglio, Diego; Tabasso, Silvia; Kwasek, Beata; Bogdal, Dariusz; Gaudino, Emanuela Calcio; Cravotto, Giancarlo

    2015-04-24

    The conversion of lignocellulosic biomass into platform chemicals is the key step in the valorization of agricultural waste. Of the biomass-derived platform chemicals currently produced, lactic acid plays a particularly pivotal role in modern biorefineries as it is a versatile commodity chemical and building block for the synthesis of biodegradable polymers. Microwave-assisted processes that furnish lactic acid avoid harsh depolymerization conditions while cutting down reaction time and energy consumption. We herein report a flash catalytic conversion (2 min) of lignocellulosic biomass into lactic and glycolic acids under microwave irradiation. The batch procedure was successfully adapted to a microwave-assisted flow process (35 mL min(-1) ), with the aim of designing a scalable process with higher productivity. The C2 and C4 units recovered from the depolymerization were directly used as the starting material for a solvent and catalyst-free microwave-assisted polycondensation that afforded oligomers in good yields.

  1. Microwave-assisted fabrication of strontium doped apatite coating on Ti6Al4V

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huan, E-mail: huanzhou@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); Kong, Shiqin [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Pan, Yan; Zhang, Zhiguo [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China); Deng, Linhong, E-mail: dlh@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164 (China)

    2015-11-01

    Strontium has been shown to be a beneficial dopant to calcium phosphates when incorporated at nontoxic level. In the present work we studied the possibility of solution derived doping strontium into calcium phosphate coatings on titanium alloy Ti6Al4V based implants by a recently reported microwave-assisted method. By using this method strontium doped calcium phosphate nuclei were deposited to pretreated titanium alloy surface dot by dot to compose a crack-free coating layer. The presence of strontium in solution led to reduced roughness of the coating and finer nucleus size formed. In vitro study found that proliferation and differentiation of osteoblast cells seeded on the coating were influenced by strontium content in coatings, showing an increasing followed by a decreasing behavior with increasing substitution of calcium by strontium. It is suggested that this new microwave-assisted strontium doped calcium phosphate coatings may have great potential in implant modification. - Highlights: • Strontium doped calcium phosphate coating is deposited with microwave irradiation. • Increase of strontium reduces coating roughness and results in finer nucleus size. • Proliferation and differentiation of osteoblasts depend on doped strontium content.

  2. Process Parameter Study on Microwave-assisted Foam-mat Drying Properties of Corn Soaking Water

    Institute of Scientific and Technical Information of China (English)

    Zheng Xian-zhe

    2016-01-01

    In order to study the microwave-assisted foam-mat drying properties of corn soaking water and optimize process parameters, a quadratic regression orthogonal rotary method was used to analyze the influence of microwave power, material weight, material thickness and drying time on moisture content (dry basis), color value and protein content. Results showed that the primary and secondary sequence of parameters with regard to moisture content (d. b.) was drying time, microwave power, material weight and material thickness; the primary and secondary sequence of parameters with regard to color value was material weight, drying time, microwave power and material thickness; the primary and secondary sequence of parameters with regard to protein content was drying time, material weight, microwave power and material thickness. Optimum conditions were obtained as microwave power of 560 W, material weight of 46.88 g, material thickness of 6.20 mm and drying time of 8.01 min. The results might provide the theoretical basis and technical support for the microwave-assisted foam-mat drying of corn soaking water to produce yeast protein power.

  3. Microwave-Assisted Surface Modification of Metallocene Polyethylene for Improving Blood Compatibility

    Directory of Open Access Journals (Sweden)

    Hemanth Mohandas

    2013-01-01

    Full Text Available A wide number of polymers are being used for various medical applications. In this work, microwave-assisted surface modification of metallocene polyethylene (mPE was studied. FTIR analysis showed no significant changes in the chemical groups after treatment. Contact angle analysis revealed a decrease in contact angle of the treated samples insinuating increasing hydrophilicity and better biocompatibility. Qualitative analysis of treated samples using scanning electron microscope (SEM depicted increasing surface roughness and holes formation further corroborating the results. Coagulation assays performed for estimating prothrombin time (PT and activated partial thromboplastin time (APTT showed an increase in the clotting time which further confirmed the improved blood compatibility of the microwave-treated surfaces. Further, the extent of hemolysis in the treated sample was lower than the untreated one. Hence, microwave-assisted surface modification of mPE resulted in enhanced blood compatibility. Improved blood compatibility of mPE may be exploited for fabrication of artificial vascular prostheses, implants, and various blood contacting devices.

  4. Microwave-assisted reactions in heterocyclic compounds with applications in medicinal and supramolecular chemistry.

    Science.gov (United States)

    de la Hoz, Antonio; Díaz-Ortiz, Angel; Moreno, Andrés; Sanchéz-Migallón, Ana; Prieto, Pilar; Carrillo, José Ramón; Vázquez, Ester; Gómez, M Victoria; Herrero, M Antonia

    2007-12-01

    Microwave irradiation has been successfully applied in organic chemistry. Spectacular accelerations, higher yields under milder reaction conditions and higher product purities have all been reported. Indeed, a number of authors have described success in reactions that do not occur under conventional heating and modifications in selectivity (chemo-, regio- and stereoselectivity) have even been reported. Recent advances in microwave-assisted combinatorial chemistry include high-speed solid-phase and polymer-supported organic synthesis, rapid parallel synthesis of compound libraries, and library generation by automated sequential microwave irradiation. In addition, new instrumentation for high-throughput microwave-assisted synthesis continues to be developed at a steady pace. The impressive speed combined with the unmatched control over reaction parameters justifies the growing interest in this application of microwave heating. In this review we highlight our recent advances in this area, with a particular emphasis on cycloaddition reactions of heterocyclic compounds both with and without supports, applications in supramolecular chemistry and the reproducibility and scalability of organic reactions involving the use of microwave irradiation techniques.

  5. Microwave-assisted methyl esters synthesis of Kapok (Ceiba pentandra seed oil: parametric and optimization study

    Directory of Open Access Journals (Sweden)

    Awais Bokhari

    2015-09-01

    Full Text Available The depleting fossil fuel reserves and increasing environmental concerns have continued to stimulate research into biodiesel as a green fuel alternative produced from renewable resources. In this study, Kapok (Ceiba pentandra oil methyl ester was produced by using microwave-assisted technique. The optimum operating conditions for the microwave-assisted transesterification of Kapok seed oil including temperature, catalyst loading, methanol to oil molar ratio, and irradiation time were investigated by using Response Surface Methodology (RSM based on Central Composite Design (CCD. A maximum conversion of 98.9 % was obtained under optimum conditions of 57.09 °C reaction temperature, 2.15 wt% catalyst (KOH loading, oil to methanol molar ratio of 1:9.85, and reaction time of 3.29 min. Fourier Transform Infra-Red (FT-IR spectroscopy was performed to verify the conversion of the fatty acid into methyl esters. The properties of Kapok oil methyl ester produced under the optimum conditions were characterized and found in agreement with the international ASTM D 6751 and EN 14214 standards.

  6. Microwave Assisted Organic Synthesis of Heterocycles in Aqueous Media: Recent Advances in Medicinal Chemistry.

    Science.gov (United States)

    Frecentese, Francesco; Saccone, Irene; Caliendo, Giuseppe; Corvino, Angela; Fiorino, Ferdinando; Magli, Elisa; Perissutti, Elisa; Severino, Beatrice; Santagada, Vincenzo

    2016-01-01

    Green chemistry is a discipline of great interest in medicinal chemistry. It involves all fields of chemistry and it is based on the principle to conduct chemical reactions protecting the environment at the same time, through the use of chemical procedures able to avoid pollution. In this context, water as solvent is a good choice because it is abundant, nontoxic, non-caustic, and non-combustible. Even if microwave assisted organic reactions in conventional solvents have quickly progressed, in the recent years medicinal chemists have focused their attention to processes deemed not dangerous for the environment, using nanotechnology and greener solvents as water. Several reports of reaction optimizations and selectivities, demonstrating the capability of microwave to allow the obtaining of increased yields have been recently published using water as solvent. In this review, we selected the available knowledge related to microwave assisted organic synthesis in aqueous medium, furnishing examples of the newest strategies to obtain useful scaffolds and novel derivatives for medicinal chemistry purposes. The intention of this review is to demonstrate the exclusive ability of MAOS in water as solvent or as co-solvent. For this purpose we report here the most representative applications of MAOS using water as solvent, focusing on medicinal chemistry processes leading to interesting nitrogen containing heterocycles with potential pharmaceutical applications.

  7. Synthesis and characterization of biodegradable peptide-based polymers prepared by microwave-assisted click chemistry.

    Science.gov (United States)

    van Dijk, Maarten; Nollet, Maria L; Weijers, Pascal; Dechesne, Annemarie C; van Nostrum, Cornelus F; Hennink, Wim E; Rijkers, Dirk T S; Liskamp, Rob M J

    2008-10-01

    In this study, the microwave-assisted copper(I)-catalyzed 1,3-dipolar cycloaddition reaction was used to synthesize peptide triazole-based polymers from two novel peptide-based monomers: azido-phenylalanyl-alanyl-lysyl-propargyl amide (1) and azido-phenylalanyl-alanyl-glycolyl-lysyl-propargyl amide (2). The selected monomers have sites for enzymatic degradation as well as for chemical hydrolysis to render the resulting polymer biodegradable. Depending on the monomer concentration in DMF, the molecular mass of the polymers could be tailored between 4.5 and 13.9 kDa (corresponding with 33-100 amino acid residues per polymer chain). As anticipated, both polymers can be enzymatically degraded by trypsin and chymotrypsin, whereas the ester bond in the polymer of 2 undergoes chemical hydrolysis under physiological conditions, as was shown by a ninhydrin-based colorimetric assay and MALDI-TOF analysis. In conclusion, the microwave-assisted copper(I)-catalyzed 1,3-dipolar cycloaddition reaction is an effective tool for synthesizing biodegradable peptide polymers, and it opens up new approaches toward the synthesis of (novel) designed biomedical materials.

  8. Enhancement of flame development by microwave-assisted spark ignition in constant volume combustion chamber

    KAUST Repository

    Wolk, Benjamin

    2013-07-01

    The enhancement of laminar flame development using microwave-assisted spark ignition has been investigated for methane-air mixtures at a range of initial pressures and equivalence ratios in a 1.45. l constant volume combustion chamber. Microwave enhancement was evaluated on the basis of several parameters including flame development time (FDT) (time for 0-10% of total net heat release), flame rise time (FRT) (time for 10-90% of total net heat release), total net heat release, flame kernel growth rate, flame kernel size, and ignitability limit extension. Compared to a capacitive discharge spark, microwave-assisted spark ignition extended the lean and rich ignition limits at all pressures investigated (1.08-7.22. bar). The addition of microwaves to a capacitive discharge spark reduced FDT and increased the flame kernel size for all equivalence ratios tested and resulted in increases in the spatial flame speed for sufficiently lean flames. Flame enhancement is believed to be caused by (1) a non-thermal chemical kinetic enhancement from energy deposition to free electrons in the flame front and (2) induced flame wrinkling from excitation of flame (plasma) instability. The enhancement of flame development by microwaves diminishes as the initial pressure of the mixture increases, with negligible flame enhancement observed above 3. bar. © 2013 The Combustion Institute.

  9. Sugarcane bagasse pyrolysis in a carbon dioxide atmosphere with conventional and microwave-assisted heating

    Directory of Open Access Journals (Sweden)

    Bo-Jhih eLin

    2015-02-01

    Full Text Available Pyrolysis is an important thermochemical method to convert biomass into bio-oil. In this study, the pyrolysis of sugarcane bagasse in a CO2 atmosphere under conventional and microwave-assisted heating is investigated to achieve CO2 utilization. In the microwave pyrolysis, charcoal is used as the microwave absorber to aid in pyrolysis reactions. The results indicate that the yields of pyrolysis products are greatly influenced by the heating modes. In the conventional heating, the prime product is bio-oil and its yield is in the range of 51-54 wt%, whereas biochar is the major product in microwave-assisted heating and its yield ranges from 61 to 84 wt%. Two different absorber blending ratios of 0.1 and 0.3 are considered in the microwave pyrolysis. The solid yield decreases when the absorber blending ratio decreases from 0.3 to 0.1, while the gas and liquid yields increase. This is attributed to more energy consumed for bagasse pyrolysis at the lower blending ratio. Hydrogen is produced under the microwave pyrolysis and its concentration is between 2 and 12 vol%. This arises from the fact that the secondary cracking of vapors and the secondary decomposition of biochar in an environment with microwave irradiation is easier than those with conventional heating.

  10. A REVIEW ON: A SIGNIFICANCE OF MICROWAVE ASSIST TECHNIQUE IN GREEN CHEMISTRY

    Directory of Open Access Journals (Sweden)

    Manoj S. Charde

    2012-05-01

    Full Text Available Microwave Assisted Synthesis is rapidly becoming the method of choice in modern synthesis and discovery chemistry laboratories. Microwave-assisted synthesis improves both throughput and turn-around time for chemists by offering the benefits of drastically reduced reaction times, increased yields, and purer products. In this type of synthesis we applying microwave irradiation to chemical reactions. The fundamental mechanism of microwave heating involves agitation of polar molecules or ions that oscillate under the effect of an oscillating electric or magnetic field. In the presence of an oscillating field, particles try to orient themselves or be in phase with the field. Only materials that absorb microwave radiation are relevant to microwave chemistry. These materials can be categorized according to the three main mechanisms of heating, namely. Dipolar polarization, Conduction mechanism, Interfacial polarization. Microwave chemistry apparatus are classified: Single-mode apparatus and Multi-mode apparatus. Although occasionally known by such acronyms as 'MEC' (Microwave-Enhanced Chemistry or ‘MORE’ synthesis (Microwave-organic Reaction Enhancement, these acronyms have had little acceptance outside a small number of groups. The ability to combine microwave technology with in-situ reaction monitoring as an analytical tools will offer opportunities for chemists to optimize the reaction conditions. Different compounds convert microwave radiation to heat by different amounts. This selectivity allows some parts of the object being heated to heat more quickly or more slowly than others (particularly the reaction vessel.

  11. Fast microwave-assisted catalytic gasification of biomass for syngas production and tar removal.

    Science.gov (United States)

    Xie, Qinglong; Borges, Fernanda Cabral; Cheng, Yanling; Wan, Yiqin; Li, Yun; Lin, Xiangyang; Liu, Yuhuan; Hussain, Fida; Chen, Paul; Ruan, Roger

    2014-03-01

    In the present study, a microwave-assisted biomass gasification system was developed for syngas production. Three catalysts including Fe, Co and Ni with Al2O3 support were examined and compared for their effects on syngas production and tar removal. Experimental results showed that microwave is an effective heating method for biomass gasification. Ni/Al2O3 was found to be the most effective catalyst for syngas production and tar removal. The gas yield reached above 80% and the composition of tar was the simplest when Ni/Al2O3 catalyst was used. The optimal ratio of catalyst to biomass was determined to be 1:5-1:3. The addition of steam was found to be able to improve the gas production and syngas quality. Results of XRD analyses demonstrated that Ni/Al2O3 catalyst has good stability during gasification process. Finally, a new concept of microwave-assisted dual fluidized bed gasifier was put forward for the first time in this study.

  12. Microwave-Assisted Extraction of Oleanolic Acid and Ursolic Acid from Ligustrum lucidum Ait

    Directory of Open Access Journals (Sweden)

    Yang Song

    2011-08-01

    Full Text Available Oleanolic acid and ursolic acid are the main active components in fruit of Ligustrum lucidum Ait, and possess anticancer, antimutagenic, anti-inflammatory, antioxidative and antiprotozoal activities. In this study, microwave-assisted extraction of oleanolic acid and ursolic acid from Ligustrum lucidum was investigated with HPLC-photodiode array detection. Effects of several experimental parameters, such as type and concentration of extraction solvent, ratio of liquid to material, microwave power, extraction temperature and microwave time, on the extraction efficiencies of oleanolic acid and ursolic acid from Ligustrum lucidum were evaluated. The influence of experimental parameters on the extraction efficiency of ursolic acid was more significant than that of oleanolic acid (p < 0.05. The optimal extraction conditions were 80% ethanol aqueous solution, the ratio of material to liquid was 1:15, and extraction for 30 min at 70 °C under microwave irradiation of 500 W. Under optimal conditions, the yields of oleanolic acid and ursolic acid were 4.4 ± 0.20 mg/g and 5.8 ± 0.15 mg/g, respectively. The results obtained are helpful for the full utilization of Ligustrum lucidum, which also indicated that microwave-assisted extraction is a very useful method for extraction of oleanolic acid and ursolic acid from plant materials.

  13. Microwave-assisted extraction of anthocyanin from Chinese bayberry and its effects on anthocyanin stability

    Directory of Open Access Journals (Sweden)

    Wenkai DUAN

    2015-09-01

    Full Text Available AbstractAnthocyanins are present in high concentrations in Chinese bayberry, Myrica rubra Sieb. & Zucc. Herein, a microwave-assisted extraction was used to extract the anthocyanins from Chinese bayberry. The HPLC chromatogram of the extracts showed that the anthocyanin components were slightly hydrolysed during the extraction process. Further experiments confirmed that microwave irradiation slightly hydrolysed cyanidin-3-O-glucoside to cyanidin, but did not significantly influence the antioxidant activity of the extracts. Optimized extraction conditions for total anthocyanin content were a solid-to-liquid ratio, extraction temperature, and extraction time of 1:50, 80 °C, and 15 min, respectively. Under these conditions, the anthocyanin content was 2.95 ± 0.08 mg·g−1, and the antioxidant activity yield was 279.96 ± 0.1 μmol.·g−1 Trolox equivalent on a dry weight basis. These results indicated that microwave-assisted extraction was a highly efficient extraction method with reduced processing time. However, under some extraction conditions it could damage the anthocyanins. These results provide an important guide for the application of microwave extraction.

  14. Evaluation of hemocompatibility and in vitro immersion on microwave-assisted hydroxyapatite–alumina nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Radha, G. [National Centre for Nanoscience and Nanotechnology, University of Madras, Guindy campus, Chennai - 600025 (India); Balakumar, S., E-mail: balasuga@yahoo.com [National Centre for Nanoscience and Nanotechnology, University of Madras, Guindy campus, Chennai - 600025 (India); Venkatesan, Balaji; Vellaichamy, Elangovan [Department of Biochemistry, University of Madras, Guindy campus, Chennai - 600025 (India)

    2015-05-01

    This study reports the microwave-assisted synthesis and characterization of nHAp (nano-hydroxyapatite)–alumina composites. The crystalline phase and interaction of alumina with nHAp was analyzed using X-ray diffraction (XRD) and Raman microscopy analysis, respectively. High resolution transmission electron microscopy (HRTEM) micrographs exhibit morphological changes of nHAp composites with increasing alumina concentrations. Microhardness studies reveal the enhanced mechanical strength of nHAp10 and nHAp20 nanocomposites than pure nHAp. In vitro bioactivity of the nanocomposites was studied by immersing samples in simulated body fluid (Hank's solution) for 21 days. The surface of biomineralized samples were analyzed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Hemolytic assay revealed acceptable compatibility for varying concentrations of all the samples. Cell proliferation assay was systematically investigated for 1 day and 3 days on Saos-2 osteoblast-like cell lines and it was found that nHAp nanocomposites improved the proliferation. - Highlights: • The microwave-assisted hydroxyapatite (nHAp)–alumina nanocomposites were prepared. • Structural and interaction between nHAp and alumina have been explored. • Increased alumina concentration enhanced mechanical strength of the nHAp. • Trace elements from SBF, incorporated on nHAp–alumina nanocomposite surface, were characterized by FESEM and EDX techniques. • Hemocompatibility of the samples were evaluated and the results are in accordance with ASTM standards.

  15. Determination of fructooligosaccharides in burdock using HPLC and microwave-assisted extraction.

    Science.gov (United States)

    Li, Jing; Liu, Xiaomei; Zhou, Bin; Zhao, Jing; Li, Shaoping

    2013-06-19

    The root of burdock ( Arctium lappa L.) is a commonly used vegetable in Asia. Fructooligosaccharides (FOS) are usually considered as its main bioactive components. Thus, quantitative analysis of these components is very important for the quality control of burdock. In this study, an HPLC-ELSD and microwave-assisted extraction method was developed for the simultaneous determination of seven FOS with degrees of polymerization (DP) between 3 and 9, as well as fructose, glucose, and sucrose in burdock from different regions. The separation was performed on a Waters XBridge Amide column (4.6 × 250 mm i.d., 3.5 μm) with gradient elution. All calibration curves for investigated analytes showed good linear regression (r > 0.9990). Their LODs and LOQs were lower than 3.63 and 24.82 μg/mL, respectively. The recoveries ranged from 99.2 to 102.6%. The developed method was successfully applied to determination of ten sugars in burdock from different locations of Asia. The results showed that the contents of FOS in different samples of burdock collected at appropriate times were similar, and the developed HPLC-ELSD with microwave-assisted extraction method is helpful to control the quality of burdock.

  16. Microwave-assisted synthesis of poly(3-hexylthiophene) via direct oxidation with FeCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nicho, M.E., E-mail: menicho@uaem.mx [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Garcia-Escobar, C.H.; Hernandez-Martinez, D. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma del Estado de Morelos (UAEM), Av. Universidad 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Linzaga-Elizalde, I. [Centro de Investigaciones Quimicas (CIQ) de la UAEM (Mexico); Cadenas-Pliego, G. [Centro de Investigacion en Quimica Aplicada, Saltillo, Coahuila (Mexico)

    2012-09-20

    In this work, CoolMate microwave synthesis system was employed to synthesize soluble poly(3-hexylthiophene) by direct oxidation of 3-hexylthiophene monomer with FeCl{sub 3} as oxidant. P3HT was synthesized varying reaction time by 2 h, 1 h and 0.5 h. According to the results optimal microwave radiation time for synthesis was 1 h. On the other hand, P3HT was synthesized in two different solvents: chloroform (CHCl{sub 3}) and dichloromethane (CH{sub 2}Cl{sub 2}). The obtained yields depend on the solvent and the reaction time used in the synthesis, microwave-assisted synthesis leads to outstanding increase in yield (with dichloromethane solvent). Homogeneous thin films were prepared by spin-coating technique from toluene. Physicochemical characterization of P3HT polymers was carried out: changes in weight molecular distribution and polydispersity were obtained by HPLC (high-performance liquid chromatography); dyads and triads percent were analyzed by NMR (nuclear magnetic resonance). Surface topographical changes were obtained by atomic force microscopy (AFM). AFM images revealed that the surface morphology depends on synthesis method, reaction time and solvent used. Finally the samples were characterized by thermogravimetric analysis (TGA) and ultraviolet-visible analysis (UV-vis). Compared with the traditional method (without microwave), this method provided considerable decrease in the reaction time, both lower polydispersity and molecular weight, less volume of solvents for the synthesis, as well as more alternatives for solvent choice. The results confirmed the versatility of the procedure by microwave, which yields polymeric materials in 1 h and has no adverse effects on the polymers quality.

  17. Efficient synthesis of sulfonamide derivatives on solid supports catalyzed using solvent-free and microwave-assisted methods

    Directory of Open Access Journals (Sweden)

    Argelia Camargo-Ordoñez

    2011-01-01

    Full Text Available In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4Å molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of sulfonamide derivatives. We found that florisil, montmorillonite KSF, and K10 could be used as inexpensive alternative catalysts that are easily separated from the reaction media. Additionally, solvent-free and microwave-assisted methods were more efficient in reducing reaction time and in increasing yield.

  18. Efficient synthesis of sulfonamide derivatives on solid supports catalyzed using solvent-free and microwave-assisted methods

    Energy Technology Data Exchange (ETDEWEB)

    Camargo-Ordonez, Argelia; Moreno-Reyes, Christian; Olazaran-Santibanez, Fabian; Martinez-Hernandez, Sheila; Bocanegra-Garcia, Virgilio; Rivera, Gildardo [Universidad Autonoma de Tamaulipas, Reynosa (Mexico). Dep. de Farmacia y Quimica Medicinal

    2011-07-01

    In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4A molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of sulfonamide derivatives. We found that florisil, montmorillonite KSF, and K10 could be used as inexpensive alternative catalysts that are easily separated from the reaction media. Additionally, solvent-free and microwave-assisted methods were more efficient in reducing reaction time and in increasing yield. (author)

  19. Microwave assisted synthesis of fluorene-based copolymers with different conjugate degreed quinoxaline segments from reactive polymer

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jixin; Song, Xiaohui; Feng, Ying [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Wang, Zhiming, E-mail: wangzm2011@yahoo.com.cn [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China); Zhang, Xiaojuan [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Shen, Fangzhong; Lu, Ping [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China)

    2013-10-31

    In this work, we prepared three fluorene-based copolymers with different conjugate degreed quinoxaline segments from one reactive polymer by microwave assisted method. The obtained quinoxaline-based copolymers exhibited different bright color emissions, high photoluminescence quantum, low electron affinity and electron injection barrier. This approach not only simplified the steps of similar-structure polymers, but also avoided the monomer solubility problem. - Highlights: • Quinoxaline-based copolymers were prepared in microwave-assisted synthesis. • Polymer-synthesis containing different acceptors was simplified from reactive polymer. • Multi-functions were tuned by controlling reactive monomer structures.

  20. Microwave assisted hydrolysis of aluminium metal and preparation of high surface area Al2O3 powder

    Indian Academy of Sciences (India)

    A K Sivadasan; I Packia Selvam; Sankara Narayanan Potty

    2010-12-01

    Phase pure boehmite particles were prepared by microwave assisted hydrolysis of aluminium sheets. These particles were calcined in air to produce Al2O3 particles with specific surface area of ∼210 m2/g. The alumina particles were characterized by studying X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. For comparison, the aluminium hydroxide particles were also prepared by normal hydrolysis of aluminium metal. Normal hydrolysis yielded a mixture of boehmite and bayerite particles whereas microwave assisted hydrolysis produced phase pure boehmite particles. The importance of using microwave radiation for the hydrolysis of aluminium metal is also manifested in a shorter reaction time.

  1. Microwave assisted hydrothermal synthesis of Ni1.5Co1.5S4 as high-performance electrode material for lithium storage

    Science.gov (United States)

    Yuan, Dongxia; Wang, Xuxu; Yin, Dongming; Liang, Fei; Wang, Limin

    2017-08-01

    Bimetallic nickel cobalt sulfide (Ni1.5Co1.5S4) is successfully fabricated by an ultrafast and cost-effective microwave assisted hydrothermal method. When used as electrode material for lithium-ion batteries, Ni1.5Co1.5S4 exhibits the remarkable electrochemical performance in terms of superior cycling stability, excellent specific capacity and good rate capability. A high specific capacity of 443 mA h g-1 after 200 charge-discharge cycles at a current density of 0.5 A g-1 is achieved. Even at 1 A g-1, the sample still delivers a discharge capacity of 386 mA h g-1 with a high columbic efficiency of 99.6% after 500 cycles.

  2. Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

    Science.gov (United States)

    Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

    2016-06-01

    This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring.

  3. Microwave-assisted Solvent-free Synthesis and in Vitro Antibacterial Screening of Quinoxalines and Pyrido[2, 3b]pyrazines

    Directory of Open Access Journals (Sweden)

    Javier Peralta-Cruz

    2012-05-01

    Full Text Available We report herein the microwave assisted synthesis, without solvents and catalysts, of 6-substituted quinoxalines and 7-substituted pyrido[2,3b]pyrazines. The compounds were obtained in good yields and short reaction times using the mentioned procedure and two new structures are reported. A complete 1H- and 13C-NMR assignment was performed using 1D and 2D-NMR. Additionally, an in vitro screening was performed on Gram-positive and Gram-negative bacteria using amoxicillin as positive reference. Compounds bearing a pyridyl group tended to have higher antibacterial activity, but the best activity against Bacillus subtilis and Proteus mirabilis was observed with quinoxaline derivatives.

  4. WO3-Doped TiO2 Coating on Charcoal Activated with Increase Photocatalytic and Antibacterial Properties Synthesized by Microwave-Assisted Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Weerachai Sangchay

    2017-01-01

    Full Text Available WO3-doped TiO2 coating on charcoal activated (CA was prepared by microwave-assisted sol-gel method. The samples calcined at the temperature of 500°C for 2 h with a heating rate of 10°C/min were characterized by XRD, EDS, and SEM. The photocatalytic and antibacterial activities of WO3-doped TiO2 coating on CA were investigated by means of degradation of a methylene blue (MB solution and against the bacteria E. coli, respectively. The effects of WO3 concentration were discussed. The 1% WO3-doped TiO2 coated CA seems to exhibit the higher photocatalytic and antibacterial activity than other samples. The WO3-doped TiO2 coated on CA are expected to be applied as a photocatalyst for water purification.

  5. Microwave assisted synthesis,sinterability and properties of Ca-Zn co-doped LaCrO_3 as interconnect material for IT-SOFCs

    Institute of Scientific and Technical Information of China (English)

    陈永红; 卢肖永; 丁岩芝; 刘杏芹; 孟广耀

    2010-01-01

    The interconnect materials La0.7Ca0.3Cr1-xZnxO3-δ(x=0,0.01,0.03,0.05,0.07) were prepared by a microwave assisted sol-gel auto-ignition process.The crystalline structures of the samples were characterized by X-ray diffraction(XRD) and the lattice parameters were evaluated with Rietveld method.For Ca-Zn co-doped LaCrO3 with x=0.03,the sintering activity was improved,and the relative density came up to 96.5% for the sample sintered at 1300 oC for 10 h.The electrical conductivity of the samples was increased fr...

  6. Fast and Green Microwave-Assisted Conversion of Essential Oil Allylbenzenes into the Corresponding Aldehydes via Alkene Isomerization and Subsequent Potassium Permanganate Promoted Oxidative Alkene Group Cleavage

    Directory of Open Access Journals (Sweden)

    Thi X. Thi Luu

    2009-09-01

    Full Text Available Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step “green” reaction pathway based on a solventless alkene group isomerization by KF/Al2O3 to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO4/CuSO4·5H2O. The assistance by microwave irradiation results in very short reaction times (<15 minutes. The green conversion of eugenol (4-allyl-2-methoxyphenol into vanillin (4-hydroxy-3-methoxybenzaldehyde has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde by KF/Al2O3 under solvent-free conditions, respectively.

  7. Fast and green microwave-assisted conversion of essential oil allylbenzenes into the corresponding aldehydes via alkene isomerization and subsequent potassium permanganate promoted oxidative alkene group cleavage.

    Science.gov (United States)

    Luu, Thi X Thi; Lam, Trinh To; Le, Thach Ngoc; Duus, Fritz

    2009-09-03

    Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step "green" reaction pathway based on a solventless alkene group isomerization by KF/Al(2)O(3) to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO(4)/CuSO(4).5H(2)O. The assistance by microwave irradiation results in very short reaction times (<15 minutes). The green conversion of eugenol (4-allyl-2-methoxyphenol) into vanillin (4-hydroxy-3-methoxybenzaldehyde) has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde) by KF/Al(2)O(3) under solvent-free conditions, respectively.

  8. Layered nickel sulfide-reduced graphene oxide composites synthesized via microwave-assisted method as high performance anode materials of sodium-ion batteries

    Science.gov (United States)

    Qin, Wei; Chen, Taiqiang; Lu, Ting; Chua, Daniel H. C.; Pan, Likun

    2016-01-01

    Layered nickel sulfide (NS)-reduced graphene oxide (RGO) composites are prepared via a simple microwave-assisted method and subsequent annealing in N2/H2 atmosphere. A detailed array of characterization tools are used to study their morphology, structure and electrochemical performance. It was found that these composites exhibit significantly improved sodium-ion storage ability as compared with pure NS under galvanostatic cycling at a specific current of 100 mA g-1 in a potential limitation of 0.005-3.0 V. Furthermore, the composite with the RGO content of 35 wt.% achieves a high maximum reversible specific capacity of about 391.6 mAh g-1 at a specific current of 100 mA g-1 after 50 cycles. These results prove that NS-RGO composites are highly promising when applied directly as anode materials in sodium-ion batteries.

  9. An Efficient and Regioselective Synthesis of 2,3-Disubstituted 6-Aminoquinoxaline Derivatives Using Alkoxylation and Microwave-assisted Sonogashira Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Doohyun; Seo, Young Ho; Bae, Jongsup; Lee, Sangkyu; Lee, Taeho [Kyungpook National Univ., Daegu (Korea, Republic of); Lee, Tae Im [Osteogenic Core Technologies, Seongnam (Korea, Republic of); Gong, Youngdae [Dongguk Univ., Seoul (Korea, Republic of)

    2013-08-15

    The yields for 2,3-disubstituted 6-amino-quinoxaline derivatives produced through regioselective subsequent synthetic reactions (alkoxylation and microwave-assisted Sonogashira coupling) ranged from 49 to 85% from known 2,3-dichloro-6-aminoqunoxaline. In addition, the desired 6-aminoqunoxalines with two-diversity points were obtained in high purities (> 95%) as judged from LC-MS and {sup 1}H NMR analyses. This strategy allows for a ready access to a large library and is potentially applicable to the preparation of other 6-aminoquinoxaline derivatives. Further studies in this area are underway, and the results of these studies will be reported in due course. The quinoxalines are a common skeleton of nitrogencontaining heterocycles with biological properties. Because of their good biological activities quinoxalines, which contain 2,3-di-substituents, are of particular interest in medicinal chemistry and drug discovery programs.

  10. Microwave Assistant Synthesis, Antifungal Activity and DFT Theoretical Study of Some Novel 1,2,4-Triazole Derivatives Containing Pyridine Moiety

    Directory of Open Access Journals (Sweden)

    Guo-Xiang Sun

    2014-05-01

    Full Text Available In order to investigate the biological activity of novel 1,2,4-triazole compounds, seventeen novel 1,2,4-triazole derivatives containing pyridine moiety were synthesized under microwave assistant condition by multi-step reactions. The structures were characterized by 1H NMR, MS and elemental analyses. The target compounds were evaluated for their fungicidal activities against Stemphylium lycopersici (Enjoji Yamamoto, Fusarium oxysporum. sp. cucumebrium, and Botrytis cinerea in vivo, and the results indicated that some of the title compounds displayed excellent fungicidal activities. Theoretical calculation of the title compound was carried out with B3LYP/6-31G (d,p. The full geometry optimization was carried out using 6-31G (d,p basis set, and the frontier orbital energy, atomic net charges were discussed, and the structure-activity relationship was also studied.

  11. Enhanced visible-light-responsive photodegradation of bisphenol A by Cu, N-codoped titanate nanotubes prepared by microwave-assisted hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Doong, Ruey-an, E-mail: radoong@nctu.edu.tw [Institute of Environmental Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liao, Chun-Yi [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2017-01-15

    Highlights: • The Cu, N-codoped TNTs were prepared by microwave assisted hydrothermal method. • The Cu(0) in codoped TNTs can serve as electron donors as well as electron meditors. • The surface normalized rate constants for BPA removal by Cu, N-TNT were 1.5–4.3 times higher than that of P25 TiO{sub 2}. • The Cu, N-codoped TNTs prolonged the generation of radicals for at least 5 min. - Abstract: In this study, a rapid and effective microwave-assisted hydrothermal method was developed for the synthesis of Cu, N-codoped titanate nanotubes (Cu, N-TNTs) to enhance the photocatalytic degradation efficiency and rate of bisphenol A (BPA) under UV and visible light irradiations. The TNTs were first synthesized at 150 °C for 3 h under microwave heating conditions followed by the calcination at 450 °C in the presence of 6 wt% Cu ions and N{sub 2}/NH{sub 3} to fabricate Cu, N-TNTs composites. The Cu, N-TNTs exhibited excellent photocatalytic activity toward BPA degradation under UV and visible light irradiations. The X-ray photoelectron spectra indicated that Cu species in Cu, N-TNTs were mainly in zerovalent form and could serve as the electron donors as well as shuttling species to accelerate the photodegradation of BPA. In addition, the nitrogen atoms were incorporated into the anatase lattices to increase the visible-light-responsive capability. The surface normalized reaction rate constants for BPA degradation were 4.3 and 1.5 times higher than those of Degussa P25 TiO{sub 2} under UV and visible light irradiations, respectively. The electron spin resonance spectra showed that Cu, N-codoped TNTs prolonged the generation of oxygen-containing radicals for at least 5 min, resulting in the significant enhancement of photodegradation efficiency and rate of BPA. Results obtained in this study open a new avenue by using simple and effective microwave-assisted hydrothermal method to fabricate low dimensional codoped TNTs which can be potentially applied in a wide

  12. Negative Feedback Effect of Microwave Irradiation in the Microwave-assisted Hydrothermal Synthesis of Bi2S3 Nanorods

    Institute of Scientific and Technical Information of China (English)

    TAO,Xiu-Cheng(陶秀成); SHAO,Ming-Wang(邵名望)

    2002-01-01

    The microwave-assisted hydrothermal synthesis of Bi2S3 nanorods was reported. The result showed that microwave irradiation can help to produce Bi2S3 nanorods in very short time.There is a negative feedback effect which increases the degree of crystallinity in the reaction.

  13. A Student-Centered First-Semester Introductory Organic Laboratory Curriculum Facilitated by Microwave-Assisted Synthesis (MAOS)

    Science.gov (United States)

    Russell, Cianán B.; Mason, Jeremy D.; Bean, Theodore G.; Murphree, S. Shaun

    2014-01-01

    An instructional laboratory curriculum for a first-semester introductory organic chemistry course has been developed using microwave-assisted organic synthesis (MAOS). Taking advantage of short reaction times, materials were developed to facilitate collaborative experimental design, analysis, and debriefing of results during the normal laboratory…

  14. Au-controlled enhancement of photoluminescence of NiS nanostructures synthesized via a microwave-assisted hydrothermal technique

    CSIR Research Space (South Africa)

    Linganiso, EC

    2014-11-01

    Full Text Available Nickel sulphide (NiS) nanostructures decorated with gold (Au) nanoparticles (NPs) were synthesized via a microwave-assisted hydrothermal technique. Binary phase NiS (a and ß) crystalline nanostructures, bare, and decorated with Au NPs were obtained...

  15. Effect of the Solvent on the Microstructure of Bi2Te3 Obtained Solvothermal Microwave-assisted Synthesis

    Directory of Open Access Journals (Sweden)

    R.A. Lyubushkin

    2014-04-01

    Full Text Available In the present work, nanoparticles and nanowires have been prepared by solvothermal microwave-assisted synthesis using isopropyl alcohol, dimethylformamide (DMF and 1,4-dioxane respectively as the solvents. The microstructures of the synthesized powders have been characterized and the relationship with the solvent has been investigated.

  16. Microwave-assisted modulated synthesis of zirconium-based metal–organic framework (Zr-MOF) for hydrogen storage applications

    CSIR Research Space (South Africa)

    Ren, Jianwei

    2014-05-01

    Full Text Available Zirconium-based metal–organic framework (Zr-MOF) was synthesized using a microwave-assisted modulated method in a short reaction time of 5 min. The Zr-MOF material was highly crystalline with well-defined octahedral shaped crystals, and it exhibited...

  17. A Student-Centered First-Semester Introductory Organic Laboratory Curriculum Facilitated by Microwave-Assisted Synthesis (MAOS)

    Science.gov (United States)

    Russell, Cianán B.; Mason, Jeremy D.; Bean, Theodore G.; Murphree, S. Shaun

    2014-01-01

    An instructional laboratory curriculum for a first-semester introductory organic chemistry course has been developed using microwave-assisted organic synthesis (MAOS). Taking advantage of short reaction times, materials were developed to facilitate collaborative experimental design, analysis, and debriefing of results during the normal laboratory…

  18. Microwave assisted alkali-catalyzed transesterification of Pongamia pinnata seed oil for biodiesel production.

    Science.gov (United States)

    Kumar, Ritesh; Kumar, G Ravi; Chandrashekar, N

    2011-06-01

    In this study, microwave assisted transesterification of Pongamia pinnata seed oil was carried out for the production of biodiesel. The experiments were carried out using methanol and two alkali catalysts i.e., sodium hydroxide (NaOH) and potassium hydroxide (KOH). The experiments were carried out at 6:1 alcohol/oil molar ratio and 60°C reaction temperature. The effect of catalyst concentration and reaction time on the yield and quality of biodiesel was studied. The result of the study suggested that 0.5% sodium hydroxide and 1.0% potassium hydroxide catalyst concentration were optimum for biodiesel production from P. pinnata oil under microwave heating. There was a significant reduction in reaction time for microwave induced transesterification as compared to conventional heating.

  19. Microwave-assisted Extraction and GC-MS Analysis of Zanthoxylum Oil from Zanthoxylum bungeanum

    Directory of Open Access Journals (Sweden)

    Xiaoguang Wang

    2015-03-01

    Full Text Available The conditions for microwave-assisted extracting oil from Zanthoxylum bungeanum seeds were studied and its chemical composition was analyzed by GC-MS. The effects of extract medium, microwave power, time and ratio of liquid to solid on extraction yield of Zanthoxylum bungeanum oil were investigated, using an orthogonal array design. The experimental results showed that using petroleum ether as extract medium, microwave power 350 w, solid-to-solvent ratio 1:5 (g/mL, 60 sec, can obtained 7.85% of Zanthoxylum bungeanum oil. Thirty-three substances in Zanthoxylum bungeanum oil were authenticated by GC-MS, of which 33 were identified for the first time and its chemical composition was analyzed. Accounting for 97.82% of the total volatile compounds.

  20. MICROWAVE ASSISTED HYDRODISTILLATION UNTUK EKSTRAKSI MINYAK ATSIRI DARI KULIT JERUK BALI SEBAGAI LILIN AROMATERAPI

    Directory of Open Access Journals (Sweden)

    Megawati -

    2015-07-01

    Full Text Available Ekstraksi minyak atsiri kulit jeruk bali dilakukan menggunakan metode Microwave Assisted Hydrodistillation dengan variasi daya (800, 600, 450, 300, dan 100 W dan massa bahan (150, 125, 100, 75,dan 50 g. Ektraksi dengan variasi daya dilakukan pada massa 150 g dan didapat daya optimum yaitu 600 W, sedangkan ekstraksi dengan variasi massa bahan dilakukan pada daya 600 W. Minyak atsiri yang diperoleh dianalisis densitas, kelarutan dalam alkohol 95% dan senyawa kimia minyak atsiri kulit jeruk bali menggunakan Gas Chromatography-Mass Spectrometry (GC-MS dan minyak atsiri kulit jeruk bali yang didapat diaplikasikan untuk lilin aromaterapi. Hasil penelitian menunjukkan semakin besar daya yang digunakan maka volum minyak yang dihasilkan semakin besar dan waktu ekstraksinya lebih cepat. Variasi massa bahan menunjukkan semakin besar massa bahan massa bahan yang digunakan maka volum minyak yang dihasilkan semakin besar. Densitas minyak atsiri kulit jeruk bali hasil penelitian yaitu 0,810 g/mL, larut pada alkohol 95% dengan perbandingan minyak-alkohol 1:6 dan terdapat tiga komponen senyawa kimia penyusun minyak atsiri kulit jeruk bali yaitu limonen (93,99%, β-pinene (3,20%, dan germakren-D (2,82%. Minyak atsiri kulit jeruk bali hasil ekstraksi yang diperoleh dapat diaplikasikan untuk lilin aromaterapi. Kata kunci: Kulit jeruk bali, lilin aromaterapi, microwave assisted hydrodistillation, minyak atsiri. Essential oils extracted from pomelo peel was performed using Microwave Assisted Hydrodistillation with variations of microwave oven power (800, 600, 450, 300, and 100 W and material mass (150, 125, 100, 75, and 50 g. The extraction with power variation was conducted with 150 g of material and the optimum extraction power was obtained at 600 W. Therefore material mass variation was conducted with microwave oven power of 600 W. The essential oils produced were analyzed for its density, solubility in alcohol of 95% v/v, and chemical composition. The chemical

  1. Subnanosecond microwave-assisted magnetization switching in a circularly polarized microwave magnetic field

    Science.gov (United States)

    Suto, Hirofumi; Kanao, Taro; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

    2017-06-01

    We study microwave-assisted magnetization switching (MAS) of a perpendicularly magnetized nanomagnet with a diameter of 50 nm in a circularly polarized microwave magnetic field. The MAS effect appears when the rotation direction of the microwave field matches that of the ferromagnetic resonance excitation, and a large switching field decrease from 7.1 kOe to 1.5 kOe is demonstrated. In comparison with a linearly polarized microwave magnetic field, the circularly polarized microwave field induces the same MAS effect at half the microwave field amplitude, thereby showing its efficiency. We also examine MAS in the subnanosecond region and show that the magnetization switching can be induced by a microwave field with the duration of 0.2 ns.

  2. Microwave assisted conversion of microcrystalline cellulose into value added chemicals using dilute acid catalyst.

    Science.gov (United States)

    Ching, Teck Wei; Haritos, Victoria; Tanksale, Akshat

    2017-02-10

    One of the grand challenges of this century is to transition fuels and chemicals production derived from fossil feedstocks to renewable feedstocks such as cellulosic biomass. Here we describe fast microwave conversion of microcrystalline cellulose (MCC) in water, with dilute acid catalyst to produce valuable platform chemicals. Single 10min microwave assisted treatment was able to convert >60% of MCC, with >50mol% yield of desirable products such as glucose, HMF, furfural and levulinic acid. Recycling of residual MCC with make-up fresh MCC resulted in an overall conversion of >93% after 5 cycles while maintaining >60% conversion in each cycle. Addition of isopropanol (70%v/v) as a co-solvent increased the yields of HMF and levulinic acid. This work shows for the first time proof of concept for complete conversion of recalcitrant microcrystalline cellulose in mild conditions of low temperature, dilute acid and short residence time using energy efficient microwave technology.

  3. Microwave assisted extraction of sulfated polysaccharides (fucoidan) from Ascophyllum nodosum and its antioxidant activity.

    Science.gov (United States)

    Yuan, Yuan; Macquarrie, Duncan

    2015-09-20

    Sulfated polysaccharides (fucoidan) from brown seaweed Ascophyllum nodosum were extracted by microwave assisted extraction (MAE) technology. Different conditions of temperature (90-150°C), extraction time (5-30 min) were evaluated and optimal fucoidan yield was 16.08%, obtained from 120°C for 15 min's extraction. Compositional analysis, GPC, HPAEC and IR analysis were employed for characterization of extracted sulfated polysaccharides. Fucose was the main monosaccharide of fucoidan extracted at 90°C while glucuronic acid was the main monosaccharide of fucoidan extracted at 150°C. Both the molecular weight and sulfate content of extracted fucoidan increased with decreasing extraction temperature. All fucoidans exhibited antioxidant activities as measured by DPPH scavenging and reducing power, among which fucoidan extracted at 90°C was highest. This study shows that MAE is an efficient technology to extract sulfated polysaccharides from seaweed and Ascophyllum nodosum could potentially be a resource for natural antioxidants.

  4. Rapid Microwave-Assisted Copper-Catalyzed Nitration of Aromatic Halides with Nitrite Salts

    Energy Technology Data Exchange (ETDEWEB)

    Paik, Seung Uk; Jung, Myoung Geun [Keimyung University, Daegu (Korea, Republic of)

    2012-02-15

    A rapid and efficient copper-catalyzed nitration of aryl halides has been established under microwave irradiation. The catalytic systems were found to be the most effective with 4-substituted aryl iodides leading to nearly complete conversions. Nitration of aromatic compounds is one of the important industrial processes as underlying intermediates in the manufacture of a wide range of chemicals such as dyes, pharmaceuticals, agrochemicals and explosives. General methods for the nitration of aromatic compounds utilize strongly acidic conditions employing nitric acid or a mixture of nitric and sulfuric acids, sometimes leading to problems with poor regioselectivity, overnitration, oxidized byproducts and excess acid waste in many cases of functionalized aromatic compounds. Several other nitrating agents or methods avoiding harsh reaction conditions have been explored using metal nitrates, nitrite salts, and ionic liquid-mediated or microwave-assisted nitrations. Recently, copper or palladium compounds have been successfully used as efficient catalysts for the arylation of amines with aryl halides under mild conditions.

  5. Microwave-assisted one-step patterning of aqueous colloidal silver.

    Science.gov (United States)

    Yang, G; Zhou, Y W; Guo, Z R; Wan, Y; Ding, Q; Bai, T T; Wang, C L; Gu, N

    2012-07-05

    A new approach of utilizing microwave to pattern gradient concentric silver nanoparticle ring structures has been presented. The width and height of a single ring and the space between adjacent rings can be adjusted by changing the silver colloidal concentration and the microwave output power. By simply enhancing the ambient vapour pressure to the saturated value during microwave-assisted evaporation, sub-100 nm rings can be deposited in between adjacent micro-rings over a distance of millimetres. Combined with microwave sintering, this approach can also create conductive silver tracks in a single step, showing huge potential in fabricating micro- and nano-electronic devices in an ultra-fast and cost-effective fashion.

  6. Process optimization and analysis of microwave assisted extraction of pectin from dragon fruit peel.

    Science.gov (United States)

    Thirugnanasambandham, K; Sivakumar, V; Prakash Maran, J

    2014-11-04

    Microwave assisted extraction (MAE) technique was employed for the extraction of pectin from dragon fruit peel. The extracting parameters were optimized by using four-variable-three-level Box-Behnken design (BBD) coupled with response surface methodology (RSM). RSM analysis indicated good correspondence between experimental and predicted values. 3D response surface plots were used to study the interactive effects of process variables on extraction of pectin. The optimum extraction conditions for the maximum yield of pectin were power of 400 W, temperature of 45 °C, extracting time of 20 min and solid-liquid ratio of 24 g/mL. Under these conditions, 7.5% of pectin was extracted. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Microwave assisted extraction process of betalain from dragon fruit and its antioxidant activities

    Directory of Open Access Journals (Sweden)

    K. Thirugnanasambandham

    2017-01-01

    Full Text Available The aim of this research was to optimize the operating parameters in microwave assisted extraction process (MIE such as temperature, mass of the sample, extraction time on the betalain content from dragon fruit peel using response surface methodology (RSM. Three factors three levels Box-Behnken response surface design (BBD was used for optimization and mathematical model development. Significant quadratic polynomial model was obtained (R2 = 0.9892 for betalain content with high coefficient determination value and numerical optimization was employed to achieve optimum conditions which was found to be; temperature of 35 °C, mass of the sample of 20 g, and treatment time of 8 min. Under these conditions, 9 mg/L of betalain content was obtained and it was validated using experimental values.

  8. Microwave-Assisted Synthesis of Alumina Nanoparticles Using Some Plants Extracts

    Directory of Open Access Journals (Sweden)

    Meisam Hasanpoor

    2017-01-01

    Full Text Available In present study we used five green plants for microwave assisted synthesis of Alumina nanoparticles from Aluminum nitrate. Structural characterization was studied using x-ray diffraction that showed semi- crystalline and possibly, amorphous structure. Fourier infrared spectroscopy was used to determine Al-O bond and functional groups responsible for synthesis of nanoparticles. FTIR confirmed existence of Al-O band and bio-functional groups, originated from plant extract. Morphology and size of nanoparticles were investigated using scanning electron microscopy, transmission electron microscopy and atomic force microscopy techniques. It was observed that nanoparticles have near-spherical shape. Average size of clusters of nanoparticles varied with different routes from of 60 nm to 300 nm. AFM images showed that Individual nanoparticles were less than 10 nm.

  9. Biodiesel from wet microalgae: extraction with hexane after the microwave-assisted transesterification of lipids.

    Science.gov (United States)

    Cheng, Jun; Huang, Rui; Li, Tao; Zhou, Junhu; Cen, Kefa

    2014-10-01

    A chloroform-free novel process for the efficient production of biodiesel from wet microalgae is proposed. Crude biodiesel is produced through extraction with hexane after microwave-assisted transesterification (EHMT) of lipids in wet microalgae. Effects of different parameters, including reaction temperature, reaction time, methanol dosage, and catalyst dosage, on fatty acids methyl esters (FAMEs) yield are investigated. The yield of FAME extracted into the hexane from the wet microalgae is increased 6-fold after the transesterification of lipids. The yield of FAME obtained through EHMT of lipids in wet microalgae is comparable to that obtained through direct transesterification of dried microalgae biomass with chloroform; however, FAME content in crude biodiesel obtained through EHMT is 86.74%, while that in crude biodiesel obtained through the chloroform-based process is 75.93%. EHMT ensures that polar pigments present in microalgae are not extracted into crude biodiesel, which leads to a 50% reduction in nitrogen content in crude biodiesel.

  10. Antioxidant/antiradical properties of microwave-assisted extracts of three wild edible mushrooms.

    Science.gov (United States)

    Özyürek, Mustafa; Bener, Mustafa; Güçlü, Kubilay; Apak, Reşat

    2014-08-15

    A microwave-assisted extraction (MAE) process for polyphenols from three wild edible mushrooms was studied. The optimal extraction conditions were found to be methanol concentration of 80%, extraction temperature of 80 °C, and extraction time of 5 min. Different antioxidant assays (i.e., total antioxidant capacity (TAC) and total phenolic content (TPC)) were utilized to evaluate the antioxidant capacity of the methanolic extracts of Terfezia boudieri Chatin, Boletus edulis, and Lactarius volemus. The reactive species scavenging activities of these extracts were also investigated in vitro. High contents of phenolic and flavonoid compounds may be the major contributors to the observed high antioxidant activities of these extracts. B. edulis showed the higher TAC and TPC; highest inhibitory effect on DPPH and on other studied reactive oxygen species (ROS). MAE showed obvious advantages of high extraction efficiency with lower solvent consumption in terms of high antioxidant capacity/activity of extracts achieved within the shortest time.

  11. Thermal analysis on the process of microwave-assisted biodiesel production.

    Science.gov (United States)

    Wu, Li; Zhu, Huacheng; Huang, Kama

    2013-04-01

    The aim of this work was firstly to do a precise thermal analysis of microwave assisted production of biodiesel. In this paper, the effective permittivity of biodiesel synthesis was updated with two methods: a traditional method and a bivariate function of temperature and concentration of one component, then the thermal analysis of the reaction process were accomplished with multi-physics calculation. The results show that there exists large distinction in temperature between these two simulation results calculated by the two methods. The two hot spots locate in the opposite side and their temperature's difference is up to 9°C when the reaction is just carried out for 18s. But the temperature risings and distributions calculated by the new method are closer to the measured results. The thermal analysis based on the new method will be helpful for the industrial design of biodiesel production.

  12. Microwave-assisted synthesis and characterization of ZnO-nanorod arrays

    Institute of Scientific and Technical Information of China (English)

    ZHU Jian-yu; ZHANG Jing-xia; ZHOU Hui-fen; QIN Wen-qing; CHAI Li-yuan; HU Yue-hua

    2009-01-01

    High density ZnO-nanorod arrays (rod length 1.59 μm) were successfully synthesized via a microwave-assisted solution-phase method using zinc chloride and ammonia solution as reactants.The influence of concentration of ammonia solution,work power,and microwave irradiation time on the morphology and size of final products was carefully investigated.The crystal structure,chemical composition and morphologies of final products were characterized using X-ray powder diffraction (XRD),scanning electron microscopy (SEM) and photoluminescence (PL).The as-synthesized ZnO is composed of single crystalline and possesses three photoluminescence emissions centered at 400,469 and 534.5 nm,respectively.

  13. Microwave-Assisted γ-Valerolactone Production for Biomass Lignin Extraction: A Cascade Protocol

    Directory of Open Access Journals (Sweden)

    Silvia Tabasso

    2016-03-01

    Full Text Available The general need to slow the depletion of fossil resources and reduce carbon footprints has led to tremendous effort being invested in creating “greener” industrial processes and developing alternative means to produce fuels and synthesize platform chemicals. This work aims to design a microwave-assisted cascade process for a full biomass valorisation cycle. GVL (γ-valerolactone, a renewable green solvent, has been used in aqueous acidic solution to achieve complete biomass lignin extraction. After lignin precipitation, the levulinic acid (LA-rich organic fraction was hydrogenated, which regenerated the starting solvent for further biomass delignification. This process does not requires a purification step because GVL plays the dual role of solvent and product, while the reagent (LA is a product of biomass delignification. In summary, this bio-refinery approach to lignin extraction is a cascade protocol in which the solvent loss is integrated into the conversion cycle, leading to simplified methods for biomass valorisation.

  14. Microwave-assisted extraction of Shenfu coal and its macromolecule structure

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; LI Jian-wei; LEI Zhao; GE Ling-mei

    2009-01-01

    Coals consist of some molecules trapped within an organic matrix from which some organic compounds can be extracted by solvents. The Soxhlet technique has been widely used for extracting organic compounds. Microwave heating methods may be successfully applied in the field of coal science. Acetone extraction yields and the chemical composition of the extract were inves-tigated using a typical Chinese coal, Shenfu coal, with microwave-assisted extraction. The acetone extract and residue were ana-lyzed by GC/MS and carbon-13 nuclear magnetic resonance spectroscopy respectively. The carbon spectra were converted into several numerical parameters, fa, Ha, Xb, which indicate the difference in macromolecular structure between Shenfu coal and its residue. Furthermore, a hybrid genetic algorithm was employed using these parameters to approximate a coal macromolecule by assembling the structural fragments or functional groups into a large and complicated structure.

  15. Microwave-Assisted γ-Valerolactone Production for Biomass Lignin Extraction: A Cascade Protocol.

    Science.gov (United States)

    Tabasso, Silvia; Grillo, Giorgio; Carnaroglio, Diego; Calcio Gaudino, Emanuela; Cravotto, Giancarlo

    2016-03-26

    The general need to slow the depletion of fossil resources and reduce carbon footprints has led to tremendous effort being invested in creating "greener" industrial processes and developing alternative means to produce fuels and synthesize platform chemicals. This work aims to design a microwave-assisted cascade process for a full biomass valorisation cycle. GVL (γ-valerolactone), a renewable green solvent, has been used in aqueous acidic solution to achieve complete biomass lignin extraction. After lignin precipitation, the levulinic acid (LA)-rich organic fraction was hydrogenated, which regenerated the starting solvent for further biomass delignification. This process does not requires a purification step because GVL plays the dual role of solvent and product, while the reagent (LA) is a product of biomass delignification. In summary, this bio-refinery approach to lignin extraction is a cascade protocol in which the solvent loss is integrated into the conversion cycle, leading to simplified methods for biomass valorisation.

  16. Antioxidant Activity and Phenolic Content of Microwave-Assisted Solanum melongena Extracts

    Directory of Open Access Journals (Sweden)

    Loredana Salerno

    2014-01-01

    Full Text Available Eggplant fruit is a very rich source of polyphenol compounds endowed with antioxidant properties. The aim of this study was to extract polyphenols from eggplant entire fruit, pulp, or skin, both fresh and dry, and compare results between conventional extraction and microwave-assisted extraction (MAE. The effects of time exposure (15, 30, 60, and 90 min and solvent (water 100% or ethanol/water 50% were also evaluated. The highest amount of polyphenols was found in the extract obtained from dry peeled skin treated with 50% aqueous ethanol, irradiated with microwave; this extract contained also high quantity of flavonoids and showed good antioxidant activity expressed by its capacity to scavenge superoxide anion and to inhibit lipid peroxidation.

  17. Microwave-assisted Ionothermal Synthesis and Characteriza- tion of Zeolitic Imidazolate Framework-8

    Institute of Scientific and Technical Information of China (English)

    杨丽莎; 卢惠民

    2012-01-01

    The zeolitic imidazolate framework-8 (ZIF-8) was successfully synthesized using ionic liquids as struc- ture-directing agent under microwave irradiation. Ionic liquids are green solvents with low vapour pressure and good thermal stability. They are appropriate templates for microporous materials and ideal microwave absorbers. The microwave-assisted ionothermal synthesis applied in this paper was expected to be a promising method for the preparation of microporous materials. Results showed that the as-synthesized samples (300---500 nm in diameter) could be synthesized in a short time (60 min) and possessed regular morphology, stable structure and high thermal stability (up to 720 ~C in argon atmosphere). Nitrogen adsorption-desorption test illustrated that samples produced by microwave heating had a higher surface area. Carbon dioxide adsorption test indicated that the samples synthe- sized by microwave heating had better carbon dioxide adsorption ability than those by conventional heating.

  18. Microwave-Assisted Chemical Functionalization of Single-Walled Carbon Nanotubes with Organic Peroxides

    Institute of Scientific and Technical Information of China (English)

    WAN Li; WANG Xianbao; LI Shaoqing; LI Qin; TIAN Rong; LI Mingjian; CHENG Jing

    2009-01-01

    Microwave-assisted chemical functionalization of single-walled carbon nanotubes, with undecyl groups de-composed from lauroyl peroxides was reported. This rapid efficient procedure reduced the reaction time to 10 min, and obtained the products with higher functionalized degree than that by the conventional refluxing method. The in-fluence of different reaction time and microwave power on the functionalized degree has been explored by using FT-IR, TGA and Raman analyses. The results show that longer treatment time will lead to partial defunctionaliza-tion, and higher microwave power (higher than 900 W) can reduce the functionalized degree by removing some ini-tially-attached functional groups. Dispersion stability images and HRTEM images show that the resulting SWNT has enhanced dispersivity in organic solvents compared to the pristine nanotubes.

  19. Microwave assisted synthesis of zinc stannate nanocubes for dye sensitized solar cell application

    Science.gov (United States)

    Jayabal, P.; Sasirekha, V.; Mayandi, J.; Ramakrishnan, V.

    2014-11-01

    The ternary complex oxide Zn2SnO4 (ZS) has become more essential because of its photonic energy conversion, tremendous stability and higher electron mobility compared to the binary counterparts. The ZS nanocubes were prepared by simple microwave assisted route. The cubic spinel structured ZS was confirmed by X-ray diffraction (XRD) and micro-Raman techniques. Scanning electron micrograph revealed the formation of nanocubes with size of ∼90 nm. The Dye Sensitized Solar Cells (DSSCs) were fabricated using the synthesized ZS as photoanode and low cost organic dyes such as Rose Bengal (RB), Eosin Yellow (EY) and Fluorescein sodium salt (FY) as sensitizers to study their light conversion efficiencies. The DSSCs exhibited power conversion efficiency (PCE) of 0.64%, 0.05% and 0.02% for RB, EY and FY sensitized films, respectively.

  20. Microwave-assisted grinding of metallurgical coke; Molienda asistida con microondas de un coque metalurgico

    Energy Technology Data Exchange (ETDEWEB)

    Ruisanchez, E.; Juarez-Perez, E. J.; Arenillas, A.; Bermudez, J. M.; Menendez, J. A.

    2014-10-01

    Metallurgical cokes are composed of graphitic carbon (s2p2) and different inorganic compounds with very different capacities to absorb microwave radiation. Moreover, due to the electric conductivity shown by the metallurgical cokes, microwave radiation produces electric arcs or microplasmas, which gives rise to hot spots. Therefore, when these cokes are irradiated with microwaves some parts of the particle experiment a rapid heating, while some others do not heat at all. As a result of the different expansion and stress caused by thermal the shock, small cracks and micro-fissures are produced in the particle. The weakening of the coke particles, and therefore an improvement of its grind ability, is produced. This paper studies the microwave-assisted grinding of metallurgical coke and evaluates the grinding improvement and energy saving. (Author)

  1. Kinetics and Quality of Microwave-Assisted Drying of Mango (Mangifera indica)

    Science.gov (United States)

    Abano, Ernest Ekow

    2016-01-01

    The effect of microwave-assisted convective air-drying on the drying kinetics and quality of mango was evaluated. Both microwave power and pretreatment time were significant factors but the effect of power was more profound. Increase in microwave power and pretreatment time had a positive effect on drying time. The nonenzymatic browning index of the fresh samples increased from 0.29 to 0.60 while the ascorbic acid content decreased with increase in microwave power and time from 3.84 mg/100g to 1.67 mg/100g. The effective moisture diffusivity varied from 1.45 × 10−9 to 2.13 × 10−9 m2/s for microwave power range of 300-600 W for 2 to 4 minutes of pretreatment. The Arrhenius type power-dependent activation energy was found to be in the range of 8.58–17.48 W/mm. The fitting of commonly used drying models to the drying data showed the Midilli et al. model as the best. Microwave power of 300 W and pretreatment time of 4 minutes emerged as the optimum conditions prior to air-drying at 7°C. At this ideal condition, the energy savings as a result of microwave application was approximately 30%. Therefore, microwave-assisted drying should be considered for improved heat and mass transfer processes during drying to produce dried mangoes with better quality. PMID:26904667

  2. Beneficial effects of microwave-assisted heating versus conventional heating in noble metal nanoparticle synthesis.

    Science.gov (United States)

    Dahal, Naween; García, Stephany; Zhou, Jiping; Humphrey, Simon M

    2012-11-27

    An extensive comparative study of the effects of microwave versus conventional heating on the nucleation and growth of near-monodisperse Rh, Pd, and Pt nanoparticles has revealed distinct and preferential effects of the microwave heating method. A one-pot synthetic method has been investigated, which combines nucleation and growth in a single reaction via precise control over the precursor addition rate. Using this method, microwave-assisted heating enables the convenient preparation of polymer-capped nanoparticles with improved monodispersity, morphological control, and higher crystallinity, compared with samples heated conventionally under otherwise identical conditions. Extensive studies of Rh nanoparticle formation reveal fundamental differences during the nucleation phase that is directly dependent on the heating method; microwave irradiation was found to provide more uniform seeds for the subsequent growth of larger nanostructures of desired size and surface structure. Nanoparticle growth kinetics are also markedly different under microwave heating. While conventional heating generally yields particles with mixed morphologies, microwave synthesis consistently provides a majority of tetrahedral particles at intermediate sizes (5-7 nm) or larger cubes (8+ nm) upon further growth. High-resolution transmission electron microscopy indicates that Rh seeds and larger nanoparticles obtained from microwave-assisted synthesis are more highly crystalline and faceted versus their conventionally prepared counterparts. Microwave-prepared Rh nanoparticles also show approximately twice the catalytic activity of similar-sized conventionally prepared particles, as demonstrated in the vapor-phase hydrogenation of cyclohexene. Ligand exchange reactions to replace polymer capping agents with molecular stabilizing agents are also easily facilitated under microwave heating, due to the excitation of polar organic moieties; the ligand exchange proceeds with excellent retention of

  3. Microwave-assisted steam distillation for simple determination of polychlorinated biphenyls and organochlorine pesticides in sediments.

    Science.gov (United States)

    Numata, Masahiko; Yarita, Takashi; Aoyagi, Yoshie; Takatsu, Akiko

    2003-03-15

    A novel sample extraction technique for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) analysis using microwave-heating device is developed. In this study, microwave-assisted extraction (MAE) and steam distillation techniques were combined. Desorption of the anatytes from solid matrixes was accelerated with water vapor which was generated by microwave irradiation. A sample holder in a commercial microwave extraction cell kept the sample from direct contact with the organic solvent for analytes trapping during the treatment process. Therefore, relatively clean extracts were obtained with small amount of solvents. Without any cleanup steps, the obtained extract could be analyzed with gas chromatograph/mass spectrometers (GC/MS). Six PCB congeners (PCB15, 28, 70, 101, 180, 194, 209) and three OCPs (gamma-HCH, 4,4'-DDE, 4,4'-DDD) in two marine sediment samples (a sediment collected from a bay of Kyusyu Island, Japan, and a certified reference material NIST SRM1944) were analyzed by using this microwave-assisted steam distillation (MASD) technique and another extraction method (exhaustive steam distillation, MAE, and Soxhlet extraction); and comparisons of the results are shown in this report. Although recovery yields of highly chlorinated biphenyls (PCB180, 194, 209) and relatively polar OCPs (gamma-HCH, 4,4'-DDD) were low (30-60%) compared with other analytes (PCB15, 28, 70, 101, 4,4'-DDE; recovery, 80-100%), use of isotope labeled internal standards for the MASD technique gave comparable results with the values obtained by other extraction methods and the certified values in the samples.

  4. New Approaches for Effective Microwave Assisted Extraction of Caffeine and Catechins from Green Tea

    Directory of Open Access Journals (Sweden)

    Gönül SERDAR

    2016-01-01

    Full Text Available This study was designed to develop an effective microwave assisted extraction (MAE method for extraction of caffeine and catechins from green tea samples. A series of solvents (water, ethanol:water mixture or citric acid:water mixture were used for extraction of green tea samples (fresh, frozen or dried collected in three collection periods (first, second and third collection periods. Tea samples were extracted using water in a close microwave system under the certain extraction conditions. Extraction was carried out under a controlled 600 W microwave power at 80 oC temperature for 4 min irradiation time. Alternative to water, an ethanol-water mixture (1:1 or a citric acid-water (1:1 mixture was used as extracting solvent under the same conditions. After MAE crude aqueous extract was partitioned first with chloroform to separate caffeine then ethyl acetate for catechins.  Both caffeine and catechin extraction was quite successful with microwave assisted system employing only 4 minutes treatment. The highest caffeine yield was obtained in the second collection period using frozen green tea samples and ethanol-water as extracting solvent. The yield of catechin extracts was between 0.84-3.96% depending on the solvent system used for extraction. Ethanol-water mixture seems to be appropriate for effective extraction in the basis of extract yields. However, HPLC results showed that individual catechin content of each extraction is more important criteria for the evaluation of most effective extraction medium rather than the mass of the extract.  Using citric acid as extracting solvent in MAE seem to be more fruitful providing 100% catechin mixture with the highest EGCG content. 

  5. Kinetics and Quality of Microwave-Assisted Drying of Mango (Mangifera indica

    Directory of Open Access Journals (Sweden)

    Ernest Ekow Abano

    2016-01-01

    Full Text Available The effect of microwave-assisted convective air-drying on the drying kinetics and quality of mango was evaluated. Both microwave power and pretreatment time were significant factors but the effect of power was more profound. Increase in microwave power and pretreatment time had a positive effect on drying time. The nonenzymatic browning index of the fresh samples increased from 0.29 to 0.60 while the ascorbic acid content decreased with increase in microwave power and time from 3.84 mg/100g to 1.67 mg/100g. The effective moisture diffusivity varied from 1.45 × 10−9 to 2.13 × 10−9 m2/s for microwave power range of 300-600 W for 2 to 4 minutes of pretreatment. The Arrhenius type power-dependent activation energy was found to be in the range of 8.58–17.48 W/mm. The fitting of commonly used drying models to the drying data showed the Midilli et al. model as the best. Microwave power of 300 W and pretreatment time of 4 minutes emerged as the optimum conditions prior to air-drying at 7°C. At this ideal condition, the energy savings as a result of microwave application was approximately 30%. Therefore, microwave-assisted drying should be considered for improved heat and mass transfer processes during drying to produce dried mangoes with better quality.

  6. Microwave-assisted synthesis and optical properties of cuprous oxide micro/nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Dandan [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Du, Yi, E-mail: duyi234@126.com [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Tian, Xiuying, E-mail: xiuyingt@yahoo.com [Department of Chemistry and Materials Science, Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Li, Zhongfu; Chen, Zhongtao; Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China)

    2014-12-15

    Graphical abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. Growth mechanism of the prepared Cu{sub 2}O microcrystals were investigated carefully. Furthermore, the optical properties of the prepared cuprous oxide microcrystals were investigated by UV–vis diffuse reflectance spectroscopy, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies. - Abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. It was observed that the addition amounts of NaOH had a prominent effect on the morphologies and size of cuprous oxide products, and microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. The as-obtained samples were characterized by X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results indicated that the samples were pure cuprous oxide. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Furthermore, the UV–vis diffuse reflectance spectroscopy was used to investigate the optical properties of the prepared cuprous oxide microcrystals, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies.

  7. Final Technical Report Microwave Assisted Electrolyte Cell for Primary Aluminum Production

    Energy Technology Data Exchange (ETDEWEB)

    Xiaodi Huang; J.Y. Hwang

    2007-04-18

    This research addresses the high priority research need for developing inert anode and wetted cathode technology, as defined in the Aluminum Industry Technology Roadmap and Inert Anode Roadmap, with the performance targets: a) significantly reducing the energy intensity of aluminum production, b) ultimately eliminating anode-related CO2 emissions, and c) reducing aluminum production costs. This research intended to develop a new electrometallurgical extraction technology by introducing microwave irradiation into the current electrolytic cells for primary aluminum production. This technology aimed at accelerating the alumina electrolysis reduction rate and lowering the aluminum production temperature, coupled with the uses of nickel based superalloy inert anode, nickel based superalloy wetted cathode, and modified salt electrolyte. Michigan Technological University, collaborating with Cober Electronic and Century Aluminum, conducted bench-scale research for evaluation of this technology. This research included three sub-topics: a) fluoride microwave absorption; b) microwave assisted electrolytic cell design and fabrication; and c) aluminum electrowinning tests using the microwave assisted electrolytic cell. This research concludes that the typically used fluoride compound for aluminum electrowinning is not a good microwave absorbing material at room temperature. However, it becomes an excellent microwave absorbing material above 550°C. The electrowinning tests did not show benefit to introduce microwave irradiation into the electrolytic cell. The experiments revealed that the nickel-based superalloy is not suitable for use as a cathode material; although it wets with molten aluminum, it causes severe reaction with molten aluminum. In the anode experiments, the chosen superalloy did not meet corrosion resistance requirements. A nicked based alloy without iron content could be further investigated.

  8. Rapid metal extractability tests from polluted mining soils by ultrasound probe sonication and microwave-assisted extraction systems.

    Science.gov (United States)

    García-Salgado, Sara; Quijano, M Ángeles

    2016-12-01

    Ultrasonic probe sonication (UPS) and microwave-assisted extraction (MAE) were used for rapid single extraction of Cd, Cr, Cu, Ni, Pb, and Zn from soils polluted by former mining activities (Mónica Mine, Bustarviejo, NW Madrid, Spain), using 0.01 mol L(-1) calcium chloride (CaCl2), 0.43 mol L(-1) acetic acid (CH3COOH), and 0.05 mol L(-1) ethylenediaminetetraacetic acid (EDTA) at pH 7 as extracting agents. The optimum extraction conditions by UPS consisted of an extraction time of 2 min for both CaCl2 and EDTA extractions and 15 min for CH3COOH extraction, at 30% ultrasound (US) amplitude, whereas in the case of MAE, they consisted of 5 min at 50 °C for both CaCl2 and EDTA extractions and 15 min at 120 °C for CH3COOH extraction. Extractable concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The proposed methods were compared with a reduced version of the corresponding single extraction procedures proposed by the Standards, Measurements and Testing Programme (SM&T). The results obtained showed a great variability on extraction percentages, depending on the metal, the total concentration level and the soil sample, reaching high values in some areas. However, the correlation analysis showed that total concentration is the most relevant factor for element extractability in these soil samples. From the results obtained, the application of the accelerated extraction procedures, such as MAE and UPS, could be considered a useful approach to evaluate rapidly the extractability of the metals studied.

  9. Quantitative phase analysis and microstructure characterization of magnetite nanocrystals obtained by microwave assisted non-hydrolytic sol–gel synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Sciancalepore, Corrado, E-mail: corrado.sciancalepore@unimore.it [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10, 41100 Modena (Italy); Bondioli, Federica [Department of Industrial Engineering, University of Parma, Parco Area delle Scienze, 181/A, 43124 Parma (Italy); INSTM Consortium, Via G. Giusti 9, 51121 Firenze (Italy); Manfredini, Tiziano [Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Pietro Vivarelli 10, 41100 Modena (Italy); INSTM Consortium, Via G. Giusti 9, 51121 Firenze (Italy); Gualtieri, Alessandro [Department of Chemical and Geological Science, University of Modena and Reggio Emilia, Via S. Eufemia 19, 41121 Modena Italy (Italy)

    2015-02-15

    An innovative preparation procedure, based on microwave assisted non-hydrolytic sol–gel synthesis, to obtain spherical magnetite nanoparticles was reported together with a detailed quantitative phase analysis and microstructure characterization of the synthetic products. The nanoparticle growth was analyzed as a function of the synthesis time and was described in terms of crystallization degree employing the Rietveld method on the magnetic nanostructured system for the determination of the amorphous content using hematite as internal standard. Product crystallinity increases as the microwave thermal treatment is increased and reaches very high percentages for synthesis times longer than 1 h. Microstructural evolution of nanocrystals was followed by the integral breadth methods to obtain information on the crystallite size-strain distribution. The results of diffraction line profile analysis were compared with nanoparticle grain distribution estimated by dimensional analysis of the transmission electron microscopy (TEM) images. A variation both in the average grain size and in the distribution of the coherently diffraction domains is evidenced, allowing to suppose a relationship between the two quantities. The traditional integral breadth methods have proven to be valid for a rapid assessment of the diffraction line broadening effects in the above-mentioned nanostructured systems and the basic assumption for the correct use of these methods are discussed as well. - Highlights: • Fe{sub 3}O{sub 4} nanocrystals were obtained by MW-assisted non-hydrolytic sol–gel synthesis. • Quantitative phase analysis revealed that crystallinity up to 95% was reached. • The strategy of Rietveld refinements was discussed in details. • Dimensional analysis showed nanoparticles ranging from 4 to 8 nm. • Results of integral breadth methods were compared with microscopic analysis.

  10. Shape-control by microwave-assisted hydrothermal method for the synthesis of magnetite nanoparticles using organic additives

    Energy Technology Data Exchange (ETDEWEB)

    Rizzuti, Antonino [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Dassisti, Michele [Politecnico di Bari, Dipartimento di Meccanica, Management e Matematica (Italy); Mastrorilli, Piero, E-mail: p.mastrorilli@poliba.it [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Sportelli, Maria C.; Cioffi, Nicola; Picca, Rosaria A. [Università di Bari, Dipartimento di Chimica (Italy); Agostinelli, Elisabetta; Varvaro, Gaspare [Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia (Italy); Caliandro, Rocco [Consiglio Nazionale delle Ricerche, Istituto di Cristallografia (Italy)

    2015-10-15

    A simple and fast microwave-assisted hydrothermal method is proposed for the synthesis of magnetite nanoparticles. The addition of different surfactants (polyvinylpyrrolidone, oleic acid, or trisodium citrate) was studied to investigate the effect on size distribution, morphology, and functionalization of the magnetite nanoparticles. Microwave irradiation at 150 °C for 2 h of aqueous ferrous chloride and hydrazine without additives resulted in hexagonal magnetite nanoplatelets with a facet-to-facet distance of 116 nm and a thickness of 40 nm having a saturation magnetization of ∼65 Am{sup 2} kg{sup −1}. The use of polyvinylpyrrolidone led to hexagonal nanoparticles with a facet-to-facet distance of 120 nm and a thickness of 53 nm with a saturation magnetization of ∼54 Am{sup 2} kg{sup −1}. Additives such as oleic acid and trisodium citrate yielded quasi-spherical nanoparticles of 25 nm in size with a saturation magnetization of ∼70 Am{sup 2} kg{sup −1} and spheroidal nanoparticles of 60 nm in size with a saturation magnetization up to ∼82 Am{sup 2} kg{sup −1}, respectively. A kinetic control of the crystal growth is believed to be responsible for the hexagonal habit of the nanoparticles obtained without additive. Conversely, a thermodynamic control of the crystal growth, leading to spheroidal nanoparticles, seems to occur when additives which strongly interact with the nanoparticle surface are used. A thorough characterization of the materials was performed. Magnetic properties were investigated by Superconducting Quantum Interference Device and Vibrating Sample magnetometers. Based on the observed magnetic properties, the magnetite obtained using citrate appears to be a promising support for magnetically transportable catalysts.

  11. 1,2,3-Triazole-Functionalized Polysulfone Synthesis through Microwave-Assisted Copper-Catalyzed Click Chemistry: A Highly Proton Conducting High Temperature Membrane.

    Science.gov (United States)

    Sood, Rakhi; Donnadio, Anna; Giancola, Stefano; Kreisz, Aurélien; Jones, Deborah J; Cavaliere, Sara

    2016-07-06

    Microwave heating holds all the aces regarding development of effective and environmentally friendly methods to perform chemical transformations. Coupling the benefits of microwave-enhanced chemistry with highly reliable copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry paves the way for a rapid and efficient synthesis procedure to afford high performance thermoplastic materials. We describe herein fast and high yielding synthesis of 1,2,3-triazole-functionalized polysulfone through microwave-assisted CuAAC as well as explore their potential as phosphoric acid doped polymer electrolyte membranes (PEM) for high temperature PEM fuel cells. Polymers with various degrees of substitution of the side-chain functionality of 1,4-substituted 1,2,3-triazole with alkyl and aryl pendant structures are prepared by sequential chloromethylation, azidation, and microwave-assisted CuAAC using a range of alkynes (1-pentyne, 1-nonyne, and phenylacetylene). The completeness of reaction at each step and the purity of the clicked polymers were confirmed by (1)H-(13)C NMR, DOSY-NMR and FTIR-ATR spectroscopies. The thermal and thermochemical properties of the modified polymers were characterized by differential scanning calorimetry and thermogravimetric analysis coupled with mass spectroscopy (TG-MS), respectively. TG-MS analysis demonstrated that the commencement of the thermal degradation takes place with the decomposition of the triazole ring while its substituents have critical influence on the initiation temperature. Polysulfone functionalized with 4-phenyl-1,2,3-triazole demonstrates significantly higher Tg, Td, and elastic modulus than the ones bearing 4-propyl-1,2,3-triazole and 4-heptyl-1,2,3-triazole groups. After doping with phosphoric acid, the functionalized polymers with acid doping level of 5 show promising performance with high proton conductivity in anhydrous conditions (in the range of 27-35 mS/cm) and satisfactorily high elastic modulus (in the range

  12. Microwave assisted one-pot catalyst free green synthesis of new methyl-7-amino-4-oxo-5-phenyl-2-thioxo-2,3,4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates as potent in vitro antibacterial and antifungal activity

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2015-11-01

    Full Text Available An efficiently simple protocol for the synthesis of methyl 7 amino-4-oxo-5-phenyl-2-thioxo-2, 3, 4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates via one-pot three component condensation pathway is established via microwave irradiation using varied benzaldehyde derivatives, methylcyanoacetate and thio-barbituric acid in water as a green solvent. A variety of functionalized substrates were found to react under this methodology due to its easy operability and offers several advantages like, high yields (78–94%, short reaction time (3–6 min, safety and environment friendly without used any catalyst. The synthesized compounds (4a–4k showed comparatively good in vitro antimicrobial and antifungal activities against different strains. The Compounds 4a, 4b, 4c, 4d 4e and 4f showed maximum antimicrobial activity against Staphylococcus aureus, Bacillus cereus (gram-positive bacteria, Escherichia coli, Klebshiella pneumonia, Pseudomonas aeruginosa (gram-negative bacteria. The synthesized compound 4f showed maximum antifungal activity against Aspergillus Niger and Penicillium chrysogenum strains. Streptomycin is used as standard for bacterial studies and Mycostatin as standards for fungal studies. Structure of all newly synthesized products was characterized on the basis of IR, 1H NMR, 13C NMR and mass spectral analysis.

  13. Multicapillary Flow Reactor: Synthesis of 1,2,5-Thiadiazepane 1,1-Dioxide Library Utilizing One-Pot Elimination and Inter-/Intramolecular Double aza-Michael Addition Via Microwave-Assisted, Continuous-Flow Organic Synthesis (MACOS).

    Science.gov (United States)

    Ullah, Farman; Zang, Qin; Javed, Salim; Zhou, Aihua; Knudtson, Christopher A; Bi, Danse; Hanson, Paul R; Organ, Michael G

    2012-12-01

    A microwave-assisted, continuous-flow organic synthesis (MACOS) protocol for the synthesis of functionalized 1,2,5-thiadiazepane 1,1-dioxide library, utilizing a one-pot elimination and inter-/intramolecular double aza-Michael addition strategy is reported. The optimized protocol in MACOS was utilized for scale-out and further extended for library production using a multicapillary flow reactor. A 50-member library of 1,2,5-thiadiazepane 1,1-dioxides was prepared on a 100- to 300-mg scale with overall yields between 50 and 80% and over 90 % purity determined by proton nuclear magnetic resonance ((1)H-NMR) spectroscopy.

  14. Multicapillary Flow Reactor: Synthesis of 1,2,5-Thiadiazepane 1,1-Dioxide Library Utilizing One-Pot Elimination and Inter-/Intramolecular Double aza-Michael Addition Via Microwave-Assisted, Continuous-Flow Organic Synthesis (MACOS)

    Science.gov (United States)

    Ullah, Farman; Zang, Qin; Javed, Salim; Zhou, Aihua; Knudtson, Christopher A.; Bi, Danse; Hanson, Paul R.; Organ, Michael G.

    2013-01-01

    A microwave-assisted, continuous-flow organic synthesis (MACOS) protocol for the synthesis of functionalized 1,2,5-thiadiazepane 1,1-dioxide library, utilizing a one-pot elimination and inter-/intramolecular double aza-Michael addition strategy is reported. The optimized protocol in MACOS was utilized for scale-out and further extended for library production using a multicapillary flow reactor. A 50-member library of 1,2,5-thiadiazepane 1,1-dioxides was prepared on a 100- to 300-mg scale with overall yields between 50 and 80% and over 90 % purity determined by proton nuclear magnetic resonance (1H-NMR) spectroscopy. PMID:24244871

  15. Improvement of rate capability of spinel lithium titanate anodes using microwave-assisted zinc nanocoating

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Chien-Te, E-mail: cthsieh@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan Ze Fuel Cell Center, Yuan Ze University, Taoyuan 320, Taiwan (China); Chang, Bi-Sheng; Lin, Jia-Yi; Juang, Ruey-Shin [Department of Chemical Engineering and Materials Science, Yuan Ze Fuel Cell Center, Yuan Ze University, Taoyuan 320, Taiwan (China)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Microwave-assisted Zn layers onto Li{sub 4}Ti{sub 5}O{sub 12} crystals serves as superior anode materials. Black-Right-Pointing-Pointer Microwave heating is capable of depositing Zn layers over the surface of spinel Li{sub 4}Ti{sub 5}O{sub 12} within 6 min. Black-Right-Pointing-Pointer The thickness of Zn layer is an increasing function of zinc nitrate concentration. Black-Right-Pointing-Pointer The deposition of Zn coating shows a positive effect on the rate-capability improvement of anodes. - Abstract: In this study, the deposition of microwave-assisted Zn layers onto spinel lithium titanate (Li{sub 4}Ti{sub 5}O{sub 12}) crystals as superior anode materials for Li-ion batteries has been investigated. Microwave heating is capable of rapidly depositing Zn layers over the surface of spinel Li{sub 4}Ti{sub 5}O{sub 12} within 6 min. The thickness of Zn layer (i.e., 1-10 nm) is an increasing function of zinc nitrate concentration under the microwave irradiation. The charge-discharge curve of Zn-Li{sub 4}Ti{sub 5}O{sub 12} anode still maintains the plateau at 1.5 V, contributing to the major portion in the overall specific capacity. The presence of Zn coating significantly facilitates the capacity retention (78.1% at 10 C/0.2 C) of the composite anodes with high Coulombic efficiency (>99.9%), indicating an excellent reversibility of insertion/de-insertion of Li ions. This can be ascribed to the fact that well-dispersed Zn layer offers an electronic pathway over the Li{sub 4}Ti{sub 5}O{sub 12} powder, thus imparting electronic conduction and reducing cell polarization. Accordingly, the deposition of Zn coating, prepared by the rapid microwave heating, shows a positive effect on the rate-capability improvement of Li{sub 4}Ti{sub 5}O{sub 12} anodes.

  16. Solution-based formation of high-quality gate dielectrics on epitaxial graphene by microwave-assisted annealing

    Science.gov (United States)

    Kim, Kwan-Soo; Park, Goon-Ho; Fukidome, Hirokazu; Suemitsu, Tetsuya; Otsuji, Taiichi; Cho, Won-Ju; Suemitsu, Maki

    2017-06-01

    We propose a damage-free formation method for high-quality gate dielectrics on epitaxial graphene (EG), which involves solution-based Al2O3 coating combined with microwave-assisted annealing (MW-sol-Al2O3). This method substantially preserves the pristine properties of EG with minimized hole doping and strain induction. The MW-sol-Al2O3 showed a surface roughness of ˜0.237 nm and a dielectric constant of 7.5. A leakage current of 8.7 × 10-6 A/cm2, which is 3 orders of magnitude smaller than that of natural Al2O3 at the same electric field, was obtained. These excellent MW-sol-Al2O3 properties are ascribed to the effective elimination of hydroxyl- and carboxyl-related components from the film by microwave-assisted annealing.

  17. Kinetic study on microwave-assisted esterification of free fatty acids derived from Ceiba pentandra Seed Oil.

    Science.gov (United States)

    Lieu, Thanh; Yusup, Suzana; Moniruzzaman, Muhammad

    2016-07-01

    Recently, a great attention has been paid to advanced microwave technology that can be used to markedly enhance the biodiesel production process. Ceiba pentandra Seed Oil containing high free fatty acids (FFA) was utilized as a non-edible feedstock for biodiesel production. Microwave-assisted esterification pretreatment was conducted to reduce the FFA content for promoting a high-quality product in the next step. At optimum condition, the conversion was achieved 94.43% using 2wt% of sulfuric acid as catalyst where as 20.83% conversion was attained without catalyst. The kinetics of this esterification reaction was also studied to determine the influence of factors on the rate of reaction and reaction mechanisms. The results indicated that microwave-assisted esterification was of endothermic second-order reaction with the activation energy of 53.717kJ/mol.

  18. Microwave assisted esterification of acidified oil from waste cooking oil by CERP/PES catalytic membrane for biodiesel production.

    Science.gov (United States)

    Zhang, Honglei; Ding, Jincheng; Zhao, Zengdian

    2012-11-01

    The traditional heating and microwave assisted method for biodiesel production using cation ion-exchange resin particles (CERP)/PES catalytic membrane were comparatively studied to achieve economic and effective method for utilization of free fatty acids (FFAs) from waste cooking oil (WCO). The optimal esterification conditions of the two methods were investigated and the experimental results showed that microwave irradiation exhibited a remarkable enhanced effect for esterification compared with that of traditional heating method. The FFAs conversion of microwave assisted esterification reached 97.4% under the optimal conditions of reaction temperature 60°C, methanol/acidified oil mass ratio 2.0:1, catalytic membrane (annealed at 120°C) loading 3g, microwave power 360W and reaction time 90min. The study results showed that it is a fast, easy and green way to produce biodiesel applying microwave irradiation.

  19. Enhanced photocatalytic degradation of methylene blue by ZnO-reduced graphene oxide composite synthesized via microwave-assisted reaction

    Energy Technology Data Exchange (ETDEWEB)

    Lv Tian [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Pan Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Liu Xinjuan; Lu Ting; Zhu Guang; Sun Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China)

    2011-10-13

    Highlights: > ZnO-reduced graphene oxide composite is synthesized via microwave assisted reaction. > The method allows a facile, safe and rapid reaction in aqueous media. > A high dye degradation efficiency is achieved under UV light irradiation. - Abstract: A quick and facile microwave-assisted reaction is used to synthesize ZnO-reduced graphene oxide (RGO) hybrid composites by reducing graphite oxide dispersion with zinc nitrate using a microwave synthesis system. Their photocatalytic performance in degradation of methylene blue is investigated and the results show that the RGO plays an important role in the enhancement of photocatalytic performance and the ZnO-RGO composite with 1.1 wt. % RGO achieves a maximum degradation efficiency of 88% in a neutral solution under UV light irradiation for 260 min as compared with pure ZnO (68%) due to the increased light absorption, the reduced charge recombination with the introduction of RGO.

  20. Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents

    Energy Technology Data Exchange (ETDEWEB)

    Saucier, Caroline [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Adebayo, Matthew A. [Department of Chemical Sciences, Ajayi Crowther University, Oyo, Oyo State (Nigeria); Lima, Eder C., E-mail: eder.lima@ufrgs.br [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Cataluña, Renato [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Thue, Pascal S. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Department of Applied Chemistry, University of Ngaoundere, P.O. Box 455, Ngaoundere (Cameroon); Prola, Lizie D.T.; Puchana-Rosero, M.J. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS (Brazil); Machado, Fernando M. [Technology Development Center, Federal University of Pelotas (UFPEL), Pelotas (Brazil); Pavan, Flavio A. [Institute of Chemistry, Federal University of Pampa (UNIPAMPA), Bagé, RS (Brazil); Dotto, G.L. [Chemical Engineering Department, Federal University of Santa Maria (UFSM), Santa Maria, RS (Brazil)

    2015-05-30

    Highlights: • Microwave-assisted cocoa shell activated carbon was prepared and characterized. • The anti-inflammatories, diclofenac and nimesulide, were adsorbed onto MWCS-1.0. • Adsorption maximum values are 63.47 (diclofenac) and 74.81 mg g{sup −1} (nimesulide). • General order kinetic model suitably explained the adsorption process. • MWCS-1.0 was effectively used for treatment of simulated hospital effluents. - Abstract: Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L{sup −1} HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N{sub 2} adsorption/desorption curves, X-ray diffraction, and point of zero charge (pH{sub pzc}). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g{sup −1}, respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations.

  1. The microwave adsorption behavior and microwave-assisted heteroatoms doping of graphene-based nano-carbon materials

    OpenAIRE

    Tang, Pei; Hu, Gang; Gao, Yongjun; Li, Wenjing; Yao, Siyu; Liu, Zongyuan; Ma, Ding

    2014-01-01

    Microwave-assisted heating method is used to treat graphite oxide (GO), pyrolytic graphene oxide (PGO) and hydrogen-reduced pyrolytic graphene oxide (HPGO). Pure or doped graphene are prepared in the time of minutes and a thermal deoxygenization reduction mechanism is proposed to understand their microwave adsorption behaviors. These carbon materials are excellent catalysts in the reduction of nitrobenzene. The defects are believed to play an important role in the catalytic performance.

  2. Study on chromatographic fingerprint of sarcandra glabra (Thunb.) by microwave-assisted extraction coupled to HPLC/DAD

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Microwave-assisted extraction(MAE)was used for extraction of effective components of sarcandra glabra(Thunb.),and then chromatographic fingerprint of sarcandra glabra(Thunb.)was studied by high performance liquid chromatography/diode array detector(HPLC/DAD).The conditions of MAE were optimized by an orthogonal experiment,and then the authentication and validation of the chromatographic fingerprint were conducted.Nine peaks were identified as common peaks in the fingerprint chromatograms,and isofraxidin was...

  3. Microwave-assisted modulated synthesis of zirconium-based metal-organic framework (Zr-MOF) for hydrogen storage applications

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jianwei; Segakweng, Tshiamo; Langmi, Henrietta W.; Musyoka, Nicholas M.; North, Brian C.; Mathe, Mkhulu [Council for Scientific and Industrial Research (CSIR), Pretoria (South Africa). HySA Infrastructure Centre of Competence, Materials Science and Manufacturing; Bessarabov, Dmitri [North-West Univ. (NWU), Potchefstroom (South Africa). HySA Infrastructure Centre of Competence

    2014-05-15

    Zirconium-based metal-organic framework (Zr-MOF) was synthesized using a microwave-assisted modulated method in a short reaction time of 5 min. The Zr-MOF material was highly crystalline with well-defined octahedral shaped crystals, and it exhibited comparable hydrogen storage capacity to Zr-MOF of similar specific surface area synthesized using conventional methods with much longer synthesis time. (orig.)

  4. Optimization of microwave-assisted extraction of polyphenols from Myrtus communis L. leaves.

    Science.gov (United States)

    Dahmoune, Farid; Nayak, Balunkeswar; Moussi, Kamal; Remini, Hocine; Madani, Khodir

    2015-01-01

    Phytochemicals, such as phenolic compounds, are of great interest due to their health-benefitting antioxidant properties and possible protection against inflammation, cardiovascular diseases and certain types of cancer. Maximum retention of these phytochemicals during extraction requires optimised process parameter conditions. A microwave-assisted extraction (MAE) method was investigated for extraction of total phenolics from Myrtus communis leaves. The total phenolic capacity (TPC) of leaf extracts at optimised MAE conditions was compared with ultrasound-assisted extraction (UAE) and conventional solvent extraction (CSE). The influence of extraction parameters including ethanol concentration, microwave power, irradiation time and solvent-to-solid ratio on the extraction of TPC was modeled by using a second-order regression equation. The optimal MAE conditions were 42% ethanol concentration, 500 W microwave power, 62 s irradiation time and 32 mL/g solvent to material ratio. Ethanol concentration and liquid-to-solid ratio were the significant parameters for the extraction process (pMyrtus leaves using MAE compared with UAE and CSE, it was also observed that tannins (32.65 ± 0.01 mg/g), total flavonoids (5.02 ± 0.05 mg QE/g) and antioxidant activities (38.20 ± 1.08 μg GAE/mL) in MAE extracts were higher than the other two extracts. These findings further illustrate that extraction of bioactive phytochemicals from plant materials using MAE method consumes less extraction solvent and saves time.

  5. Facile Microwave-Assisted Synthesis of Klockmannite CuSe Nanosheets and Their Exceptional Electrical Properties

    Science.gov (United States)

    Liu, Yong-Qiang; Wang, Feng-Xia; Xiao, Yan; Peng, Hong-Dan; Zhong, Hai-Jian; Liu, Zheng-Hui; Pan, Ge-Bo

    2014-08-01

    Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200-500 nm × 400-800 nm and the thickness is 55 +/- 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu2+/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

  6. Microwave assisted extraction of biodiesel feedstock from the seeds of invasive chinese tallow tree.

    Science.gov (United States)

    Boldor, Dorin; Kanitkar, Akanksha; Terigar, Beatrice G; Leonardi, Claudia; Lima, Marybeth; Breitenbeck, Gary A

    2010-05-15

    Chinese tallow tree (TT) seeds are a rich source of lipids and have the potential to be a biodiesel feedstock, but currently, its invasive nature does not favor large scale cultivation. Being a nonfood material, they have many advantages over conventional crops that are used for biodiesel production. The purpose of this study was to determine optimal oil extraction parameters in a batch-type and laboratory scale continuous-flow microwave system to obtain maximum oil recovery from whole TT seeds using ethanol as the extracting solvent. For the batch system, extractions were carried out for different time-temperature combinations ranging from 60 to 120 degrees C for up to 20 min. The batch system was modified for continuous extractions, which were carried out at 50, 60, and 73 degrees C and maintained for various residence times of up to 20 min. Control runs were performed under similar extraction conditions and the results compared well, especially when accounting for extremely short extraction times (minutes vs hours). Maximum yields of 35.32% and 32.51% (by weight of dry mass) were obtained for the continuous and batch process, respectively. The major advantage of microwave assisted solvent extraction is the reduced time of extraction required to obtain total recoverable lipids, with corresponding reduction in energy consumption costs per unit of lipid extracted. This study indicates that microwave extraction using ethanol as a solvent can be used as a viable alternative to conventional lipid extraction techniques for TT seeds.

  7. Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging

    Directory of Open Access Journals (Sweden)

    Guan WW

    2014-10-01

    Full Text Available Weiwei Guan,1,* Wei Gu,2,* Ling Ye,2 Chenyang Guo,1 Su Su,1 Pinxiang Xu,1,3 Ming Xue1,3 1Department of Pharmacology, School of Basic Medical Sciences, Capital Medical University, Beijing, People’s Republic of China; 2Department of Chemical Biology, School of Chemical Biology and Pharmaceutical Sciences, Capital Medical University, Beijing, People’s Republic of China; 3Beijing Laboratory for Biomedical Detection Technology and Instrument, Beijing, People’s Republic of China *These authors contributed equally to this work Abstract: A green, one-step microwave-assisted polyol synthesis was employed to prepare blue luminescent carbon nitride dots (CNDs using folic acid molecules as both carbon and nitrogen sources. The as-prepared CNDs had an average size of around 4.51 nm and could be well dispersed in water. Under excitation at 360 nm, the CNDs exhibited a strong blue luminescence and the quantum yield was estimated to be 18.9%, which is greater than that of other reported CNDs. Moreover, the CNDs showed low cytotoxicity and could efficiently label C6 glioma cells, demonstrating their potential in cell imaging. Keywords: carbon nitride dots (CNDs, folic acid, photoluminescence, cell imaging

  8. Microwave assisted synthesis of ZnO nanoparticles for lighting and dye removal application

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay, E-mail: vijays_phy@rediffmail.com [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Gohain, M. [Department of Chemistry, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Som, S.; Kumar, Vinod [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Bezuindenhoudt, B.C.B. [Department of Chemistry, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Swart, Hendrik C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

    2016-01-01

    In this study, we report on the synthesis of ZnO nanoparticles (NPs) via the microwave-assisted technique. The as-synthesized ZnO nanoparticles were annealed at 500 °C for three hours. The ZnO NPs were characterized by X-ray diffraction (XRD) and scanning electron microscopic techniques. XRD results confirmed the formation of as-synthesized ZnO powder oriented along the (101) direction. The Kubelka–Munk function has been employed to determine the band gap of the ZnO powder. ZnO powder has been studied by photoluminescence (PL) before and after annealing to identify the emission of defects in the visible range. The intensity of the PL emission has decreased after annealing. The synthesized ZnO samples were also studied for methyl orange dye removal from waste water. It has been found that the as-synthesized ZnO shows better adsorption behaviour as compared to the annealed sample.

  9. Microwave assisted synthesis and optimization of Aegle marmelos-g-poly(acrylamide): release kinetics studies.

    Science.gov (United States)

    Setia, A; Kumar, R

    2014-04-01

    Microwave assisted grafting of poly(acrylamide) on to Aegle marmelos gum was carried out employing 3-factor 3-level full factorial design. Microwave power, microwave exposure time and concentration of gum were selected as independent variable and grafting efficiency was taken as dependent variable. A. marmelos-g-poly(acrylamide) was characterized by FTIR, DSC, X-ray diffraction and scanning electron microscopy. Microwave power, microwave exposure time had synergistic effect on grafting efficiency where as concentration of the gum did not contributed much to grafting efficiency. Batch having microwave power - 80%, microwave exposure time -120 s and concentration of A. marmelos gum - 2% was selected as the optimized formulation. Comparative release behaviour of diclofenac sodium from the matrix tablets of A. marmelos gum and A. marmelos-g-polyacrylamide was evaluated. The results of kinetic studies revealed that the graft copolymer matrix, marketed tablets and polymer matrix tablets of A. marmelos gum released the drug by zero order kinetics and with n value greater than 1, indicating that the mechanism for release as super case II transport i.e. dominated by the erosion and swelling of the polymer.

  10. Short Time and Low Temperature Reaction between Metal Oxides through Microwave-Assisted Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    S. M. V. Novais

    2016-01-01

    Full Text Available This work demonstrates the possibility of synthesis of cadmium tungstate at low temperatures using oxide precursors. Cadmium tungstate (CdWO4 scintillator was produced via microwave-assisted hydrothermal reaction using the precursors CdO and WO3. The methodology was based on microwave radiation for heating, which is remarkably faster than the solid-state route or conventional hydrothermal procedure. CdWO4 monoclinic (wolframite structure was successfully obtained at 120°C for synthesis times as short as 20 min. This route does not require the use of templates or surfactants and yields self-assembled nanorods with size of around 24 ± 9 nm width and 260 ± 47 nm length. The growth mechanism for the formation of CdWO4 involves microwave-induced dissociation of the reagents and solvation of Cd2+ and WO42- ions, which are free to move and start the nucleation process. The luminescence properties of the produced nanoparticles were investigated, presenting a broad emission band at around 500 nm, which is comparable to that observed for samples produced using other chemical routes. This result highlights the great potential of the proposed method as a low-cost and time saving process to fabricate luminescent oxide nanoparticles.

  11. Synthesis of wurtzite ZnS nanoparticles using the microwave assisted solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    La Porta, Felipe A., E-mail: felipe_laporta@yahoo.com.br [Instituto de Química, UNESP, PO Box 355, 14801-970 Araraquara, SP (Brazil); Department of Analytical and Physical Chemistry, Univ. Jaume I, Castelló de la Plana 12071 (Spain); Ferrer, Mateus M.; Santana, Yuri V.B. de; Raubach, Cristiane W. [Departamento de Química, UFSCar, PO Box 676, 13565-905 São Carlos, SP (Brazil); Longo, Valéria M. [Instituto de Química, UNESP, PO Box 355, 14801-970 Araraquara, SP (Brazil); Sambrano, Júlio R. [Laboratório de Simulação Molecular, UNESP, PO Box 473, 17033-360 Bauru, SP (Brazil); Longo, Elson [Instituto de Química, UNESP, PO Box 355, 14801-970 Araraquara, SP (Brazil); Andrés, Juan [Department of Analytical and Physical Chemistry, Univ. Jaume I, Castelló de la Plana 12071 (Spain); Li, Máximo S. [Departamento de Física, USP, PO Box 369, 13560-970 São Carlos, São Paulo (Brazil); Varela, José A. [Instituto de Química, UNESP, PO Box 355, 14801-970 Araraquara, SP (Brazil)

    2013-04-15

    Highlights: ► This work details the efficiency of microwave solvothermal synthesis in obtaining ZnS nanocrystals. ► The structure, surface chemical composition and optical properties were investigated as function of the precursor. ► According to the different precursors used, the PL behavior of ZnS causes a red shift which enables the design of LEDs with different colors. ► Photoluminescence is one more interesting property for technological applications this material. -- Abstract: In this article, we report the development of an efficient and rapid microwave assisted solvothermal (MAS) method to prepare wurtzite ZnS nanoparticles at 413 K using different precursors. The materials obtained were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (MET) ultraviolet–visible (UV–vis) and photoluminescence (PL) measurements. The structure, surface chemical composition and optical properties were investigated as a function of the precursor. In addition, effects as well as merits of microwave heating on the processing and characteristics of ZnS nanoparticles obtained are reported. The possible formation mechanism and optical properties of these nanoparticles were also reported.

  12. MICROWAVE-ASSISTED EXTRACTION OF PHENOLIC COMPOUNDS FROM POLYGONUM MULTIFLORUM THUNB. ROOTS

    Directory of Open Access Journals (Sweden)

    Le Pham Tan Quoc

    2016-06-01

    Full Text Available Background. The aim of this study was to determine the best extraction conditions for total phenolic con- tent (TPC and antioxidant capacity (AC of Polygonum multiflorum Thunb. root using microwave-assisted extraction (MAE. Material and methods. The raw material used was Polygonum multiflorum Thunb. root powder. Five fac- tors such as solvent type, solvent concentrations, solvent/material ratio, extraction time and microwave power were studied; TPC and AC values were determined by the Folin-Ciocalteu method and DPPH free radical scavenging activity measurement, respectively. In addition, studies involved assaying the HPLC test of extracts and SEM of samples. Results. Optimal results pointed to acetone as the solvent, acetone concentration of 60%, solvent/material ratio of 40/1 (v/w, extraction time of 5 mins and microwave power of 127 W. TPC and AC obtained were approximates 44.3 ±0.13 mg GAE/g DW and 341.26 ±1.54 μmol TE/g DW, respectively. The effect of mi- crowaving on the cell destruction of Polygonum multiflorum Thunb. root was observed by scanning electron microscopy (SEM. Some phenolic compounds were determined by the HPLC method, for instance, gallic acid, catechin and resveratrol. Conclusion. These factors significantly affected TPC and AC. We can use acetone as a solvent with micro- wave-assisted extraction to achieve the best result.

  13. Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hiep

    2016-01-01

    Full Text Available The purpose of this study was to fabricate chitosan/poly(vinyl alcohol/Ag nanoparticles (CPA gels with microwave-assistance for skin applications. Microwave irradiation was employed to reduce silver ions to silver nanoparticles and to crosslink chitosan (CS with polyvinyl alcohol (PVA. The presence of silver nanoparticles in CPA gels matrix was examined using UV-Vis spectroscopy, transmission electron microscopy, and X-ray diffraction. The interaction of CS and PVA was analysed by Fourier transform infrared spectroscopy. The release of silver ions was determined by atomic absorption spectrometry. The antimicrobial properties of CPA gels against P. aeruginosa and S. aureus were investigated using agar diffusion method. Finally, the biocompatibility and wound-healing ability of the gels were studied using fibroblast cells (in vitro and mice models (in vivo. In conclusion, the results showed that CPA gels were successfully fabricated using microwave irradiation method. These gels can be applied to heal an open wound thanks to their antibacterial activity and biocompatibility.

  14. ZnS nanosheets: Egg albumin and microwave-assisted synthesis and optical properties

    Science.gov (United States)

    Tian, Xiuying; Wen, Jin; Hu, Jilin; Chen, Zhanjun; Wang, Shumei; Peng, Hongxia; Li, Jing

    2016-09-01

    ZnS nanosheets were prepared via egg albumin and microwave-assisted method. The phases, crystalline lattice structures, morphologies, chemical and optical properties were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscope(FE-SEM), selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and fluorescence(FL) spectrometer and growth mechanism of ZnS nanosheets was investigated. The results showed that all samples were pure cubic zinc blende with polycrystalline structure. The width of ZnS nanosheets with a rectangular nanostructure was in the range of 450-750 nm. The chemical interaction existed between egg albumin molecules and ZnS nanoparticles via the amide/carboxylate group. The band gap value calculated was 3.72 eV. The band at around 440 nm was attributed to the sulfur vacancies of the ZnS nanosheets. With increasing volumes of egg albumin, the photoluminescence (PL) intensity of ZnS samples firstly increased and then decreased, attributed to concentration quenching.

  15. Microwave assisted leaching and electrochemical recovery of copper from printed circuit boards of computer waste

    Science.gov (United States)

    Ivǎnuş, R. C.; ǎnuş, D., IV; Cǎlmuc, F.

    2010-06-01

    Due to the rapid technological progress, the replacement of electronic equipment is very often necessary, leading to huge amounts that end up as waste. In addition, waste electrical and electronic equipment (WEEE) contains metals of high commercial value and others that are supposed to be hazardous for the environment. Consequently, WEEE could be considered as a significant source for recovery of nonferrous metals. Among these wastes, computers appear to be distinctive, as far as further exploitation is concerned. The most ″useful″ parts of the computers are the printed circuit boards that contain many metals of interest. A study on microwave assisted electronic scrap (printed circuit boards of computer waste - PCBs) leaching was carried out with a microwave hydrothermal reactor. The leaching was conducted with thick slurries (50-100 g/L). The leaching media is a mixed solution of CuCl2 and NaCl. Preliminary electrolysis from leaching solution has investigated the feasibility of electrodeposition of copper. The results were discussed and compared with the conventional leaching method and demonstrated the potential for selective extraction of copper from PCBs.

  16. Photocatalytic perfermance of sandwich-like BiVO4 sheets by microwave assisted synthesis

    Science.gov (United States)

    Liu, Suqin; Tang, Huiling; Zhou, Huan; Dai, Gaopeng; Wang, Wanqiang

    2017-01-01

    Sandwich-like BiVO4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO4 sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO4 sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO4 sheets can be attributed to its large surface area over the irregular BiVO4 particles.

  17. Microwave-assisted extraction of polyphenols from Camellia oleifera fruit hull.

    Science.gov (United States)

    Zhang, Liangliang; Wang, Yongmei; Wu, Dongmei; Xu, Man; Chen, Jiahong

    2011-05-27

    The abundant fruit hulls of tea-oil tree (Camellia oleifera) are still underutilized and wastefully discaded to pollute the environment. In order to solve this problem and better utilize the fruit hulls of C. oleifera, a microwave-assisted extraction system was used to extract their polyphenols using water as the extraction solvent. A central composite design (CCD) was used to monitor the effects of three extraction processing parameters--liquid:solid ratio (mL/g), extraction time (min) and extraction temperature (°C)--on the polyphenol yield (%). The results showed that the optimal conditions were liquid:solid ratio of 15.33:1 (mL/g), extraction time of 35 min and extraction temperature of 76 °C. Validation tests indicated that under the optimized conditions the actual yield of polyphenols was 15.05 ± 0.04% with RSD = 0.21% (n = 5), which was in good agreement with the predicted yield. Phenolic compounds in the extracts were analysed by HPLC, and gallic acid was found to be the predominant constituent. The total flavonoid content in the extracts was determined and high total flavonoid content was revealed (140.06 mg/g dry material).

  18. Solution-phase microwave-assisted synthesis of unsubstituted and modified alpha-quinque- and sexithiophenes.

    Science.gov (United States)

    Melucci, M; Barbarella, G; Zambianchi, M; Di Pietro, P; Bongini, A

    2004-07-09

    The facile synthesis of poorly soluble unsubstituted and modified alpha-quinque- and sexithiophenes under microwave irradiation in the liquid phase is described. The use of microwave irradiation allowed these compounds to be prepared in a few minutes and at high yields by means of the Suzuki cross-coupling reaction. Unsubstituted sexithiophene was obtained in 10 min via the one-pot borylation/Suzuki reaction, purified according to a very simple procedure, and isolated in 84% yield. The efficient synthesis of two new methylated quinque- and sexithiophenes displaying liquid crystalline properties is reported. A new microwave-assisted methodology for the conversion of aldehyde-terminated quinque- and sexithiophenes into the corresponding cyano derivatives is also described. The use of microwaves was extended to the Sonogashira coupling reaction and found to be very effective in the preparation of a quinquethiophene containing acetylenic spacers. The electronic and optical characterization of this compound is reported and discussed in relation to that of unsubstituted quinquethiophene.

  19. Solvent-free, microwave-assisted synthesis of thiophene oligomers via Suzuki coupling.

    Science.gov (United States)

    Melucci, Manuela; Barbarella, Giovanna; Sotgiu, Giovanna

    2002-12-13

    The purpose of this study was to obtain a rapid, efficient, and environmentally friendly methodology for the synthesis of highly pure thiophene oligomers. The solvent-free, microwave-assisted coupling of thienyl boronic acids and esters with thienyl bromides, using aluminum oxide as the solid support, allowed us to rapidly check the reaction trends on changing times, temperature, catalyst, and base and easily optimize the experimental conditions to obtain the targeted product in fair amounts. This procedure offers a novel, general, and very rapid route to the preparation of soluble thiophene oligomers. Thus, for example, quaterthiophene was obtained in 6 min by reaction of 2-bromo-2,2'-bithiophene with bis(pinacolato)diboron (isolated yield 65%), whereas quinquethiophene was obtained in 11 min by reaction of dibromoterthiophene with thienylboronic acid (isolated yield 74%). The synthesis of new chiral 2,2'-bithiophenes is reported. The detailed analysis of the byproducts of some reactions allowed us to elucidate a few aspects of reaction mechanisms. While the use of microwaves proved to be very convenient for the coupling between conventional thienyl moieties, the same was not true for the coupling of thienyl rings to thienyl-S,S-dioxide moieties. Indeed, in this case, the targeted product was obtained in low yields because of the competitive, accelerated, Diels-Alder reaction that affords a variety of condensation products.

  20. Microwave assisted synthesis of nanocrystalline Fe-phosphates electrode materials and their electrochemical properties.

    Science.gov (United States)

    Kim, D H; Kang, J W; Jung, I O; Im, J S; Kim, E J; Song, S J; Lee, J S; Kim, J

    2008-10-01

    LiFePO4 nanocrystalline particles were synthesized using microwave assisted polyol process within a fast reaction time of 20 minutes without any further heating as a post step. The synthesized LiFePO4 nanocrystalline particles showed mono-dispersed rod and orthorhombic-like shapes with a size of 60 approximately 180 nm. The refined X-ray diffraction pattern of the sample was indexed well to the olivine crystal structure (space group: Pnma) without any impurity phases. The LiFePO4 nanocrystalline particles show a capacity of 161 mAh/g in a voltage range of 2.5-4.2 V with a current density of 0.1 mA/cm2 without any observable capacity fading in extended cycles of 100th. A cyclic voltammetry analysis exhibits distinctly sharp peaks corresponding to the typical LiFePO4/FePO4 redox couples and demonstrates a good reversibility of the sample.

  1. Microwave-assisted synthesis of bismuth oxybromochloride nanoflakes for visible light photodegradation of pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Bijanzad, Keyvan; Tadjarodi, Azadeh; Moghaddasi Khiavi, Mohammad [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.ir [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2015-10-15

    BiOBr{sub x}Cl{sub 1−x} (0microwave-assisted synthesis method. The X-ray diffraction (XRD) studies confirmed the formation of pure crystalline phase of BiOBr{sub x}Cl{sub 1−x}. The UV–visible diffuse reflectance and photoluminescence (PL) spectroscopies revealed the indirect band gap of ~2.82 eV for the bismuth oxybromochloride nanoflakes. Visible light-assisted photocatalytic studies showed that the degradation efficiency of the as-prepared BiOBr{sub x}Cl{sub 1−x} for (100 mL of 10 mg L{sup −1}) Rhodamine B (RhB), Natural Red 4 (N-Red) dye solutions was 98.14% and for the colorless organic pentachlorophenol (PCP) solution was 91.09% over 150 min. The possible mechanisms involved in the visible light photodegradation of the pollutants by BiOBr{sub x}Cl{sub 1−x} photocatalyst were also discussed.

  2. Analysis of Switchable Spin Torque Oscillator for Microwave Assisted Magnetic Recording

    Directory of Open Access Journals (Sweden)

    Mingsheng Zhang

    2015-01-01

    Full Text Available A switchable spin torque oscillator (STO with a negative magnetic anisotropy oscillation layer for microwave assisted magnetic recording is analyzed theoretically and numerically. The equations for finding the STO frequency and oscillation angle are derived from Landau-Lifshitz-Gilbert (LLG equation with the spin torque term in spherical coordinates. The theoretical analysis shows that the STO oscillating frequency remains the same and oscillation direction reverses after the switching of the magnetization of the spin polarization layer under applied alternative magnetic field. Numerical analysis based on the derived equations shows that the oscillation angle increases with the increase of the negative anisotropy energy density (absolute value but decreases with the increase of spin current, the polarization of conduction electrons, the saturation magnetization, and the total applied magnetic field in the z direction. The STO frequency increases with the increase of spin current, the polarization of conduction electrons, and the negative anisotropy energy density (absolute value but decreases with the increase of the saturation magnetization and the total applied magnetic field in the z direction.

  3. Microwave assisted extraction of flavonoids from pomegranate peel and its antioxidant activity

    Directory of Open Access Journals (Sweden)

    Huang Ju

    2017-01-01

    Full Text Available Pomegranate peel, a waste generated from fruit processing industry, which contains maximum amounts of bioactive compounds than the juice, is a potential source of active ingredient such as flavonoids that are known for their antioxidant properties. Microwave-assisted extraction (MAE of flavonoids from pomegranate peel and its antioxidant activity were investigated. Three independent and main variables, including ethanol concentration(%, solvent/solid ratio(mL/g and MAE time(min, which were of significance for the yields of flavonoids were studied. The optimal conditions were determined by the orthogonal design. The maximum extraction yield of 4.260% was achieved at ethanol concentration of 60%, ratio of solvent to material of 40:1 and MAE time of 3min. In vitro antioxidant assays showed that the extract exhibited a strong DPPH radical-scavenging ability with IC50 value of 0.187 mg/mL. Results indicated that MAE was a suitable approach for the extraction of flavonoids from pomegranate peel.

  4. The influence of microwave irradiation on rocks for microwave-assisted underground excavation

    Directory of Open Access Journals (Sweden)

    Ferri Hassani

    2016-02-01

    Full Text Available Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of McGill University to make a real application of microwave-assisted mechanical rock breakage to full-face tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks (norite, granite, and basalt for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs (SEMs highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics® software generated temperature profiles that were in close agreement with experimental results.

  5. Microwave-Assisted Decarboxylation of Sodium Oleate and Renewable Hydrocarbon Fuel Production

    Institute of Scientific and Technical Information of China (English)

    Wang Yunpu; Liu Yuhuan; Ruan Rongsheng; Wen Pingwei; Wan Yiqin; Zhang Jinsheng

    2013-01-01

    The carboxyl terminal of sodium oleate has a stronger polarity than that of oleic acid;this terminal is more likely to be dipole polarized and ionically conductive in a microwave ifeld. Sodium oleate was used as the model compound to study the decarboxylation of oleic acid leading to hydrocarbon formation via microwave-assisted pyrolysis technology. The pyrolysis gas, liquid, and solid products were precisely analyzed to deduce the mechanism for decarboxylation of sodium oleate. Microwave energy was able to selectively heat the carboxyl terminal of sodium oleate. During decarboxylation, the double bond in the long hydrocarbon chain formed a p-πconjugated system with the carbanion intermediate. The resulting p-πconjugated system was more stable and beneifcial to the pyrolysis reaction (decarboxylation, terminal allylation, isomeriza-tion, and aromatization). The physical properties of pyrolysis liquid were generally similar to those of diesel fuel, thereby demonstrating the possible use of microwaves for controlling the decarboxylation of sodium oleate in order to manufacture renewable hydrocarbon fuels.

  6. Fast microwave-assisted pyrolysis of microalgae using microwave absorbent and HZSM-5 catalyst.

    Science.gov (United States)

    Borges, Fernanda Cabral; Xie, Qinglong; Min, Min; Muniz, Luis Antônio Rezende; Farenzena, Marcelo; Trierweiler, Jorge Otávio; Chen, Paul; Ruan, Roger

    2014-08-01

    Fast microwave-assisted pyrolysis (fMAP) in the presence of a microwave absorbent (SiC) and catalyst (HZSM-5) was tested on a Chlorella sp. strain and on a Nannochloropsis strain. The liquid products were characterized, and the effects of temperature and catalyst:biomass ratio were analyzed. For Chlorella sp., a temperature of 550 °C, with no catalyst were the optimal conditions, resulting in a maximum bio-oil yield of 57 wt.%. For Nannochloropsis, a temperature of 500 °C, with 0.5 of catalyst ratio were shown to be the optimal condition, resulting in a maximum bio-oil yield of 59 wt.%. These results show that the use of microwave absorbents in fMAP increased bio-oil yields and quality, and it is a promising technology to improve the commercial application and economic outlook of microwave pyrolysis technology. Additionally, the use of a different catalyst needs to be considered to improve the bio-oil characteristics.

  7. Flexible composite via rapid titania coating by microwave-assisted hydrothermal synthesis

    Indian Academy of Sciences (India)

    RICARDO MARQUES E SILVA; ANDERSON THESING; VINICIUS GONÇALVES DEON; ALICE GONÇALVES OSÓRIO; BRUNO DA SILVEIRA NOREMBERG; NATÁLIA HADLER MARINS; MARCELO ORNAGHI ORLANDI; FABIANA VILLELA DA MOTTA; RUBENS MARIBONDO DO NASCIMENTO; NEFTALI LENIN VILLARREAL CARREÑO

    2017-06-01

    The aim of this work was to prepare a flexible nanocomposite from ultra-fine titanium oxide (TiO$_2$) growth on carbon fibre via microwave-assisted hydrothermal synthesis (MHS) and to evaluate its photocatalytic properties. The TiO$_2$ nanoparticles were directly grown on the carbon fibre (CF). Thus, a study comparing the conventional titania coating vs. the MHS were performed. The significant layer interaction as a function of the coating method on the visible and dark dye photodegradation performance was observed. Techniques such as X-ray diffraction, electron microscopy (field-emission scanning electron microscope (FESEM)), Raman spectroscopy, among others were used aiming to characterize the different route samples. This study reports a reproducible and single method to manufacture of nanocomposites through the growth ofTiO$_2$ nanoparticle on CF by MHS that allow controlling the thickness layer. Similar procedure of synthesized nanocomposite could be applied in different chemical compositions to advanced applications, based on the electrochemical nanostructure.

  8. Microwave assisted extraction for trace element analysis of plant materials by ICP-AES

    Energy Technology Data Exchange (ETDEWEB)

    Borkowska-Burnecka, J. [Wroclaw Univ. (Poland). Inst. Chemii

    2000-11-01

    Application of microwave assisted extraction for the decomposition and dissolution of plant samples for trace metal determination by ICP-AES was examined. Dried onion, leaves of spinach beet and three reference materials CTA-OTL-1, CTA-VTL-2 and CL-1 were analyzed. Water, EDTA and hydrochloric acid (0.01, 0.10 and 1.0 M, respectively) were used as leaching solutions. The extraction efficiency was investigated by comparison of the results with those obtained after microwave wet digestion. HCl was found to be very suitable for quantitative extraction of B, Ba, Cd, Cu, Mn, Ni, Pb, Sr and Zn from the samples. For reference materials, the measured concentrations are well consistent with the certified values. The use of EDTA led to a complete extraction of B, Cd, Ni, Pb, Sr and Zn. Water was found to be a good leaching solution for boron. For extraction with HCl and EDTA, the RSD values for the concentrations measured were below 8% for most of the elements. (orig.)

  9. Microwave-assisted extraction of active pharmaceutical ingredient from solid dosage forms.

    Science.gov (United States)

    Hoang, T H; Sharma, R; Susanto, D; Di Maso, M; Kwong, E

    2007-07-13

    The microwave assisted extraction (MAE) technique has been evaluated for the extraction of active pharmaceutical ingredients (API) from various solid dosage forms. Using immediate release tablets of Compound A as a model, optimization of the extraction method with regards to extraction solvent composition, extraction time and temperature was briefly discussed. Complete recovery of Compound A was achieved when samples were extracted using acetonitrile as the extraction solvent under microwave heating at a constant cell temperature of 50 degrees C for 5 min. The optimized MAE method was applied for content uniformity (single tablet extraction) and potency (multiple tablets extraction) assays of release and stability samples of two products of Compound A (5 and 25mg dose strength) stored at various conditions. To further demonstrate the applicability of MAE, the instrumental extraction conditions (50 degrees C for 5 min) were adopted for the extraction of montelukast sodium (Singulair) from various solid dosage forms using methanol-water (75:25, v/v) as the extraction solvent. The MAE procedure demonstrated an extraction efficiency of 97.4-101.9% label claim with the greatest RSD at 1.4%. The results compare favorably with 97.6-102.3% label claim with the greatest RSD at 2.9% obtained with validated mechanical extraction procedures. The system is affordable, user-friendly and simple to operate and troubleshoot. Rapid extraction process (7 min/run) along with high throughput capacity (up to 23 samples simultaneously) would lead to reduced cycle time and thus increased productivity.

  10. Microwave-Assisted Extraction of Polyphenols from Camellia oleifera Fruit Hull

    Directory of Open Access Journals (Sweden)

    Jiahong Chen

    2011-05-01

    Full Text Available The abundant fruit hulls of tea-oil tree (Camellia oleifera are still underutilized and wastefully discaded to pollute the environment. In order to solve this problem and better utilize the fruit hulls of C. oleifera, a microwave-assisted extraction system was used to extract their polyphenols using water as the extraction solvent. A central composite design (CCD was used to monitor the effects of three extraction processing parameters – liquid:solid ratio (mL/g, extraction time (min and extraction temperature (°C – on the polyphenol yield (%. The results showed that the optimal conditions were liquid:solid ratio of 15.33:1 (mL/g, extraction time of 35 min and extraction temperature of 76 °C. Validation tests indicated that under the optimized conditions the actual yield of polyphenols was 15.05 ± 0.04% with RSD = 0.21% (n = 5, which was in good agreement with the predicted yield. Phenolic compounds in the extracts were analysed by HPLC, and gallic acid was found to be the predominant constituent. The total flavonoid content in the extracts was determined and high total flavonoid content was revealed (140.06 mg/g dry material.

  11. Microwave assisted leaching and electrochemical recovery of copper from printed circuit boards of computer waste

    Directory of Open Access Journals (Sweden)

    Ivănuş R.C.

    2010-06-01

    Full Text Available Due to the rapid technological progress, the replacement of electronic equipment is very often necessary, leading to huge amounts that end up as waste. In addition, waste electrical and electronic equipment (WEEE contains metals of high commercial value and others that are supposed to be hazardous for the environment. Consequently, WEEE could be considered as a significant source for recovery of nonferrous metals. Among these wastes, computers appear to be distinctive, as far as further exploitation is concerned. The most ″useful″ parts of the computers are the printed circuit boards that contain many metals of interest. A study on microwave assisted electronic scrap (printed circuit boards of computer waste – PCBs leaching was carried out with a microwave hydrothermal reactor. The leaching was conducted with thick slurries (50-100 g/L. The leaching media is a mixed solution of CuCl2 and NaCl. Preliminary electrolysis from leaching solution has investigated the feasibility of electrodeposition of copper. The results were discussed and compared with the conventional leaching method and demonstrated the potential for selective extraction of copper from PCBs.

  12. Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers.

    Science.gov (United States)

    Lovrić, Vanja; Putnik, Predrag; Kovačević, Danijela Bursać; Jukić, Marijana; Dragović-Uzelac, Verica

    2017-06-01

    This research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70% aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95% confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70% aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50% aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15- to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.

  13. Microwave-Assisted Radiosynthesis of [18F]Fluorinated Fatty Acid Analogs

    Science.gov (United States)

    Belanger, Anthony P.; Pandey, Mukesh K.; DeGrado, Timothy R.

    2010-01-01

    Microwave reactors remain largely underutilized in the field of PET chemistry. This is particularly unfortunate since microwave synthesis elegantly addresses two of the most critical issues of PET radiochemistry with short-lived radionuclides: reaction rate and side-product formation. In this study we investigate the efficiency of synthesis of terminally [18F]fluorinated fatty acid analogs using a commercial microwave reactor in comparison with conventional heating. Methods The labeling precursors were methyl esters of terminally substituted alkyl bromides and iodides. Duration and temperatures of the [18F]fluorination reaction were varied. Chemical and radiochemical purities, and radiochemical yields were investigated for conventional (CH) and microwave-assisted (MW) radiosyntheses. Results The results demonstrate that microwave heating enhanced [18F]fluoride incorporation to >95% (up to 55% improvement), while reducing reaction times to 2 min (~10-fold reduction) or temperatures to 55–60°C (20°C reduction). Overall decay-corrected radiochemical yields of purified [18F]fluoro fatty acids were higher (MW=49.0 ± 4.5%, CH=23.6 ± 3.5%, p<0.05) with microwave heating and side-products were notably fewer. Conclusion For routine synthesis of [18F]fluoro fatty acid analogs, microwave heating is faster, milder, cleaner, less variable and higher yielding than conventional heating and therefore the preferred reaction method. PMID:21492792

  14. Microwave-assisted extraction and mild saponification for determination of organochlorine pesticides in oyster samples.

    Science.gov (United States)

    Carro, N; García, I; Ignacio, M-C; Llompart, M; Yebra, M-C; Mouteira, A

    2002-10-01

    A sample-preparation procedure (extraction and saponification) using microwave energy is proposed for determination of organochlorine pesticides in oyster samples. A Plackett-Burman factorial design has been used to optimize the microwave-assisted extraction and mild saponification on a freeze dried sample spiked with a mixture of aldrin, endrin, dieldrin, heptachlor, heptachorepoxide, isodrin, transnonachlor, p, p'-DDE, and p, p'-DDD. Six variables: solvent volume, extraction time, extraction temperature, amount of acetone (%) in the extractant solvent, amount of sample, and volume of NaOH solution were considered in the optimization process. The results show that the amount of sample is statistically significant for dieldrin, aldrin, p, p'-DDE, heptachlor, and transnonachlor and solvent volume for dieldrin, aldrin, and p, p'-DDE. The volume of NaOH solution is statistically significant for aldrin and p, p'-DDE only. Extraction temperature and extraction time seem to be the main factors determining the efficiency of extraction process for isodrin and p, p'-DDE, respectively. The optimized procedure was compared with conventional Soxhlet extraction.

  15. Microwave-Assisted Extraction Studies of Target Analyte Artemisinin from Dried Leaves of Artemisia annua L.

    Directory of Open Access Journals (Sweden)

    Himanshu Misra

    2013-01-01

    Full Text Available Artemisia annua L. (Asteraceae is an annual herb native of Asia. This plant has been used for many centuries in traditional Chinese medicine for the treatment of fever and malaria. Conventional methods for the extraction of artemisinin from A. annua including solvent extraction, Soxhlet extraction, and heat reflux extraction are characterized by long extraction times and the consumption of large volume of solvents. A simple, rapid, and precise microwave-assisted extraction process was optimized for fast sample preparation for the faster quantitative determination of artemisinin, potential new generation antimalarial drug, from dried leaves of Artemisia annua L. A simple experiment was designed for the optimization of the appropriate solvent under same extraction conditions. The selected appropriate solvent was then standardized for various different extraction variables. The major parameters studied showed effects on extraction efficiency including processing time, strength of microwave, moisture content, volume and nature of the solvent. The most favorable conditions were obtained by using plant material of 25 mesh (particle size extracted with acetone for 120 seconds at 160 W (i.e., 20% of total power. Quantitative analysis was performed using thin-layer chromatography coupled with a densitometer (TLC densitometry. The results showed that MAE can be used as an efficient and rapid method for the extraction of the active components from plants.

  16. A rapid microwave-assisted solvothermal approach to lower-valent transition metal oxides.

    Science.gov (United States)

    Moorhead-Rosenberg, Zachary; Harrison, Katharine L; Turner, Travis; Manthiram, Arumugam

    2013-11-18

    A green, rapid microwave-assisted solvothermal process using tetraethylene glycol (TEG) as a reducing agent has been explored as a soft-chemistry route for the preparation of various lower-valent transition metal oxides. To demonstrate the feasibility of the approach, lower-valent binary oxides such as V4O9, Mn3O4 or MnO, CoO, and Cu2O have been obtained within a short reaction time of 30 min by reducing, respectively, V2O5, MnO2, Co3O4, and CuO with TEG at LaCoO3, LaNiO3, and La4Ni3O10. The oxidation state of the transition metal ions and the oxygen content in these ternary oxides could be tuned by precisely controlling the reaction temperatures from 160 to 300 °C. The products have been characterized by X-ray powder diffraction and iodometric titration. The versatility of this novel technique is demonstrated by the facile synthesis of V4O9, which has only been produced recently in single-phase form.

  17. Microwave Assisted Synthesis of Ferrite Nanoparticles: Effect of Reaction Temperature on Particle Size and Magnetic Properties.

    Science.gov (United States)

    Kalyani, S; Sangeetha, J; Philip, John

    2015-08-01

    The preparation of ferrite magnetic nanoparticles of different particle sizes by controlling the reaction temperature using microwave assisted synthesis is reported. The iron oxide nanoparticles synthesized at two different temperatures viz., 45 and 85 °C were characterized using techniques such as X-ray diffraction (XRD), small angle X-ray scattering (SAXS), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The average size of iron oxide nanoparticles synthesized at 45 and 85 °C is found to be 10 and 13.8 nm, respectively, and the nanoparticles exhibited superparamagantic behavior at room temperature. The saturation magnetization values of nanoparticles synthesized at 45 and 85 °C were found to be 67 and 72 emu/g, respectively. The increase in particle size and saturation magnetization values with increase in incubation temperature is attributed to a decrease in supersaturation at elevated temperature. The Curie temperature was found to be 561 and 566 0C for the iron oxide nanoparticles synthesized at 45 and 85 °C, respectively. The FTIR spectrum of the iron oxide nanoparticles synthesized at different temperatures exhibited the characteristic peaks that corresponded to the stretching of bonds between octahedral and tetrahedral metal ions to oxide ions. Our results showed that the ferrite nanoparticle size can be varied by controlling the reaction temperature inside a microwave reactor.

  18. Fatty Acid Characteristics of Isochrysis galbana Lipids Extracted Using a Microwave-Assisted Method

    Directory of Open Access Journals (Sweden)

    Cherng-Yuan Lin

    2015-02-01

    Full Text Available Lipids were extracted from Isochrysis galbana using a microwave-assisted method accompanied by various types of organic solvents. The effects of organic solvent type and microwave input energy on the fatty acid characteristics of the extracted lipids and their biodiesel product were investigated. Variations in the characteristics of the lipids extracted using a combination of n-hexane and iso-propanol solvents in both emulsion and direct mixtures were also compared. The experimental results showed that greater quantities of Isochrysis galbana lipids, and fatty acid methyl esters transesterified from those lipids, were extracted when using microwave irradiation with an organic solvent mixture of n-hexane and isopropanol in a 2:1 volumetric ratio than when using either n-hexane or isopropanol as the sole solvent. A greater quantity of Isochrysis galbana lipids was extracted when an emulsion of isopropanol solvent evenly dispersed in the continuous phase of n-hexane solvent was used than when a direct mixture of the two solvents was used. In addition, the quantity of lipids extracted from the dried Isochrysis galbana powder with the assistance of microwave irradiation was 9.08 wt% greater than when using traditional Soxhlet extraction without microwave irradiation.

  19. Microwave-assisted degradation of acid orange using a conjugated polymer, polyaniline, as catalyst

    Directory of Open Access Journals (Sweden)

    Ufana Riaz

    2014-01-01

    Full Text Available Microwave-assisted photocatalytic degradation of dyes is one of the emerging technologies for waste water remediation. Microwave effectively accelerates photocatalytic degradation, when microwave electrodeless lamp (MEL substitutes traditional UV lamp as light source. This setup can be extremely simplified if MEL and photocatalyst can be replaced by a catalyst which can work under microwave irradiation in the absence of any light source. The present work reports for the first time degradation of acid orange 7 (AO under microwave irradiation using polyaniline (PANI as catalyst in the absence of any UV lamp as light source. The degradation/decolourization was carried out in neutral acidic and basic media and was monitored spectrophotometrically to evaluate the ability of microwave irradiation to degrade AO. Microwave irradiation showed excellent performance as it completely decolourizes AO dye solution in 10 min. With the advantages of low cost and rapid processing, this novel catalyst is expected to gain promising application in the treatment of various dyestuff wastewaters on a large scale.

  20. Improving the efficiency of antioxidant extraction from mango peel by using microwave-assisted extraction.

    Science.gov (United States)

    Dorta, Eva; Lobo, M Gloria; González, Mónica

    2013-06-01

    The purpose of this study was to analyze the extraction efficiency of antioxidants from mango peel by comparing two techniques: microwave-assisted (MAE) and traditional solvent (TE) extraction. The number of extraction steps, water content in the extractant, peel weight-to-solvent volume ratio in extractions and extraction time all had an influence on obtaining extracts with high antioxidant capacity, but the extraction technique and the water content in the extractant were the factors with the greatest effect. Using three steps, a water content of 50 % in the ethanol:water extractant, an extraction time of 60 min and a weight-to-volume ratio of 1:10 or 1:50 (w/v) led to the highest antioxidant activity and phytochemicals content in extracts. The extraction time needed to extract phytochemicals from mango peel was similar when MAE and TE were used. However, the antioxidant capacity and phytochemical content were around 1.5-6.0 times higher in the extracts obtained by MAE.

  1. Self-assembly of nanostructures obtained in a microwave-assisted oxidative polymerization of aniline

    Directory of Open Access Journals (Sweden)

    M. R. Gizdavic-Nikolaidis

    2014-10-01

    Full Text Available For the first time, microwave assisted aniline oxidative polymerization is performed in the presence of acetic acid (CH3COOH and ammonium hydroxide (NH4OH at different microwave power levels. The reaction system is kept at constant temperature of 24±1°C. The products are investigated by Fourier Transform Infrared Spectroscopy (FTIR, Raman, solid-state Nuclear Magnetic Resonance (NMR and Electron Paramagnetic Resonance (EPR spectroscopies. EPR signals in polyaniline (PANI originate from the polarons formed upon protonation and doping by acid. The microwave radiation causes an increase in the spin concentration which is slightly more evident for 8 W than for 93 W. The morphology is investigated by using scanning electron microscopy (SEM. SEM micrographs revealed the formation of nanorods (in the presence of CH3COOH and nanospheres (in the presence of NH4OH. FTIR, Raman and solid-state NMR spectroscopies indicate the presence of PANI and aniline oligomers. X-ray Diffraction (XRD measurements showed the presence of well-ordered structures.

  2. Microwave-assisted extraction of jujube polysaccharide: Optimization, purification and functional characterization.

    Science.gov (United States)

    Rostami, Hosein; Gharibzahedi, Seyed Mohammad Taghi

    2016-06-05

    The operational parameters involved in microwave-assisted extraction (MAE) of jujube polysaccharide including microwave power, water to raw material ratio and extraction temperature and time were optimized by RSM. MAE at 400W, 75°C, 60 min, using 30 g water/g powdered jujube was the best condition for maximum yield (9.02%) of polysaccharide. Two novel water-soluble polysaccharides (JCP-1 and JCP-2) with average molecular weights of 9.1×10(4)-1.5×10(5)Da in term of the symmetrical narrow peaks were identified using the analytical purification procedures. The JCP-1 and JCP-2 mainly composed of glucose, arabinose, galactose and rhamnose in molar ratios of 1.4:2.1:4.2:0.9 and 1.2:1.8:4.1:1.1, respectively. The use of 1.5% JCP-1 led to a high emulsifying stability (95.5%) in a model oil-in-water type emulsion with a reduced surface tension (44.1 mN/m) and droplet size (1.32 μm), and an increased apparent viscosity (0.13 Pas) during 21-day cold storage. The antioxidant activities were increased in dose-dependent manners (25-200 μg/mL).

  3. Development of microwave-assisted drying methods for sample preparation for dried spot micro-X-ray fluorescence analysis.

    Science.gov (United States)

    Link, Dirk D; Kingston, H M; Havrilla, George J; Colletti, Lisa P

    2002-03-01

    Although dried spot micro X-ray fluorescence (MXRF) is an effective analytical technique for trace elemental analysis, the sample preparation procedures currently used suffer from a number of drawbacks. These drawbacks include relatively long preparation times, lack of control of the sample preparation environment, and possibility of loss of volatile analytes during the drying process. Microwave-assisted drying offers several advantages for dried spot preparation, including control of the environment and minimized volatility because of the differences between microwave heating and conventional heating. A microwave-assisted drying technique has been evaluated for use in preparing dried spots for trace analysis. Two apparatus designs for microwave drying were constructed and tested using multielement standard solutions, a standard reference material, and a "real-world" semiconductor cleaning solution. Following microwave-assisted drying of these aqueous samples, the residues were redissolved and analyzed by ICPMS. Effective recovery was obtained using the microwave drying methods, demonstrating that the microwave drying apparatus and methods described here may be more efficient alternatives for dried spot sample preparation.

  4. Analysis of parameter and interaction between parameter of the microwave assisted transesterification process of coconut oil using response surface methodology

    Science.gov (United States)

    Hidayanti, Nur; Suryanto, A.; Qadariyah, L.; Prihatini, P.; Mahfud, Mahfud

    2015-12-01

    A simple batch process was designed for the transesterification of coconut oil to alkyl esters using microwave assisted method. The product with yield above 93.225% of alkyl ester is called the biodiesel fuel. Response surface methodology was used to design the experiment and obtain the maximum possible yield of biodiesel in the microwave-assisted reaction from coconut oil with KOH as the catalyst. The results showed that the time reaction and concentration of KOH catalyst have significant effects on yield of alkyl ester. Based on the response surface methodology using the selected operating conditions, the time of reaction and concentration of KOH catalyst in transesterification process were 150 second and 0.25%w/w, respectively. The largest predicted and experimental yield of alkyl esters (biodiesel) under the optimal conditions are 101.385% and 93.225%, respectively. Our findings confirmed the successful development of process for the transesterification reaction of coconut oil by microwave-assisted heating, which is effective and time-saving for alkyl ester production.

  5. Microwave-assisted synthesis and characterization of bimetallic PtRu alloy nanoparticles supported on carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rahsepar, Mansour, E-mail: rahsepar@shirazu.ac.ir [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Boulevard, Shiraz, 7134851154 (Iran, Islamic Republic of); Kim, Hasuck, E-mail: hasuckim@snu.ac.kr [Department of Chemistry, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-747 (Korea, Republic of); Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science & Technology, Daegu, 711-873 (Korea, Republic of)

    2015-11-15

    Multiwalled carbon nanotube (MWCNT) supported PtRu nanoparticles were synthesized by using a microwave-assisted improved impregnation technique. X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy were used to characterize the prepared PtRu/MWCNT nanoparticles. The PtRu nanoparticles with a satisfactory dispersion were formed on the external surface of MWCNTs. The CO stripping experiment was performed to evaluate the poisoning resistance of the prepared PtRu/MWCNT nanoparticles. Results of electrochemical measurements indicate that the prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning. The results of characterization revealed that microwave-assisted improved impregnation technique have a high yield of alloy phase formation and could be effectively used as a simple, quick and efficient technique for preparation of bimetallic PtRu/MWCNT nanoparticles. - Highlights: • Highly dispersed PtRu/MWCNTs were formed without use of any stabilizing agent. • Microwave irradiation enhances the uniform dispersion of the PtRu nanoparticles. • Microwave-assisted improved impregnation have a high yield of alloy phase formation. • The prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning.

  6. Factors Affecting Delignification of Oil Palm Empty Fruit Bunch by Microwave-assisted Dilute Acid/Alkali Pretreatment

    Directory of Open Access Journals (Sweden)

    Junaid Akhtar

    2014-11-01

    Full Text Available Microwave-assisted dilute acid/alkali pretreatment is an efficient and rapid method of removing lignin and hemicellulose, however, the optimized parameters for the maximum efficiency have to date not been presented in the literature. The purpose of this study was to determine those conditions by examining the effects of three factors: microwave power, temperature, and time on delignification in microwave-assisted dilute acid/alkali pretreatment. For the control condition of conventional pretreatment (CP, empty fruit bunches (EFBs were soaked in 2.5 M NaOH for two hours in the autoclave. In the experimental condition, EFB were first soaked in dilute sulfuric acid with conventional autoclave heating, which removed 90% of their hemicellulose. The acid-treated EFBs were then soaked in 2.5 M NaOH solution and microwaved at different conditions: microwave power (700 - 100 watts, time (60 - 90 min, and temperature (80 -110 °C. The amount of acid-insoluble lignin was determined by Klason method. Microwave-Alkali (Mw-A pretreatment was modeled until it attained maximum delignification. More than twice the rate of delignification that is, 71.9% was attained with microwave-assisted alkali/acid pretreatment of 900 W microwave power at 110 °C for 80 min compared to 34.6% with conventional pretreatment.

  7. Preparation of novel biodegradable pHEMA hydrogel for a tissue engineering scaffold by microwave-assisted polymerization

    Institute of Scientific and Technical Information of China (English)

    Li Zhang; Gen-Jian Zheng; Ya-Tong Guo; Lan Zhou; Jie Du; Hong He

    2014-01-01

    Objective:To prepare a novel biodegradable poly(2-hydroxyethylmethacrilate)(pHEMA) hydrogel as tissue engineering scaffold.Methods:The pHEMA hydrogel was synthesized by microwave-assisted polymerization using2-hydroxyethyl methacrylate(HEMA) as the raw material, potassium persulfate as the initiator, andPCLX as the cross-linking additive.The hydrogels was characterized withFTIR andNMR spectroscopy.The physical and chemical properties of the prepared hydrogel were evaluated, and its degradation performance was tested.The cytotoxicity of the optimum composite hydrogel was measured by anMTT assay to confirm the feasibility of its use in tissue engineering.Results:The optimum conditions under which the hydrogel was prepared by microwave-assisted polymerization are as follows:1.5 g cross-linking additive,0.3 g initiator, reaction temperature of80℃, and microwave power of800W.Degradation studies showed good degradation profiles with75% in17 days.Additionally, the hydrogels did not elicit any cytotoxic response inin vitro cytotoxic assays.Conclusion:A biodegradable pHEMA hydrogel was successfully prepared by microwave-assisted polymerization, as confirmed from FTIR andNMR results.The hydrogel shows promising applications in tissue engineering, and its healing ability and biocompatibility will be evaluated in detail in the future.

  8. Microwave-assisted synthesis, crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Youming; LIN; Qi; WEI; Taibao

    2004-01-01

    [1]Prasad, A.S. Nutritional metabolic role of zinc, Fed. Proc., 1967,26(1): 172-185.[2]Slagueiro, M. J., Zubillaga, M. B., Lysionek, A. E. et al., The role of zinc in the growth and development of children, Nutrition,2002, 18: 510-519.[3]Mossad, S. B., Zinc and the common cold: Are we close to a true?Nutrition, 1997, 13: 708-709.[4]Prasad, A. S., Clinical and biochemical manifestations of zinc deficiency in human subjects, J. Am. Coll. Nutr., 1985, 4(1):73-82.[5]Prasad, A. S., Zinc deficiency in sickle cell disease, Prog. Clin.Biol. Res., 1984, 165: 49-58.[6]Prasad, A. S., Discovery of zinc deficiency: Impact on human health, Nutrition, 2001, 17: 685-687.[7]Gao, S. -L., Fan, Y., Hu, R. -Z. et al., Synthesis, properties and phase equilibrian of Zn(NO3)2-Leu-H2O system (25℃), Chem. J.Chinese Universities (in Chinese), 2003, 24(2): 195-199.[8]Viladkar, S., Kamaluddin, Nath, M., Hydrolysis of phosphate by (amino acidato)zinc complexes, Bull. Chem. Soc. Jpn., 1993,66(10): 2922-2926.[9]Ashby, C. I. H., Paton, W. F., Brown, T. L., Nitrogen-14 nuclear quadrupole resonance spectra of the coordinated amino group and of coordinated imidazole. Crystal and molecular structures of chloroglycylglycinato(imidazole)cadmium, J. Am. Chem. Soc.,1980, 102(9): 2990-2998.[10]Jia, D. -Z., Yang, L. -X., Xia, X. et al., Studies on application of microwave heating techniques for the solid state reactions of coordination Compounds (Ⅰ), Chem. J. Chinese Universities (in Chinese), 1997, 18(9): 1432-1435.[11]Lidstrom, P., Tierney, J., Wathey, B. et al., Microwave assisted organic synthesis-a review, Tetrahedron, 2001, 57: 9925-9283.[12]Zhang, Y. M., Bai, J. F., Lu, M. Q. et al., Preparation of amino-acid Zinc and its character, Huaxue Shijie (in Chinese),1997, (2): 82-84.

  9. Preparation of highly photocatalytic active CdS/TiO{sub 2} nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Li, E-mail: qqhrll@163.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Key Laboratory of Composite Modified Material of Colleges in Heilongjiang Province, Qiqihar 161006 (China); Wang, Lili [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Hu, Tianyu [College of Environment and Resources, Jilin University, Changchun 130024 (China); Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China)

    2014-10-15

    CdS/TiO{sub 2} nanocomposites were prepared from Cd and Ti (1:1 M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6 h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N{sub 2} adsorption–desorption measurements. The results show that the CdS/TiO{sub 2} nanocomposites were composed of anatase TiO{sub 2} and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer–Emmett–Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO{sub 2} (6 h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO{sub 2} nanocomposites. The CdS/TiO{sub 2} (6 h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO{sub 2} nanocomposites, controlled experiments were performed by adding different radical scavengers. - Graphical abstract: CdS/TiO{sub 2} nanocomposites were prepared using CTAB by CBD combined with MAHS method. In addition, with increasing microwave irradiation time, the morphology of CdS/TiO{sub 2} changed from popcorn-like to wedge-like structure. - Highlights: • The CdS/TiO{sub 2} was prepared by CBD combined with MAHS two-step method under CTAB. • The morphologies of as-samples were different with the time of

  10. Surfactant-Free Microwave-Assisted Synthesis of Fe-Doped ZnO Nanostars as Photocatalyst for Degradation of Tropaeolin O in Water under Visible Light

    Directory of Open Access Journals (Sweden)

    Tsz-Lung Kwong

    2015-01-01

    Full Text Available Iron-doped zinc oxide nanostar was synthesized by the microwave-assisted surfactant-free hydrolysis method. The as-synthesized Fe-doped ZnO nanostars catalyst was fully characterized by scanning electron microscope (SEM, transmission electron microscopy (TEM, energy dispersive X-ray spectroscopy (EDX, powder X-ray diffraction (XRD, and diffuse reflectance UV-vis spectroscopy (UV-DRA. The photocatalytic activity of the photocatalyst was investigated for the photocatalytic degradation of Tropaeolin O under visible light irradiation. It is observed that the doping of Fe ions enhances the absorption of the visible light and thus the photocatalytic degradation rate of Tropaeolin O would increase. Despite the Taguchi orthogonal experimental design method, the photocatalytic conversion could be achieved at 99.8% in the Fe-doped ZnO catalyzed photodegradation reaction under the optimal reaction conditions of catalyst loading (30 mg, temperature (60°C, light distance (0 cm, initial pH (pH = 9, and irradiation time (3 h. The Fe-doped ZnO photocatalyst can also be easily recovered and directly reused for eight cycles with over 70% conversion.

  11. Microwave-assisted solid-phase peptide synthesis of the 60-110 domain of human pleiotrophin on 2-chlorotrityl resin.

    Science.gov (United States)

    Friligou, Irene; Papadimitriou, Evangelia; Gatos, Dimitrios; Matsoukas, John; Tselios, Theodore

    2011-05-01

    A fast and efficient microwave-assisted solid phase peptide synthesis (MW-SPPS) of a 51mer peptide, the main heparin-binding site (60-110) of human pleiotrophin (hPTN), using 2-chlorotrityl chloride resin (CLTR-Cl) following the 9-fluorenylmethyloxycarbonyl/tert-butyl (Fmoc/tBu) methodology and with the standard N,N'-diisopropylcarbodiimide/1-hydroxybenzotriazole (DIC/HOBt) coupling reagents, is described. An MW-SPPS protocol was for the first time successfully applied to the acid labile CLTR-Cl for the faster synthesis of long peptides (51mer peptide) and with an enhanced purity in comparison to conventional SPPS protocols. The synthesis of such long peptides is not trivial and it is generally achieved by recombinant techniques. The desired linear peptide was obtained in only 30 h of total processing time and in 51% crude yield, in which 60% was the purified product obtained with 99.4% purity. The synthesized peptide was purified by reversed phase high performance liquid chromatography (RP-HPLC) and identified by electrospray ionization mass spectrometry (ESI-MS). Then, the regioselective formation of the two disulfide bridges of hPTN 60-110 was successfully achieved by a two-step procedure, involving an oxidative folding step in dimethylsulfoxide (DMSO) to form the Cys(77)-Cys(109) bond, followed by iodine oxidation to form the Cys(67)-Cys(99) bond.

  12. Microwave assisted transformation of N,N-diphenylamine as precursors of organic light emitting diodes (OLED)

    Energy Technology Data Exchange (ETDEWEB)

    Jefri,; Wahyuningrum, Deana, E-mail: deana@chem.itb.ac.id [Organic Chemistry Research Division, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    In this research, study on the transformation of N,N-diphenylamine (DPA) using iodine (I2) utilizing solid state Microwave Assisted Organic Synthesis (MAOS) method has been carried out. The reaction was performed by variations of three parameters namely the mole of reagents, the amount and type of solid support (alumina/Al2O3), and the reaction conditions. Experimental results showed that neutral-alumina was a better solid support than basic-alumina. The optimum temperature for the reaction was approximately at 125-133 °C with reaction time of 15 minutes and microwave reactor power at 500-600 W. The separation of the yellowish green product solution with preparative Thin Layer Chromatography (TLC) method using n-hexane:ethyl acetate = 4:1 (v/v) as eluent yielded two fractions (I and II) and both fractions can undergo fluorescence under 365 nm UV light. Based on the LC chromatogram with methanol:water = 95:5 (v/v) as eluent and its corresponding mass spectra (ESI+), fraction I contained three compounds, which were tetracarbazole A, triphenylamine, and impurities in the form of plasticizer such as bis(2-ethylhexyl) phthalate. Fraction II also contained three compounds, which were tetracarbazole C, tetraphenylhydrazine, and plasticizer such as bis(2-ethylhexyl) phthalate. Both FT-IR (KBr disks) and NMR (500 MHz, CDCl{sub 3}) spectra of fraction I and II confirmed the aromatic amine groups in those compounds. The observed fluorescence colors of fraction I and II were violet and violet-blue, respectively. Based on their structures and fluorescence characters, the compounds in fraction I and II have the potential to be used as Organic Light Emitting Diode (OLED) compound precursors.

  13. Microwave assisted hydrothermal synthesis and characterization of ZnO–TNT composites

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sung Hun; Gyawali, Gobinda; Adhikari, Rajesh [Department of Metallurgy and Materials Engineering, SunMoon University, Asan (Korea, Republic of); Kim, Tae Ho [Department of Environmental Engineering, SunMoon University, Asan (Korea, Republic of); Lee, Soo Wohn, E-mail: swlee@sunmoon.ac.kr [Department of Environmental Engineering, SunMoon University, Asan (Korea, Republic of)

    2014-06-01

    TiO{sub 2} nanotubes with different contents of ZnO (3–40 wt.% ZnO) have been successfully synthesized by microwave assisted hydrothermal process by using commercial TiO{sub 2}-P25 as a precursor. The phase and crystallinity of the obtained ZnO–TNT were analyzed by X-ray Diffraction (XRD). The surface area of the ZnO–TNT was determined by BET method. The effect of the different contents of ZnO on morphology of TiO{sub 2} nanotubes was investigated by SEM and TEM. Optical properties and band gap energy of ZnO–TNT were calculated by using UV–vis DRS spectroscopy and modified Kubelka–Munk equation. Photocatalytic performance of ZnO–TNT was investigated by degradation of rhodamine B (RhB) dye under UV and visible light irradiation. Increasing ZnO content in TNT gradually decreased the diameter and length of nanotubes. Furthermore, addition of 40 wt.% ZnO into the TNT exceeded the saturation limit of ion exchangeability of Zn{sup 2+} and Na{sup +} ions and aggregation of finely dispersed ZnO particles on the surface of TNT were observed. The ZnO–TNT has shown relatively larger band gap energies than that of TiO{sub 2}-P25. However, ZnO–TNT has shown considerable increase in photo-activity for degradation of RhB dye in visible light as compared to UV light irradiation. - Highlights: • ZnO–TNT composites were successfully synthesized. • Investigation of the structural changes in the composites is confirmed. • The photocatalytic activity of the composites was studied. • Composites exhibited better performance under visible light than in UV light.

  14. Ionic liquid-based microwave-assisted extraction of rutin from Chinese medicinal plants.

    Science.gov (United States)

    Zeng, Huan; Wang, Yuzhi; Kong, Jinhuan; Nie, Chan; Yuan, Ya

    2010-12-15

    An ionic liquid-based microwave-assisted extraction (ILMAE) method has been developed for the effective extraction of rutin from Chinese medicinal plants including Saururus chinensis (Lour.) Bail. (S. chinensis) and Flos Sophorae. A series of 1-butyl-3-methylimidazolium ionic liquids with different anions were investigated. The results indicated that the characteristics of anions have remarkable effects on the extraction efficiency of rutin and among the investigated ionic liquids, 1-butyl-3-methylimidazolium bromide ([bmim]Br) aqueous solution was the best. In addition, the ILMAE procedures for the two kinds of medicinal herbs were also optimized by means of a series of single factor experiments and an L(9) (3(4)) orthogonal design. Compared with the optimal ionic liquid-based heating extraction (ILHE), marinated extraction (ILME), ultrasonic-assisted extraction (ILUAE), the optimized approach of ILMAE gained higher extraction efficiency which is 4.879 mg/g in S. chinensis with RSD 1.33% and 171.82 mg/g in Flos Sophorae with RSD 1.47% within the shortest extraction time. Reversed phase high performance liquid chromatography (RP-HPLC) with ultraviolet detection was employed for the analysis of rutin in Chinese medicinal plants. Under the optimum conditions, the average recoveries of rutin from S. chinensis and Flos Sophorae were 101.23% and 99.62% with RSD lower than 3%, respectively. The developed approach is linear at concentrations from 42 to 252 mg L(-1) of rutin solution, with the regression coefficient (r) at 0.99917. Moreover, the extraction mechanism of ILMAE and the microstructures and chemical structures of the two researched samples before and after extraction were also investigated. With the help of LC-MS, it was future demonstrated that the two researched herbs do contain active ingredient of rutin and ionic liquids would not influence the structure of rutin.

  15. Bit patterned media with composite structure for microwave assisted magnetic recording

    Science.gov (United States)

    Eibagi, Nasim

    Patterned magnetic nano-structures are under extensive research due to their interesting emergent physics and promising applications in high-density magnetic data storage, through magnetic logic to bio-magnetic functionality. Bit-patterned media is an example of such structures which is a leading candidate to reach magnetic densities which cannot be achieved by conventional magnetic media. Patterned arrays of complex heterostructures such as exchange-coupled composites are studied in this thesis as a potential for next generation of magnetic recording media. Exchange-coupled composites have shown new functionality and performance advantages in magnetic recording and bit patterned media provide unique capability to implement such architectures. Due to unique resonant properties of such structures, their possible application in spin transfer torque memory and microwave assisted switching is also studied. This dissertation is divided into seven chapters. The first chapter covers the history of magnetic recording, the need to increase magnetic storage density, and the challenges in the field. The second chapter introduces basic concepts of magnetism. The third chapter explains the fabrication methods for thin films and various lithographic techniques that were used to pattern the devices under study for this thesis. The fourth chapter introduces the exchanged coupled system with the structure of [Co/Pd] / Fe / [Co/Pd], where the thickness of Fe is varied, and presents the magnetic properties of such structures using conventional magnetometers. The fifth chapter goes beyond what is learned in the fourth chapter and utilizes polarized neutron reflectometry to study the vertical exchange coupling and reversal mechanism in patterned structures with such structure. The sixth chapter explores the dynamic properties of the patterned samples, and their reversal mechanism under microwave field. The final chapter summarizes the results and describes the prospects for future

  16. Microwave assisted transformation of N,N-diphenylamine as precursors of organic light emitting diodes (OLED)

    Science.gov (United States)

    Jefri, Wahyuningrum, Deana

    2015-09-01

    In this research, study on the transformation of N,N-diphenylamine (DPA) using iodine (I2) utilizing solid state Microwave Assisted Organic Synthesis (MAOS) method has been carried out. The reaction was performed by variations of three parameters namely the mole of reagents, the amount and type of solid support (alumina/Al2O3), and the reaction conditions. Experimental results showed that neutral-alumina was a better solid support than basic-alumina. The optimum temperature for the reaction was approximately at 125-133 °C with reaction time of 15 minutes and microwave reactor power at 500-600 W. The separation of the yellowish green product solution with preparative Thin Layer Chromatography (TLC) method using n-hexane:ethyl acetate = 4:1 (v/v) as eluent yielded two fractions (I and II) and both fractions can undergo fluorescence under 365 nm UV light. Based on the LC chromatogram with methanol:water = 95:5 (v/v) as eluent and its corresponding mass spectra (ESI+), fraction I contained three compounds, which were tetracarbazole A, triphenylamine, and impurities in the form of plasticizer such as bis(2-ethylhexyl) phthalate. Fraction II also contained three compounds, which were tetracarbazole C, tetraphenylhydrazine, and plasticizer such as bis(2-ethylhexyl) phthalate. Both FT-IR (KBr disks) and NMR (500 MHz, CDCl3) spectra of fraction I and II confirmed the aromatic amine groups in those compounds. The observed fluorescence colors of fraction I and II were violet and violet-blue, respectively. Based on their structures and fluorescence characters, the compounds in fraction I and II have the potential to be used as Organic Light Emitting Diode (OLED) compound precursors.

  17. Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis

    Directory of Open Access Journals (Sweden)

    Diego A. Esquivel-Hernández

    2016-05-01

    Full Text Available Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE and microwave-assisted extraction (MAE. The temperature (T factor was evaluated for MAE, while for SFE, pressure (P, temperature (T, and co-solvent (ethanol (CS were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14% and (4.27% ± 0.10% for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS and gas chromatography flame ionization detector (GC-FID. The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 μg/g and 629 ± 0.13 μg/g, respectively; for tocopherols 5.01 ± 0.05 μg/g and 2.46 ± 0.09 μg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO2 produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis.

  18. Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis

    Science.gov (United States)

    Esquivel-Hernández, Diego A.; López, Víctor H.; Rodríguez-Rodríguez, José; Alemán-Nava, Gibrán S.; Cuéllar-Bermúdez, Sara P.; Rostro-Alanis, Magdalena; Parra-Saldívar, Roberto

    2016-01-01

    Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE) and microwave-assisted extraction (MAE). The temperature (T) factor was evaluated for MAE, while for SFE, pressure (P), temperature (T), and co-solvent (ethanol) (CS) were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14%) and (4.27% ± 0.10%) for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID). The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 μg/g and 629 ± 0.13 μg/g, respectively; for tocopherols 5.01 ± 0.05 μg/g and 2.46 ± 0.09 μg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO2 produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis. PMID:27164081

  19. Accelerated, microwave-assisted, and conventional solvent extraction methods affect anthocyanin composition from colored grains.

    Science.gov (United States)

    Abdel-Aal, El-Sayed M; Akhtar, Humayoun; Rabalski, Iwona; Bryan, Michael

    2014-02-01

    Anthocyanins are important dietary components with diverse positive functions in human health. This study investigates effects of accelerated solvent extraction (ASE) and microwave-assisted extraction (MAE) on anthocyanin composition and extraction efficiency from blue wheat, purple corn, and black rice in comparison with the commonly used solvent extraction (CSE). Factorial experimental design was employed to study effects of ASE and MAE variables, and anthocyanin extracts were analyzed by spectrophotometry, high-performance liquid chromatography-diode array detector (DAD), and liquid chromatography-mass spectrometry chromatography. The extraction efficiency of ASE and MAE was comparable with CSE at the optimal conditions. The greatest extraction by ASE was achieved at 50 °C, 2500 psi, 10 min using 5 cycles, and 100% flush. For MAE, a combination of 70 °C, 300 W, and 10 min in MAE was the most effective in extracting anthocyanins from blue wheat and purple corn compared with 50 °C, 1200 W, and 20 min for black rice. The anthocyanin composition of grain extracts was influenced by the extraction method. The ASE extraction method seems to be more appropriate in extracting anthocyanins from the colored grains as being comparable with the CSE method based on changes in anthocyanin composition. The method caused lower structural changes in anthocaynins compared with the MAE method. Changes in blue wheat anthocyanins were lower in comparison with purple corn or black rice perhaps due to the absence of acylated anthocyanin compounds in blue wheat. The results show significant differences in anthocyanins among the 3 extraction methods, which indicate a need to standardize a method for valid comparisons among studies and for quality assurance purposes.

  20. Rapid synthesis of tin oxide nanostructures by microwave-assisted thermal oxidation for sensor applications

    Science.gov (United States)

    Phadungdhitidhada, S.; Ruankham, P.; Gardchareon, A.; Wongratanaphisan, D.; Choopun, S.

    2017-09-01

    In the present work nanostructures of tin oxides were synthesized by a microwave-assisted thermal oxidation. Tin precursor powder was loaded into a cylindrical quartz tube and further radiated in a microwave oven. The as-synthesized products were characterized by scanning electron microscope, transmission electron microscope, and x-ray diffractometer. The results showed that two different morphologies of SnO2 microwires (MWs) and nanoparticles (NPs) were obtained in one minute of microwave radiation under atmospheric ambient. A few tens of the SnO2 MWs with the length of 10-50 µm were found. Some parts of the MWs were decorated with the SnO2 NPs. However, most of the products were SnO2 NPs with the diameter ranging from 30-200 nm. Preparation under loosely closed system lead to mixed phase SnO-SnO2 NPs with diameter of 30-200 nm. The single-phase of SnO2 could be obtained by mixing the Sn precursor powders with CuO2. The products were mostly found to be SnO2 nanowires (NWs) and MWs. The diameter of SnO2 NWs was less than 50 nm. The SnO2 NPs, MWs, and NWs were in the cassiterite rutile structure phase. The SnO NPs was in the tetragonal structure phase. The growth direction of the SnO2 NWs was observed in (1 1 0) and (2 2 1) direction. The ethanol sensor performance of these tin oxide nanostructures showed that the SnO-SnO2 NPs exhibited extremely high sensitivity. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  1. Shape effect on the antibacterial activity of silver nanoparticles synthesized via a microwave-assisted method.

    Science.gov (United States)

    Hong, Xuesen; Wen, Junjie; Xiong, Xuhua; Hu, Yongyou

    2016-03-01

    Silver nanoparticles (AgNPs) are used as sustained-release bactericidal agents for water treatment. Among the physicochemical characteristics of AgNPs, shape is an important parameter relevant to the antibacterial activity. Three typically shaped AgNPs, nanocubes, nanospheres, and nanowires, were prepared via a microwave-assisted method and characterized by TEM, UV-vis, and XRD. The antibacterial activity of AgNPs was determined by OD growth curves tests, MIC tests, and cell viability assay against Escherichia coli. The interaction between AgNPs and bacterial cells was observed by TEM. The results showed that the three differently shaped AgNPs were nanoscale, 55 ± 10 nm in edge length for nanocubes, 60 ± 15 nm in diameter for nanospheres, 60 ± 10 nm in diameter and 2-4 μm in length for nanowires. At the bacterial concentration of 10(4) CFU/mL, the MIC of nanocubes, nanospheres, and nanowires were 37.5, 75, and 100 μg/mL, respectively. Due to the worst contact with bacteria, silver nanowires exhibited the weakest antibacterial activity compared with silver nanocubes and silver nanospheres. Besides, silver nanocubes mainly covered by {100} facets showed stronger antibacterial activity than silver nanospheres covered by {111} facets. It suggests that the shape effect on the antibacterial activity of AgNPs is attributed to the specific surface areas and facets reactivity; AgNPs with larger effective contact areas and higher reactive facets exhibit stronger antibacterial activity.

  2. Thrust Stand Measurements of the Microwave Assisted Discharge Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.; Emsellem, Gregory D.

    2011-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. This type of pulsed thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Dis- charge Inductive Plasma Accelerator (MAD-IPA), shown in Fig. 1, is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta-pinch coil is high. The use of a conical theta-pinch coil also serves to provide neutral propellant containment and plasma plume focusing that is improved relative to the more common planar geometry of the Pulsed Inductive Thruster (PIT) [1, 2]. In this paper, we describe thrust stand measurements performed to characterize the performance (specific impulse, thrust efficiency) of the MAD-IPA thruster. Impulse data are obtained at various pulse energies, mass flow rates and inductive coil geometries. Dependencies on these experimental parameters are discussed in the context of the current sheet formation and electromagnetic plasma

  3. Microwave-assisted rapid synthesis of Fe{sub 2}O{sub 3}/ACF hybrid for high efficient As(V) removal

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Huiyun; Lv, Kangle; Du, Ying; Ye, Hengpeng; Du, Dongyun, E-mail: dydu666@mail.scuec.edu.cn

    2016-07-25

    In this paper, an efficient adsorbent, iron-modified activated carbon fiber (Fe{sub 2}O{sub 3}/ACF), was rapidly fabricated by microwave-assisted heating treatment strategy, which is used to remove As(V) from simulated wastewater. The adsorbent was characterized by scanning electron microscopy (SEM), TEM, N{sub 2} sorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The characterization results showed that rod-like Fe{sub 2}O{sub 3} particles in sizes of about 20 nm × 50 nm were homogeneously anchored on the surface of ACF. The goal of high As(V) removal efficiency was achieved with maximum adsorption capacity of 20.33 mg g{sup −1}. The effects of temperature on thermodynamics and kinetics of As(V) adsorption were systematically studied. It was found that the adsorption of As(V) on the surface of Fe{sub 2}O{sub 3}/ACF is an endothermic process with a standard enthalpy change (ΔH{sup 0}) of 24.79 kJ mol{sup −1}. Batch experimental result showed that almost all of the As(V) with initial concentration of 3.0 mg L{sup −1} can be removed in the presence of Fe{sub 2}O{sub 3}/ACF, where the residual As(V) in filtrate was less than 0.01 mg L{sup −1}, below the tolerance level of drinking water suggested by World Health Organization (WHO). The presence of salt such as NaCl, Na{sub 2}SO{sub 4}, and MgSO{sub 4} showed little effects on the adsorption of As(V), indicating the promising application of Fe{sub 2}O{sub 3}/ACF in industrial wastewater. - Highlights: • Fe{sub 2}O{sub 3}/ACF hybrid was rapidly fabricated using a microwave-assisted heating strategy. • Fe{sub 2}O{sub 3} nanorods in sizes of 20 × 50 nm were homogeneously anchored on the surface of ACF. • The maximum adsorption capacity of 20.33 mg g{sup −1} As (V) on Fe{sub 2}O{sub 3}/ACF was achieved. • The adsorption of As (V) is an endothermic process (ΔH{sup 0} = 24.79 kJ mol{sup −1}). • The presence of salt shows little effect on the adsorption of As (V).

  4. Long Life Cold Cathodes for Hall effect Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An electron source incorporating long life, high current density cold cathodes inside a microchannel plate for use with ion thrusters is proposed. Cathode lifetime...

  5. Extraction of Dihydroquercetin from Larix gmelinii with Ultrasound-Assisted and Microwave-Assisted Alternant Digestion

    Directory of Open Access Journals (Sweden)

    Yuangang Zu

    2012-07-01

    Full Text Available An ultrasound and microwave assisted alternant extraction method (UMAE was applied for extracting dihydroquercetin (DHQ from Larix gmelinii wood. This investigation was conducted using 60% ethanol as solvent, 1:12 solid to liquid ratio, and 3 h soaking time. The optimum treatment time was ultrasound 40 min, microwave 20 min, respectively, and the extraction was performed once. Under the optimized conditions, satisfactory extraction yield of the target analyte was obtained. Relative to ultrasound-assisted or microwave-assisted method, the proposed approach provides higher extraction yield. The effect of DHQ of different concentrations and synthetic antioxidants on oxidative stability in soy bean oil stored for 20 days at different temperatures (25 °C and 60 °C was compared. DHQ was more effective in restraining soy bean oil oxidation, and a dose-response relationship was observed. The antioxidant activity of DHQ was a little stronger than that of BHA and BHT. Soy bean oil supplemented with 0.08 mg/g DHQ exhibited favorable antioxidant effects and is preferable for effectively avoiding oxidation. The L. gmelinii wood samples before and after extraction were characterized by scanning electron microscopy. The results showed that the UMAE method is a simple and efficient technique for sample preparation.

  6. Optimisation of Microwave-Assisted Extraction of Pomegranate (Punica granatum L.) Seed Oil and Evaluation 
of Its Physicochemical and Bioactive Properties

    Science.gov (United States)

    Çavdar, Hasene Keskin; Gök, Uğur; Göğüş, Fahrettin

    2017-01-01

    Summary Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil, such as fatty acid composition, free fatty acidity, total phenolic content, antioxidant activity and colour, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimise extraction conditions: power (176–300 W), time (5–20 min), particle size (d=0.125–0.800 mm) and solvent to sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19%) was obtained using microwave power of 220 W, particle size in the range of d=0.125–0.450 mm and solvent-to-sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70% in 8 h) or cold (17.50% in 8 h) extraction. The dominant fatty acid of pomegranate seed oil was punicic acid (86%) irrespective of the extraction method. Oil obtained by MASE had better physicochemical properties, total phenolic content and antioxidant activity than the oil obtained by cold solvent extraction. PMID:28559737

  7. Optimized microwave-assisted extraction of 6-gingerol from Zingiber officinale Roscoeand evaluation of antioxidant activity in vitro

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2014-06-01

    Full Text Available Background. 6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques. Material and methods. Fresh gingers (Zingiber officinale Rose. were harvested at commercial maturity (originally from Shandong, laiwu, China. In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD was applied to determine the best combination of extraction variables on the yield of 6-gingerol. Results. The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL g1, extraction time 31s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC, Stirring Extraction (SE, Heat reflux extraction (HRE, Ultrasound-assisted extraction (UAE, as well as the antioxidant capacity. Conclusion. Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the

  8. Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

    Directory of Open Access Journals (Sweden)

    Jimena E. Díaz

    2016-09-01

    Full Text Available The first general procedure for the synthesis of 5 to 7-membered 1-aryl-2-iminoazacycloalkanes is presented, by microwave-assisted ring closure of ω-arylaminonitriles promoted by polyphosphoric acid (PPA esters. 1-Aryl-2-iminopyrrolidines were easily prepared from the acyclic precursors employing a chloroformic solution of ethyl polyphosphate (PPE. The use of trimethylsilyl polyphosphate (PPSE in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic synthesis.

  9. Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots

    OpenAIRE

    Sai Li-Man; Kong Xiang Yang

    2011-01-01

    Abstract A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent...

  10. Microwave-assisted synthesis under solvent-free conditions of (E)-2-(Benzo[d]thiazol-2-yl)-3-arylacrylonitriles

    Energy Technology Data Exchange (ETDEWEB)

    Trilleras, Jorge E.; Velasquez, Kelly J.; Pacheco, Dency J., E-mail: jorgetrilleras@mail.uniatlantico.edu.co [Grupo de Investigacion en Compuestos Heterociclicos, Programa de Quimica, Facultad de Ciencias Basicas, Universidad del Atlantico, Barranquilla-Atlantico (Colombia); Quiroga, Jairo; Ortiz, Alejandro [Grupo de Investigacion de Compuestos Heterociclicos, Departamento de Quimica, Universidad del Valle, Cali (Colombia)

    2011-09-15

    A series of (E)-2-(benzo[d]thiazol-2-yl)-3-arylacrylonitriles was synthesized by microwave assisted Knoevenagel condensation under solvent-free conditions from the corresponding 2-(benzo[d]thiazol-2-yl)acetonitrile and aromatic aldehydes with electrondonating/electron withdrawing groups. The reaction times were considerably short and the products obtained in moderate yields (50 to 75%) and good purity. The configuration of the acrylonitrile double bond could not be established by regular NMR methods. However, theoretical studies suggest that the E isomer is more stable than Z, which is in good agreement with some experimental evidences. (author)

  11. Microwave-assisted synthesis of high-loading, highly dispersed Pt/carbon aerogel catalyst for direct methanol fuel cell

    Indian Academy of Sciences (India)

    Zhijun Guo; Hong Zhu; Xinwei Zhang; Fanghui Wang; Yubao Guo; Yongsheng Wei

    2011-06-01

    A Pt supported on carbon aerogel catalyst has been synthesized by the microwave-assisted polyol process. The Pt supported on carbon aerogel catalyst was characterized by high resolution transmission electron microscopy and X-ray diffraction. The results show a uniform dispersion of spherical Pt nanoparticles 2.5–3.0 nm in diameter. Cyclic voltammetry and chronoamperometry were used to evaluate the electrocatalytic activity of the Pt/carbon aerogel catalyst for methanol oxidation at room temperature. The Pt/carbon aerogel catalyst shows higher electrochemical catalytic activity and stability for methanol oxidation than a commercial Pt/C catalyst of the same Pt loading.

  12. Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

    Science.gov (United States)

    Díaz, Jimena E; Mollo, María C

    2016-01-01

    Summary The first general procedure for the synthesis of 5 to 7-membered 1-aryl-2-iminoazacycloalkanes is presented, by microwave-assisted ring closure of ω-arylaminonitriles promoted by polyphosphoric acid (PPA) esters. 1-Aryl-2-iminopyrrolidines were easily prepared from the acyclic precursors employing a chloroformic solution of ethyl polyphosphate (PPE). The use of trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic synthesis. PMID:27829907

  13. Microwave-Assisted Synthesis of (±-Mandelic Acid-d5, Optical Resolution, and Absolute Configuration Determination

    Directory of Open Access Journals (Sweden)

    Claudio Bruno

    2013-01-01

    Full Text Available An efficient microwave-assisted synthesis of (±-mandelic acid-d5 was developed. The racemic mixture was resolved by diastereomeric salt formation using 1-phenylethylamine enantiomers as resolving agents. At each step, the resolution process was checked by determining mandelic acid-d5 enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (−- and (+-mandelic acid-d5 (95% and 90% ee, resp. were obtained and their absolute configurations—R and S, respectively—were determined by correlation of the (−-mandelic acid-d5 circular dichroism spectrum to the (R-mandelic acid one.

  14. Microwave assisted synthesis of polyacrylamide grafted starch (St-g-PAM) and its applicability as flocculant for water treatment.

    Science.gov (United States)

    Mishra, Sumit; Mukul, Ankita; Sen, Gautam; Jha, Usha

    2011-01-01

    Polyacrylamide grafted starch (St-g-PAM) was made by a novel method of synthesis, involving combination of microwave radiation and a chemical free radical initiator (ceric ammonium nitrate) to initiate grafting reaction. This method (microwave assisted synthesis) is quick, highly reliable, reproducible and yields high quality product as compared to the conventional method (which uses a chemical free radical initiator alone to initiate the grafting reaction).The St-g-PAM grades synthesized were characterized by various physicochemical techniques. Further, its application as flocculant for wastewater treatment was investigated.

  15. cis-Apa: a practical linker for the microwave-assisted preparation of cyclic pseudopeptides via RCM cyclative cleavage.

    Science.gov (United States)

    Baron, Alice; Verdié, Pascal; Martinez, Jean; Lamaty, Frédéric

    2011-02-04

    A new linker cis-5-aminopent-3-enoic acid (cis-Apa) was prepared for the synthesis of cyclic pseudopeptides by cyclization-cleavage by using ring-closing methatesis (RCM). We developed a new synthetic pathway for the preparation of the cis-Apa linker that was tested in the cyclization-cleavage process of different RGD peptide sequences. Different macrocyclic peptidomimetics were prepared by using this integrated microwave-assisted method, showing that the readily available cis-Apa amino acid is well adapted as a linker in the cyclization-cleavage process.

  16. Heat-Modeling of Microwave Assisted Epoxidation of Palm Acid Oil

    Directory of Open Access Journals (Sweden)

    N. Saifuddin

    2011-01-01

    Full Text Available Problem statement: While microwave chemistry could well be the most convenient, rapid and energy-saving way to initiate a chemical reaction, the issues of thermal versus microwave specific effect remain unaddressed. Approach: A three-dimensional Finite Element Model (FEM was developed to predict temperature profile during the enzymatic epoxidation of palm acid oil using microwave heating. Three-dimensional partial differential equations are formulated for the electromagnetic field and heat and mass transfer processes. The temperature profile of the FEM generated from the commercial software (ANSYS Emag was verified using experimental data from microwave oven heated samples containing palm acid oil and reactants in cylindrical bottles and has compared favorably with real time data. An Infra Red thermometer was used to measure temperature of the reactants during the real time experiment to ensure less contact with the reaction vessel. Results: Apart from ascertaining the temperature profile of the epoxidation process in the cylindrical bottle, the heat-modeling of this reaction can predict the Energy required during the reaction and provide insights to non-thermal microwave effects. It has shown the possibility of Microwave Non-Thermal Effects and Microwave Selectivity in Substrate Specificity. The energy used by the microwave irradiated reaction is by far much lesser than the energy used in conventional heating. This study has also improved the epoxidation process of Palm Acid Oil by incorporating enzyme as a catalyst and using microwave heating. Epoxidation can be done rapidly and at a lower level of activation energy of 27.767 kJ mol−1. It is a green process with increased efficiency as it reduced a typically 5-hour reaction to less than an hour. Conclusion: In this study, a quantitative view of a microwave assisted process of enzymatic epoxidation has been established. We have successfully developed and experimentally

  17. Thrust Stand Measurements Using Alternative Propellants in the Microwave Assisted Discharge Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.

    2011-01-01

    Storable propellants (for example water, ammonia, and hydrazine) are attractive for deep space propulsion due to their naturally high density at ambient interplanetary conditions, which obviates the need for a cryogenic/venting system. Water in particular is attractive due to its ease of handling and availability both terrestrially and extra-terrestrially. While many storable propellants are reactive and corrosive, a propulsion scheme where the propellant is insulated from vulnerable (e.g. metallic) sections of the assembly would be well-suited to process these otherwise incompatible propellants. Pulsed inductive plasma thrusters meet this criterion because they can be operated without direct propellant-electrode interaction. During operation of these devices, electrical energy is capacitively stored and then discharged through an inductive coil creating a time-varying current in the coil that interacts with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, many pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA) is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta

  18. Automated radioanalytical system incorporating microwave-assisted sample preparation, chemical separation, and online radiometric detection for the monitoring of total 99Tc in nuclear waste processing streams.

    Science.gov (United States)

    Egorov, Oleg B; O'Hara, Matthew J; Grate, Jay W

    2012-04-03

    An automated fluidic instrument is described that rapidly determines the total (99)Tc content of aged nuclear waste samples, where the matrix is chemically and radiologically complex and the existing speciation of the (99)Tc is variable. The monitor links microwave-assisted sample preparation with an automated anion exchange column separation and detection using a flow-through solid scintillator detector. The sample preparation steps acidify the sample, decompose organics, and convert all Tc species to the pertechnetate anion. The column-based anion exchange procedure separates the pertechnetate from the complex sample matrix, so that radiometric detection can provide accurate measurement of (99)Tc. We developed a preprogrammed spike addition procedure to automatically determine matrix-matched calibration. The overall measurement efficiency that is determined simultaneously provides a self-diagnostic parameter for the radiochemical separation and overall instrument function. Continuous, automated operation was demonstrated over the course of 54 h, which resulted in the analysis of 215 samples plus 54 hly spike-addition samples, with consistent overall measurement efficiency for the operation of the monitor. A sample can be processed and measured automatically in just 12.5 min with a detection limit of 23.5 Bq/mL of (99)Tc in low activity waste (0.495 mL sample volume), with better than 10% RSD precision at concentrations above the quantification limit. This rapid automated analysis method was developed to support nuclear waste processing operations planned for the Hanford nuclear site.

  19. Fast removal of tetracycline from wastewater by reduced graphene oxide prepared via microwave-assisted ethylenediamine-N,N'-disuccinic acid induction method.

    Science.gov (United States)

    Yuan, Xingzhong; Wu, Zhibin; Zhong, Hua; Wang, Hou; Chen, Xiaohong; Leng, Lijian; Jiang, Longbo; Xiao, Zhihua; Zeng, Guangming

    2016-09-01

    A green reagent of ethylenediamine-N,N'-disuccinic acid (EDDS) was reported herein for reduction of graphene oxide (GO) with microwave assistance. The characteristics of EDDS reduced graphene oxide (ERG), and the tetracycline (TC) adsorption behavior of ERG was investigated. The results showed that the deoxygenation efficiency of GO strongly depended on the EDDS amount and the ERG can be successively obtained by recycled EDDS. The ERG obtained at EDDS/GO ratio of 5 (ERG5) exhibited a maximum capacity of 558.66 mg/g for TC adsorption, which is superior to GO and ERGs obtained at other EDDS/GO ratio. The adsorption reached equilibrium within 10 min, and the driving forces are likely the van der Waals forces, π-π electron-donor-acceptor (EDA) interaction and cation-π bonding between TC and the ERG surface. The adsorbent dose, pH, temperature, initial TC concentration, and ionic strength significantly affect the TC adsorption. The pseudo-second-order kinetics describes TC adsorption process very well, with correlation coefficients (R (2) ) greater than 0.99. The adsorption isotherm was best fitted by Freundlich equation, followed by Langmuir, Temkin, and Hill model equations. Analysis on adsorption thermodynamics shows that the adsorption is a spontaneous endothermic process. The ERG could be a cost-effective and promising sorbent for TC wastewater treatment due to its high-efficiency performance in real river water, medical wastewater, and municipal wastewater.

  20. Accurate Analysis and Evaluation of Acidic Plant Growth Regulators in Transgenic and Nontransgenic Edible Oils with Facile Microwave-Assisted Extraction-Derivatization.

    Science.gov (United States)

    Liu, Mengge; Chen, Guang; Guo, Hailong; Fan, Baolei; Liu, Jianjun; Fu, Qiang; Li, Xiu; Lu, Xiaomin; Zhao, Xianen; Li, Guoliang; Sun, Zhiwei; Xia, Lian; Zhu, Shuyun; Yang, Daoshan; Cao, Ziping; Wang, Hua; Suo, Yourui; You, Jinmao

    2015-09-16

    Determination of plant growth regulators (PGRs) in a signal transduction system (STS) is significant for transgenic food safety, but may be challenged by poor accuracy and analyte instability. In this work, a microwave-assisted extraction-derivatization (MAED) method is developed for six acidic PGRs in oil samples, allowing an efficient (<1.5 h) and facile (one step) pretreatment. Accuracies are greatly improved, particularly for gibberellin A3 (-2.72 to -0.65%) as compared with those reported (-22 to -2%). Excellent selectivity and quite low detection limits (0.37-1.36 ng mL(-1)) are enabled by fluorescence detection-mass spectrum monitoring. Results show the significant differences in acidic PGRs between transgenic and nontransgenic oils, particularly 1-naphthaleneacetic acid (1-NAA), implying the PGRs induced variations of components and genes. This study provides, for the first time, an accurate and efficient determination for labile PGRs involved in STS and a promising concept for objectively evaluating the safety of transgenic foods.

  1. ILs-based microwave-assisted extraction coupled with aqueous two-phase for the extraction of useful compounds from Chinese medicine.

    Science.gov (United States)

    Lin, Xiao; Wang, Yuzhi; Liu, Xiaojie; Huang, Songyun; Zeng, Qun

    2012-09-07

    Ionic liquids-based microwave-assisted extraction (ILs-MAE) of medicinal or useful compounds from plants was investigated as an alternative to conventional organic solvent extractions. The extraction and the preconcentration of aqueous two-phase (ATP) systems have been integrated. Various operating parameters were systematically considered by single-factor and L(9) (3(4)) orthogonal array experiments. 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) has been selected to extract Apocynum venetum. The extract was then converted to the top phase by [bmim][BF(4)]/NaH(2)PO(4) system which was suitable for the preconcentration. Reversed phase high performance liquid chromatography (RP-HPLC) with ultraviolet detection was employed for the analysis of hyperin and isoquercitrin in Apocynum venetum. The optimal experiment approach could provide higher detection limit of hyperin and isoquercitrin which were 3.82 μg L(-1) and 3.00 μg L(-1) in Apocynum venetum. The recoveries of hyperin and isoquercitrin were 97.29% (RSD = 1.02%) and 99.40% (RSD = 1.13%), respectively, from aqueous samples of Apocynum venetum by the proposed method. Moreover, the extraction mechanism of ILs-MAE and the microstructures and chemical structures of the herb before and after extraction were also investigated. The method exhibited potential applicability with other complicated samples.

  2. Focused microwave-assisted extraction combined with solid-phase microextraction and gas chromatography-mass spectrometry for the selective analysis of cocaine from coca leaves.

    Science.gov (United States)

    Bieri, Stefan; Ilias, Yara; Bicchi, Carlo; Veuthey, Jean-Luc; Christen, Philippe

    2006-04-21

    An effective combination of focused microwave-assisted extraction (FMAE) with solid-phase microextraction (SPME) prior to gas chromatography (GC) is described for the selective extraction and quantitative analysis of cocaine from coca leaves (Erythroxylum coca). This approach required switching from an organic extraction solvent to an aqueous medium more compatible with SPME liquid sampling. SPME was performed in the direct immersion mode with a universal 100 microm polydimethylsiloxane (PDMS) coated fibre. Parameters influencing this extraction step, such as solution pH, sampling time and temperature are discussed. Furthermore, the overall extraction process takes into account the stability of cocaine in alkaline aqueous solutions at different temperatures. Cocaine degradation rate was determined by capillary electrophoresis using the short end injection procedure. In the selected extraction conditions, less than 5% of cocaine was degraded after 60 min. From a qualitative point of view, a significant gain in selectivity was obtained with the incorporation of SPME in the extraction procedure. As a consequence of SPME clean-up, shorter columns could be used and analysis time was reduced to 6 min compared to 35 min with conventional GC. Quantitative results led to a cocaine content of 0.70 +/- 0.04% in dry leaves (RSD <5%) which agreed with previous investigations.

  3. Microwave-assisted synthesis of simonkolleite nanoplatelets on nickel foam-graphene with enhanced surface area for high-performance supercapacitors.

    Science.gov (United States)

    Khamlich, S; Mokrani, T; Dhlamini, M S; Mothudi, B M; Maaza, M

    2016-01-01

    Simonkolleite (Zn5(OH)8Cl2·H2O) nanoplatelets has been deposited on nickel foam-supported graphene by using an efficient microwave-assisted hydrothermal method. The three-dimensional (3D) porous microstructure of the as-fabricated nickel foam-graphene/simonkolleite (NiF-G/SimonK) composite is beneficial to electrolyte penetration and ions exchange, whereas graphene provide improved electronic conductivity. Structural and morphological characterizations confirmed the presence of highly crystalline hexagonal-shaped nanoplatelets of simonkolleite. Field emission scanning electron microscope (FE-SEM) of the NiF-G/SimonK composite revealed that the SimonK nanoplatelets were evenly distributed on the surface of NiF-G and interlaced with each other, resulting in a higher specific surface area of 35.69 m(2) g(-1) compared to SimonK deposited directly on NiF 17.2 m(2) g(-1). Electrochemical measurements demonstrated that the NiF-G/SimonK composite exhibit a high specific capacitance of 836 F g(-1) at a current density of 1 A g(-1), and excellent rate capability and cycling stability with capacitance retention of 92% after 5000 charge/discharge cycles.

  4. Preparation of N doped TiO2 via microwave-assisted method and its photocatalytic activity for degradation of Malathion.

    Science.gov (United States)

    Kadam, A N; Dhabbe, R S; Kokate, M R; Gaikwad, Y B; Garadkar, K M

    2014-12-10

    We report herein, nitrogen doped TiO2 nanostructure synthesized by simple microwave assisted method, where ammonia was used as hydrolyzing agent. The synthesized nanomaterials were characterized by means of X-ray diffraction (XRD) which demonstrated that N-doped TiO2 is in anatase phase with average crystallite size of 10nm. Doping of N into the lattice of TiO2 was supported by X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), CHNS analysis, energy dispersive spectroscopy (EDS). The diffuse reflectance spectroscopy (DRS) showed shifting of absorption edge toward the visible region. Thermogravimetric-differential thermal analysis (TGA-DTA) points out N-doped TiO2 nanoparticles are thermally stable. In order to achieve maximum degradation efficiency, the effect of catalyst loading, pH and light sources (UV and sunlight) were studied. A maximum 97% degradation efficiency was achieved under optimized conditions. A 80% reduction in the chemical oxygen demand (COD) was observed after 150min that indicated mineralization of Malathion. The cytotoxicological studies indicate that photocatalytically degraded products were less toxic as compared to Malathion.

  5. 微波辅助提取红花黄色素工艺优化%Optimization of Microwave Assisted Extraction of Yellow Pigment from Carthamus tinctorius L.

    Institute of Scientific and Technical Information of China (English)

    李书静; 李可; 姚新建; 李壮

    2013-01-01

    以红花(Crocus sativus L.)黄色素提取率为评价指标,研究了微波辅助提取红花黄色素的工艺条件.结果表明,各因素对红花黄色素提取率的影响为提取次数>提取温度>水料质量比>提取时间,最佳提取工艺条件为微波功率1000W、提取温度70℃、提取时间2.0 h、水料质量比60∶1、提取3次,在此工艺条件下,红花黄色素提取率高达7.73%.%Using the yield of yellow pigment as main indicator,the microwave assisted extraction technology of yellow pigment from Carthamus tinctorius L.was studied.The results showed that the order of factors influencing extracting effect was extraction times > extraction temperature > water to solid mass ratio> extraction time.The optimal extraction craft was microwave power at 1 000 W,extraction temperature at 70 ℃,extraction time for 2.0 h,water to solid mass ratio at 60∶1,extraction for 3 times,under which the yield of yellow pigment could be up to 7.73%.

  6. Microwave-assisted preparation of flower-like cobalt phosphate and its application as a new heterogeneous Fenton-like catalyst

    Science.gov (United States)

    Hu, Xiaoxia; Li, Rong; Zhao, Shuyu; Xing, Yanjun

    2017-02-01

    A novel flower-like 3D hierarchical cobalt phosphate Co3(PO4)2·8H2O (fCoP), and a plate-like cobalt phosphate (pCoP) were successfully synthesized via a microwave-assisted method at low temperature under atmospheric pressure using hexamethylene tetramine (HMTA) or urea as a template. All CoPs were characterized using XRD, FESEM, TEM, DRS and surface photovoltage spectra (SPS). The performance of the photocatalytic degradation of Rhodamine B (RhB) via a Fenton-like process on CoPs was evaluated both in the dark and under illumination. The results showed that the morphology and composition of the CoPs affected the RhB degradation. The flower-like hierarchical fCoP favored the photo degradation of RhB. fCoP was also confirmed to have the merits of easy recycling and good stability based on successive degradation experiments. The active species trapping experiments showed that the superoxide radical (rad O2-) was the dominant active species in the Fenton-like process. The catalytic activation was confirmed to be related to both the Co(II) on the surface and the fCoP framework.

  7. One-step microwave-assisted headspace solid-phase microextraction for the rapid determination of synthetic polycyclic musks in oyster by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Wu, Shin-Fang; Liu, Li-Lian; Ding, Wang-Hsien

    2012-07-15

    A rapid, simple and solvent-free procedure was developed for the determination of synthetic polycyclic musks in oyster samples by using one-step microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Two commonly used synthetic polycyclic musks, galaxolide (HHCB) and tonalide (AHTN), were selected in the method development and validation. The parameters (microwave irradiation power, extraction time, amount of water added, pH value and addition of NaCl) affecting the extraction efficiency of analytes from oyster slurry were systematically investigated and optimised. The best extraction conditions were achieved when the oyster tissue mixed with 10-mL deionised water (containing 3g of NaCl in a 40-mL sample-vial) was microwave irradiated at 80 W for 5 min. The limit of quantification (LOQ) was 0.1 ng/g in 5-g of wet tissue. The good precision and accuracy of one-step MA-HS-SPME coupled with GC-MS for the determination of trace level of AHTN in oyster samples was also demonstrated.

  8. Effect of HF addition on the microwave-assisted acid-digestion for the determination of metals in coal by inductively coupled plasma-atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yan-Hua [Department of Environmental Science and Engineering, College of Urban Construction and Safety and Environmental Engineering, Nanjing University of Technology, No. 200 Zhongshan Beilu, Nanjing 210009, Jiangsu (China); Iwashita, A.; Nakajima, T.; Yamashita, H.; Takanashi, H.; Ohki, A. [Department of Bioengineering, Faculty of Engineering, Kagoshima University, 1-21-40, Korimoto, Kagoshima 890-0065 (Japan)

    2005-03-31

    The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO{sub 3}+H{sub 2}O{sub 2} was used) was very effective for the pretreatment of ICP-AES measurement. Both major metals (Al, Ca, Fe, and Mg) and minor or trace metals (Co, Cr, Cu, Mn, Ni, Pb, and Zn) in coal gave good recoveries for their certified or reference values. The possibility of 'HF-memory effect' was cancelled by the use of a set of vessels which had been never contacted with HF. Twenty-four Japanese standard coals (SS coals) were analyzed by the present method, and the concentrations of major metals measured by the present method provided very high accordance with those from the authentic JIS (Japanese Industrial Standard) method.

  9. Effect of HF addition on the microwave-assisted acid-digestion for the determination of metals in coal by inductively coupled plasma-atomic emission spectrometry.

    Science.gov (United States)

    Xu, Yan-Hua; Iwashita, Akira; Nakajima, Tsunenori; Yamashita, Hiroyuki; Takanashi, Hirokazu; Ohki, Akira

    2005-03-31

    The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO(3)+H(2)O(2) was used) was very effective for the pretreatment of ICP-AES measurement. Both major metals (Al, Ca, Fe, and Mg) and minor or trace metals (Co, Cr, Cu, Mn, Ni, Pb, and Zn) in coal gave good recoveries for their certified or reference values. The possibility of 'HF-memory effect' was cancelled by the use of a set of vessels which had been never contacted with HF. Twenty-four Japanese standard coals (SS coals) were analyzed by the present method, and the concentrations of major metals measured by the present method provided very high accordance with those from the authentic JIS (Japanese Industrial Standard) method.

  10. Separation and Purification of Ombuoside from Gynostemma Pentaphyllum by Microwave-Assisted Extraction Coupled with High-Speed Counter-current Chromatography.

    Science.gov (United States)

    Jiang, Wenhui; Shan, Hu; Song, Jiying; Lü, Haitao

    2017-01-01

    A rapid and efficient method for the separation and purification of ombuoside from Gynostemma pentaphyllum by microwave-assisted extraction coupled with high-speed counter-current chromatography (HSCCC) was successfully developed. Using an orthogonal array design L9 (3(4)), the extraction conditions, including microwave power, irradiation time, solid-to-liquid ratio and extraction times, were optimized. Ombuoside was isolated and purified from the crude extraction by HSCCC with two-phase solvent system composed of n-hexane:ethyl acetate:ethanol:water (5:6:5:5, v/v) in a single run. A 210 mg quantity of the crude extract containing 2.16% ombuoside was loaded, yielding 3.9 mg of ombuoside at 96.7% purity. The chemical structure of ombuoside was determined by comparison with the high-performance liquid chromatography retention time of standard substance as well as UV, FT-IR, ESI-MS, (1)H NMR and (13)C NMR spectra. The purified ombuoside had strong 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radical scavenging activities. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Ionic Liquid-based Microwave-assisted Liquid-liquid Microextraction and High Performance Liquid Chromatography Determination of Sulfonamides from Animal Oils

    Institute of Scientific and Technical Information of China (English)

    FENG Xu-dong; LIANG Fang-hui; SU Rui; WU Li-jie; LI Xue-yuan; WANG Xing-hua; ZHANG Han-qi

    2013-01-01

    The authors performed ionic liquid-based microwave-assisted liquid-liquid microextraction(IL-based MALLME) coupled with high performance liquid chromatographic separation for the determination of 6 sulfonamides (SAs) from animal oils.The target analytes were extracted from animal oil samples with sodium hydroxide solution containing 1-butyl-3-methylimidazolium tetrafluoroborateand as the extraction solvent under microwave irradiation.The experimental parameters of the IL-based MALLME,including types of ILs,volume of IL,amount of ion-pairing agent(NH4PF6),pH value of sample solution,and extraction temperature and time were evaluated.The limits of detection and quantification obtained were in a range of 0.4-0.5 μg/kg and a range of 1.2-1.8 μg/kg,respectively.The accuracy of the method was evaluated by analyzing five spiked animal oil samples at two fortified levels(5 and 50 μg/kg),and the recoveries of SAs varied from 81.4% to 114.5% with relative standard deviations ranging from 0.8% to 9.0%.

  12. Microwave-assisted extraction and determination of cyanuric acid residue in pet food samples by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Han, Chao; Zhou, Yongfang; Xia, Biqi; Zhu, Zhenou; Liu, Cuiping; Shen, Yan

    2011-02-01

    Cyanuric acid (CYA) is attracting more attention due to its potential toxicity. In the present work, microwave-assisted extraction method in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was proposed for the determination of CYA in pet food samples. Among different solvents, diethylamine-acetonitrile-water mixture (1:5:4, v/v) was found to be the best one as the extractant due to the strong polarity of CYA in the pet food. An internal standard, (13) C(3) -labeled CYA, was used in the extractions. The separation was performed on a MERCK ZIC HILIC column (150 mm × 2.1 mm id, 5 μm) with gradient elution of 20 mM ammonium acetate solution-acetonitrile. CYA was well retained (Rt = 5.10 min) and eluted with good peak shape. The method could respond linearly with CYA at concentrations from 1.0 to 50 ng/mL with a quantification limit of 0.25 mg/kg. The intra- and inter-day precision was less than 4.0% and the recovery of the assay was in the range of 90.4-108.1%. In the analysis of practical spiked pet food samples, the new method yielded satisfactory results. Due to its simplicity and accuracy the straightforward method is particularly suitable for routine CYA detection. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A Microwave-Assisted Simultaneous Distillation and Extraction Method for the Separation of Polysaccharides and Essential Oil from the Leaves of Taxus chinensis Var. mairei

    Directory of Open Access Journals (Sweden)

    Chunjian Zhao

    2016-01-01

    Full Text Available An efficient microwave-assisted simultaneous distillation and extraction (MA-SDE method has been developed for the separation of polysaccharides and essential oil from Taxus chinensis var. mairei. The key operating parameters for MA-SDE were optimized by single factor and central composite design experiments, and the optimal conditions were found to include a particle size of 60–80 mesh, liquid/solid ratio of 22.5 mL/g, extraction time of 17.5 min, microwave power of 547 W, and dichloromethane was used as the extraction solvent of the essential oil. The yields obtained for polysaccharides and essential oil under the optimized conditions were 6.39% ± 0.12% and 0.27% ± 0.03%, respectively. The MA-SDE method was also compared with conventional heat reflux extraction (HRE and hydrodistillation extraction (HDE. The MA-SDE method not only allowed for the simultaneous extraction of polysaccharides and essential oil, but also completed the task with a much shorter extraction time of 17.5 min (HRE and HDE required 3 and 6 h, respectively. Furthermore, the MA-SDE method gave increased extraction yields for polysaccharides (1.14-fold higher than HRE and essential oil (1.23-fold higher than HDE. Based on these results, this MA-SDE method represents a rapid and efficient technique for the simultaneous extraction of polysaccharides and essential oil.

  14. Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L.

    Science.gov (United States)

    Wang, Zhibing; Hu, Jianxue; Du, Hongxia; He, Shuang; Li, Qing; Zhang, Hanqi

    2016-06-01

    The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant.

  15. Application of ionic liquids based microwave-assisted simultaneous extraction of carnosic acid, rosmarinic acid and essential oil from Rosmarinus officinalis.

    Science.gov (United States)

    Liu, Tingting; Sui, Xiaoyu; Zhang, Rongrui; Yang, Lei; Zu, Yuangang; Zhang, Lin; Zhang, Ying; Zhang, Zhonghua

    2011-11-25

    An ionic liquid based microwave-assisted simultaneous extraction and distillation (ILMSED) method has been developed for the effective extraction of carnosic acid (CA), rosmarinic acid (RA) and essential oil (EO) from Rosmarinus officinalis. A series of 1-alkyl-3-methylimidazolium ionic liquids differing in composition of anion and cation were evaluated for extraction yield in this work. The results obtained indicated that the anions and cations of ionic liquids had influences on the extraction of CA and RA, 1.0M 1-octyl-3-methylimidazolium bromide ([C8mim]Br) solution was selected as solvent. In addition, the ILMSED procedures for the three target ingredients were optimized and compared with other conventional extraction techniques. ILMSED gave the best result due to the highest extraction yield within the shortest extraction time for CA and RA. The novel process developed offered advantages in term of yield and selectivity of EO and shorter isolation time (20 min in comparison of 4h of hydrodistillation), and provides a more valuable EO (with high amount of oxygenated compounds). The microstructures and chemical structures of rosemary samples before and after extraction were also investigated. Moreover, the proposed method was validated by the stability, repeatability and recovery experiments. The results indicated that the developed ILMSED method provided a good alternative for the both extraction of non-volatile compounds (CA and RA) and EO from rosemary as well as other herbs.

  16. Efficient Cleavage of Lignin-Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave-Assisted Treatment with Deep Eutectic Solvent.

    Science.gov (United States)

    Liu, Yongzhuang; Chen, Wenshuai; Xia, Qinqin; Guo, Bingtuo; Wang, Qingwen; Liu, Shouxin; Liu, Yixing; Li, Jian; Yu, Haipeng

    2017-04-22

    Lignocellulosic biomass is an abundant and renewable resource for the production of biobased value-added fuels, chemicals, and materials, but its effective exploitation by an energy-efficient and environmentally friendly strategy remains a challenge. Herein, a facile approach for efficiently cleaving lignin-carbohydrate complexes and ultrafast fractionation of components from wood by microwave-assisted treatment with deep eutectic solvent is reported. The solvent was composed of sustainable choline chloride and oxalic acid dihydrate, and showed a hydrogen-bond acidity of 1.31. Efficient fractionation of lignocellulose with the solvent was realized by heating at 80 °C under 800 W microwave irradiation for 3 min. The extracted lignin showed a low molecular weight of 913, a low polydispersity of 1.25, and consisted of lignin oligomers with high purity (ca. 96 %), and thus shows potential in downstream production of aromatic chemicals. The other dissolved matter mainly comprised glucose, xylose, and hydroxymethylfurfural. The undissolved material was cellulose with crystal I structure and a crystallinity of approximately 75 %, which can be used for fabricating nanocellulose. Therefore, this work promotes an ultrafast lignin-first biorefinery approach while simultaneously keeping the undissolved cellulose available for further utilization. This work is expected to contribute to improving the economics of overall biorefining of lignocellulosic biomass. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  17. Microwave-assisted reaction of peptide formation by amino acid with phosphate: Exploration of the most possible channels for the origin of life

    Institute of Scientific and Technical Information of China (English)

    HU Rong; TIAN Jinping; YIN Yingwu

    2006-01-01

    Microwave-assisted reaction of peptide formation by amino acids with phosphate was studied. The results showed that the products were a mixture of peptides containing dipeptide, octapeptides and cyclic peptides, which could be obtained in a short time. Polyphosphate was also produced synchronously by the intermolecular condensation of phosphate. The polymerization degree reached 99% (pyrophosphate 64%, trimetaphosphate 35%) after 2 h at 200℃ under microwave irradiation. The intermediates of the mixed anhydrides formed by the intermolecular condensation of phosphates and glycin were determined by ESI-MS. Peptides were also produced by the reaction of amino acids with trimetaphosphate in aqueous solution. The conversion degree of valine reached 46.5% even at room temperature. The cyclic process of peptide formation and phosphate polymerization, regeneration and utilization in amino acids-phosphate system under microwave irradiation was detected and proved. Peptides could be continually formed only by inputting energy into this system. The above recycle may be the most possible process for primitive peptide formation in the origin of life.

  18. Rapid microwave-assisted nonaqueous synthesis and growth mechanism of AgCl/Ag, and its daylight-driven plasmonic photocatalysis.

    Science.gov (United States)

    Jiang, Jing; Zhang, Lizhi

    2011-03-21

    We report on a rapid microwave-assisted nonaqueous synthesis and the growth mechanism of AgCl/Ag with controlled size and shape. By rationally varying the reaction temperature and the microwave irradiation time, we achieved the transformation of nanocubes to rounded triangular pyramids by a combined process of "oriented attachment" and Ostwald ripening. The surface plasmon resonance (SPR) properties of the as-prepared AgCl/Ag have been found to be somewhat dependent on the size, morphology, and composition. The as-prepared AgCl/Ag exhibits high photocatalytic activity and good reusability for decomposing organic pollutants (such as methyl orange (MO), rhodamine B (RhB), and pentachlorophenol (PCP)) under indoor artificial daylight illumination (ca. 1 mW cm(-2)). The AgCl/Ag has also been found to display a superior ability to harvest diffuse indoor daylight (ca. 5 mW cm(-2)), and could complete the degradation of 10 mg  L(-1) MO within 15 min. Experiments involving the trapping of active species have shown that the photocatalytic degradation of organic pollutants in the AgCl/Ag system may proceed through direct hole transfer. This study has revealed that plasmonic daylight photocatalysis may open a new frontier for indoor pollutant control around the clock under fluorescent lamp illumination. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Microwave-assisted hydrothermal synthesis of Cu/Cu2O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature.

    Science.gov (United States)

    Zou, Xinwei; Fan, Huiqing; Tian, Yuming; Zhang, Mingang; Yan, Xiaoyan

    2015-05-01

    Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others.

  20. Synthesis and characterization of [BMIM]bromide using microwave-assisted organic synthesis method and its application for dissolution of palm empty fruit bunch

    Energy Technology Data Exchange (ETDEWEB)

    Arianie, Lucy, E-mail: lucy205@yahoo.com [Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Tanjungpura, Jl. A.Yani, 73 Pontianak 78124 (Indonesia); Wahyuningrum, Deana, E-mail: deana@chem.itb.ac.id; Nurrachman, Zeily, E-mail: deana@chem.itb.ac.id; Natalia, Dessy, E-mail: deana@chem.itb.ac.id [Department of Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132 (Indonesia)

    2014-03-24

    The decrease of cellulose crystallinity index of palm empty fruit bunch is crucial for the next application of cellulose as raw material for various biofuel and its derivatives. The aim of this research is to decrease the cellulose crystallinity index of palm empty fruit bunch using 1-butyl-3-methylimidazoliumbromide or [BMIM] bromide which has been synthesized using Microwave-Assisted Organic Synthesis (MAOS) method. Conventional reaction method has also been carried out to synthesize [BMIM]bromide for comparison as well. The characterization of synthesized product using FTIR, {sup 1}H-NMR, {sup 13}C-NMR and LC-MS showed that these reactions have been carried out successfully. The results showed that MAOS method is up to 90% faster in producing [BMIM]bromide compare to the conventional method. The application of [BMIM]bromide for dissolution of palm empty fruit bunch showed that cellulose and lignin could be extracted using stirring process for 20 hours. The decrease of cellulose crystallinity index and its morphology changes were identified using FTIR and Scanning Electron Microscope.

  1. Synthesis and characterization of [BMIM]bromide using microwave-assisted organic synthesis method and its application for dissolution of palm empty fruit bunch

    Science.gov (United States)

    Arianie, Lucy; Wahyuningrum, Deana; Nurrachman, Zeily; Natalia, Dessy

    2014-03-01

    The decrease of cellulose crystallinity index of palm empty fruit bunch is crucial for the next application of cellulose as raw material for various biofuel and its derivatives. The aim of this research is to decrease the cellulose crystallinity index of palm empty fruit bunch using 1-butyl-3-methylimidazoliumbromide or [BMIM] bromide which has been synthesized using Microwave-Assisted Organic Synthesis (MAOS) method. Conventional reaction method has also been carried out to synthesize [BMIM]bromide for comparison as well. The characterization of synthesized product using FTIR, 1H-NMR, 13C-NMR and LC-MS showed that these reactions have been carried out successfully. The results showed that MAOS method is up to 90% faster in producing [BMIM]bromide compare to the conventional method. The application of [BMIM]bromide for dissolution of palm empty fruit bunch showed that cellulose and lignin could be extracted using stirring process for 20 hours. The decrease of cellulose crystallinity index and its morphology changes were identified using FTIR and Scanning Electron Microscope.

  2. Determination of metal concentrations in certified plastic reference materials after small-size autoclave and microwave-assisted digestion followed with inductively coupled plasma optical emission spectrometry

    Science.gov (United States)

    Lehtimäki, Esa; Väisänen, Ari

    2017-01-01

    The digestion methods for the determination of As, Cd, Cr, Pb, Sb, Sn and Zn concentrations in plastic samples using microwave-assisted digestion (MW-AD) and small-size autoclave digestion was developed. The certified polyethylene, polypropylene, polyvinyl chloride and acrylonitrile butadiene styrene certified reference materials were used in order to find digestion method working properly for several sample matrices. Efficiency of the digestion methods was evaluated by analyzing the residual carbon in digests by TOC analyzer. MW-AD using a mixture of 7 mL of HNO3 and 3 mL of H2O2 as a digestion solution resulted in excellent recoveries for As, Cd, Pb, Sb and Zn, and were in the range of 92-107% for all the analytes except Pb in polyethylene material. Autoclave digestion using 5 mL of concentrated HNO3 as a digestion solution resulted in similar recoveries with the exception of a higher As recovery (98%). Tin recovery resulted in low level after both MW-AD and autoclave digestion. Autoclave digestion was further developed resulting in a partially open two-step digestion process especially for the determination of Sn and Cr. The method resulted in higher recoveries of Sn and Cr (87 and 76%) but with the lower concentration of easily volatile As, Cd and Sb.

  3. 4,6-二芳基-4,5-二氢-3-羟基-1(1H)-吲唑衍生物的微波促进合成及抗细菌活性评价%Microwave Assisted Synthesis and Antibacterial Activity of 4,6-Diaryl-4,5-dihydro-3-hydroxy-1H-indazole Derivatives

    Institute of Scientific and Technical Information of China (English)

    李小六; 王彦坡; 陈华; 赵莲; 曹克强

    2008-01-01

    利用微波促进有机合成的方法,以查尔酮为起始物,合成了系列的4,6-二芳基-4,5-二氢-3-羟基-1(1H)-吲唑衍生物,并对其结构及互变异构现象进行了研究,初步测定了化合物的抗细菌活性.

  4. Application of Ionic Liquids in the Microwave-Assisted Extraction of Proanthocyanidins from Larix gmelini Bark

    Directory of Open Access Journals (Sweden)

    Yuangang Zu

    2012-04-01

    Full Text Available Ionic liquid based, microwave-assisted extraction (ILMAE was successfully applied to the extraction of proanthocyanidins from Larix gmelini bark. In this work, in order to evaluate the performance of ionic liquids in the microwave-assisted extraction process, a series of 1-alkyl-3-methylimidazolium ionic liquids with different cations and anions were evaluated for extraction yield, and 1-butyl-3-methylimidazolium bromide was selected as the optimal solvent. In addition, the ILMAE procedure for the proanthocyanidins was optimized and compared with other conventional extraction techniques. Under the optimized conditions, satisfactory extraction yield of the proanthocyanidins was obtained. Relative to other methods, the proposed approach provided higher extraction yield and lower energy consumption. The Larix gmelini bark samples before and after extraction were analyzed by Thermal gravimetric analysis, Fourier-transform infrared spectroscopy and characterized by scanning electron microscopy. The results showed that the ILMAE method is a simple and efficient technique for sample preparation.

  5. Microwave-assisted rapid synthesis of birnessite-type MnO{sub 2} nanoparticles for high performance supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiong; Miao, Wang; Li, Chen; Sun, Xianzhong; Wang, Kai; Ma, Yanwei, E-mail: ywma@mail.iee.ac.cn

    2015-11-15

    Highlights: • Birnessite-type MnO{sub 2} nanoparticles were prepared by the microwave-assisted reflux. • The microwave reaction duration was only 5 min. • A specific capacitance of 329 F g{sup −1} was obtained for birnessite-type MnO{sub 2}. - Abstract: Birnessite-type MnO{sub 2} nanoparticles have been successfully synthesized by the microwave-assisted reflux as short as 5 min. The microstructure and morphology of the products were characterized by X-ray diffraction, N{sub 2} adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy. The electrochemical properties of the as-prepared MnO{sub 2} as an electrode material for supercapacitor were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements in 1 M Na{sub 2}SO{sub 4} electrolyte, and a high specific capacitance of 329 F g{sup −1} was achieved at a current density of 0.2 A g{sup −1}. The specific capacitance retention was 92% after 1000 cycles at 2 A g{sup −1}, suggesting that it is a promising electrode material for supercapacitors.

  6. Single-step microwave-assisted hot water extraction of hemicelluloses from selected lignocellulosic materials - A biorefinery approach.

    Science.gov (United States)

    Mihiretu, Gezahegn T; Brodin, Malin; Chimphango, Annie F; Øyaas, Karin; Hoff, Bård H; Görgens, Johann F

    2017-10-01

    The viability of single-step microwave-induced pressurized hot water conditions for co-production of xylan-based biopolymers and bioethanol from aspenwood sawdust and sugarcane trash was investigated. Extraction of hemicelluloses was conducted using microwave-assisted pressurized hot water system. The effects of temperature and time on extraction yield and enzymatic digestibility of resulting solids were determined. Temperatures between 170-200°C for aspenwood and 165-195°C for sugarcane trash; retention times between 8-22min for both feedstocks, were selected for optimization purpose. Maximum xylan extraction yields of 66 and 50%, and highest cellulose digestibilities of 78 and 74%, were attained for aspenwood and sugarcane trash respectively. Monomeric xylose yields for both feedstocks were below 7%, showing that the xylan extracts were predominantly in non-monomeric form. Thus, single-step microwave-assisted hot water method is viable biorefinery approach to extract xylan from lignocelluloses while rendering the solid residues sufficiently digestible for ethanol production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Microwave assisted synthesis and characterization of Ni/NiO nanoparticles as electrocatalyst for methanol oxidation in alkaline solution

    Science.gov (United States)

    Arunachalam, Prabhakarn; Ghanem, Mohamed A.; Al-Mayouf, Abdullah M.; Al-shalwi, Matar; Hamed Abd-Elkader, Omar

    2017-02-01

    Nickel/Nickel oxide (Ni/NiO) nanoparticles catalyst is prepared by microwave-assisted liquid-phase deposition using ethylene glycol (EG) and water mixture under atmospheric conditions. The physicochemical characterizations of the catalyst carried out by surface area analyzer, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electron microscopes measurements suggest the formation of crystalline nanoparticles structure of NiO. The surface area of Ni/NiO prepared using EG/water mixture reaches 70 m2 g-1 which is 2-fold enhsancement in surface area in comparison with NiO prepared in pure EG and an order of magnitude higher than that of bulk nickel prepared in pure water. The methanol electro-oxidation activity of the Ni/NiO nanoparticles obtained in EG/water mixture displayed more than 4-fold increase in oxidation current at 1.7 V versus RHE in comparison with NiO nanoparticles obtained in EG and 20-fold increase compared to bulk nickel catalyst concord with the enhancement of electro-active surface area. The results show the Ni/NiO nanoparticles produced by microwave assisted synthesis has superior activity for methanol oxidation in alkaline solution over the other nickel based catalysts and has potential for mass production.

  8. Deep Eutectic Solvent-Based Microwave-Assisted Method for Extraction of Hydrophilic and Hydrophobic Components from Radix Salviae miltiorrhizae

    Directory of Open Access Journals (Sweden)

    Jue Chen

    2016-10-01

    Full Text Available Deep eutectic solvents (DESs have attracted significant attention as a promising green media. In this work, twenty-five kinds of benign choline chloride-based DESs with microwave-assisted methods were applied to quickly extract active components from Radix Salviae miltiorrhizae. The extraction factors, including temperature, time, power of microwave, and solid/liquid ratio, were investigated systematically by response surface methodology. The hydrophilic and hydrophobic ingredients were extracted simultaneously under the optimized conditions: 20 vol% of water in choline chloride/1,2-propanediol (1:1, molar ratio as solvent, microwave power of 800 W, temperature at 70 °C, time at 11.11 min, and solid/liquid ratio of 0.007 g·mL−1. The extraction yield was comparable to, or even better than, conventional methods with organic solvents. The microstructure alteration of samples before and after extraction was also investigated. The method validation was tested as the linearity of analytes (r2 > 0.9997 over two orders of magnitude, precision (intra-day relative standard deviation (RSD < 2.49 and inter-day RSD < 2.96, and accuracy (recoveries ranging from 95.04% to 99.93%. The proposed DESs combined with the microwave-assisted method provided a prominent advantage for fast and efficient extraction of active components, and DESs could be extended as solvents to extract and analyze complex environmental and pharmaceutical samples.

  9. Fast preparation of LiFePO4 nanoparticles for lithium batteries by microwave-assisted hydrothermal method.

    Science.gov (United States)

    Yang, Gang; Ji, Hongmei; Liu, Haidong; Huo, Kaifu; Fu, Jijiang; Chu, Paul K

    2010-02-01

    Nanomaterial for lithium batteries can decrease mechanical strain upon lithium intercalation/ deintercalation from lattice, and lead to high rate capability. The currently available microwave technology permits the development and implantation of a temperature-controlled microwave-assisted hydrothermal synthesis (TCMH) of nano-sized cathode material for lithium batteries. Unlike in previous reported traditional hydrothermal synthesis of cathode material LiFePO4, the pure phase of LiFePO4 can be simply and rapidly synthesized for 5 minutes in water under hydrothermal treatment with microwave irradiation. The homogeneous effects induced by microwave irradiation could create a uniform seeding condition. The colloid precursor Li3PO4 plays the key role to be the nucleation center for the new phase while the formation energy for LiFePO4 would be decreased during the following microwave irradiation. The as-prepared pristine LiFePO4 without carbon coating are characterized by X-ray diffraction, Raman, scanning and transmission electron microscopy, and tested as the cathode in lithium batteries. The particle sizes of pristine LiFePO4 are dependent on hydrothermal and microwave-assisted hydrothermal condition and the electrochemical performance are relatively determined.

  10. Suitability of microwave-assisted extraction coupled with solid-phase extraction for organophosphorus pesticide determination in olive oil.

    Science.gov (United States)

    Fuentes, Edwar; Báez, María E; Quiñones, Adalí

    2008-10-17

    A systematic study of the microwave-assisted extraction coupled to solid-phase extraction of nine organophosphorus pesticides (dimethoate, diazinon, pirimiphos methyl, parathion methyl, malathion, fenthion, chlorpyriphos, methidathion and azinphos methyl) from olive oil is described. The method is based on microwave-assisted liquid-liquid extraction with partition of organophosphorus pesticides between an acetonitrile-dichloromethane mixture and oil. Cleanup of extracts was performed with ENVI-Carb solid-phase extraction cartridge using dichloromethane as the elution solvent. The determination of pesticides in the final extracts was carried out by gas chromatography-flame photometric detection and gas chromatography-tandem mass spectrometry, using a triple quadrupole mass analyzer, for confirmative purposes. The study and optimization of the method was achieved through experimental design where recovery of compounds using acetonitrile for partition ranged from 62 to 99%. By adding dichloromethane to the extracting solution, the recoveries of more hydrophobic compounds were significantly increased. Under optimized conditions recoveries of pesticides from oil were equal to or higher than 73%, except for fenthion and chlorpyriphos at concentrations higher than 0.06microgg(-1) and diazinon at 0.03microgg(-1), with RSDs equal to or lower than 11% and quantification limits ranging from 0.007 to 0.020microgg(-1). The proposed method was applied to residue determination of the selected pesticides in commercial olive and avocado oil produced in Chile.

  11. Microwave-assisted chemical reduction routes for direct synthesis of (fct) L1 phase of Fe-Pt.

    Science.gov (United States)

    Acharya, Smita; Singh, Kamal

    2011-01-01

    Microwave-assisted chemical reduction route has been explored for the direct synthesis of fct L1(0) - phase of Fe-Pt nanoparticles in the present work. Effects of microwave power and irradiation time on the growth process are systematically studied. Using this facile and high yield technique we could tune particle size from 7 to 17 nm. Prepared Fe-Pt NPs exhibited ordered face centered tetragonal (fct) L1(0) phase without any post-synthesis treatment. The particle size and magnetic properties of the prepared Fe-Pt were found to be very sensitive to the microwave irradiation power, while influence of exposure time was insignificant. The hysteresis measurements were performed at 300 K to study magnetic properties of the synthesized Fe-Pt as a function of crystallite size. Coercivity and saturation magnetization were observed to be decreasing with diminishing particle size. The microwave-assisted route is found to be a simple technique for direct synthesis of metal alloys and may prove to be a potential tool of high density data storage materials such as Fe-Pt.

  12. Optimization of microwave-assisted extraction with saponification (MAES) for the determination of polybrominated flame retardants in aquaculture samples.

    Science.gov (United States)

    Fajar, N M; Carro, A M; Lorenzo, R A; Fernandez, F; Cela, R

    2008-08-01

    The efficiency of microwave-assisted extraction with saponification (MAES) for the determination of seven polybrominated flame retardants (polybrominated biphenyls, PBBs; and polybrominated diphenyl ethers, PBDEs) in aquaculture samples is described and compared with microwave-assisted extraction (MAE). Chemometric techniques based on experimental designs and desirability functions were used for simultaneous optimization of the operational parameters used in both MAES and MAE processes. Application of MAES to this group of contaminants in aquaculture samples, which had not been previously applied to this type of analytes, was shown to be superior to MAE in terms of extraction efficiency, extraction time and lipid content extracted from complex matrices (0.7% as against 18.0% for MAE extracts). PBBs and PBDEs were determined by gas chromatography with micro-electron capture detection (GC-muECD). The quantification limits for the analytes were 40-750 pg g(-1) (except for BB-15, which was 1.43 ng g(-1)). Precision for MAES-GC-muECD (%RSD < 11%) was significantly better than for MAE-GC-muECD (%RSD < 20%). The accuracy of both optimized methods was satisfactorily demonstrated by analysis of appropriate certified reference material (CRM), WMF-01.

  13. Optimization of microwave-assisted extraction for anthocyanins, polyphenols, and antioxidants from raspberry (Rubus Coreanus Miq.) using response surface methodology.

    Science.gov (United States)

    Teng, Hui; Lee, Won Young; Choi, Yong Hee

    2013-09-01

    Anthocyanins (Acys), polyphenols, and antioxidants were extracted from raspberry (Rubus Coreanus Miq.) using a highly efficient microwave-assisted extraction technique. Different solvents, including methanol, ethanol, and acetone, were tested. The colors of the extracts varied from light yellow to purple red or dark red. SEM and other nutrient analyses verified that ethanol was the most favorable medium for the microwave-assisted extraction of raspberry due to its high output and low toxicity. Effects of process parameters, including microwave power, irradiation time, and solvent concentration, were investigated through response surface methodology. Canonical analysis estimated that the highest total Acys content, total polyphenols content, and antioxidant activity of raspberry were 17.93 mg cyanidin-3-O-glucoside equivalents per gram dry weight, 38.57 mg gallic acid equivalents per gram dry weight, and 81.24%, respectively. The polyphenol compositions of raspberry extract were identified by HPLC with diode array detection, and nine kinds of polyphenols were identified and quantified, revealing that chlorogenic acid, syringic acid, and rutin are the major polyphenols contained in raspberry fruits. Compared with other fruits and vegetables, raspberry contains higher Acy and polyphenol contents with stronger antioxidant activity, suggesting that raspberry fruits are a good source of natural food colorants and antioxidants.

  14. Microwave Assisted Synthesis of Some Bioactive 1,8-Naphthyridinyl Heterocycles and Development of New Synthetic Methodologies in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    K. Mogilaiah

    2005-01-01

    @@ 1Introduction Organic synthesis is a powerful discipline, which forms the basis for numerous other areas of research in chemistry and chemical biology. Organic chemists and chemical research in general are under great demand to develop environmentally benign technologies for the synthesis of well-defined precursors and target molecules.It is at this juncture that the microwave assisted technique comes into the picture.Microwave assisted organic reactions have blossomed into an important tool with a variety of applications,particularly after the development of Microwave-induced Organic Reaction Enhancement (MORE) chemistry techniques[1-3]. These techniques require open vessels with little or no solvents and are free of the risk of explosion. MORE chemistry reactions are extremely fast, cleaner than conventional reactions and lead to higher atom economy. Because of short time requirement, ease of workability and eco-friendliness, microwaves provide an alternative green approach to environmentally unacceptable procedures using toxic and expensive reagents. Recently, the use of inorganic solid supports as catalysts[4] have been developed for solvent-free reactions resulting in higher selectivity, milder conditions and easy handling. Clay catalyzed organic reactions are gaining importance owing to their inexpensive nature and special catalytic attributes in heterogeneous reactions[5].

  15. Recent Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nanotubes and Their Applications

    Directory of Open Access Journals (Sweden)

    Sarah C. Motshekga

    2012-01-01

    Full Text Available The study of coating carbon nanotubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nanotubes in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of carbon nanotubes and metal/oxides is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nanotube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.

  16. Microwave-assisted McMurry polymerization utilizing low-valent titanium for the synthesis of poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] (PNV)

    DEFF Research Database (Denmark)

    Thomas, Henrik; Stuhr-Hansen, Nicolai; Westerlund, Fredrik;

    2009-01-01

    Poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] is synthesized by microwave-assisted McMurry polymerization utilizing low-valent titanium generated from titanium tetrachloride and zinc. The obtained polymer is fluorescent with an average molecular weight of approximately 65,000 g/mol and a pol......Poly 2,6-[1,5-bis(dodecyloxy)naphthylene vinylene] is synthesized by microwave-assisted McMurry polymerization utilizing low-valent titanium generated from titanium tetrachloride and zinc. The obtained polymer is fluorescent with an average molecular weight of approximately 65,000 g...

  17. Exceptional memory performance in the Long Life Family Study

    DEFF Research Database (Denmark)

    Barral, Sandra; Cosentino, Stephanie; Costa, Rosann;

    2013-01-01

    Research to understand variability at the highest end of the cognitive performance distribution has been scarce. Our aim was to define a cognitive endophenotype based on exceptional episodic memory (EM) performance and to investigate familial aggregation of EM in families from the Long Life Family...

  18. Proton-conducting beta"-alumina via microwave-assisted synthesis and mechanism of enhanced corrosion prevention of a zinc rich coating with electronic control

    Science.gov (United States)

    Kirby, Brent William

    Proton Conducting beta-alumina via Microwave Assisted Synthesis. The microwave assisted synthesis of proton conducting Mg- and Li-stabilized NH4+/H3O+ beta-alumina from a solution based gel precursor is reported. beta-alumina is a ceramic fast ion conductor containing two-dimensional sheets of mobile cations. Na +-beta-alumina is the most stable at the sintering temperatures (1740°C) reached in a modified microwave oven, and can be ion exchanged to the K+ form and then to the NH4+/H 3O+ form. beta-phase impurity is found to be 20% for Mg-stabilized material and 30-40% for Li-stabilized material. The composition of the proton conducting form produced here is deficient in NH4 + as compared to the target composition (NH4)1.00 (H3O)0.67Mg0.67Al10.33O 17. Average grain conductivity for Li-stabilized material at 150°C is 6.6x10-3 +/- 1.6x10-3 S/cm with 0.29 +/- 0.05 eV activation energy, in agreement with single crystal studies in the literature. Grain boundary conductivity is found to be higher in the Li-stabilized material. A hydrogen bond energy hypothesis is presented to explain these differences. Li-stabilized NH4+/H3O + beta-alumina is demonstrated as a fuel cell electrolyte, producing 28 muA/cm2 of electrical current at 0.5 V. Mechanism of Enhanced Corrosion Prevention of a Zinc Rich Coating with Electronic Control. A corrosion inhibition system consisting of high weight-loading zinc rich coating applied to steel panels is examined. An electronic control unit (ECU) consisting of a battery and a large capacitor in series with the panel is shown to improve corrosion protection upon immersion in 3% NaCl solution. Weekly solution changes to avoid zinc saturation in solution system were necessary to see well differentiated results. The corrosion product, hydrozincite [Zn5(CO3) 2(OH)6] is observed to deposit within the pores of the coating and on the surface as a barrier layer. Simonkolleite [Zn5(OH) 8Cl2·H2O] is found to form in place of the original zinc particles

  19. Microwave assisted synthesis of molybdenum and tungsten tetracarbonyl complexes with a pyrazolylpyridine ligand. Crystal structure of cis-[Mo(CO)4{ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate}].

    Science.gov (United States)

    Coelho, Ana C; Almeida Paz, Filipe A; Klinowski, Jacek; Pillinger, Martyn; Gonçalves, Isabel S

    2006-12-06

    We report the one-step syntheses in good yields of the complexes cis-[M(CO)4(pzpy)] {M = Mo, W; pzpy = ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate} directly from the corresponding M(CO)6 starting materials by using microwave-assisted heating and reaction times of either 30 s (M = Mo) or 15 min (M = W). The structure of the molybdenum tetracarbonyl complex was determined by single crystal X-ray diffraction. The compound is monomeric and the molybdenum atom has a highly distorted octahedral geometry. The close packing of the individual cis-[Mo(CO)4(pzpy)] species is essentially driven by the need to fill the space effectively, closely mediated by weak C-H-O and pi-pi interactions.

  20. Size-dependent and intra-band photoluminescence of NiS2 nano-alloys synthesized by microwave assisted hydrothermal technique

    CSIR Research Space (South Africa)

    Linganiso, C

    2013-03-01

    Full Text Available Journal of Alloys and Compounds March 2013/ Vol 552, pp 345-350 Size-dependent and intra-band photoluminescence of NiS2 nano- alloys synthesized by microwave assisted hydrothermal technique Ella Cebisa Linganiso a,b, Sabelo Dalton Mhlanga b...

  1. Mathematical modeling and Monte Carlo simulation of thermal inactivation of non-proteolytic Clostridium botulinum spores during continuous microwave-assisted pasteurization

    Science.gov (United States)

    The objective of this study is to develop a mathematical method to simulate the internal temperature history of products processed in a prototype microwave-assisted pasteurization system (MAPS) developed by Washington State University. Two products (10 oz. beef meatball trays and 16 oz. salmon fill...

  2. A facile microwave-assisted synthesis of 8,9-cycloalkathieno[3,2-] [1,2,4]triazolo[1,5-]pyrimidin-5(6)-ones

    Indian Academy of Sciences (India)

    Rajwinder Kaur; D Pran Kishore; B Lakshmi Narayana; K Venkat Rao; C Balakumar; V Rajkumar; A Raghuram Rao

    2011-01-01

    A new series of fused thieno[3,2-][1,2,4]triazolo[1,5-]pyrimidinones was synthesized by condensation of ethyl-3-cyano-4,5,6,7-tetrahydrobenzo[]thiophene-2-yl carbamate with aryl acid hydrazides in quantitative yields using a facile, one-pot procedure under microwave-assisted conditions.

  3. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory

    Science.gov (United States)

    Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W.

    2006-01-01

    A detailed investigation of the clay-catalyzed condensation of sesamol and other phenols with 3-methyl-2-butenal to give methylenedioxyprecocene (MDP) and other chromenes is presented. The clay-catalyzed microwave-assisted condensation of sesamol with 3-methyl-2-butenal is appropriate for incorporation into undergraduate organic laboratory…

  4. Optical and morphological properties of ZnO- and TiO2-derived nanostructures synthesized via a microwave-assisted hydrothermal method

    CSIR Research Space (South Africa)

    Moloto, N

    2012-01-01

    Full Text Available A microwave-assisted hydrothermal method was used to synthesize ZnO and TiO2 nanostructures. The experimental results show that the method resulted in crystalline monodispersed ZnO nanorods that have pointed tips with hexagonal crystal phase. TiO2...

  5. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory

    Science.gov (United States)

    Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W.

    2006-01-01

    A detailed investigation of the clay-catalyzed condensation of sesamol and other phenols with 3-methyl-2-butenal to give methylenedioxyprecocene (MDP) and other chromenes is presented. The clay-catalyzed microwave-assisted condensation of sesamol with 3-methyl-2-butenal is appropriate for incorporation into undergraduate organic laboratory…

  6. Extraction of Maltol from Fraser Fir: A Comparison of Microwave-Assisted Extraction and Conventional Heating Protocols for the Organic Chemistry Laboratory

    Science.gov (United States)

    Koch, Andrew S.; Chimento, Clio A.; Berg, Allison N.; Mughal, Farah D.; Spencer, Jean-Paul; Hovland, Douglas E.; Mbadugha, Bessie; Hovland, Allan K.; Eller, Leah R.

    2015-01-01

    Two methods for the extraction of maltol from Fraser fir needles are performed and compared in this two-week experiment. A traditional benchtop extraction using dichloromethane is compared to a microwave-assisted extraction using aqueous ethanol. Students perform both procedures and weigh the merits of each technique. In doing so, students see a…

  7. A study of pressureless microwave sintering, microwave-assisted hot press sintering and conventional hot pressing on properties of aluminium/alumina nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Abedinzadeh, Reza; Safavi, Seyed Mohsen; Karimzadeh, Fathallah [Isfahan University, Isfahan (Iran, Islamic Republic of)

    2016-05-15

    Bulk Al/4wt-%Al{sub 2}O{sub 3} nanocomposites were prepared by consolidating nanocomposite powders using pressureless microwave sintering, microwave-assisted hot press sintering and conventional hot pressing techniques. Microstructural observations revealed that the microwave-assisted hot press sintering at different sintering temperatures of 400.deg.C and 500.deg.C resulted in more densification and smaller grain size for Al/Al{sub 2}O{sub 3} nanocomposite as compared with the conventional hot pressing. Moreover, the application of pressure in microwave sintering process led to more densification and grain growth. Mechanical properties resulting from microhardness and nanoindentation tests were also compared between three-method processed samples. It was found that the microwave-assisted hot-pressed sample exhibited higher hardness and elastic modulus in comparison with microwave-sintered and conventional hot-pressed samples. The improvement in the mechanical properties can be ascribed to lower porosity of microwave-assisted hot-pressed sample.

  8. Extraction of Maltol from Fraser Fir: A Comparison of Microwave-Assisted Extraction and Conventional Heating Protocols for the Organic Chemistry Laboratory

    Science.gov (United States)

    Koch, Andrew S.; Chimento, Clio A.; Berg, Allison N.; Mughal, Farah D.; Spencer, Jean-Paul; Hovland, Douglas E.; Mbadugha, Bessie; Hovland, Allan K.; Eller, Leah R.

    2015-01-01

    Two methods for the extraction of maltol from Fraser fir needles are performed and compared in this two-week experiment. A traditional benchtop extraction using dichloromethane is compared to a microwave-assisted extraction using aqueous ethanol. Students perform both procedures and weigh the merits of each technique. In doing so, students see a…

  9. Microwave Assisted Synthesis and Antimicrobial Activities of Some 2-Amino-4-aryl-3-cyano-6-(4’-hydroxy phenyl-pyridines

    Directory of Open Access Journals (Sweden)

    Priya Gothwal

    2011-01-01

    Full Text Available 4’-Hydroxy chalcones were treated with malononitrile in the presence of ammonium acetate under solventless microwave assisted condition to get 2-amino-4-aryl-3-cyano-6-(4’-hydroxy phenyl-pyridines. The prepared compounds were screened for their antimicrobial activity; some of them have exhibited promising antimicrobial activity.

  10. Microwave-assisted synthesis and complexation of luminescent cyanobipyridyl-zinc(II) bis(thiolate) complexes with intrinsic and ancillary photophysical tunability.

    Science.gov (United States)

    Bagley, Mark C; Lin, Zhifan; Pope, Simon J A

    2010-04-07

    A series of cyanobipyridine-derived zinc(II) bis(thiolate) complexes are prepared rapidly and efficiently by a microwave-assisted cross-coupling/complexation sequence and display luminescence that can be modulated using intrinsic functionality and ancillary ligands.

  11. Fabrication of Zeolite A Rods with Irregular Macropores by Self-assembly of Zeolite A Microcrystals Using Microwave-assisted Hydrothermal Synthesis

    Institute of Scientific and Technical Information of China (English)

    程志林; 万惠霖; 刘赞

    2004-01-01

    Zeolite A rods by self-assembly of zeolite A microcrystal were successfully synthesized by microwave-assisted hydrothermal synthesis. The average size of zeolite crystals consisting of self-assembling materials was about 300 nm and the length of zeolite rods was in the range of 15-30 μm.

  12. Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods

    Science.gov (United States)

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-01

    In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (24) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL-1 with detection limit of 6.7 ng mL-1 (3δB/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n = 7, c = 50 ng mL-1). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination.

  13. The microwave assisted synthesis of 1-alkyl-3-methylimidazolium bromide as potential corrosion inhibitor toward carbon steel in 1 M HCl solution saturated with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Pasasa, Norman Vincent A., E-mail: npasasa@gmail.com; Bundjali, Bunbun; Wahyuningrum, Deana [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha No. 10 Bandung, Jawa Barat (Indonesia)

    2015-09-30

    Injection of corrosion inhibitor into the fluid current of oil and gas pipelines is an effective way to mitigate corrosion rate on the inner-surface parts of pipelines, especially carbon steel pipelines. In this research, two alkylimidazolium ionic liquids, 1-decyl-3-methylimidazolium bromide (IL1) and 1-dodecyl-3-methylimidazolium bromide (IL2) have been synthesized and studied as a potential corrosion inhibitor towards carbon steel in 1 M HCl solution saturated with carbon dioxide. IL1 and IL2 were synthesized using microwave assisted organic synthesis (MAOS) method. Mass Spectrometry analysis of IL1 and IL2 showed molecular mass [M-H+] peak at 223.2166 and 251.2484, respectively. The FTIR,{sup 1}H-NMR and {sup 13}C-NMR spectra confirmed that IL1 and IL2 were successfully synthesized. Corrosion inhibition activity of IL1 and IL2 were determined using weight loss method. The results showed that IL1 and IL2 have the potential as good corrosion inhibitors with corrosion inhibition efficiency of IL1 and IL2 are 96.00% at 100 ppm (343 K) and 95.60% at 50 ppm (343 K), respectively. The increase in the concentration of IL1 and IL2 tends to improve their corrosion inhibition activities. Analysis of the data obtained from the weight loss method shows that the adsorption of IL1 and IL2 on carbon steel is classified into chemisorption which obeys Langmuir’s adsorption isotherm.

  14. Microwave-assisted ultraviolet digestion of petroleum coke for the simultaneous determination of nickel, vanadium and sulfur by ICP-OES.

    Science.gov (United States)

    Oliveira, Jussiane S S; Picoloto, Rochele S; Bizzi, Cezar A; Mello, Paola A; Barin, Juliano S; Flores, Erico M M

    2015-11-01

    A method for the simultaneous determination of Ni, V and S in petroleum coke by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted ultraviolet digestion (MW-UV) in closed vessels was proposed. Digestion was performed using electrodeless discharge lamps positioned inside quartz vessels and turned on by microwave radiation. The following parameters were evaluated: HNO3 concentration (15 mL of 1, 4, 7, 10 or 14.4 mol L(-1)), volume of H2O2 (30%, 1 or 3 mL), sample mass (100, 250 or 500 mg) and heating time (40 or 60 min) with or without the use of UV lamps. Digestion efficiency was evaluated by the determination of the residual carbon content (RCC) in digests. Using UV lamps lower RCC was obtained and the combination of 4 mol L(-1) HNO3 with 3 mL of H2O2 and 60 min of heating allowed a suitable digestion of up to 500 mg of petroleum coke (RCCdigestion of petroleum coke by microwave-induced combustion) and with a certified reference material of petroleum coke was between 96 and 101%. The proposed method was considered as advantageous when compared to American Society for Testing and Materials method because it allowed the simultaneous determination of Ni, V and S with lower limit of detection (0.22, 0.12 and 8.7 µg g(-1) for Ni, V and S, respectively) avoiding the use of concentrated nitric acid and providing digests suitable for routine analysis by ICP-OES.

  15. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingting, E-mail: tingtingli1983@hotmail.com [Department of Chemistry and Chemical Engineering, Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Changsha 410082 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Department of Environment and Chemical Engineering, Key Laboratory of Jiangxi Province for Ecological Diagnosis, Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian, E-mail: sllou@hnu.edu.cn [Department of Chemistry and Chemical Engineering, Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Changsha 410082 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Department of Environment and Chemical Engineering, Key Laboratory of Jiangxi Province for Ecological Diagnosis, Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China); Yang, Lixia [Department of Environment and Chemical Engineering, Key Laboratory of Jiangxi Province for Ecological Diagnosis, Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China)

    2013-10-15

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C{sub 16}mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O{sub 2}·{sup −}, Br{sup 0} and photogenerated h{sup +} play key roles in the photocatalytic degradation process.

  16. Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods.

    Science.gov (United States)

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-25

    In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (2(4)) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL(-1) with detection limit of 6.7 ng mL(-1) (3δB/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n=7, c=50 ng mL(-1)). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination. Copyright © 2014. Published by Elsevier B.V.

  17. Microwave-assisted green synthesis of silver nanoparticles from Fraxinus excelsior leaf extract and its antioxidant assay

    Science.gov (United States)

    Parveen, Mehtab; Ahmad, Faheem; Malla, Ali Mohammed; Azaz, Shaista

    2016-02-01

    The biosynthesis of nanoparticles has been proposed as a cost effective and environmentally benevolent alternative to chemical and physical methods. In the present study, microwave assisted synthesis of silver nanoparticles (AgNPs) has been demonstrated using leaf extract of Fraxinus excelsior reducing aqueous AgNO3 solution. The synthesized nanoparticles have been characterized on the basis of fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. The presence of a characteristic surface plasmon resonance (SPR) absorption band at 425 nm in UV-Vis reveals the reduction of silver metal ions into silver nanoparticles. FT-IR analysis was carried out to probe the possible functional group involved in the synthesis of AgNPs. Further leaf extracts and AgNPs were evaluated for antiradical scavenging activity by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay.

  18. Microwave-assisted synthesis of spheroidal vaterite CaCO 3 in ethylene glycol-water mixed solvents without surfactants

    Science.gov (United States)

    Chen, Yinxia; Ji, Xianbing; Wang, Xiaobo

    2010-10-01

    Spheroidal vaterite CaCO 3 composed of irregular nanoparticals have been synthesized by a fast microwave-assisted method. The structures are fabricated by the reaction of Ca(CH 3COO) 2 with (NH 4) 2CO 3 at 90 °C in ethylene glycol-water mixed solvents without any surfactants. The diameters of the spheroidal vaterite CaCO 3 range from 1 to 2 μm, and the average size of the nanoparticals is about 70 nm. Bundle-shaped aragonite and rhombohedral calcite are also obtained by adjusting the experimental parameters. Our experiments show that the ratio of ethylene glycol to water, microwave power, reaction time, and two sources of ammonium ions and acetate anions are key parameters for the fabrication of spheroidal vaterite CaCO 3. A possible growth mechanism for the spheroidal structures has been proposed, which suggests that the spheroidal vaterite CaCO 3 is formed by an aggregation mechanism.

  19. Magnetic and Structural Properties of Cobalt- and Zinc-Substituted Nickel Ferrite Synthesized by Microwave-Assisted Hydrothermal Method

    Science.gov (United States)

    Sinfrônio, F. S. M.; Santana, P. Y. C.; Coelho, S. F. N.; Silva, F. C.; de Menezes, A. S.; Sharma, S. K.

    2017-02-01

    Ceramic spinel-based ferrites of cobalt, nickel and zinc were prepared by means of the microwave-assisted hydrothermal method. All samples were thoroughly characterized using different techniques for their structural, compositional, phonic and magnetic properties. The Rietveld analysis of x-ray powder diffraction data revealed the crystallinity as well single-phase partially inverse spinel structure. Wavelength dispersive x-ray fluorescence measurement indicates a good correlation between the empirical stoichiometry. The estimated average crystallite size varies between 9 nm and 13 nm (XRPD) and 6 and 14 nm for high-resolution transmission electron microscopy measurements. In addition, the observed micro-strain varies in the range of 0.01-0.6%. All samples show a quasi-spherical morphology and slight agglomeration. Infrared and Raman data spectra exhibit characteristic modes for spinel-based ferrites. Direct current magnetic measurements indicate behavior typical of magnetically soft materials system at 300 K.

  20. Using GC to determinate polychlorinated biphenyls in soil after pretreated with microwave-assisted alkaline degradation method

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-qing; LI Gong-ke; LUO Mei-zhong; ZHANG Zhan-xia

    2006-01-01

    A new and simple microwave-assisted alkaline degradation (MAAD) method for the elimination of organochlorine-pesticide interference on the determination of polychlorinated biphenyls (PCBs) in soil by GC is presented. Under the optimal conditions, the interference of α-HCH, β-HCH, γ-HCH, δ-HCH, o. p'-DDT, p. p'-DDD and p. p'-DDT could be eliminated completely, and p. p'-DDE, Aldrin and Dieldrin could be partially eliminated; however, Dieldrin could be completely eliminated by using concentrated sulphuric acid. The method was evaluated by analyzing the spiked-soil sample. The mean recovery obtained was 84. 1%and the Relative Standard Deviation (RSD) was 2.7%. Experimental results also indicate that the degradation of the interference and the extraction of the target analytes, PCBs, could be carried out simultaneously. Compared with the traditional methods, the MAAD method is a rapid, efficient and solvent-saving method.

  1. Microwave assisted synthesis of 2′- / 3′-azaflavones/azaflavonones and their N-alkyl derivatives

    Directory of Open Access Journals (Sweden)

    Ahmet Yaşar

    2016-12-01

    Full Text Available 2′-Azaflavonone (6 and 3′-azaflavonone (7; were synthesized by a simple environmentally friendly microwave-assisted one-pot method for the cyclization of 2′-hydroxy β′-2-azachalcanon-β-ol (1, 2′-hydroxy (E-2-azachalcone (2, 2′-hydroxy (E-3-azachalcone (3 under solventless conditions using K-10 clay. In addition to these synthesis, 3-(pyridin-2-yl methyl-2′-azaflavone (8 and 3-(pyridin-3-yl methyl-3′-azaflavone (9 were synthesized using silica-supported sodium hydrogen sulphate then the treatment with base, respectively. Additionally, for antimicrobial activities N-alkyl substituted 3′-azaflavonium and 2′-azaflavonium bromides (10-12 were prepared from compounds 3, 4 - 5 and 8 - 9.

  2. Microwave-Assisted Improved Synthesis of Oxazolidin-2-ones, Oxazolidine-2-thiones and Thiazolidine-2-thione Chiral Auxiliaries

    Directory of Open Access Journals (Sweden)

    Mario Ordóñez

    2011-10-01

    Full Text Available A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S-phenylalaninol, (S-phenylglycinol, (S-valinol and (1S, 2R-norephedrine with ethyl carbonate or carbon disulfide under the appropriate and specific microwave reaction conditions, led to an efficient synthesis of some oxazolidin-2-ones, oxazolidine-2-thiones and thiazolidine-2-thiones. The methodology reported in this paper provides these chiral auxiliaries with improved yields and a remarkable reduction on the reaction times, particularly in the case of thiazolidine-2-thiones, as compared with the conventional methods. All the auxiliaries prepared here show spectroscopic data in full agreement with those previously reported in the literature.

  3. Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Makama, A. B., E-mail: abmakama@hotmail.com; Salmiaton, A., E-mail: mie@upm.edu.my; Choong, T. S. Y., E-mail: csthomas@upm.edu.my; Abdullah, N., E-mail: nhafizah@upm.edu.my [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia); Saion, E. B., E-mail: elias@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia)

    2016-07-06

    Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl{sub 2} and Na{sub 2}S) in the presence of fixed amount of ZnCO{sub 3} nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-C{sub t}/C{sub 0}) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

  4. Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots.

    Science.gov (United States)

    Sai, Li-Man; Kong, Xiang Yang

    2011-05-27

    A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

  5. Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots

    Directory of Open Access Journals (Sweden)

    Sai Li-Man

    2011-01-01

    Full Text Available Abstract A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

  6. Mixtures of Steel-Making Slag and Carbons as Catalyst for Microwave-Assisted Dry Reforming of CH4

    Institute of Scientific and Technical Information of China (English)

    Jose M. BERMUDEZ; Beatriz FIDALGO; Ana ARENILLAS; J. Angel MENENDEZ

    2012-01-01

    The use of steel-making slag as catalysts for microwave-assisted dry reforming of CH4 was studied.Two carbon materials (an activated carbon and a metallurgical coke),mixtures of the carbon materials and Fe-rich slag,and mixtures of the carbon materials and Ni/Al2O3 were tested as catalysts.The mixtures of slag with carbons gave rise to higher and steadier conversions than those achieved over the carbon materials alone.In addition,the use of the metallurgical coke mixed with metal-rich catalysts gave rise to remarkable results.Thus,no CH4 and CO2 conversions were achieved when coke was used alone,whereas high conversions were obtained when it was mixed with the metal-rich catalysts.

  7. Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens

    Science.gov (United States)

    Karthik, K.; Dhanuskodi, S.; Gobinath, C.; Sivaramakrishnan, S.

    2015-03-01

    CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus.

  8. Voltammetric and liquid chromatographic identification of organic products of microwave-assisted wet ashing of biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, K.W.; Kingston, H.M.; MacCrehan, W.A.; Kock, W.F.

    1988-10-01

    Residual organic species in nitric acid digest of freeze-dried bovine liver (NBS SRM 1577a) have been identified by use of voltammetry, liquid chromatography, spectrophotometry, and classical chemical tests. Data from these techniques show that major products of microwave-assisted dissolution by nitric acid include o-, m-, and p-nitrobenzoic acids (NBA). In addition to these compounds, other organic species present in these digests irreversibly complex copper, but not zinc, and result in low values for copper by polarography. The NBAs and these other organic species are all eliminated by refluxing the nitric acid digest in perchloric acid at atmospheric pressure. Polarographic results obtained for copper following treatment with perchloric acid agree with the certified value. The use of voltammetry in the evaluation of wet ashing procedures is discussed.

  9. Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu; Li, Pingjian; Wang, Zegao; Cao, Bingqiang; Qi, Fei; Liu, Jinbo; Qiu, Zhiwen; Zhang, Wanli

    2017-01-01

    For the first time, a facile, ultrafast, ammonia-driven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs) at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL) emission peak at 390 nm is observed, which might be attributed to the doped nitrogen atoms into the GQDs. An interesting red-shift is observed by comparing the FL excitation spectra to the UV-visible absorption spectra. Based on the optical properties, the detailed Jablonski diagram representing the energy level structure of NGQDs is derived.

  10. Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

    Directory of Open Access Journals (Sweden)

    Zheng Binjie

    2016-06-01

    Full Text Available For the first time, a facile, ultrafast, ammonia-driven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL emission peak at 390 nm is observed, which might be attributed to the doped nitrogen atoms into the GQDs. An interesting red-shift is observed by comparing the FL excitation spectra to the UV-visible absorption spectra. Based on the optical properties, the detailed Jablonski diagram representing the energy level structure of NGQDs is derived.

  11. Optimization and comparison of ultrasound/microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomatoes.

    Science.gov (United States)

    Lianfu, Zhang; Zelong, Liu

    2008-07-01

    The extracting technology including ultrasonic and microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomato paste were optimized and compared. The results showed that the optimal conditions for UMAE were 98 W microwave power together with 40 KHz ultrasonic processing, the ratio of solvents to tomato paste was 10.6:1 (V/W) and the extracting time should be 367 s; as for UAE, the extracting temperature was 86.4 degrees C, the ratio of the solvents to tomato paste was 8.0:1 (V/W) and the extracting time should be 29.1 min, while the percentage of lycopene yield was 97.4% and 89.4% for UMAE and UAE, respectively. These results implied that UMAE was far more efficient extracting method than UAE.

  12. Immobilization of trypsin on graphene oxide for microwave-assisted on-plate proteolysis combined with MALDI-MS analysis.

    Science.gov (United States)

    Xu, Guobin; Chen, Xiaoyi; Hu, Jianhua; Yang, Pengyuan; Yang, Dong; Wei, Liming

    2012-06-21

    With an ultra-high surface area and abundant functional groups, graphene oxide (GO) provides an ideal substrate for the immobilization of trypsin. We demonstrated that trypsin could be immobilized on GO sheets assisted by polymers as molecular spacers to maintain the activity of the enzyme. And with the trypsin-linked GO as the enzyme immobilization probe, a novel microwave-assisted on-plate digestion method has been developed with subsequent analysis by MALDI-MS. The feasibility and performance of the digestion approach were demonstrated by the proteolysis of standard proteins. The results show that this novel approach substantially accelerated proteolysis and reduced the time required for traditional procedures involving on-plate enzymatic digestion and sample preparation prior to MALDI-MS analysis. The novel digestion approach is simple and efficient, offering great promise for high throughput protein identification.

  13. Synthesis of an Isoindoline-Annulated, Tricyclic Sultam Library via Microwave-Assisted, Continuous-Flow Organic Synthesis (MACOS).

    Science.gov (United States)

    Ullah, Farman; Zang, Qin; Javed, Salim; Porubsky, Patrick; Neuenswander, Benjamin; Lushington, Gerald H; Hanson, Paul R; Organ, Michael G

    2012-01-01

    A microwave-assisted, continuous-flow organic synthesis (MACOS) protocol for the synthesis of an isoindoline-annulat-ed, tricyclic sultam library, utilizing a Heck-aza-Michael (HaM) strategy, is reported. This sequence involves a Heck reaction on vi-nylsulfonamides with batch microwave heating followed by a one-pot, sequential intramolecular aza-Michael cyclization/Boc-deprot-ection using MACOS. Subsequent cyclization with either 1,1'-carbonyldiimidazole or chloromethyl pivalate using MACOS provided an array of tricyclic sultams. This efficient three-step protocol requires only a few hours to produce the target sultams starting from simple starting materials. Using this strategy, a 38-member library of isoindoline-annulated sultams was generated in good to excellent overall yields (53-87%).

  14. Determination of flumequine and oxolinic acid in sediments and soils by microwave-assisted extraction and liquid chromatography-fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Prat, M.D. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain)]. E-mail: mdprat@ub.edu; Ramil, D. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Compano, R. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Hernandez-Arteseros, J.A. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain); Granados, M. [Departament de Quimica Analitica, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona (Spain)

    2006-05-17

    A method is reported for the determination of the quinolones oxolinic acid and flumequine in aquatic sediments and agricultural soils. The analytes are extracted by liquid-liquid partitioning between a sample homogenated in an aqueous buffer solution and dichloromethane. Microwave-assisted extraction (MAE) was tested to improve the speed and efficiency of the extraction process. The parameters affecting the efficiency of MAE, such as irradiation time and temperature, were studied. The clean-up consists of back-extraction in 1 M sodium hydroxide. The determination is carried out by reversed phase liquid chromatography on an octyl silica-based column and fluorimetric detection. The optimised method was applied to the analysis of two sediments and one agricultural soil spiked with the analytes. The absolute recovery rates for the whole process range from 79% to 94% (RSD 3-7%), and detection limits are in the low {mu}g kg{sup -1} level.

  15. Synthesis of an Isoindoline-Annulated, Tricyclic Sultam Library via Microwave-Assisted, Continuous-Flow Organic Synthesis (MACOS)

    Science.gov (United States)

    Ullah, Farman; Zang, Qin; Javed, Salim; Porubsky, Patrick; Neuenswander, Benjamin; Lushington, Gerald H.

    2013-01-01

    A microwave-assisted, continuous-flow organic synthesis (MACOS) protocol for the synthesis of an isoindoline-annulat-ed, tricyclic sultam library, utilizing a Heck–aza-Michael (HaM) strategy, is reported. This sequence involves a Heck reaction on vi-nylsulfonamides with batch microwave heating followed by a one-pot, sequential intramolecular aza-Michael cyclization/Boc-deprot-ection using MACOS. Subsequent cyclization with either 1,1′-carbonyldiimidazole or chloromethyl pivalate using MACOS provided an array of tricyclic sultams. This efficient three-step protocol requires only a few hours to produce the target sultams starting from simple starting materials. Using this strategy, a 38-member library of isoindoline-annulated sultams was generated in good to excellent overall yields (53–87%). PMID:24244052

  16. Microwave-Assisted Syntheses of Bioactive Seven-Membered, Macro-Sized Heterocycles and Their Fused Derivatives

    Directory of Open Access Journals (Sweden)

    Mohsine Driowya

    2016-08-01

    Full Text Available This review describes the recent advances in the microwave-assisted synthesis of 7-membered and larger heterocyclic compounds. Several types of reaction for the cyclization step are discussed: Ring Closing Metathesis (RCM, Heck and Sonogashira reactions, Suzuki-Miyaura cross-coupling, dipolar cycloadditions, multi-component reactions (Ugi, Passerini, etc. Green syntheses and solvent-free procedures have been introduced whenever possible. The syntheses discussed herein have been selected to illustrate the huge potential of microwave in the synthesis of highly functionalized molecules with potential therapeutic applications, in high yields, enhanced reaction rates and increased chemoselectivity, compared to conventional methods. More than 100 references from the recent literature are listed in this review.

  17. Determination of cadmium by electrothermal atomic absorption spectrometry after microwave-assisted digestion of animal tissues and sewage sludges.

    Science.gov (United States)

    Chakraborty, R; Das, A K; Cervera, M L; De La Guardia, M

    1996-04-01

    The determination of cadmium in different sample types has been carried out by electrothermal atomization atomic absorption spectrometry with D(2)-background correction using a unpyrocoated graphite tube, after pressurized microwave-assisted digestion. Five chemical modifiers [(NH(4))(2)HPO(4), Pd(NO)(3))(2), Ni(NO(3))(2), thiourea and Triton X-100] have been assayed and nickel nitrate has been found to be most effective for an accurate determination of cadmium in mussel tissue, pig kidney and sewage sludge. The characteristic mass of the method is of the order of 1 pg and the limit of detection is lower than 0.1 ng/ml.

  18. Microwave-Assisted Preparation of CdS Nanoparticles in a Halide-Free Ionic Liquid and Their Photocatalytic Activities

    Institute of Scientific and Technical Information of China (English)

    M. ESMAILI, A; HABIBI-YANGJEH

    2011-01-01

    A microwave-assisted (4-6 min) method was used for the preparation ofCdS nanoparticles in 1-ethyl-3-methylimidazolium ethyl sulfate, a halide-free room-temperature ionic liquid (RTIL). The samples were characterized by powder X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy. Diffuse reflectance spectra showed a 1.33 eV blue shift relative to bulk CdS. The photocatalytic activities of the nanoparticles for photodegradation of methylene blue (MB) using UV and visible light were measured. The photodegradation of MB decreased with calcination temperature. First order rate constants for the reaction under visible and UV irradiations over the nanoparticles prepared in the RTIL rich media were 5.4 and 2.5 higher, respectively, than the sample prepared in water.

  19. Reduced leakage current and improved ferroelectricity in magneto-electric composite ceramics prepared with microwave assisted radiant hybrid sintering

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar Upadhyay

    2015-04-01

    Full Text Available Structural, electrical and magnetic properties of magneto-electric composite ceramics viz., 0.9 BaTi0.95Sn0.05O3 (BTSO- 0.1 Ni0.8Zn0.2Fe2O4 (NZFO prepared with microwave assisted radiant hybrid sintering (MARH are reported. Phase purity and isovalent substitution of Ti4+ by Sn4+ of the samples is confirmed from x-ray diffraction and 119Sn Mossbauer measurements respectively. Significant suppression of leakage current and improvement of ferroelectricity is observed for the composites prepared with MARH. The observed results are explained in terms of uniform dispersion of ferrite (NZFO phase in the ferroelectric (BTSO matrix as evidenced from back-scattered scanning electron micrographs.

  20. Microwave-assisted synthesis of carbon dots and its potential as analysis of four heterocyclic aromatic amines.

    Science.gov (United States)

    López, C; Zougagh, M; Algarra, M; Rodríguez-Castellón, E; Campos, B B; Esteves da Silva, J C G; Jiménez-Jiménez, J; Ríos, A

    2015-01-01

    Fluorescent water soluble carbon nanoparticles, in short carbon dots (CDs), was synthesized from lactose by microwave assisted hydrochloric acid method. Characterized by TEM and DLS to obtain the morphology shape (average 10nm in size), with a higher negative surface charge supported by the composition was obtained by XPS spectroscopy. The maximum of the emission was centered at 450 nm with a lifetime of 2.1 ns. Without further functionalization of the CDs a nanosensor was obtained that responded exponentially to HAAs in the 0.35-0.45 mg L(-1) concentration range by fluorescence static quenching, demonstrated by the lifetime analysis of the CDs in presence of HAAs. Some amino compounds were selected as model for interferences to evaluate the selectivity of this method, showing a notorious added value, with recoveries around 98%. The accuracy of the method was in terms of RSD about 2.5%. The results suggest their promising applications in chemical sensing.