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Sample records for microwave assisted solvent

  1. 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.

  2. Microwave assisted solvent free synthesis of 1,3-diphenylpropenones

    Directory of Open Access Journals (Sweden)

    Sarma Jadab C

    2011-02-01

    Full Text Available Abstract Background 1,3-Diphenylpropenones (chalcones are well known for their diverse array of bioactivities. Hydroxyl group substituted chalcones are the main precursor in the synthesis of flavonoids. Till date various methods have been developed for the synthesis of these very interesting molecules. Continuing our efforts for the development of simple, eco-friendly and cost-effective methodologies, we report here a solvent free condensation of aryl ketones and aldehydes using iodine impregnated alumina under microwave activation. This new protocol has been applied to a variety of substituted aryl carbonyls with excellent yield of substituted 1,3-diphenylpropenones. Results Differently substituted chalcones were synthesized using iodine impregnated neutral alumina as catalyst in 79-95% yield in less than 2 minutes time under microwave activation without using any solvent. The reaction was studied under different catalytic conditions and it was found that molecular iodine supported over neutral alumina gives the best yield. The otherwise difficult single step condensation of hydroxy substituted aryl carbonyls is an attractive feature of this protocol to obtain polyhydroxychalcones in excellent yields. In order to find out the general applicability of this new endeavor it was successfully applied for the synthesis of 15 different chalcones including highly bioactive prenylated hydroxychalcone xanthohumol. Conclusion A new, simple and solvent free method was developed for the synthesis of substituted chalcones in environmentally benign way. The mild reaction conditions, easy work-up, clean reaction profiles render this approach as an interesting alternative to the existing methods.

  3. 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.

  4. [Investigation on low power microwave irradiation-assisted enzymatic esterification in organic solvent by fluorescence spectroscopy].

    Science.gov (United States)

    Min, Rui; Fang, Yun; Xia, Yong-Mei

    2009-02-01

    The authors studied the fluorescence change of immobilized lipase from Rhizomucor miehei in the microwave assisted enzymatic esterification of caprylic acid and butanol in organic medium by investigating the fluorescence spectra in solvent or aqueous buffer after incubating the lipase with the solvent, caprylic acid and butanol under microwave irradiation, respectively. A comparison was made with the conventional heated enzymatic esterification in the solvents. Both of the heating modes, the microwave irradiation and conventional heating, can enhance the fluorescence intensity without shifting the emission wavelength of the lipase. In the circumstance that the irradiation can accelerate the esterification, the irradiation can enhance the exposure of the lipase protein molecules in the aqueous environment after incubating the lipase with solvents or the substrates. The effect of the reaction mixture on the fluorescence intensity was dominated by the solvents. The trend of the plot of log P versus the initial reaction rate was similar to that of log P versus fluorescence intensity of lipase in aqueous buffer after esterification; but was different from that of log P versus fluorescence intensity of lipase in organic medium.

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

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    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.

  6. Rapid and solvent-saving liquefaction of woody biomass using microwave-ultrasonic assisted technology.

    Science.gov (United States)

    Lu, Zexiang; Wu, Zhengguo; Fan, Liwei; Zhang, Hui; Liao, Yiqiang; Zheng, Deyong; Wang, Siqun

    2016-01-01

    A novel process to rapidly liquefy sawdust using reduced quantities of solvent, was successfully carried out via microwave-ultrasonic assisted technology (MUAT) in a sulphuric acid/polyethylene glycol 400-glycerol catalytic system. The influences of some key parameters on the liquefaction yield were investigated. The results showed that compared with traditional liquefaction, the introduction of MUAT allowed the solvent dosage to be halved and shortened the liquefaction time from 60 to 20 min. The liquefaction yield reached 91% under the optimal conditions. However, the influence on the yield of some parameters such as catalyst concentration, was similar to that of traditional liquefaction, indicating that the application of MUAT possibly only intensified heat and mass transfer rather than altering either the degradation mechanism or pathway. The introduction of MUAT as a process intensification technology has good industrial application potential for woody biomass liquefaction.

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

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    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.

  8. 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)

  9. 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.

  10. 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.

  11. Microwave-assisted silica-promoted solvent-free synthesis of triazoloquinazolinone and benzimidazoquinazolinones

    Indian Academy of Sciences (India)

    G Krishnamurthy; K V Jagannath

    2013-07-01

    The derivative of triazolo/benzimidazoquinazolinones is prepared via silica-promoted solvent-free method using microwave irradiation with an excellent yield. The newly synthesized compounds were characterized by various techniques like IR, NMR and Mass spectroscopy. The compound with 1a was crystallized and analysed by single crystal X-ray diffraction studies.

  12. 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.

  13. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

    Energy Technology Data Exchange (ETDEWEB)

    Wang Ziming, E-mail: wangziming@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ma Qiang [Chinese Academy of Inspection and Quarantine, Beijing 100123 (China); Lu Chunmei [College of Technology Center, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Dong Deming [College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2013-01-14

    Highlights: Black-Right-Pointing-Pointer An absorbing microwave {mu}-SPE device packed with activated carbon was used. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to enrich the analytes. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to heat samples directly. Black-Right-Pointing-Pointer MAE-{mu}-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction ({mu}-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave {mu}-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in {mu}-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave {mu}-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 Degree-Sign C for 10 min. The extracts obtained by MAE-{mu}-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%.

  14. Microwave-Assisted Solvent-Free Synthesis of Zeolitic Imidazolate Framework-67

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    Heng Zhang

    2016-01-01

    Full Text Available A microporous metal-organic framework (MOF, cobalt-based zeolitic imidazolate framework-67 (ZIF-67, was synthesized by the combination of solvent-free hand-mill and microwave irradiation, without any organic solvent and within 30 minutes. The hand-milling process can mix the reactants well by the virtue of high moisture/water absorption capacity of reactants. In addition, the outstanding electromagnetic wave absorption capability of cobalt leads to efficient conversion to MOF structures before carbonization. The obtained ZIF-67 possesses high surface area and micropore volume.

  15. Comparison of microwave, ultrasound and accelerated-assisted solvent extraction for recovery of polyphenols from Citrus sinensis peels.

    Science.gov (United States)

    Nayak, Balunkeswar; Dahmoune, Farid; Moussi, Kamal; Remini, Hocine; Dairi, Sofiane; Aoun, Omar; Khodir, Madani

    2015-11-15

    Peel of Citrus sinensis contains significant amounts of bioactive polyphenols that could be used as ingredients for a number of value-added products with health benefits. Extraction of polyphenols from the peels was performed using a microwave-assisted extraction (MAE) technique. The effects of aqueous acetone concentration, microwave power, extraction time and solvent-to-solid ratio on the total phenolic content (TPC), total antioxidant activity (TAA) (using DPPH and ORAC-values) and individual phenolic acids (IPA) were investigated using a response surface method. The TPC, TAA and IPA of peel extracts using MAE was compared with conventional, ultrasound-assisted and accelerated solvent extraction. The maximum predicted TPC under the optimal MAE conditions (51% acetone concentration in water (v/v), 500 W microwave power, 122 s extraction time and 25 mL g(-1) solvent to solid ratio), was 12.20 mg GAE g(-1) DW. The TPC and TAA in MAE extracts were higher than the other three extracts.

  16. 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.

  17. 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)

  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. Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

    Directory of Open Access Journals (Sweden)

    Manuela Oliverio

    2016-10-01

    Full Text Available Background: The peracetylation is a simple chemical modification that can be used to enhance the bioavailability of hydrophilic products and to obtain safe and stable pro-drugs.Results: A totally green, solvent-free and catalyst-free microwave (MW-assisted method for peracetylation of natural products such as oleuropein, alpha-hederin, quercetin and rutin is presented. By simply tuning the MW heating program, polyols with chemical diverse –OH groups or thermolabile functionalities can be peracetylated to improve the biological activity without degradation of the natural starting molecules. An evaluation of the process greenness was performed.Conclusion: The method is potentially universally applicable for green acetylation of hydrophilic biological molecules, potentially easily scalable for industrial applications, including pharmaceutical, cosmetic and food industry.

  20. Synthesis of quinoxaline 1,4-di-n-oxide derivatives on solid support using room temperature and microwave-assisted solvent-free procedures

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Caro, Lilia C.; Sanchez-Sanchez, Mario; Bocanegra-Garcia, Virgilio; Rivera, Gildardo [Universidad Autonoma de Tamaulipas, Reynosa (Mexico). Dept. de Farmacia y Quimica Medicinal; Monge, Antonio [Universidad de Navarra, Pamplona (Spain). Centro de Investigacion en Farmacobiologia Aplicada. Unidad de Investigacion y Desarrollo de Medicamentos

    2011-07-01

    We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield. (author)

  1. Solvent-Free Microwave-Assisted Extraction of Polyphenols from Olive Tree Leaves: Antioxidant and Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    Selin Şahin

    2017-06-01

    Full Text Available Response surface methodology (RSM and artificial neural networks (ANN were evaluated and compared in order to decide which method was the most appropriate to predict and optimize total phenolic content (TPC and oleuropein yields in olive tree leaf (Olea europaea extracts, obtained after solvent-free microwave-assisted extraction (SFMAE. The SFMAE processing conditions were: microwave irradiation power 250–350 W, extraction time 2–3 min, and the amount of sample 5–10 g. Furthermore, the antioxidant and antimicrobial activities of the olive leaf extracts, obtained under optimal extraction conditions, were assessed by several in vitro assays. ANN had better prediction performance for TPC and oleuropein yields compared to RSM. The optimum extraction conditions to recover both TPC and oleuropein were: irradiation power 250 W, extraction time 2 min, and amount of sample 5 g, independent of the method used for prediction. Under these conditions, the maximal yield of oleuropein (0.060 ± 0.012 ppm was obtained and the amount of TPC was 2.480 ± 0.060 ppm. Moreover, olive leaf extracts obtained under optimum SFMAE conditions showed antibacterial activity against S. aureus and S. epidermidis, with a minimum inhibitory concentration (MIC value of 1.25 mg/mL.

  2. Microwave Assisted Solvent Free Synthesis of Azomethines from Aryl Aldehydes on Melamin Formaldehyde as Solid Support

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    Ramin Rezaei

    2011-01-01

    Full Text Available Various aryl aldehydes underwent prompt one pot conversion into the corresponding azomethines in high yields by reacting with hydroxylamine hydrochloride supported on melamine formaldehyde under microwave irradiation.

  3. Microwave-assisted synthesis of new N4-[bi-(4-fluorophenyl)-methyl]-piperazine thiosemicarbazones under solvent-free conditions

    Institute of Scientific and Technical Information of China (English)

    Qing Han Li; Zhi Gang Zhao

    2008-01-01

    Six new N4-[bi-(4-fluorophenyl)-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-(4-fluor-ophenyl)-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.

  4. Nafion®-catalyzed microwave-assisted Ritter reaction: An atom-economic solvent-free synthesis of amides

    Science.gov (United States)

    An atom-economic solvent-free synthesis of amides by the Ritter reaction of alcohols and nitriles under microwave irradiation is reported. This green protocol is catalyzed by solid supported Nafion®NR50 with improved efficiency and reduced waste production.

  5. An Unexpected Green and Facile Synthesis of 2,6-Diaryl-4-styrylpyridines via Multi-component Reactions in Microwave-assisted Solvent-free Conditions

    Institute of Scientific and Technical Information of China (English)

    SHI Feng; ZHANG Ge; ZHOU Dianxiang; MA Ning; ZHANG Yajie; CHEN Rongshun; TU Shujiang

    2009-01-01

    An unexpected green and facile synthesis of 2,6-diaryl-4-styryipyridines was realized via microwave-assisted multi-component reactions of 3-arylacrylaldehyde oximes,l-arylethanones and ammonium acetate in solvent-free conditions.This protocol has the prominent advantages of environmental-friendliness,short reaction time,high yields,low cost,easy operation as well as broad scope of applicability.

  6. Solvent-enhanced microwave-assisted derivatization following solid-phase extraction combined with gas chromatography-mass spectrometry for determination of amphetamines in urine.

    Science.gov (United States)

    Chung, Li-Wen; Liu, Geng-Jhih; Li, Zu-Guang; Chang, Yan-Zin; Lee, Maw-Rong

    2008-10-15

    An approach using microwave-assisted derivatization (MAD) following solid-phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) was developed to determine amphetamines in urine samples. The parameters affecting the derivatization efficiency - including microwave power and irradiation time - were investigated. Besides, solvent is thought critically important to MAD. Derivatization performance was studied using various solvents and compared with the performance obtained without solvent. Derivatization efficiency was clearly found to be enhanced by the presence of solvent. The highest derivatization efficiencies were obtained in ethyl acetate (EA) under microwave power of 250W for 1min. Calibration curves for all amphetamines were linear over a range from 1 to 1000ng/mL, with correlation coefficients above 0.9992. The intra-day and inter-day precision were less than 15%. The applicability of the method was tested by analyzing amphetamine-abusing subjects urine samples. Accordingly, the solvent-enhanced MAD-GC-MS method appears to be adequate for determining amphetamines in urine.

  7. Speciation of organotin in sediments by multicapillary gas chromatography with atomic emission detection after microwave-assisted leaching and solvent extraction-derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Pereiro, I.; Wasik, A.; Lobinski, R. [CNRS, Pau (France)

    1999-03-01

    Microwave-assisted leaching of organotin compounds from sediment samples followed by the simultaneous extraction-derivatization of the extracted species was revisited with the goal to compare the existing procedures, improve their recoveries and extend them to phenyltin compounds. The stability of butyl- and phenyltin compounds under microwave field, real recoveries of the whole analytical procedure, effect of the extraction solvent, and the necessity for an internal standard were evaluated using two candidate reference sediments. The combination of the optimized sample preparation procedure with multicapillary chromatography resulted in a rapid (2 min leaching + 5 min extraction-derivatization + 3 min chromatographic separation) and efficient analytical procedure for speciation analysis of organotin compounds in sediment samples. The detection limit achieved with a microwave-induced plasma atomic emission detector was 2 ng g{sup -1}. (orig.) With 4 figs., 3 tabs., 24 refs.

  8. Evaluating the performances of accelerated-solvent extraction, microwave-assisted extraction, and ultrasonic-assisted extraction for determining PCBs, HCHs and DDTs in sediments

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; GE Linke; ZHOU Chuanguang; YAOZiwei

    2011-01-01

    Three extraction techniques have been recently used for the quantitative extraction of semi-volatile organic pollutants in sediments,i.e.accelerated solvent extraction (ASE),microwave assisted extraction (MAE) and ultrasonic assisted extraction (UAE).However,their extraction efficiencies have rarely been quantitatively compared using rigorous mathematical methods.In this paper,one-way analysis of variance (ANOVA) was employed to evaluate the performance of ASE,MAE and UAE in the overall extraction of PCBs,DDTs and HCHs by analysis of their recoveries from the Standard Reference Material IAEA-417,a sediment sample certified by many international laboratories.Conclusions were drawn at a significance level of P≤0.05.No significant differences were found among the mean values for method recoveries using ASE,MAE and UAE.The mean values for real recoveries using ASE and MAE were nearly identical,but the real recovery using UAE was much lower.The concentrations of all PCBs,DDTs and HCHs except for CB52 and o,p'-DDT using UAE were the lowest.Comparing the results obtained using ASE with MAE,the concentrations of CB28,CB52,CB138,α-HCH,β-HCH,p,p'-DDE and p,p'-DDD were nearly identical,while the concentrations of other compounds were significantly different.Based on the low recoveries,it was concluded that UAE is a relatively inefficient extraction method,while ASE and MAE are equivalent methods.Taking into consideration the relative standard deviation (RSD)values,solvent volume,extraction time,and purchasing costs of the apparatus,MAE was considered superior to ASE for extraction of PCBs,DDTs and HCHs.

  9. Microwave-Assisted Solvent-Free Acetylation of Cellulose with Acetic Anhydride in the Presence of Iodine as a Catalyst

    Directory of Open Access Journals (Sweden)

    Feng Xu

    2009-09-01

    Full Text Available In this work an optimization of the solvent-free acetylation of cellulose with acetic anhydride under microwave heating with iodine as a catalyst was performed. The optimized parameters included the microwave irradiation power from 300 W to 800 W, the reaction time between 5 to 40 min, the reaction temperature from 80 to 130 °C, and the amount of iodine from 1 to 15 mol%. The extent of the acetylation was measured by yield and the degree of substitution (DS, which was determined by a back-titration method. Acetylated cellulose was characterized by FT-IR, CP/MAS 13C-NMR, WRXD, and thermogravimetric analysis. The results showed that within the range of catalyst amounts studied, the DS increased as the amount of iodine used increased, however, it was barely affected by microwave output. It was also found that the reaction time and temperature had an active influence on the extent of acetylation, however, this did not mean that at the higher temperature a better acetylation of cellulose would be obtained. The optimal reaction time and temperature found in this work were 30 min and 130 °C.

  10. Development, comparison and application of sorbent-assisted accelerated solvent extraction, microwave-assisted extraction and ultrasonic-assisted extraction for the determination of polybrominated diphenyl ethers in sediments.

    Science.gov (United States)

    Song, Shanjun; Shao, Mingwu; Tang, Hua; He, Yajuan; Wang, Weihua; Liu, Liliang; Wu, Jiajia

    2016-12-02

    Fast and selective analytical methods were developed based on sorbent-assisted mechanism and microwave-assisted extraction (SA-MAE), accelerate solvent extraction (SA-ASE) and ultrasonic-assisted extraction (SA-UAE) for the determination of polybrominated diphenyl ethers (PBDEs) in sediments. The experimental parameters, such as extraction conditions and sorbent amounts, were optimized according to Taguchi Orthogonal Arrays. The accuracy of developed SA-methods was a satisfactory ranging from 71% to 118%. The inter/intra-day RSDs were extraction intensity may produce various matrix effects. In addition, the developed SA-ASE method was successfully applied on real environmental samples collected from a typical polluted area. The data and calculation suggested local environmental contamination pattern and potential pollution source.

  11. 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.

  12. Effect of Dielectric Properties of a Solvent-Water Mixture Used in Microwave-Assisted Extraction of Antioxidants from Potato Peels.

    Science.gov (United States)

    Singh, Ashutosh; Nair, Gopu Raveendran; Liplap, Pansa; Gariepy, Yvan; Orsat, Valerie; Raghavan, Vijaya

    2014-02-24

    The dielectric properties of a methanol-water mixture were measured at different temperatures from 20 to 80 °C at two frequencies 915 MHz and 2450 MHz. These frequencies are most commonly used on industrial and domestic scales respectively. In this study, the dielectric properties of a methanol-water mixture were found to be dependent on temperature, solvent concentration, and presence of plant matrix. Linear and quadratic equations were developed to establish the dependency between factors. At 2450 MHz, the dielectric constant of methanol-water mixtures was significantly affected by concentration of methanol rather than by temperature, whereas the dielectric loss factor was significantly affected by temperature rather than by methanol concentration. Introduction of potato peel led to an increase in the effect of temperature on the dielectric properties of the methanol fractions. At 915 MHz, both the dielectric properties were significantly affected by the increase in temperature and solvent concentration, while the presence of potato peel had no significant effect on the dielectric properties. Statistical analysis of the dissipation factor at 915 and 2450 MHz revealed that both temperature and solvent concentration had a significant effect on it, whereas introduction of potato peels at 915 MHz reduced the effect of temperature as compared to 2450 MHz. The total phenolic yield of the microwave-assisted extraction process was significantly affected by the solvent concentration, the dissipation factor of the methanol-water mixture and the extraction time.

  13. Effect of Dielectric Properties of a Solvent-Water Mixture Used in Microwave-Assisted Extraction of Antioxidants from Potato Peels

    Directory of Open Access Journals (Sweden)

    Ashutosh Singh

    2014-02-01

    Full Text Available The dielectric properties of a methanol-water mixture were measured at different temperatures from 20 to 80 °C at two frequencies 915 MHz and 2450 MHz. These frequencies are most commonly used on industrial and domestic scales respectively. In this study, the dielectric properties of a methanol-water mixture were found to be dependent on temperature, solvent concentration, and presence of plant matrix. Linear and quadratic equations were developed to establish the dependency between factors. At 2450 MHz, the dielectric constant of methanol-water mixtures was significantly affected by concentration of methanol rather than by temperature, whereas the dielectric loss factor was significantly affected by temperature rather than by methanol concentration. Introduction of potato peel led to an increase in the effect of temperature on the dielectric properties of the methanol fractions. At 915 MHz, both the dielectric properties were significantly affected by the increase in temperature and solvent concentration, while the presence of potato peel had no significant effect on the dielectric properties. Statistical analysis of the dissipation factor at 915 and 2450 MHz revealed that both temperature and solvent concentration had a significant effect on it, whereas introduction of potato peels at 915 MHz reduced the effect of temperature as compared to 2450 MHz. The total phenolic yield of the microwave-assisted extraction process was significantly affected by the solvent concentration, the dissipation factor of the methanol-water mixture and the extraction time.

  14. 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.

  15. Particle size-controllable microwave-assisted solvothermal synthesis of the high-voltage cathode material LiCoPO4 using water/ethylene glycol solvent blends

    Science.gov (United States)

    Ludwig, Jennifer; Haering, Dominik; Doeff, Marca M.; Nilges, Tom

    2017-03-01

    Particle size-tuned platelets of the high-voltage cathode material LiCoPO4 for Li-ion batteries have been synthesized by a simple one-step microwave-assisted solvothermal process using an array of water/ethylene glycol (EG) solvent mixtures. Particle size control was achieved by altering the concentration of the EG co-solvent in the mixture between 0 and 100 vol%, with amounts of 0-80 vol% EG producing single phase, olivine-type LiCoPO4. The particle sizes of the olivine materials were significantly reduced from about 1.2 μm × 1.2 μm × 500 nm (0 vol% EG) to 200 nm × 100 nm × 50 nm (80 vol% EG) with increasing EG content, while specific surface areas increased from 2 to 13 m2 g-1. The particle size reduction could mainly be attributed to the modified viscosities of the solvent blends. Owing to the soft template effect of EG, the crystals exhibited the smallest dimensions along the [010] direction of the Li diffusion pathways in the olivine crystal structure, resulting in enhanced lithium diffusion properties. The relationship between the synthesis, crystal properties and electrochemical performance was further elucidated, indicating that the electrochemical performances of the as-prepared materials mainly depend on the solvent composition and the respective particle size range. LiCoPO4 products obtained from reaction media with low and high EG contents exhibited good electrochemical performances (initial discharge capacities of 87-124 mAh g-1 at 0.1 C), whereas materials made from medium EG concentrations (40-60 vol% EG) showed the highest capacities and gravimetric energy densities (up to 137 mAh g-1 and 658 Wh kg-1 at 0.1 C), excellent rate capabilities, and cycle life.

  16. Study on microwave-assisted solvent extraction of rubber seed oil%微波辅助溶剂法提取橡胶籽油工艺

    Institute of Scientific and Technical Information of China (English)

    仵缘; 蒋丹; 包瑛; 杨志达; 刘宇; 黄耀江

    2015-01-01

    为了优化微波辅助溶剂提取橡胶籽油的工艺,以橡胶籽为材料,采用微波辅助溶剂提取法,提取橡胶籽油,在单因素试验基础上,采用Box-Benhnken响应面法优化橡胶籽油的提取工艺,以提取温度、提取时间、液料比和微波功率为自变量,橡胶籽油的得率为因变量建立数学模型,并且同时对橡胶籽油的脂肪酸组成进行分析.结果显示:优化得到微波辅助提取橡胶籽油的工艺条件为——提取温度80℃,提取时间2h,液料比(mL:g)7∶1,微波功率555W.在最佳工艺条件下,橡胶籽油得率为41.32%;共测出9种脂肪酸——肉豆蔻酸、花生酸、硬脂酸、棕榈酸、棕榈油酸、亚油酸、α-亚麻酸、油酸、二十碳烯酸.其含量分别为0.115 74%、0.244 23%、6.609 85%、9.645 46%、0.288 59%、40.911 7%、18.403 1%、23.632 4%、0.1489 2%.%Optimize the method on Microwave-assisted solvent extraction of rubber seed oil from rubber seeds.The rubber seed oil was extracted by Microwave-assisted solvent method and the extraction technique parameters were optimized by response surface method (RSM).The three-level four-factor Box-Benhnken design was used to investigate the effects of different extraction temperature,extraction time,the ratio of solid to solution and microwave power on the extraction yield.The composition of the rubber seed oil was analyzed by the gas chromatograph.The optimum extraction conditions are:extraction temperature is 80 ℃,extraction time is 2 h,the ratio of solid to solution is 7∶1 and microwave power is 555 W.Under the above conditions,the maximum yield of rubber seed oil was 41.32%,nine kinds of aliphatic acid were determined.The fatty acids include myristic acid,arachidic acid,octadecanoic acid,palmitic acid,palmitoleic acid,linoleic acid,α-Linolenic acid,oleic acid and eicosenoic acid.The fatty acid content was 0.115 74%,0.244 23%,6.609 85%,9.645 46%,0.288 59%,40.911 7%,18

  17. 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...

  18. Solvent-free microwave-assisted synthesis of novel pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidines with potential antifungal activity

    Directory of Open Access Journals (Sweden)

    Paola Acosta

    2016-05-01

    Full Text Available Novel fused pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidines 5 were prepared by a solvent-free microwave assisted reaction of heterocyclic o-aminonitriles 3 and cyanopyridines 4 in the presence of tBuOK as catalyst. This protocol provides a versatile procedure for the synthesis of the title compounds with the advantages of easy work-up, mild reaction conditions and good yields. All compounds were also tested for antifungal properties against two clinically important fungi; Candida albicans and Cryptococcus neoformans. Several compounds showed moderate activity against both fungi, being 5a the most active compound. Analysis of the antifungal behavior of properly grouped compounds allowed to determine that the position of the N in the pyrimidyl moiety per se does not play a role in the activity. In turn, the type of 4-R substituent appears to influence the activity. In addition to the above considerations, the lipophilicity of compounds measured as logP showed to be not related to the activity and regarding the dipole moment (D, no net correlation was observed, although it is the most active compounds (% inhibition >50% that have a D ⩾ 7.5, mainly against C. albicans.

  19. Extraction by solvent using microwave and ultrasound-assisted techniques followed by HPLC analysis of Harpagoside from Harpagophytum procumbens and comparison with conventional solvent extraction methods

    OpenAIRE

    Filly, Aurore; Fabiano-Tixier, Anne-Sylvie; Petitcolas, Emmanuel; Mabrouki, Fathi; Chemat, Farid; Ollivier, Évelyne

    2016-01-01

    This research paper presents a quick and ecofriendly technique for the extraction of harpagoside (HS), the active marker of Harpagophytum procumbens (HP), along with a comparison with conventional methods so as to propose an efficient HPLC method. HP is widely used as an anti-inflammatory in phytotherapy. The quality control of the herbal drug and extract calls for a time consuming method of conventional extraction, which involves a high consumption of solvents. In this study, HP has been ...

  20. Microwave-Assisted, Solvent Free and Parallel Synthesis of Some Newer 2, 4-Disubstituted 1, 5- Benzodiazepines of Biological Interest

    Directory of Open Access Journals (Sweden)

    Reena Singh

    2013-07-01

    Full Text Available Benzodiazepines and their derivatives were reported to have wide biological activities and were synthesized by the reaction between substituted benzaldehydes and substituted ketones in presence of sodium hydroxide to afford chalcones and further reaction between 1, 2-diamine under smooth condensation with chalcones in presence of glacial acetic acid afforded a new class of 1, 5-benzodiazepines in good yield. 2, 4-disubstituted 1, 5-benzodiazepine derivatives (1B-19B were synthesized by microwave and conventional methods. The synthesized compounds were evaluated for their antibacterial, antifungal, anthelmintic and cytotoxic activity. The chemical structures of the newly synthesized compounds have been confirmed by IR, 1H-NMR, MASS spectral data and elemental analysis. All the synthesized substituted benzodiazepines have shown good antimicrobial activity, moderate to good anthelmintic activity and possessed significant cytotoxic activity.

  1. 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)

  2. Microwave-Assisted Condensation Reactions of Acetophenone Derivatives and Activated Methylene Compounds with Aldehydes Catalyzed by Boric Acid under Solvent-Free Conditions.

    Science.gov (United States)

    Brun, Elodie; Safer, Abdelmounaim; Carreaux, François; Bourahla, Khadidja; L'helgoua'ch, Jean-Martial; Bazureau, Jean-Pierre; Villalgordo, Jose Manuel

    2015-06-23

    We here disclosed a new protocol for the condensation of acetophenone derivatives and active methylene compounds with aldehydes in the presence of boric acid under microwave conditions. Implementation of the reaction is simple, healthy and environmentally friendly owing to the use of a non-toxic catalyst coupled to a solvent-free procedure. A large variety of known or novel compounds have thus been prepared, including with substrates bearing acid or base-sensitive functional groups.

  3. Microwave-Assisted Condensation Reactions of Acetophenone Derivatives and Activated Methylene Compounds with Aldehydes Catalyzed by Boric Acid under Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Elodie Brun

    2015-06-01

    Full Text Available We here disclosed a new protocol for the condensation of acetophenone derivatives and active methylene compounds with aldehydes in the presence of boric acid under microwave conditions. Implementation of the reaction is simple, healthy and environmentally friendly owing to the use of a non-toxic catalyst coupled to a solvent-free procedure. A large variety of known or novel compounds have thus been prepared, including with substrates bearing acid or base-sensitive functional groups.

  4. The Rapid Synthesis of Schiff—Base withou Solvent under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    HaiJianYANG; WenHauSUN; 等

    2002-01-01

    A microwave-assisted preparation of a series of Schiff-base via efficient condensation of salicylaldehyde and aryl amines without solvent is described in high yield as well as environmental friendship reaction in organic synthesis.

  5. The Rapid Synthesis of Schiff-Base without Solvent under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A microwave-assisted preparation of a series of Schiff-base via efficient condensation of salicylaldehyde and aryl amines without solvent is described in high yield as well as environmental friendship reaction in organic synthesis.

  6. 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...

  7. Synthesis and QSAR Study of (4-Oxo-3-aryl-3,4-dihydro-quinazolin-2-ylsulfanyl-propionic Acid arylidene/aryl-ethylidene-hydrazides via Microwave Assisted Solvent Free Reations

    Directory of Open Access Journals (Sweden)

    M. B. Deshmukh

    2004-01-01

    Full Text Available In the present work, s-alkylated derivatives of thio-quinazolinone were obtained using Methyl 2-chloro propionate via a solvent-free microwave-assisted method. The alkylated thio quinazolinones were further sequentially condensed with hydrazine hydrate and different aromatic aldehydes to get the hydrazides, which were studied for QSAR. The synthesized compounds were subjected to a prediction of biological activities. A software application (PASS was used for this purpose. . The relationship between structure and different biological activities was studied and the different derivatives were recommended for the screening of some specific activities like anti-tuberculosic, anti-mycobacterial & HDL cholesterol increasing activities.

  8. Microwave Assisted Drug Delivery

    DEFF Research Database (Denmark)

    Jónasson, Sævar Þór; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    In this work, the microwave radiation is adopted for remote activation of pharmaceutical drug capsules inside the human body in order to release drugs at a pre-determined time and location. An array of controllable transmitting sources is used to produce a constructive interference at a certain...... focus point inside the body, where the drugs are then released from the specially designed capsules. An experimental setup for microwave activation has been developed and tested on a body phantom that emulates the human torso. A design of sensitive receiving structures for integration with a drug...

  9. Microwave Assisted Drug Delivery

    DEFF Research Database (Denmark)

    Jónasson, Sævar Þór; Zhurbenko, Vitaliy; Johansen, Tom Keinicke

    2014-01-01

    In this work, the microwave radiation is adopted for remote activation of pharmaceutical drug capsules inside the human body in order to release drugs at a pre-determined time and location. An array of controllable transmitting sources is used to produce a constructive interference at a certain...... focus point inside the body, where the drugs are then released from the specially designed capsules. An experimental setup for microwave activation has been developed and tested on a body phantom that emulates the human torso. A design of sensitive receiving structures for integration with a drug...

  10. SHORT COMMUNICATION MICROWAVE ASSISTED ...

    African Journals Online (AJOL)

    a

    sensitivity and does not require extraction into toxic organic solvents. The proposed ... Patty, F.A. Industrial Hygiene and Toxicology, Vol. ... Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M. Handbook of the Analytical Chemistry of Rare. Elements, Ann ...

  11. Fast Determination of Essential Oil from Dried Menthol Mint and Orange Peel by Solvent Free Microwave Extraction Using Carbonyl Iron Powder as the Microwave Absorption Medium

    Institute of Scientific and Technical Information of China (English)

    WANG Zi-Ming; DING Lan; WANG Lu; FENG Jin; LI Tie-Chun; ZHOU Xin; ZHANG Han-Qi

    2006-01-01

    An improved solvent free microwave extraction, in which a kind of microwave absorption medium (carbonyl iron powder) was used, was applied to the extraction of essential oil from dried menthol mint and orange peel without addition of any solvent and pretreatment. It took much less time of extraction (30 min) than microwave-assisted hydrodistillation (90 min) and conventional hydrodistillation (180 min). The kinds of chemical compositions in essential oil extracted by different methods were almost the same and such improved solvent free microwave extraction can be a feasible way in extraction of essential oil from dried plant materials.

  12. 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.

  13. 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 ...

  14. Solvent-vapor-assisted imprint lithography

    NARCIS (Netherlands)

    Voicu, Nicoleta E.; Ludwigs, Sabine; Crossland, Edward J. W.; Andrew, Piers; Steiner, Ullrich

    2007-01-01

    Sub-micrometer features are replicated into high-molecular-weight polymer resists by using solvent-assisted nanoimprint lithography (see figure). By swelling the polymer in a controlled solvent-vapor atmosphere, millibar pressures and ambient temperatures are sufficient to achieve high-fidelity

  15. 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.

  16. 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.

  17. Microwave accelerated solvent-free synthesis of flavanones

    Energy Technology Data Exchange (ETDEWEB)

    Sagrera, Gabriel J. [Universidad de la Republica, Montevideo (Uruguay). Facultad de Ciencias. Dept. de Quimica Organica]. E-mail: gseoane@fq.edu.uy; Seoane, Gustavo A. [Universidad de la Republica, Montevideo (Uruguay). Facultad de Quimica

    2005-07-15

    Microwave irradiation of chalcones under solvent-free conditions resulted in a 'green-chemistry' procedure for the preparation of flavanones in very good yields. Using an unmodified household microwave oven, different mineral supports and catalysts were tested. By irradiation of chalcones with 30% TFA over silica gel, eleven known flavanones and five new compounds were prepared in high yields. (author)

  18. Solvent-and catalyst-free synthesis of dihydropyrimidinthiones in one-pot under focused microwave irradiation conditions

    Institute of Scientific and Technical Information of China (English)

    Hong Wen Zhan; Jin Xian Wang; Xi Tian Wang

    2008-01-01

    Fifteen dihydropyrimidinthiones have been synthesized by microwave-assisted Biginelli reactions without any solvent of catalyst.The advantages of this novel protocol include the excellent yield,operational simplicity,short time and the avoidance of the use of organic solvents and catalysts.

  19. Microwave-assisted chemoselective copper-catalyzed amination of o-chloro and o-bromobenzoic acids using aromatic amines under solvent free conditions

    Institute of Scientific and Technical Information of China (English)

    Yaghoub Sarrafi; Manijeh Mohadeszadeh; Kamal Alimohammadi

    2009-01-01

    Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported. Some of the advantages of this method axe high chemoselectivity, short reaction times, ease of work up procedure and elimination of the need for acid protection.

  20. Solvent Free, Microwave Assisted Conversion of Aldehydes into Nitriles and Oximes in the Presence of NH2OH·HCl and TiO2

    Directory of Open Access Journals (Sweden)

    Lucas Villas-Boas Hoelz

    2009-12-01

    Full Text Available Aromatic aldehydes bearing electron-donating groups are easily converted into their respective nitriles using NH2OH·HCl and TiO2 under microwave irradiation, while those bearing an electron-withdrawing group give the corresponding oximes.

  1. Green and solvent-free procedure for microwave-assisted synthesis of 2,4,6-triarylpyridines catalysed using MgAl2O4 nanocrystals

    Indian Academy of Sciences (India)

    Javad Safari; Soheila Gandomi-Ravandi; Mahmoud Borjian Borujeni

    2013-09-01

    Design and development of a heterogeneous nanocatalyst for condensation reaction of acetophenone derivatives, aromatic aldehydes, and ammonium acetate to yield 2,4,6-triarylpyridines followed by microwave irradiation is described. Nanocrystalline MgAl2O4 as a novel heterogeneous recyclable catalyst shows high activity for the above reaction. In addition, the easily recoverable nanosized catalysts showed good reusability.

  2. 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.

  3. Solvent-free microwave-assisted peroxidative oxidation of secondary alcohols to the corresponding ketones catalyzed by copper(ii) 2,4-alkoxy-1,3,5-triazapentadienato complexes.

    Science.gov (United States)

    Figiel, Paweł J; Kopylovich, Maximilian N; Lasri, Jamal; da Silva, M Fátima C Guedes; da Silva, João J R Fraústo; Pombeiro, Armando J L

    2010-04-28

    A facile, efficient and selective solvent-free synthesis of ketones from secondary alcohols with tert-butylhydroperoxide (TBHP) as the oxidant under microwave irradiation is achieved, where the copper(ii) 2,4-alkoxy-1,3,5-triazapentadienato complexes are efficient catalysts providing high yields (up to 100%), TONs (up to 890) and TOFs (up to 1780 h(-1)).

  4. Microwave -assisted Synthesis Calcium Carbonate in Water/Ethylene Glycol Mixed Solvents%水/乙二醇混合溶剂中微波辅助合成碳酸钙

    Institute of Scientific and Technical Information of China (English)

    孙新园; 张群; 陈敏; 潘玉锁

    2012-01-01

    在水/乙二醇混合溶剂中,通过微波辅助加热的方法,研究溶液过饱和度对碳酸钙成核生长的影响。分别采用扫描电子显微镜(SEM)、X-射线粉末衍射(XRD)对所得的样品进行了表征。结果表明,过饱和度的改变对碳酸钙形貌和晶型具有非常明显的影响,分别获得了菱面体状方解石、纤维捆扎状文石、松树枝状球霰石为主体的碳酸钙晶体。%In this paper, the influence of diffident supersaturations of the bulk solution on the nucleation and crystal growth of calcium carbonate is studied through the method of microwave - assisted beating in water/ethylene glycol mixed solvents. The ob- tained crystals are characterized by scanning electron microscopy (SEM) and X -ray diffraction (XRD). The resuh shows that the morphologies and polymorphs are obvious varied from rhombohedron calcite, fiber strapping aragonite to pine - dendritic vater- ite with the changes of supersaturations.

  5. 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.

  6. Microwave-Assisted Olefin Metathesis

    Science.gov (United States)

    Nicks, François; Borguet, Yannick; Sauvage, Xavier; Bicchielli, Dario; Delfosse, Sébastien; Delaude, Lionel; Demonceau, Albert

    Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared to conventional heating methods. The present contribution aims at illustrating the advantages of this technology in olefin metathesis and, when data are available, at comparing microwave-heated and conventionally heated experiments

  7. 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.

  8. 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.

  9. Microwave Assisted Convenient One-Pot Synthesis of Coumarin Derivatives via Pechmann Condensation Catalyzed by FeF3 under Solvent-Free Conditions and Antimicrobial Activities of the Products

    Directory of Open Access Journals (Sweden)

    Vahid Vahabi

    2014-08-01

    Full Text Available A rapid and efficient solvent-free one-pot synthesis of coumarin derivatives by Pechmann condensation reactions of phenols with ethyl acetoacetate using FeF3 as a catalyst under microwave irradiation is described. This one-pot synthesis on a solid inorganic support provides the products in good yields. The newly synthesized compounds were systematically characterized by IR, 1H-NMR, 13C-NMR, MS and elemental CHN analyses. The proposed solvent-free microwave irradiation method using the environmentally friendly catalyst FeF3 offers the unique advantages of high yields, shorter reaction times, easy and quick isolation of the products, excellent chemoselectivity, and a one-pot, green synthesis. The products were screened for antimicrobial activity, and the results showed that the compounds reacted against all the tested bacteria.

  10. 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.

  11. 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, ...

  12. 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.

  13. Saccharification of the Pretreated Corn Stover by Microwave Assisted DMSO/AmimCl Co-solvents%微波辅助DMSO/AmimCl复合溶剂预处理玉米秸秆的酶解影响

    Institute of Scientific and Technical Information of China (English)

    刘建飞; 曹妍; 杨茂华; 李会泉; 邢建民

    2012-01-01

    为了实现玉米秸秆纤维素的高效糖化,设计利用微波加热辅助的离子液体1-烯丙基-3-甲基咪唑氯盐(AmimCl)/二甲基亚砜(DMSO)复合溶剂生物质预处理体系,破坏玉米秸秆天然结构,提高纤维素酶解效率.研究发现,15%(w)DMSO,110℃,60 min及4 g秸秆/100 g复合溶剂为最适预处理条件.在此条件下,秸秆溶解率、提取率可分别达46.6%和22.9%;提取物纤维素酶解率14 h可达71.4%,相较于天然玉米秸秆的20 h酶解率12.5%有极大提高.通过XRD,SEM及1H NMR分析发现:秸秆预处理后,提取物纤维素晶型由I型变为II型,残渣纤维素相对结晶度明显降低,有利于纤维素酶解的进行,达到了生物质预处理的目的;预处理过程中使用的AmimCl离子液体经简单回收再生,结构及秸秆溶解性能未发生变化,可循环使用.为玉米秸秆生物质预处理提供了一个新的方案.%In order to enhance the enzymatic saccharification efficiency of corn stover,microwave assisted treatment with dimethyl sulfoxide(DMSO) and 1-ally-3-methylimidazolium(AmimCl) co-solvents was designed to break up the complicated chemical structure of corn stover.The pretreatment conditions were studied to increase the dissolution ratio,extraction ratio and cellulose I crystallinity index(CrI) variation.With the increase of AmimCl concentration,time and temperature of the pretreatment,the dissolution ratio,extraction ratio increased and CrI decreased.Considering the costs of high AmimCl concentration,degradation of biomass at high temperature and long time,the optimum conditions were DMSO/AmimCl co-solvents with a DMSO concentration of 15%(w) and 4 g corn stover per 100 g co-solvents.The optimum temperature and time were 110 ℃ and 60 min,respectively.Under the optimal conditions,the ratios of corn stover dissolution and extraction were as high as 46.6% and 22.9%,respectively.The cellulose saccharification ratio had a great increase

  14. Solvent-free Synthesis of Thiohydantoin Derivatives with Microwave Activation

    Institute of Scientific and Technical Information of China (English)

    LI Jian-ping; MA Chun-ming; QU Gui-rong

    2004-01-01

    The application of microwave techniques for chemical synthesis has attached considerable interests in recent years because of their enhanced selectivity, reduced reaction time ,easier work-up procedure. The synthesis of thiohydantoin derivatives is useful because they display a wide range of biological activities, including anticonvulsant1, antitumor2, antinociceptive3,thyroxine ingibitory properties4, as well as herbicidal and fungicidal reagents5. Recent studies have shown that some used as synthetic precursor of the marine natural product dispacamide6, and some used to synthesis novel optically active poly(amide-imide)s7. Therefore, many methods of synthesis of thiohydantoins have been explored8~10. Generally, these reactions were carried out in solution and using volatile and poisonous solvent, with long reaction time.In order to overcome the disadvantages discussed above, avoid the use of a solvent and synthesize these valuable compounds rapidly and efficiently, we investigated a new way---solvent-free synthesis using a microwave oven.In this paper, a new and rapid solvent-free synthesis of thiohydantoins with microwave activation was studied. It was found that the addition reaction of aryl isothiocyanates and amino acid in the presence of sodium hydroxide and the cyclizative condensation of adduct in the presence of sodium hydrogen sulphate in a microwave oven takes place quickly.By this new method, twelve thiohydantoins have been synthesized in excellent yield(83~91%).This method has significant advantages such as operational simplicity, shorter reaction time, higher yields and environmental acceptability. The structures of the products were characterized by IR, MS,1H NMR, 13C NMR and elemental analysis. And more detailed work about the application of the thiohydantoins in analytical chemistry and physiological activity is in progress in our laboratory.

  15. 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.

  16. Solvent-Free Synthesis of Modified Pectin Compounds Promoted by Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Vittoria Vittoria

    2012-10-01

    Full Text Available Microwave-assisted solvent-free modification of pectin was successfully accomplished, consisting in the esterification of several fatty acids by pectin alcoholic functions. The reaction was performed by simply mixing the reagents with a catalytic amount of the inorganic base (potassium carbonate and irradiating the obtained mixture with microwaves for a short time (3–6 min. The replacement of the traditional heating with a microwave source allowed the development of a new synthetic protocol which provided increased yield of the final products, since it eliminates the small amount of degraded polysaccharide produced during traditional oil bath heating. The desired esters were fully characterized by FT-IR spectroscopy and thermogravimetric analysis.

  17. 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.

  18. Microwave-assisted Synthesis of Modified Polyaspartic Acid in Solvent%微波溶剂法合成天冬氨酸-谷氨酸共聚物研究

    Institute of Scientific and Technical Information of China (English)

    张玉玲; 黄君礼; 程志辉; 杨士林

    2007-01-01

    Polyaspartic acid (PASP) is suitable for the inhibition of scale deposition from water.To enhance its inhibition efficiency, PASP was modified by reacting aspartic acid (Asp) with glutamic acid (Glu) to provide Asp-Glu copolymer under microwave irradiation.The influence of reaction parameters on conversion, molecular weight and inhibition of CaCOa precipitation was investigated Infra-red.(IR),1H nuclear magnetic resonance (1H NMR) and 13C nuclear magnetic resonance (13C NMR) spectroscopies were used to characterize the copolymer.The results show that copolymerization of aspartic acid and glutamic acid is catalyzed by a small amount of phosphorous acid (H3PO4) in solvent, the product conversion is 98.05% under the following conditions: the molar ratio of glutamic acid to reactant [Glu/(Asp+Glu)] is 0.3 and that of catalyst (Cat) to reactant [Cat/(Glu+Asp)] is 0.05 (0.65ml H3PO4), the volume of solvent dimethylformamide is 16ml, the microwave power used is 720W and the reaction for 3 rnin.The weight average molecular weight of copolymer synthesized under these conditions is 2709 and the inhibition rate for CaCO3 is 97.75%.

  19. Solvent-free Synthesis of 5-Azacytosine with Microwave Activation

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-bin; QU Gui-rong

    2004-01-01

    5-Azacytosine (4-amino-1,2-dihydro-1,3,5-triazin-2-one) is a very important intermediate in the synthesis of 5-azacytidine which showed remarkable bacteriostatic and cytostatic activity as well as against T-4 lymphoma and L-1210 leukemia in mice. Starting with N-cyanoguanidine (dicyandiamide) and formic acid, under the solvent-free microwave activation,we synthesized 5-azacytosine in short time (4min) with good yield (60.4%). The structure of the product was confirmed by 1HNMR and Elemental analysis.In this paper, a new and rapid synthesis of 5-azacytosine has been reported for the first time in microwave oven. N-cyanoguanidine (0.05tmol) and anhydride formic acid (0.18mol) were stirred well. Then irradiate the reaction mixture in microwave oven for the specified time (4min) under solvent-free condition. After the reaction was complete, the resulting solid was disperated in warm absolute ethanol (10ml), cooled to 0℃, filtered and dried in vacuum to yield the crude product. The pure product was obtained by recrystallization.

  20. 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 ...

  1. Kinetics study of oil extraction from Citrus auranticum L. by solvent-free microwave extraction

    OpenAIRE

    Heri Septya Kusuma; Prilia Dwi Amelia; Cininta Admiralia; Mahfud Mahfud

    2016-01-01

    Citrus and its oil are of high economic and medicinal value because of their multiple uses, such as in the food industry, cosmetics and folk medicine. The aim of this study is to investigate the potential of solvent-free microwave extraction for the extraction of essential oils from Citrus auranticum L. peels. Specifically, this study verifies the kinetics based on second-order model and mechanism of solvent-free microwave extraction of Citrus auranticum L. peels. Solvent-free microwave extra...

  2. 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.

  3. 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...

  4. 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.

  5. 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.

  6. Pyrazole synthesis under microwave irradiation and solvent-free conditions

    Energy Technology Data Exchange (ETDEWEB)

    Buriol, Lilian; Frizzo, Clarissa P.; Marzari, Mara R.B.; Moreira, Dayse N.; Prola, Lizie D.T.; Zanatta, Nilo; Bonacorso, Helio G.; Martins, Marcos A.P., E-mail: mmartins@base.ufsm.b [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Dept. de Quimica. Nucleo de Quimica de Heterociclos

    2010-07-01

    This paper presents a study of solvent-free reaction conditions using microwave irradiation (MW) to obtain 4,5-dihydro-{sup 1}H-pyrazoles and dehydrated pyrazoles by the cyclocondensation reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF{sub 3}C(O)CH=C(R{sup 1})OR, where R/R{sup 1} Et/H, Me/Me and Me/Ph] with hydrazines [NH{sub 2}NH-R{sub 2}, where R{sub 2} = CO{sub 2}Me, Ph, CH{sub 2}CH{sub 2}OH]. Some reactions were performed under the same reaction conditions using methanol as solvent. The results obtained using MW equipment for synthesis under solvent-free conditions were also compared with those described in literature for conventional thermal heating and heating with a domestic MW oven. In general, the products furnished by reaction in MW equipment for synthesis presented better yields and shorter reaction times. In addition, it was demonstrated that the reaction temperature altered the formation of products for each hydrazine showing that MW equipment for synthesis is efficient for reacting hydrazines and 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones to procedure the products 4,5-dihydro-{sup 1}H-pyrazoles and dehydrated pyrazoles. (author)

  7. An Expedient Method for the Synthesis of Thiosemicarbazones under Microwave Irradiation in Solvent-free Medium

    Institute of Scientific and Technical Information of China (English)

    LI, Jian-Ping; ZHENG, Peng-Zhi; ZHU, Jun-Ge; LIU, Rui-Jie; QU, Gui-Rong

    2006-01-01

    A simple, efficient and eco-friendly method for the synthesis of thiosemicarbazones from thiosemicarbazides and aldehyde under microwave irradiation has been reported, and no solvent and catalyst were used. And the technique of microwave irradiation coupled with solvent-free condition proved to be a quite valuable method in the organic synthesis.

  8. 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.

  9. Microwave-assisted solvent extraction and analysis of shikimic acid from plant tissues Extração por solvente assistida por micro-ondas e análise do ácido chiquímico dos tecidos de plantas

    Directory of Open Access Journals (Sweden)

    M.B Matallo

    2009-12-01

    Full Text Available A better method for determination of shikimate in plant tissues is needed to monitor exposure of plants to the herbicide glyphosate [N-(phosphonomethylglycine] and to screen the plant kingdom for high levels of this valuable phytochemical precursor to the pharmaceutical oseltamivir. A simple, rapid, and efficient method using microwave-assisted extraction (MWAE with water as the extraction solvent was developed for the determination of shikimic acid in plant tissues. High performance liquid chromatography was used for the separation of shikimic acid, and chromatographic data were acquired using photodiode array detection. This MWAE technique was successful in recovering shikimic acid from a series of fortified plant tissues at more than 90% efficiency with an interference-free chromatogram. This allowed the use of lower amounts of reagents and organic solvents, reducing the use of toxic and/or hazardous chemicals, as compared to currently used methodologies. The method was used to determine the level of endogenous shikimic acid in several species of Brachiaria and sugarcane (Saccharum officinarum and on B. decumbens and soybean (Glycine max after treatment with glyphosate. The method was sensitive, rapid and reliable in all cases.Um método melhor para a determinação do chiquimato em tecidos de plantas é necessário para monitorar a exposição destas ao herbicida glyphosate N-(fosfonometilglicina] e selecionar o gênero da planta para altos níveis desse valioso precursor fitoquímico ao fármaco oseltamivir. Um método simples, rápido e eficiente, que usa a extração assistida por micro-ondas (MWAE com água como solvente de extração, foi desenvolvido para a determinação do ácido chiquímico em tecidos de plantas. Foi empregada cromatografia líquida de alto desempenho para a separação do ácido chiquímico, e os dados cromatográficos foram obtidos utilizando arranjo de fotodiodo. Essa técnica de MWAE obteve sucesso na recupera

  10. 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.

  11. 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.

  12. short communication microwave assisted oxidative coupling of thiols ...

    African Journals Online (AJOL)

    Preferred Customer

    minimal amount of solvent under microwave irradiation. ... [7-8] and also the industrial applications of disulfides in the vulcanization of rubbers and ..... Holbrook, D.L. Handbook of Petroleum Refining Processes, Meyers, R.A. (Ed.), McGraw.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. A novel and an efficient catalyst for one-pot synthesis of 2,4,5-trisubstituted imidazoles by using microwave irradiation under solvent-free conditions

    Indian Academy of Sciences (India)

    Javad Safari; Shiva Dehghan Khalili; Sayed Hossein Banitaba

    2010-05-01

    (NH4)6Mo7O24.4H2O has been used as an efficient catalyst for an improved and rapid synthesis of 2,4,5-trisubstituted imidazoles by a three-component, one-pot condensation of benzil, aryl aldehydes and ammonium acetate in good yields under solvent-free conditions using microwave irradiation. The reactions in conventional heating conditions were compared with the microwave-assisted reactions.

  19. Improved solvent-free microwave extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim.

    Science.gov (United States)

    Wang, Ziming; Ding, Lan; Li, Tiechun; Zhou, Xin; Wang, Lu; Zhang, Hanqi; Liu, Li; Li, Ying; Liu, Zhihong; Wang, Hongju; Zeng, Hong; He, Hui

    2006-01-13

    Solvent-free microwave extraction (SFME) is a recently developed green technique which is performed in atmospheric conditions without adding any solvent or water. SFME has already been applied to extraction of essential oil from fresh plant materials or dried materials prior moistened. The essential oil is evaporated by the in situ water in the plant materials. In this paper, it was observed that an improved SFME, in which a kind of microwave absorption solid medium, such as carbonyl iron powders (CIP), was added and mixed with the sample, can be applied to extraction of essential oil from the dried plant materials without any pretreatment. Because the microwave absorption capacity of CIP is much better than that of water, the extraction time while using the improved SFME is no more than 30 min using a microwave power of 85 W. Compared to the conventional SFME, the advantages of improved SFME were to speed up the extraction rate and need no pretreatment. Improved SFME has been compared with conventional SFME, microwave-assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) for the extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim. By using GC-MS system the compositions of essential oil extracted by applying four kinds of extraction methods were identified. There was no obvious difference in the quality of essential oils obtained by the four kinds of extraction methods.

  20. 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).

  1. 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.

  2. 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...

  3. Semi-automated microwave assisted solid-phase peptide synthesis

    DEFF Research Database (Denmark)

    Pedersen, Søren Ljungberg

    with microwaves for SPPS has gained in popularity as it for many syntheses has provided significant improvement in terms of speed, purity, and yields, maybe especially in the synthesis of long and "difficult" peptides. Thus, precise microwave heating has emerged as one new parameter for SPPS, in addition...... to coupling reagents, resins, solvents etc. We have previously reported on microwave heating to promote a range of solid-phase reactions in SPPS. Here we present a new, flexible semi-automated instrument for the application of precise microwave heating in solid-phase synthesis. It combines a slightly modified...... Biotage Initiator microwave instrument, which is available in many laboratories, with a modified semi-automated peptide synthesizer from MultiSynTech. A custom-made reaction vessel is placed permanently in the microwave oven, thus the reactor does not have to be moved between steps. Mixing is achieved...

  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. 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...

  6. Microwave assisted centrifuge and related methods

    Science.gov (United States)

    Meikrantz, David H [Idaho Falls, ID

    2010-08-17

    Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

  7. 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.

  8. 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.

  9. 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

  10. 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…

  11. 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

  12. 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. 

  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 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.

  15. 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.

  16. 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.

  17. Solvent-free microwave-mediated Michael addition reactions

    Indian Academy of Sciences (India)

    H Surya Prakash Rao; S Jothilingam

    2005-07-01

    Facile Michael addition of active methylene compounds to ,-unsaturated carbonyl compounds takes place on the surface of potassium carbonate under microwave irradiation. Further studies on microwave-mediated Robinson annulations reveal a convenient and facile method for condensation of chalcone with methylene compounds to furnish cyclohexenones.

  18. Microwave-assisted synthesis of photochromic fulgides

    Indian Academy of Sciences (India)

    Sivasankaran Nithyanandan; Chinnusamy Saravanan; Sengodan Senthil; Palaninathan Kannan

    2010-03-01

    The oxazole and indole based heterocyclic photochromic fulgides were synthesized from their corresponding fulgenic acid derivatives by clay catalysed microwave irradiation methodology. Improved yields of fulgides were observed by the microwave irradiation method as compared other chemical methods employed so far. The proportions of clay (montmorillonite KSF) and isopropenyl acetate play a key role in increasing the yields of fulgides.

  19. 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.

  20. Synthesis of New Pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU Cyanosilylated Derivatives Using Sulphated Zirconia and Hydrotalcite as Catalysts in Microwave-Assisted Reactions under Solvent Free Conditions

    Directory of Open Access Journals (Sweden)

    Juan Navarrete-Bolaños

    2011-08-01

    Full Text Available A comparison was made of the effectiveness of the functionalization reactions of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (PCU using sulphated zirconia in protection-deprotection reactions and Mg/Al hydrotalcite in a cyanosilylation reaction, under classical thermal conditions and imposing microwave radiation; improved yields and reaction times were considered.

  1. 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.

  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 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.

  4. Microwave synthesis under solvent-free conditions and spectral studies of some mesoporphyrinic complexes.

    Science.gov (United States)

    Boscencu, Rica

    2012-05-10

    A series of A₃B and A₄ type mesoporphyrinic complexes were synthesized with superior yields using microwave irradiation under solvent-free conditions. The structures of the complexes were confirmed using elemental analysis, FT-IR, UV-Vis, EPR and NMR spectral data. The influence of environmental polarity on spectral properties of the mesoporphyrinic complexes was investigated. The obtained results indicate that the shape of absorption and fluorescence spectra does not depend on the solvent polarity under the experimental conditions used. The small shifts of the absorption and emission maximums that occur by increasing of solvent polarity reflects the physical interaction between the porphyrinic substituents and the solvent molecules.

  5. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Farid Chemat

    2007-07-01

    Full Text Available The purpose of the study was to investigate microwave selective heatingphenomena and their impact on heterogeneous chemical reactions. We also present a toolwhich will help microwave chemists to answer to such questions as “My reaction yields90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes undermicrowaves?” and to have an approximation of their reactions when conducted undermicrowaves with different heterogeneous procedures. This model predicting reactionkinetics and yields under microwave heating is based on the Arrhenius equation, inagreement with experimental data and procedures.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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 ...

  17. 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.

  18. Oil recovery from petroleum sludge through ultrasonic assisted solvent extraction.

    Science.gov (United States)

    Hu, Guangji; Li, Jianbing; Huang, Shuhui; Li, Yubao

    2016-09-18

    The effect of ultrasonic assisted extraction (UAE) process on oil recovery from refinery oily sludge was examined in this study. Two types of UAE treatment including UAE probe (UAEP) system and UAE bath (UAEB) system were investigated. Their oil recovery efficiencies were compared to that of mechanical shaking extraction (MSE). Three solvents including cyclohexane (CHX), ethyl acetate (EA), and methyl ethyl ketone (MEK) were examined as the extraction solvents. The influence of experimental factors on oil and solvent recovery was investigated using an orthogonal experimental design. Results indicated that solvent type, solvent-to-sludge (S/S) ratio, and treatment duration could have significant effects on oil recovery in UAE treatment. Under the optimum conditions, UAEP treatment can obtain an oil recovery of 68.8% within 20 s, which was higher than that (i.e., 62.0%) by MSE treatment after 60 min' extraction. UAEB treatment can also obtain a promising oil recovery within shorter extraction duration (i.e., 15 min) than MSE. UAE was thus illustrated as an effective and improved approach for oily sludge recycling.

  19. Microwave Assisted Synthesis of Biorelevant Benzazoles.

    Science.gov (United States)

    Seth, Kapileswar; Purohit, Priyank; Chakraborti, Asit K

    2016-10-25

    The benzazole scaffolds are present in various therapeutic agents and have been recognized as the essential pharmacophore for diverse biological activities. These have generated interest and necessity to develop efficient synthetic methods of these privileged classes of compounds to generate new therapeutic leads for various diseases. The biological activities of the benzazoles and efforts towards their synthesis have been summarized in a few review articles. In view of these, the aim of this review is to provide an account of the developments that have taken place in the synthesis of biorelevant benzazoles under microwave irradiation as the application of microwave heating has long been recognized as a green chemistry tool for speedy generation of synthetic targets. Attention has been focused to those literature reports wherein the use of microwave irradiation is the key step in the formation of the heterocyclic ring system or in functionalization of the benzazole ring system to generate the essential pharmacophoric feature. The convenient and economic way to synthesize these privileged class of heterocycles through the use of microwave irradiation that would be beneficial for the drug discovery scientist to synthesize biologically active benzazoles and provide access to wide range of reactions for the synthesis of benzazoles constitute the theme of this review. Examples have been drawn wherein the use of microwave heating offers distinct advantage in terms of improved product yields and reduction of reaction time as compared to those observed for the synthesis under conventional heating.

  20. An expendient method for the synthesis of bis(acylhydrazones) under microwave irradiation in solvent-free medium

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.P.; Zheng, P.Z.; Zhu, J.G.; Liu, R.J.; Qu, G.R. [Henan Normal University, Xinxiang (China). College of Chemical and Environmental Science. Key Lab. of Environmental Pollution Control Technology of Henan Province]. E-mail: jplig@163.com

    2007-10-15

    A simple, efficient and eco-friendly method for the synthesis of bis(acylhydrazones) from hexanediohydrazide and aldehydes under microwave irradiation without the use of solvent and catalyst is reported. The technique of microwave irradiation under solvent-free condition proved to be quite a valuable method in organic synthesis. (author)

  1. 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.

  2. 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.

  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. Solvent-Free Microwave Synthesis of Aryloxypropanolamines by Ring Opening of Aryloxy Epoxides

    Directory of Open Access Journals (Sweden)

    Rukhsana I. Kureshy

    2009-01-01

    Full Text Available The ring opening reaction of aryloxyepoxides with isopropylamine under solvent-free microwave irradiation produced therapeutically useful -blockers-aryloxypropanolamines in excellent yield (up to 98% in 10 minutes which is considerably less than the time taken in classical heating (∼16 hours.

  5. Kinetics study of oil extraction from Citrus auranticum L. by solvent-free microwave extraction

    Directory of Open Access Journals (Sweden)

    Heri Septya Kusuma

    2016-05-01

    Full Text Available Citrus and its oil are of high economic and medicinal value because of their multiple uses, such as in the food industry, cosmetics and folk medicine. The aim of this study is to investigate the potential of solvent-free microwave extraction for the extraction of essential oils from Citrus auranticum L. peels. Specifically, this study verifies the kinetics based on second-order model and mechanism of solvent-free microwave extraction of Citrus auranticum L. peels. Solvent-free microwave extraction is used to extract essential oils from Citrus auranticum L. peels. The initial extraction rate, the extraction capacity and the second-order extraction rate constant were calculated using the model. Using a three-step experimental design of the kinetics of oil extraction from Citrus auranticum L. peels by solvent-free microwave extraction, this study showed that the extraction process was based on the second-order extraction model. The initial extraction rate (h, the extraction capacity (CS, the second-order extraction rate constant (k, and coefficient of determination (R2 was 0.7483 g L-1 min-1, 0.7291 g L-1, 1.4075 L g-1 min-1 and 0.9992, respectively.

  6. Synthesis of new hyodeoxycholic acid thiosemicarbazone derivatives under solvent-free conditions using microwave

    Institute of Scientific and Technical Information of China (English)

    Zhi Chuan Shi; Zhi Gang Zhao; Xing Li Liu; Yu Chen

    2011-01-01

    An efficient and simple method for synthesis of new hyodeoxycholic acid thiosemicarbazone derivatives under solvent-free conditions using microwave has been developed. Its main advantages are short reaction times, good conversions and the environmentally friendly nature of the process. The preliminary results indicate that some of these compounds possess inhibitory effects against E. coli.

  7. 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.

  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. Extraction of phenols from lignin microwave-pyrolysis oil using a switchable hydrophilicity solvent.

    Science.gov (United States)

    Fu, Dongbao; Farag, Sherif; Chaouki, Jamal; Jessop, Philip G

    2014-02-01

    Microwave pyrolysis of lignin, an aromatic polymer byproduct from paper-pulping industry, produces char, gases, and lignin pyrolysis oil. Within the oil are valuable phenolic compounds such as phenol, guaiacol and catechol. In this work, we describe a method using switchable hydrophilicity solvents (SHS) to extract phenols as a mixture from lignin microwave-pyrolysis oil at the scale of 10 g of bio-oil. Even at this small scale, losses are small; 96% of the bio-oil was recovered in its three fractions, 72% of guaiacol and 70% of 4-methylguaiacol, the most abundant phenols in the bio-oil, were extracted and 91% of the solvent SHS was recovered after extraction. The starting material (lignin microwave-pyrolysis oil) and the three fractions resulted from SHS extraction were characterized by GC-MS and quantitative (13)C{(1)H} and (31)P{(1)H} NMR spectroscopy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Antimicrobial activity of ultrasound-assisted solvent-extracted spices.

    Science.gov (United States)

    Thongson, C; Davidson, P M; Mahakarnchanakul, W; Weiss, J

    2004-01-01

    The objective of this research was to determine the antimicrobial activity of conventional and high-intensity ultrasound-assisted (HI-US) solvent-extracted Thai spices, including ginger (Zingiber officinale Rose), fingerroot (Bosenbergia pandurata Holtt) and turmeric (Curouma longa Linn). Extracts were obtained using hexane, isopropanol and a 7 : 3 isopropanol : hexane mixture as solvents with and without HI-US. The antimicrobial activity of the extracts was assayed against four strains each of Listeria monocytogenes and Salmonella Typhimurium DT 104 using an agar dilution assay. Application of HI-US did not alter antibacterial activity against S. Typhimurium, but antilisterial activity of some HI-US spice extracts decreased. Solvent type affected antimicrobial efficacy of extracts with hexane producing the least antimicrobial activity. Fingerroot extracted with isopropanol-hexane and without HI-US had the best antilisterial effect while HI-US-isopropanol fingerroot extract had the greatest antimicrobial efficacy against S. Typhimurium. Application of HI-US reduced time of extraction to 5 min, compared with the 24 h required for conventional extraction and maintained antimicrobial activity against Salmonella but slightly reduced activity against Listeria. HI-US in combination with proper solvent selection may offer a new tool to optimize extraction of spice essential oil for use as antimicrobial agents, and reduce processing time and costs.

  11. 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.

  12. 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.

  13. 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...

  14. Comparative study on sulphur reduction from heavy petroleum - Solvent extraction and microwave irradiation approach

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Abdullahi Dyadya; Isah, Abubakar Garba; Umaru, Musa; Ahmed, Shehu [Department of Chemical Engineering, Federal University of Technology, P.M.B 65, Minna (Nigeria); Abdullahi, Yababa Nma [National Petroleum Investment Management Services (Nigeria National Petroleum Corporation), Lagos (Nigeria)

    2012-07-01

    Sulphur- containing compounds in heavy crude oils are undesirable in refining process as they affect the quality of the final product, cause catalyst poisoning and deactivation in catalytic converters as well as causing corrosion problems in oil pipelines, pumps and refining equipment aside environmental pollution from their combustion and high processing cost. Sulphur reduction has being studied using microwave irradiation set at 300W for 10 and 15minutes and oxidative- solvent extraction method using n- heptane and methanol by 1:1, 1:2 and 1:3 crude- solvent ratios after being oxidized with hydrogen peroxide, H2O2 oxidants. Percentage sulphur removal with n- heptane solvent by 1:1 and 1:2 are 81.73 and 85.47%; but extraction using methanol by different observed ratios gave less sulphur reduction. Indeed when microwave irradiated at 300W for 10 and 15minutes, 53.68 and 78.45% reduction were achieved. This indicates that microwave irradiation had caused oxidation by air in the oven cavity and results to formation of alkyl radicals and sulphoxide from sulphur compound in the petroleum. The prevailing sulphur found in the crude going by FT-IR results is sulphides which oxidized to sulphoxide or sulphones. It is clear that sulphur extraction with heptane is more efficient than microwave irradiation but economically due to demands for solvent and its industrial usage microwave irradiation can serve as alternative substitute for sulphur reduction in petroleum. Sulphur reduction by microwave radiation should be up- scaled from laboratory to a pilot plant without involving extraction column in the refining.

  15. Comparative study on sulphur reduction from heavy petroleum - Solvent extraction and microwave irradiation approach

    Directory of Open Access Journals (Sweden)

    Abdullahi Dyadya Mohammed, Abubakar Garba Isah, Musa Umaru, Shehu Ahmed, Yababa Nma Abdullahi

    2012-01-01

    Full Text Available Sulphur- containing compounds in heavy crude oils are undesirable in refining process as they affect the quality of the final product, cause catalyst poisoning and deactivation in catalytic converters as well as causing corrosion problems in oil pipelines, pumps and refining equipment aside environmental pollution from their combustion and high processing cost. Sulphur reduction has being studied using microwave irradiation set at 300W for 10 and 15minutes and oxidative- solvent extraction method using n- heptane and methanol by 1:1, 1:2 and 1:3 crude- solvent ratios after being oxidized with hydrogen peroxide, H2O2 oxidants. Percentage sulphur removal with n- heptane solvent by 1:1 and 1:2 are 81.73 and 85.47%; but extraction using methanol by different observed ratios gave less sulphur reduction. Indeed when microwave irradiated at 300W for 10 and 15minutes, 53.68 and 78.45% reduction were achieved. This indicates that microwave irradiation had caused oxidation by air in the oven cavity and results to formation of alkyl radicals and sulphoxide from sulphur compound in the petroleum. The prevailing sulphur found in the crude going by FT-IR results is sulphides which oxidized to sulphoxide or sulphones. It is clear that sulphur extraction with heptane is more efficient than microwave irradiation but economically due to demands for solvent and its industrial usage microwave irradiation can serve as alternative substitute for sulphur reduction in petroleum. Sulphur reduction by microwave radiation should be up- scaled from laboratory to a pilot plant without involving extraction column in the refining.

  16. Microwave-Assisted Synthesis – Catalytic Applications in Aqueous Media

    Science.gov (United States)

    The development of sustainable methods directed towards the synthesis of molecules is due to the heightened awareness and recognition of alternative eco-friendly and economical protocols that have minimum impact on environment. Among others, microwave (MW)-assisted methodology ha...

  17. 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.

  18. Microwave Assisted Healing of Thermally Mendable Composites

    Directory of Open Access Journals (Sweden)

    Edward D. Sosa

    2015-01-01

    Full Text Available Polymer matrix composites offer high specific strength; however, their potential weight savings have been limited by the concern of damage tolerance. If microcracking and similar incurred damage could be autonomously sealed, composite structures could be built thinner and lighter while still addressing damage tolerance, thus achieving the weight savings they promise. Various self-healing mechanisms have been proposed to this end. Herein, a method of thermally reversible polymerization is investigated. To date, thermally activated repair of composites have been accomplished typically through resistive heating, which has certain inherent complexities. An alternate heating method, via microwave exposure of carbon nanotubes incorporated throughout a thermal reversible polymer matrix, is demonstrated. Carbon nanotube-doped composites exhibit enhanced microwave absorption over an undoped control sample. Furthermore, it is shown that these composites can be heated locally by a focused microwave source. The particular composite formulation and layup studied could be uniformly heated to the targeted healing temperature of 100°C in as little as 20 seconds, followed by a healing time on the scale of minutes with total time depending upon the extent of damage.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Microwave-assisted extraction of Lupeol from Cuscuta reflexa Roxb. growing on different hosts and its quantitation by high-performance thin layer chromatography

    Directory of Open Access Journals (Sweden)

    Sunita Shailajan

    2011-01-01

    Full Text Available Microwave-assisted extraction (MAE of phytochemicals has grown as a promising technique in recent years. MAE method was developed for extraction of Lupeol from Cuscuta reflexa Roxb. growing on different hosts. An open vessel modified microwave system has been used for extraction of Lupeol. Various critical parameters such as use of solvent, solvent volume, power and time of irradiation were optimized. Methanol was selected as an extraction solvent based on its high dielectric constant value and maximum solubility of Lupeol. The solvent volume, microwave power and irradiation time were optimized to 10 mL, 160 Watts and 3 min respectively. The developed method is a good alternative to time consuming conventional extraction techniques.

  7. Microwave Synthesis Under Solvent-Free Conditions and Spectral Studies of Some Mesoporphyrinic Complexes

    Directory of Open Access Journals (Sweden)

    Rica Boscencu

    2012-05-01

    Full Text Available A series of A3B and A4 type mesoporphyrinic complexes were synthesized with superior yields using microwave irradiation under solvent-free conditions. The structures of the complexes were confirmed using elemental analysis, FT-IR, UV-Vis, EPR and NMR spectral data. The influence of environmental polarity on spectral properties of the mesoporphyrinic complexes was investigated. The obtained results indicate that the shape of absorption and fluorescence spectra does not depend on the solvent polarity under the experimental conditions used. The small shifts of the absorption and emission maximums that occur by increasing of solvent polarity reflects the physical interaction between the porphyrinic substituents and the solvent molecules.

  8. 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.

  9. 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.

  10. 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.

  11. Microwave Synthesis Under Solvent-Free Conditions and Spectral Studies of Some Mesoporphyrinic Complexes

    OpenAIRE

    Rica Boscencu

    2012-01-01

    A series of A3B and A4 type mesoporphyrinic complexes were synthesized with superior yields using microwave irradiation under solvent-free conditions. The structures of the complexes were confirmed using elemental analysis, FT-IR, UV-Vis, EPR and NMR spectral data. The influence of environmental polarity on spectral properties of the mesoporphyrinic complexes was investigated. The obtained results indicate that the shape of absorption and fluoresc...

  12. Catalyst-free and solvent-free method for the synthesis of quinoxalines under microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    Jian Feng Zhou; Gui Xia Gong; Kun Bao Shi; San Jun Zhi

    2009-01-01

    A facile procedure for the synthesis.of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. Thereactions were carried out catalyst-free, solvent-free and under microwave irradiation conditions in high yield (84-98%) with short time (3-6 rain) and environmental benign, as well as convenient operation. The structures of all the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, mass spectral data.

  13. Montmorillonite Clay-Promoted, Solvent-Free Cross-Aldol Condensations under Focused Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Damiano Rocchi

    2014-06-01

    Full Text Available An environmentally benign, clean and general protocol was developed for the synthesis of aryl and heteroaryl trans-chalcones. This method involved solvent-free reaction conditions under microwave irradiation in the presence of a clay-based catalyst, and afforded the target compounds in good yields and short reaction times. Furthermore, the same conditions allowed the synthesis of symmetrical, diarylmethylene-α,β-unsaturated ketones from aromatic aldehydes and ketones.

  14. Green procedure with a green solvent for fats and oils' determination. Microwave-integrated Soxhlet using limonene followed by microwave Clevenger distillation.

    Science.gov (United States)

    Virot, Matthieu; Tomao, Valérie; Ginies, Christian; Visinoni, Franco; Chemat, Farid

    2008-07-04

    Here is described a green and original alternative procedure for fats and oils' determination in oleaginous seeds. Extractions were carried out using a by-product of the citrus industry as extraction solvent, namely d-limonene, instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using microwave energy: at first, extractions are attained using microwave-integrated Soxhlet, followed by the elimination of the solvent from the medium using a microwave Clevenger distillation in the second step. Oils extracted from olive seeds were compared with both conventional Soxhlet and microwave-integrated Soxhlet extraction procedures performed with n-hexane in terms of qualitative and quantitative determination. No significant difference was obtained between each extract allowing us to conclude that the proposed method is effective and valuable.

  15. 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.

  16. 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).

  17. 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.

  18. 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].

  19. Program for Assisting the Replacement of Industrial Solvents PARIS III User’s Guide

    Science.gov (United States)

    PARIS III is a third generation Windows-based computer software to assist the design of less harmful solvent replacements by estimating values of the solvent properties that characterize the static, dynamic, performance, and environmental behavior of the original solvent mixture ...

  20. 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.

  1. 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.

  2. 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.

  3. Vacuum-assisted microwave drying characteristics of green bell pepper

    Directory of Open Access Journals (Sweden)

    Vivek Kumar

    2017-04-01

    Full Text Available Chopped green bell pepper pieces were blanched (95 °C, 5 min and chemically pretreated (1% potassium metabisulphite solution, 25 min at room temperature before drying in hot air dryer (HAD at various temperature ranges (60 – 80 °C. Three vacuum levels (200, 400, 600 mm Hg and microwave power levels (100, 200, 300 W were also used to dry green bell pepper samples in a vacuum assisted microwave (VAM (2.45 GHz, 0.8 kW dryer. VAM drying methods offered a maximum reduction by four to five times in drying time as compared to that in HAD. The logarithmic model was found to have the best fit based on high R2 and small values of reduced χ2 and RMSE.  VAM method has higher values for effective moisture diffusivity (Deff and lower values for activation energy (Ea, in comparison to the HAD method. 

  4. Application of 2k Full Factorial Design in Optimization of Solvent-Free Microwave Extraction of Ginger Essential Oil

    Directory of Open Access Journals (Sweden)

    Mumtaj Shah

    2014-01-01

    Full Text Available The solvent-free microwave extraction of essential oil from ginger was optimized using a 23 full factorial design in terms of oil yield to determine the optimum extraction conditions. Sixteen experiments were carried out with three varying parameters, extraction time, microwave power, and type of sample for two levels of each. A first order regression equation best fits the experimental data. The predicted values calculated by the regression model were in good agreement with the experimental values. The results showed that the extraction time is the most prominent factor followed by microwave power level and sample type for extraction process. An average of 0.25% of ginger oil can be extracted using current setup. The optimum conditions for the ginger oil extraction using SFME were the extraction time 30 minutes, microwave power level 640 watts, and sample type, crushed sample. Solvent-free microwave extraction proves a green and promising technique for essential oil extraction.

  5. 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.

  6. 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.

  7. Microwave-Promoted Synthesis of Sulfonated Metallophthalocyanines and Aggregation in Different Solvents

    Directory of Open Access Journals (Sweden)

    Zhenhua Cheng

    2015-01-01

    Full Text Available Five metallosulfophthalocyanines (Fe, Ni, Zn, Co, and Cu compounds were synthesized by microwave irradiation. Compared to the conventional method of synthesis in terms of reaction time and yields, the microwave-promoted synthesis is preferred with high product yield and short reaction time. All synthesized products were characterized with MALDI-TOF mass spectrum, Fourier transform infrared spectroscopy (FT-IR, ultraviolet-visible spectroscopy (UV-Vis, and X-ray diffraction (XRD. Aggregation behavior of the five metallosulfophthalocyanines (MSPc in different solvents was studied by UV-Vis spectroscopy separately in N,N-dimethyl formamide (DMF and NaOH aqueous solution (5%wt. A redshift of maximum absorption wavelength and deviations from Lambert-Beer law with increasing the concentration were observed. The dimerization equilibrium constants (K of the five MSPc were determined, respectively.

  8. 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...

  9. 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.

  10. Solvent-free microwave extraction of essential oils from Laurus nobilis and Melissa officinalis: comparison with conventional hydro-distillation and ultrasound extraction.

    Science.gov (United States)

    Uysal, Burcu; Sozmen, Fazli; Buyuktas, Birsen S

    2010-01-01

    Solvent-free microwave extraction (SFME) has been applied to the extraction of essential oils from Melissa officinalis L. and Laurus nobilis L. The results of SFME were compared with those obtained by hydro-distillation (HD) and ultrasound-assisted extraction (USE) of essential oils from dried plant materials. The compositions of the essential oils were identified by GC-MS. The essential oil obtained with SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than the oils obtained by conventional methods. The three different extraction methods used showed differences in the compositions and contents of the essential oils.

  11. 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.

  12. 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.

  13. 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.

  14. Solvent

    OpenAIRE

    Hamida Y. Mostafa; Ebaa A. El-Shamy; Amal S. Farag; Nadia G. Kandile

    2013-01-01

    Neat ethylacetoacetate (EAA) and its mixtures with a co-solvent and an anti-solvent have been studied for refining of heavy wax distillate fraction to produce substantially non-carcinogenic base oil. The co-solvent and anti-solvent used are dipropylene glycol (DPG) and ethylene glycol (EG) respectively. The solubility characteristics of the main solvent and its mixed solvent systems were studied. Selection of the optimum solvent mixture and extraction variables has been studied. The effect of...

  15. 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

  16. 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.

  17. 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.

  18. Microwave Assisted Synthesis of N-Arylheterocyclic Substituted-4-aminoquinazoline Derivatives

    Directory of Open Access Journals (Sweden)

    Ping Lu

    2006-04-01

    Full Text Available A simple, efficient, and general method has been developed for the synthesis of various N-aryl heterocylic substituted-4-aminoquinazoline compounds from 4-chloro- quinazoline and aryl heterocyclic amines under microwave irradiation using 2-propanol as solvent. The advantages of the use of microwave irradiation in relation to the classical method were demonstrated.

  19. Optimization of microwave-assisted extraction of polyphenols from apple pomace using response surface methodology and HPLC analysis.

    Science.gov (United States)

    Bai, Xue-Lian; Yue, Tian-Li; Yuan, Ya-Hong; Zhang, Hua-Wei

    2010-12-01

    A simple and efficient microwave-assisted extraction of polyphenols from industrial apple pomace was developed and optimized by the maximization of the yield using response surface methodology. A Box-Behnken design was used to monitor the effect of microwave power, extraction time, ethanol concentration and ratio of solvent to raw material (g/mL) on the polyphenols yield. The results showed that the optimal conditions were as follows: microwave power 650.4 W, extraction time 53.7 s, ethanol concentration 62.1% and ratio of solvent to raw material 22.9:1. Validation tests indicated that the actual yield of polyphenols was 62.68±0.35 mg gallic acid equivalents per 100 g dry apple pomace with RSD=0.86% (n=5) under the optimal conditions, which was in good agreement with the predicted yield and higher than those of reflux and ultrasonic-assisted extraction methods. HPLC analysis indicated that the major polyphenols of apple pomace consisted of chlorogenic acid, caffeic acid, syrigin, procyanidin B2, (-)-epicatechin, cinnamic acid, coumaric acid, phlorizin and quercetin, of which procyanidin B2 had the highest content of 219.4 mg/kg.

  20. 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.

  1. 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…

  2. Ionic liquid as a promising biobased green solvent in combination with microwave irradiation for direct biodiesel production.

    Science.gov (United States)

    Wahidin, Suzana; Idris, Ani; Shaleh, Sitti Raehanah Muhamad

    2016-04-01

    The wet biomass microalgae of Nannochloropsis sp. was converted to biodiesel using direct transesterification (DT) by microwave technique and ionic liquid (IL) as the green solvent. Three different ionic liquids; 1-butyl-3-metyhlimidazolium chloride ([BMIM][Cl], 1-ethyl-3-methylimmidazolium methyl sulphate [EMIM][MeSO4] and 1-butyl-3-methylimidazolium trifluoromethane sulfonate [BMIM][CF3SO3]) and organic solvents (hexane and methanol) were used as co-solvents under microwave irradiation and their performances in terms of percentage disruption, cell walls ruptured and biodiesel yields were compared at different reaction times (5, 10 and 15 min). [EMIM][MeSO4] showed highest percentage cell disruption (99.73%) and biodiesel yield (36.79% per dried biomass) after 15 min of simultaneous reaction. The results demonstrated that simultaneous extraction-transesterification using ILs and microwave irradiation is a potential alternative method for biodiesel production.

  3. HIGHLY DIASTEREOSELECTIVE MICHAEL REACTION UNDER SOLVENT-FREE CONDITIONS USING MICROWAVES: CONJUGATE ADDITION OF FLAVANONE TO ITS CHALCONE PRECURSOR

    Science.gov (United States)

    Microwave-assisted reaction of 2'-hydroxychalcones in the presence of DBU resulted in the formation of hitherto unknown dimers by conjugate addition of the intermediate cyclic ketone to the starting enone.

  4. Microwave activation of electrochemical processes: enhanced electrodehalogenation in organic solvent media.

    Science.gov (United States)

    Tsai, Yu-Chen; Coles, Barry A; Compton, Richard G; Marken, Frank

    2002-08-21

    The effect of high-intensity microwave radiation focused into a "hot spot" region in the vicinity of an electrode on electrochemical processes with and without coupled chemical reaction steps has been investigated in organic solvent media. First, the electrochemically reversible oxidation of ferrocene in acetonitrile and DMF is shown to be affected by microwave-induced thermal activation, resulting in increased currents and voltammetric wave shape effects. A FIDAP simulation investigation allows quantitative insight into the temperature distribution and concentration gradients at the electrode / solution interface. Next, the effect of intense microwave radiation on electroorganic reactions is considered for the case of ECE processes. Experimental data for the reduction of p-bromonitrobenzene, o-bromonitrobenzene, and m-iodonitrobenzene in DMF and acetonitrile are analyzed in terms of an electron transfer (E), followed by a chemical dehalogenation step (C), and finally followed by another electron-transfer step (E). The presence of the "hot spot" in the solution phase favors processes with high activation barriers.

  5. Application of 2k Full Factorial Design in Optimization of Solvent-Free Microwave Extraction of Ginger Essential Oil

    OpenAIRE

    Mumtaj Shah; S K Garg

    2014-01-01

    The solvent-free microwave extraction of essential oil from ginger was optimized using a 23 full factorial design in terms of oil yield to determine the optimum extraction conditions. Sixteen experiments were carried out with three varying parameters, extraction time, microwave power, and type of sample for two levels of each. A first order regression equation best fits the experimental data. The predicted values calculated by the regression model were in good agreement with the experimental ...

  6. Extraction of orange peel's essential oil by solvent-free microwave extraction

    Science.gov (United States)

    Qadariyah, Lailatul; Amelia, Prilia Dwi; Admiralia, Cininta; Bhuana, Donny S.; Mahfud, Mahfud

    2017-05-01

    Sweet orange peel (Citrus sinensis) is part of orange plant that contains essential oils. Generally, taking essential oil from orange peel is still using hydrodistillation and steam-hydrodistillation method which still needs solvent and takes a long time to produce high quality essential oil. Therefore, the objectives of this experiment are to study the process of orange peel's essential oil extraction using Solvent Free Microwave Extraction (SFME) and to study the operating condition that effect an optimum yield and quality of the essential oil. In this experiment, extraction process with SFME method goes for 60 minutes at atmospheric pressure. Variables for SFME are: variation of orange peel condition (fresh and dry), ratio orange peel mass to distiller volume (0,1; 0,2; 0,3; 0,4 g/mL), orange peel size (±0,5; ±2; ±3,5 cm width), and microwave power (100, 264, 400 Watt). Moisture content of fresh peel is 71,4% and for dry peel is 17,37% which is obtained by sun drying. The result of this experiment will be analyzed with GC-MS, SEM, density, and miscibility in ethanol 90%. The optimum result obtained from this experiment based on the number of the yield under condition of fresh orange peel is at peel mass/distiller volume 0,1 g/mL, orange peel size ±3,5 cm width, and microwave power 400 Watt, results 1,6738% yield. The result of GC-MS for fresh orange peel shows that the dominant compound is Limonene 54,140% and for dry orange peel is Limonene 59,705%. The density obtained is around 0,8282-0,8530 g/mL and miscibility in ethanol 90% is 1:5.

  7. 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

  8. Solvent-Free Synthesis of New Coumarins

    Directory of Open Access Journals (Sweden)

    Redah I. Al-Bayati

    2012-01-01

    Full Text Available A solvent-free synthesis of five series of coumarin derivatives using microwave assistant is presented herein. The synthesized compounds are fully characterized by UV-VIS, FT-IR, and NMR spectroscopy.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. A rapid fractionation method for heavy metals in soil by continuous-flow sequential extraction assisted by focused microwaves.

    Science.gov (United States)

    Nakazato, Tetsuya; Akasaka, Mikio; Tao, Hiroaki

    2006-11-01

    A microwave-assisted continuous-flow sequential extraction system was developed for rapid fractionation analysis of heavy metals in soil. Insertion of pressure-adjusted air between the extractants provided stable flows of the extractants without mutual mixing and back-pressure influence of a column packed with soil, thereby facilitating reliable continuous-flow extractions. In addition, use of pure water as a pumping solvent removed metal contamination because of direct contact between corrosive extractants and the pump containing metallic materials. Focused microwave irradiation to the soil accelerated the selective extractions of the acid-soluble and reducible fractions of heavy metals in soil in the first and second steps of the sequential extraction conditions, as defined by the Commission of the European Bureau of Reference (BCR). The microwave-assisted continuous-flow extraction provided high correlations in amounts of six heavy metals except Zn in the first step and Cu in the second step extracted from a reference sludge soil, BCR CRM 483, with a conventional batchwise extraction proposed by BCR; continuous-flow extraction assisted by conductive heating provided lower correlations for all the six metals. The proposed method drastically reduced the time required for the sequence extraction to ca. 65 min without losing accuracy and precision of the fractionation analysis of heavy metals in soil, whereas the BCR batchwise method requires ca. 33 h.

  16. Microwave-assisted Extraction of Isoflavones from Belamcanda chinensis%微波协同萃取射干异黄酮的研究

    Institute of Scientific and Technical Information of China (English)

    龚盛昭; 程江; 杨卓如

    2005-01-01

    Microwave-assisted extraction (MAE) of isoflavones from Belamcanda chinensis was studied using ethanol as the solvent. The single factor experiment and the orthogonal method were used to optimize the MAE condition. It was concluded that two doses of intermittent microwave power radiation, 300 W each for 4 min, were needed for extraction. The mass ratio of solvent to material was 8:1 and the alcohol mass fraction was 80%. The extracted liquor was then concentrated under vacuum and degreased with petroleum ether. The yield of total isoflavones was about 8.8% and the contents of tectoridin and iridin were 67.6% and 16.3% respectively. Compared with direct-heating extraction (DHE), MAE may shorten extracting duration, reduce solvent consumption, and improve yield and purity of isoflavones from Belamcanda chinensis.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Rapid and efficient synthesis of new chiral aromatic amide molecular tweezers under solvent-free conditions using microwave

    Institute of Scientific and Technical Information of China (English)

    Xiao Xiang Zhao; Zhi Gang Zhao; Xing Li Liu; Xiu Ming Wu

    2009-01-01

    An efficient and simple method for the synthesis of new chiral aromatic amide molecular tweezers by irradiation with microwave under solvent-free conditions has been developed.Its main advantages are short reaction times.good conversions and the environmentally friendly nature of the process.

  4. One-pot synthesis of quinaldine derivatives by using microwave irradiation without any solvent - A green chemistry approach

    Indian Academy of Sciences (India)

    Javad Safari; Sayed Hossein Banitaba; Sepehr Sadegh Samiei

    2009-07-01

    A convenient and efficient procedure for synthesis of quinaldine derivatives has been developed by a simple one-pot reaction of aniline derivatives and acetaldehyde on the surface of neutral alumina impregnated with hydrochloric acid under microwave irradiation without any solvent according to green chemistry.

  5. Determination of Quinolones and Nonsteroidal anti-Inflammatory Agents in Animal Tissues and Bovine Milk by Microwave-assisted Extraction High Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-Liu; DING Lan; JIN Hai-Yan; LIU Miao; CHENG Jian-Hua; WU Xiu-Feng; ZHAI Yu-Juan; SUN Yan-Tao; ZHANG Han-Qi; YU Yong; WANG Xiu-Pin

    2008-01-01

    A rapid,specific microwave-assisted extraction high performance liquid chromatography is described for assaying three quinolones(fleroxacin,lomefloxacin and sparfloxacin)and two nonsteroidal anti-inflammatory agents(ketoprofen and ibuprofen)in samples of sheep liver,bovine muscle and milk.The optimal microwave-assisted extraction conditions such as extraction temperature(40 ℃),extraction time(6 min),solvent volume(10 mL)and solvent(acetonitrile)were determined by an orthogonal experiment.Recoveries were 60.0%-107% in the concentration range 0.25-0.75 μg·g with good precision(< 11%)from three varieties of spiked animal samples.

  6. 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.

  7. Microwave-assisted extraction of lignin from triticale straw: optimization and microwave effects.

    Science.gov (United States)

    Monteil-Rivera, Fanny; Huang, Guang Hai; Paquet, Louise; Deschamps, Stéphane; Beaulieu, Chantale; Hawari, Jalal

    2012-01-01

    Presently lignin is used as fuel but recent interests in biomaterials encourage the use of this polymer as a renewable feedstock in manufacturing. The present study was undertaken to explore the potential applicability of microwaves to isolate lignin from agricultural residues. A central composite design (CCD) was used to optimize the processing conditions for the microwave (MW)-assisted extraction of lignin from triticale straw. Maximal lignin yield (91%) was found when using 92% EtOH, 0.64 N H(2)SO(4), and 148 °C. The yield and chemical structure of MW-extracted lignin were compared to those of lignin extracted with conventional heating. Under similar conditions, MW irradiation led to higher lignin yields, lignins of lower sugar content, and lignins of smaller molecular weights. Except for these differences the lignins resulting from both types of heating exhibited comparable chemical structures. The present findings should provide a clean source of lignin for potential testing in manufacturing of biomaterials. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  8. Solvent-free microwave extraction of essential oil from aromatic herbs: from laboratory to pilot and industrial scale.

    Science.gov (United States)

    Filly, Aurore; Fernandez, Xavier; Minuti, Matteo; Visinoni, Francesco; Cravotto, Giancarlo; Chemat, Farid

    2014-05-01

    Solvent-free microwave extraction (SFME) has been proposed as a green method for the extraction of essential oil from aromatic herbs that are extensively used in the food industry. This technique is a combination of microwave heating and dry distillation performed at atmospheric pressure without any added solvent or water. The isolation and concentration of volatile compounds is performed in a single stage. In this work, SFME and a conventional technique, hydro-distillation HD (Clevenger apparatus), are used for the extraction of essential oil from rosemary (Rosmarinus officinalis L.) and are compared. This preliminary laboratory study shows that essential oils extracted by SFME in 30min were quantitatively (yield and kinetics profile) and qualitatively (aromatic profile) similar to those obtained using conventional hydro-distillation in 2h. Experiments performed in a 75L pilot microwave reactor prove the feasibility of SFME up scaling and potential industrial applications.

  9. Comparison of heat and mass transfer of different microwave-assisted extraction methods of essential oil from Citrus limon (Lisbon variety) peel.

    Science.gov (United States)

    Golmakani, Mohammad-Taghi; Moayyedi, Mahsa

    2015-11-01

    Dried and fresh peels of Citrus limon were subjected to microwave-assisted hydrodistillation (MAHD) and solvent-free microwave extraction (SFME), respectively. A comparison was made between MAHD and SFME with the conventional hydrodistillation (HD) method in terms of extraction kinetic, chemical composition, and antioxidant activity. Higher yield results from higher extraction rates by microwaves and could be due to a synergy of two transfer phenomena: mass and heat acting in the same way. Gas chromatography/mass spectrometry (GC/MS) analysis did not indicate any noticeable differences between the constituents of essential oils obtained by MAHD and SFME, in comparison with HD. Antioxidant analysis of the extracted essential oils indicated that microwave irradiation did not have adverse effects on the radical scavenging activity of the extracted essential oils. The results of this study suggest that MAHD and SFME can be termed as green technologies because of their less energy requirements per ml of essential oil extraction.

  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. Determination of volatile compounds in Magnolia bark by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sha, Yun F; Huang, Tao M; Shen, Shun; Duan, Geng L

    2004-05-01

    A method is described for the determination of volatile compounds in Magnolia bark using microwave-assisted extraction coupled to headspace solid-phase microextraction (MAE-HS-SPME), followed by gas chromatography with mass spectrometry (GC-MS). Parameters affecting the extraction efficiency, such as sampling time and temperature, microwave irradiation power and desorption time, were investigated to achieve the optimal conditions. The result obtained was compared with that of steam distillation; only small differences existed between these two methods. Therefore, the proposed method seems to be a feasible and relatively simple, fast and solvent-free procedure for identification of essential oils in Magnolia bark.

  12. 微波辅助胶团提取甘草中的甘草酸和甘草甙%Microwave-assisted Micellar Extraction and Determination of Glycyrrhizic Acid and Liquiritin in Licorice Root by HPLC

    Institute of Scientific and Technical Information of China (English)

    孙晨; 谢渝春; 刘会洲

    2007-01-01

    The feasibility of employing non-ionic surfactant (Triton X-100) as an alternative and effective solvent for the microwave-assisted extraction of glycyrrhizic acid (GA) and liquiritin (LQ) from licorice root was studied.The optimal extraction parameters based on the microwave-assisted micellar extraction technique were determined.Under the optimal conditions, i.e. 5% (by volume) Triton X-100, microwave-assisted extraction for 3-5min at 373K, the percentage extraction of active ingredients reached the highest value. The preconcentration factor for GA and LQ (about 13.5) and the extraction efficiency for these two ingredients approached 100% showed the coupling of microwave-assisted extraction and cloud-point extraction could be employed as a new and effective technique for the rapid extraction and preconcentration of pharmacologically active ingredients from medicinal plants such as licorice root without disturbing chromatographic analysis.

  13. Extractive-transesterification of algal lipids under microwave irradiation with hexane as solvent.

    Science.gov (United States)

    Martinez-Guerra, Edith; Gude, Veera Gnaneswar; Mondala, Andro; Holmes, William; Hernandez, Rafael

    2014-03-01

    This study describes the use of microwaves (MW) for enhanced extractive-transesterification of algal lipids from dry algal biomass (Chlorella sp.). Two different single-step extractive-transesterification methods under MW irradiation were evaluated: (1) with ethanol as solvent/reactant and sodium hydroxide catalyst; and (2) with ethanol as reactant and hexane as solvent (sodium hydroxide catalyst). Biodiesel (fatty-acid-ethyl-esters, FAEE) yields from these two methods were compared with the conventional Bligh and Dyer (BD) method which followed a two-step extraction-transesterification process. The maximum lipid yields for MW, MW with hexane and BD methods were 20.1%, 20.1%, and 13.9%, respectively; while the FAEE conversion of the algal lipids were 96.2%, 94.3%, and 78.1%, respectively. The algae-biomass:ethanol molar ratio of 1:250-500 and 2.0-2.5% catalyst with reaction times around 6min were determined as optimum conditions for both methods. This study confers that the single-step non-conventional methods can contribute to higher algal lipid and FAEE yields.

  14. Microwave assisted organic modification and surface functionalization of Phyllosilicates

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2012-11-01

    Full Text Available Organically modified phyllosilicates (montmorillonite and palygorskite) using Arquad 2HT-75 surfactant were effectively synthesized utilizing a microwave irradiation technique. The microwave method was successfully used also for the surface...

  15. 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...

  16. 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...

  17. Microwave Assisted Synthesis and Characterization of Perovskite Oxides

    OpenAIRE

    Prado-Gonjal, Jesus; Schmidt, Rainer; Moran, Emilio

    2014-01-01

    The use of microwave irradiation is a promising alternative heat source for the synthesis of inorganic materials such as perovskite oxides. The method offers massive energy and time savings as compared to the traditional ceramic method. In this work we review the basic principles of the microwave heating mechanism based on interactions between dipoles in the material and the electromagnetic microwave. Furthermore, we comment on and classify all different sub-types of microwave synthesis such ...

  18. 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

  19. Microwave assisted flow synthesis: Coupling of electromagnetic and hydrodynamic phenomena

    NARCIS (Netherlands)

    Patil, N.G.; Benaskar, F.; Meuldijk, J.; Hulshof, L.A.; Hessel, V.; Schouten, J.C.; Esveld, D.C.; Rebrov, E.V.

    2014-01-01

    This article describes the results of a modeling study performed to understand the microwave heating process in continuous-flow reactors. It demonstrates the influence of liquid velocity profiles on temperature and microwave energy dissipation in a microwave integrated milli reactor-heat exchanger.

  20. Microwave-assisted extraction of silkworm pupal oil and evaluation of its fatty acid composition, physicochemical properties and antioxidant activities.

    Science.gov (United States)

    Hu, Bin; Li, Cheng; Zhang, Zhiqing; Zhao, Qing; Zhu, Yadong; Su, Zhao; Chen, Yizi

    2017-09-15

    Microwave-assisted extraction (MAE) of oil from silkworm pupae was firstly performed in the present research. The response surface methodology was applied to optimize the parameters for MAE. The yield of oil by MAE was 30.16% under optimal conditions of a mixed solvent consisting of ethanol and n-hexane (1:1, v/v), microwave power (360W), liquid to solid ratio (7.5/1mL/g), microwave time (29min). Moreover, oil extracted by MAE was quantitatively (yield) and qualitatively (fatty acid profile) similar to those obtained using Soxhlet extraction (SE), but oil extracted by MAE exhibited favourable physicochemical properties and oxidation stability. Additionally, oil extracted by MAE had a higher content of total phenolic, and it showed stronger antioxidant activities. Scanning electron microscopy revealed that microwave technique efficiently promoted the release of oil by breaking down the cell structure of silkworm pupae. Therefore, MAE can be an effective method for the silkworm pupal oil extraction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. 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...

  2. 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…

  3. 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...

  4. 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...

  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. Bio-refinery of orange peels waste: a new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin.

    Science.gov (United States)

    Boukroufa, Meryem; Boutekedjiret, Chahrazed; Petigny, Loïc; Rakotomanomana, Njara; Chemat, Farid

    2015-05-01

    In this study, extraction of essential oil, polyphenols and pectin from orange peel has been optimized using microwave and ultrasound technology without adding any solvent but only "in situ" water which was recycled and used as solvent. The essential oil extraction performed by Microwave Hydrodiffusion and Gravity (MHG) was optimized and compared to steam distillation extraction (SD). No significant changes in yield were noticed: 4.22 ± 0.03% and 4.16 ± 0.05% for MHG and SD, respectively. After extraction of essential oil, residual water of plant obtained after MHG extraction was used as solvent for polyphenols and pectin extraction from MHG residues. Polyphenols extraction was performed by ultrasound-assisted extraction (UAE) and conventional extraction (CE). Response surface methodology (RSM) using central composite designs (CCD) approach was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE). The statistical analysis revealed that the optimized conditions of ultrasound power and temperature were 0.956 W/cm(2) and 59.83°C giving a polyphenol yield of 50.02 mgGA/100 g dm. Compared with the conventional extraction (CE), the UAE gave an increase of 30% in TPC yield. Pectin was extracted by conventional and microwave assisted extraction. This technique gives a maximal yield of 24.2% for microwave power of 500 W in only 3 min whereas conventional extraction gives 18.32% in 120 min. Combination of microwave, ultrasound and the recycled "in situ" water of citrus peels allow us to obtain high added values compounds in shorter time and managed to make a closed loop using only natural resources provided by the plant which makes the whole process intensified in term of time and energy saving, cleanliness and reduced waste water. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. The Effect of Solvent, Hydrogen Peroxide and Dioxide Titanium on Degradation of PCBs, Using Microwave Radiation in Order to Reduce Occupational Exposure

    Directory of Open Access Journals (Sweden)

    Tajik Reza

    2014-07-01

    Full Text Available Polychlorinated biphenyls (PCBs are one group of persistent organic pollutants (POPs that are of international concern because of global distribution, persistence, and toxicity. Removal of these compounds from the environment remains a very difficult challenge because the compounds are highly hydrophobic and have very low solubility in water. A 900 W domestic microwave oven, pyrex vessel reactor, pyrex tube connector and condensing system were used in this experiment. Radiation was discontinuous and ray powers were 540, 720 and 900 W. The PCBS were analyzed by GC-ECD. The application of microwave radiation and H2O2/TiO2 agents for the degradation of polychlorinated biphenyl contaminated oil was explored in this study. PCB – contaminated oil was treated in a pyrex reactor by microwave irradiation at 2450 MHz with the addition of H2O2/TiO2. A novel grain TiO2 (GT01 was used. The determination of PCB residues in oil by gas chromatography (GC revealed that rates of PCB decomposition were highly dependent on microwave power, exposure time, ratio to solvent with transformer oil in 3:1, the optimal amount of GT01 (0.2 g and 0.116 mol of H2O2 were used in the study. It was suggested that microwave irradiation with the assistance of H2O2/TiO2 might be a potential technology for the degradation of PCB – contaminated oil. The experiments show that MW irradiation, H2O2 oxidant and TiO2 catalyst lead to a degradation efficiency of PCBs only in the presence of ethanol. The results showed that the addition of ethanol significantly enhanced degradation efficiency of PCBs.

  8. 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.

  9. 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.

  10. 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.

  11. Microwave-Assisted Extraction of Natural Antioxidants from the Exotic Gordonia axillaris Fruit: Optimization and Identification of Phenolic Compounds.

    Science.gov (United States)

    Li, Ya; Li, Sha; Lin, Sheng-Jun; Zhang, Jiao-Jiao; Zhao, Cai-Ning; Li, Hua-Bin

    2017-09-06

    Our previous study reported that the fruit of Gordonia axillaris , an edible wild fruit, possessed strong antioxidant activity. In this study, a microwave-assisted extraction (MAE) method was established to extract antioxidants from the fruit of Gordonia axillaris . The influence of five parameters, including ethanol concentration, solvent/material ratio, extraction time, extraction temperature and microwave power, was investigated by single-factor experiments. Three factors, namely ethanol concentration, solvent/material ratio, extraction time, were found to exert a major influence on extraction efficacy, and were further studied by response surface methodology to investigate their interactions. Ethanol concentration of 36.89%, solvent/material ratio of 29.56 mL/g, extraction time of 71.04 min, temperature of 40 °C, and microwave power of 400 W were found to be the optimal condition. The TEAC value was 198.16 ± 5.47 µmol Trolox/g DW under the optimal conditions, which was in conformity to the predicted value (200.28 µmol Trolox/g DW). In addition, the MAE method was compared with two conventional methods (Soxhlet extraction and maceration extraction). Results showed that the antioxidant capacity of the extract obtained by MAE method was stronger than that obtained by maceration (168.67 ± 3.88 µmol Trolox/g DW) or Soxhlet extraction (114.09 ± 2.01 µmol Trolox/g DW). Finally, several phenolic compounds in the extract were identified and quantified by UPLC-MS/MS, which were rutin, gallic acid, protocatechuic acid, epicatechin, epicatechin gallate, 2-hydrocinnamic acid, p -coumaric acid, quercetin, chlorogenic acid and ferulic acid.

  12. A Review of Microwave-Assisted Reactions for Biodiesel Production

    Science.gov (United States)

    Nomanbhay, Saifuddin; Ong, Mei Yin

    2017-01-01

    The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to accomplish superior outcomes over the conventional methods in biodiesel production is presented. A green process for biodiesel production using a non-catalytic method is still new and very costly because of the supercritical condition requirement. Hence, non-catalytic biodiesel conversion under ambient pressure using microwave technology must be developed, as the energy utilization for microwave-based biodiesel synthesis is reported to be lower and cost-effective. PMID:28952536

  13. Microwave-assisted synthesis of graphene–Ni composites with enhanced microwave absorption properties in Ku-band

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zetao [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing (China); Sun, Xin [Science and Technology on Electromagnetic Scattering Laboratory, 100854 Beijing (China); Li, Guoxian [Shenyang National Laboratory for Materials Science Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang (China); Xue, Hairong; Guo, Hu; Fan, Xiaoli; Pan, Xuchen [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing (China); He, Jianping, E-mail: jianph@nuaa.edu.cn [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing (China)

    2015-03-01

    Recently, graphene has been applied as a new microwave absorber because of its high dielectric loss and low density. Nevertheless, the high dielectric constant of pristine graphene has caused unbalanced electromagnetic parameters and results in a bad impedance matching characteristic. In this study, we report a facile microwave-assisted heating approach to produce reduced graphene oxide–nickel (RGO–Ni) composites. The phase and morphology of as-synthesized RGO–Ni composites are characterized by XRD, Raman, FESEM and TEM. The results show that Ni nanoparticles with a diameter around 20 nm are grown densely and uniformly on the RGO sheets. In addition, enhanced microwave absorption properties in Ku-band of RGO–Ni composites is mainly due to the synergistic effect of dielectric loss and magnetic loss and the dramatically electron polarizations caused by the formation of large conductive network. The minimum reflection loss of RGO–Ni-2 composite with the thickness of 2 mm can reaches −42 dB at 17.6 GHz. The RGO–Ni composite is an attractive candidate for the new type of high performance microwave absorbing material. - Highlights: • Ni nanoparticles are grown densely and uniformly on the RGO sheets via microwave-assisted heating approach. • Ni resistance effect is proposed to explain the mechanism to decrease the permittivity with the rising combination of Ni and RGO. • The microwave absorption properties in Ku-band of RGO–Ni composites are effectively enhanced. • The mechanism to improve the microwave absorption properties is discussed.

  14. Solvent-free microwave extraction of essential oil from aromatic herbs: comparison with conventional hydro-distillation.

    Science.gov (United States)

    Lucchesi, Marie E; Chemat, Farid; Smadja, Jacqueline

    2004-07-23

    Solvent-free microwave extraction (SFME) is a combination of microwave heating and dry distillation, performed at atmospheric pressure without added any solvent or water. Isolation and concentration of volatile compounds are performed by a single stage. SFME has been compared with a conventional technique, hydro-distillation (HD), for the extraction of essential oil from three aromatic herbs: basil (Ocimum basilicum L.), garden mint (Mentha crispa L.), and thyme (Thymus vulgaris L.). The essential oils extracted by SFME for 30min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional hydro-distillation for 4.5 h. The SFME method yields an essential oil with higher amounts of more valuable oxygenated compounds, and allows substantial savings of costs, in terms of time, energy and plant material. SFME is a green technology and appears as a good alternative for the extraction of essential oils from aromatic plants.

  15. 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.

  16. Solvent-free microwave extraction of essential oil from Dryopteris fragrans and evaluation of antioxidant activity.

    Science.gov (United States)

    Li, Xiao-Juan; Wang, Wei; Luo, Meng; Li, Chun-Ying; Zu, Yuan-Gang; Mu, Pan-Song; Fu, Yu-Jie

    2012-07-15

    Solvent-free microwave extraction (SFME) of the essential oil from Dryopteris fragrans and its antioxidant activity were investigated. A central composite design combined with response surface methodology was applied to study the influences of extraction time, irradiation power and humidity (proportion of water pretreatment). A maximal extraction yield of 0.33% was achieved under optimal conditions of extraction time 34 min, irradiation power 520 W and humidity 51%. Sixteen compounds, representing 89.65% of the oil, were identified, of which the major ones, (1R,4S,11R)-4,6,6,11-tetramethyltricyclo[5.4.0.0(4,8)]undecan-1-ol (30.49%), 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo[5.3.1.0(4,11)]undec-8-ene (22.91%) and, 1,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethyl-1-naphthalenemethanol (15.11%), accounted for 68.51% of the oil. The antioxidant activity of the essential oil was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene/linoleic acid, and reducing power assay, the IC50 values were 0.19, 0.09 and 0.18 mg/mL, respectively. All these results suggest that SFME represents an excellent alternative protocol for production of essential oils from plant materials.

  17. The Microwave Assisted Composite Manufacturing and Repair (MACMAR) Project

    Science.gov (United States)

    Falker, John; Terrier, Douglas; Clayton, Ronald G.; Worthy, Erica; Sosa, Edward

    2015-01-01

    The inherent microwave property of carbon nanotubes (CNTs) generates the thermal energy required to induce reversible polymerization of the matrix in these self-healing composites. Microwaves will be used to demonstrate advanced composite manufacturing and repair using self-healing composites.

  18. Palladium(II)-catalyzed direct alkoxylation of arenes: evidence for solvent-assisted concerted metalation deprotonation.

    Science.gov (United States)

    Anand, Megha; Sunoj, Raghavan B

    2011-09-16

    Density functional theory investigations on the mechanism of palladium acetate catalyzed direct alkoxylation of N-methoxybenzamide in methanol reveal that the key steps involve solvent-assisted N-H as well as C-H bond activations. The transition state for the critical palladium-carbon bond formation through a concerted metalation deprotonation (CMD) process leading to a palladacycle intermediate has been found to be more stable in the methanol-assisted pathway as compared to an unassisted route.

  19. 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.

  20. 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).

  1. 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).

  2. 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.

  3. 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.

  4. Microwave-assisted rock breaking modelling and application

    CSIR Research Space (South Africa)

    Monchusi, B

    2012-10-01

    Full Text Available As part of the ongoing development of novel mining methods, the CSIR has developed alternative methods to break rocks. In this case, we show the application of microwave energy to break narrow tabular ore bodies....

  5. Microwave-assisted additive free synthesis of nanocrystalline zinc oxide

    OpenAIRE

    Bhatte, Kushal D.; Tambade, Pawan; Fujita, Shin-ichiro; Arai, Masahiko; Bhalchandra M. Bhanage

    2010-01-01

    An additive free synthesis of nanocrystalline zinc oxide using microwave technique is reported. Current methodology is faster, cleaner and cost effective compared with conventional method for the synthesis of zinc oxide nanocrystalline materials. The structure and morphology of nanocrystalline zinc oxide was investigated by TEM, XRD, EDAX, UV-Vis spectroscopy. The results demonstrate that microwave heating can produce polygonal zinc oxide within a short span of time.

  6. 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.

  7. 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.

  8. 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

  9. Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator

    Science.gov (United States)

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2016-06-01

    We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities.

  10. 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.

  11. 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.

  12. 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.

  13. Aqueous microwave-assisted solid-phase peptide synthesis using Fmoc strategy. III: racemization studies and water-based synthesis of histidine-containing peptides.

    Science.gov (United States)

    Hojo, Keiko; Shinozaki, Natsuki; Hidaka, Koushi; Tsuda, Yuko; Fukumori, Yoshinobu; Ichikawa, Hideki; Wade, John D

    2014-10-01

    In this study, we describe the first aqueous microwave-assisted synthesis of histidine-containing peptides in high purity and with low racemization. We have previously shown the effectiveness of our synthesis methodology for peptides including difficult sequences using water-dispersible 9-fluorenylmethoxycarbonyl-amino acid nanoparticles. It is an organic solvent-free, environmentally friendly method for chemical peptide synthesis. Here, we studied the racemization of histidine during an aqueous-based coupling reaction with microwave irradiation. Under our microwave-assisted protocol using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride, the coupling reaction can be efficiently performed with low levels of racemization of histidine. Application of this water-based microwave-assisted protocol with water-dispersible 9-fluorenylmethoxycarbonyl-amino acid nanoparticles led to the successful synthesis of the histidine-containing hexapeptide neuropeptide W-30 (10-15), Tyr-His-Thr-Val-Gly-Arg-NH₂, in high yield and with greatly reduced histidine racemization.

  14. 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.

  15. 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.

  16. Extraction of bioactives from Orthosiphon stamineus using microwave and ultrasound-assisted techniques: Process optimization and scale up.

    Science.gov (United States)

    Chan, Chung-Hung; See, Tiam-You; Yusoff, Rozita; Ngoh, Gek-Cheng; Kow, Kien-Woh

    2017-04-15

    This work demonstrated the optimization and scale up of microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) of bioactive compounds from Orthosiphon stamineus using energy-based parameters such as absorbed power density and absorbed energy density (APD-AED) and response surface methodology (RSM). The intensive optimum conditions of MAE obtained at 80% EtOH, 50mL/g, APD of 0.35W/mL, AED of 250J/mL can be used to determine the optimum conditions of the scale-dependent parameters i.e. microwave power and treatment time at various extraction scales (100-300mL solvent loading). The yields of the up scaled conditions were consistent with less than 8% discrepancy and they were about 91-98% of the Soxhlet extraction yield. By adapting APD-AED method in the case of UAE, the intensive optimum conditions of the extraction, i.e. 70% EtOH, 30mL/g, APD of 0.22W/mL, AED of 450J/mL are able to achieve similar scale up results. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. Ultrasonic-assisted extraction of essential oil from Botryophora geniculate using different extracting solvents

    Science.gov (United States)

    Habibullah, Wilfred, Cecilia Devi

    2016-11-01

    This study compares the performance of ionic liquids to substitute conventional solvents (hexane, dichloromethane and methanol) to extract essential oil from Botryophora geniculate plant. Two different Ionic liquids ([C3MIM][Ac], [C4MIM][Ac]) with co-solvent diethyl ether were used in the ultrasonic-assisted extraction. The effect of various experimental conditions such as time, temperature and solvent were studied. Gas chromatography-mass spectroscopy (GC-MS) was used to analyze essential oils. The results showed that in ultrasonic-assisted extraction using ionic liquids as a solvent gave highest yield (9.5%) in 30 min at temperature 70°C. When using ultrasonic bath with hexane, dichloromethane and methanol, yields was (3.34%), (3.6%) and (3.81%) at 90 min, respectively were obtained. The ultrasonic-assisted extraction under optimal extraction conditions (time 30 min, temperature of 70°C) gave the best yield for the essential oil extraction.

  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. 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.

  1. 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.

  2. A novel application of microwave-assisted extraction of polyphenols from brewer's spent grain with HPLC-DAD-MS analysis.

    Science.gov (United States)

    Moreira, Manuela M; Morais, Simone; Barros, Aquiles A; Delerue-Matos, Cristina; Guido, Luís F

    2012-05-01

    This paper reports a novel application of microwave-assisted extraction (MAE) of polyphenols from brewer's spent grains (BSG). A 2(4) orthogonal composite design was used to obtain the optimal conditions of MAE. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the extraction yield of ferulic acid was investigated through response surface methodology. The results showed that the optimal conditions were 15 min extraction time, 100 °C extraction temperature, 20 mL of solvent, and maximum stirring speed. Under these conditions, the yield of ferulic acid was 1.31 ± 0.04% (w/w), which was fivefold higher than that obtained with conventional solid-liquid extraction techniques. The developed new extraction method considerably reduces extraction time, energy and solvent consumption, while generating fewer wastes. HPLC-DAD-MS analysis indicated that other hydroxycinnamic acids and several ferulic acid dehydrodimers, as well as one dehydrotrimer were also present, confirming that BSG is a valuable source of antioxidant compounds.

  3. Dynamic microwave-assisted extraction combined with continuous-flow microextraction for determination of pesticides in vegetables.

    Science.gov (United States)

    Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Yu, Cui; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2016-02-01

    A simple, rapid, solventless and cost-effective dynamic microwave-assisted extraction (DMAE) combined with continuous-flow microextraction (CFME) system was firstly assembled and validated for extraction of eight organophosphorus pesticides in vegetables. The method combines the advantages of DMAE and CFME, and extends the application of the single drop microextraction to complex solid samples. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, analytes were first extracted from the vegetables using 3% NaCl solution as extraction solvent, then concentrated into microextraction solvent. After extraction, the microextraction solvent containing the enriched analyte was directly analyzed by GC-MS without any filtration or clean-up process. Several parameters affecting the extraction efficiency were investigated and optimized. Real vegetable samples were analyzed, satisfactory recoveries were obtained in the range of 80.7-106.7%, and relative standard deviations were lower than 8.7%.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Fly-ash:H2SO4 catalyzed solvent free efficient synthesis of some aryl chalcones under microwave irradiation

    Science.gov (United States)

    Thirunarayanan, G.; Mayavel, P.; Thirumurthy, K.

    2012-06-01

    Some 2E aryl chalcones have been synthesized using greener catalyst Fly-ash:H2SO4 assisted solvent free environmentally benign Crossed-Aldol reaction. The yields of chalcones are more than 90%. The synthesized chalcones are characterized by their physical constants and spectral data.

  9. Comparison of Conventional Microwave and Focused Microwave-assisted Extraction to Enhance the Efficiency of the Extraction of Antioxidant Flavonols from Jocote Pomace (Spondias purpurea L.).

    Science.gov (United States)

    Reis, Letícia C B; Carneiro, Larissa M; Branco, Carla R C; Branco, Alexsandro

    2015-06-01

    Jocote (Spondias purpurea L.) is rich in phenolic compounds which have antioxidant properties. The focused microwave-assisted extraction (FMAE) was compared with the conventional microwave-assisted extraction (MAE) to obtain flavonols from jocote pomace. The effects of parameters such as the extraction time, the temperature and the composition of the solvent mixture (i.e., the ethanol to water ration) were evaluated and optimized using a statistical experimental design approach. Response surface methodology (RSM) was applied to determine the important effects and interactions of these independent variables on the extractive yield and quantification of some flavonoids. In addition, the antioxidant activity was analyzed. The total phenolic and flavonoid content was determined according to the Folin-Ciocalteu and aluminum chloride methods, respectively. The free radical scavenging activity of the extract was evaluated according to the DPPH assay. The results showed that the optimum extracting parameters used FMAE with extraction time of 20 min, temperature of 68 °C and ethanol composition of 80% in water. Under these conditions, a yield of 3.42% was obtained. Rutin and quercetin were quantified (0.19 mg/mL and 0.024 mg/mL, respectively) through HPLC-DAD. The total phenol and flavonoid contents were found to be 0.897 g GAE/g and 1.271 g QE/g, respectively. In the DPPH scavenging assay, the IC50 value of the extract occurred at 43.10 μg/mL. This study shows that FMAE is suitable as an efficient extraction procedure for the extraction of flavonols from jocote pomace.

  10. Microwave assisted dehulling of black gram (Vigna mungo L).

    Science.gov (United States)

    Joyner, J Jerish; Yadav, B K

    2015-04-01

    This article summarises the results of the investigation of application of microwave exposure on the dehulling characteristics of the black gram and the properties of the dehulled grains. Black gram was exposed to 3 microwave power levels, viz., 450, 630 and 810 W for 7 different exposure, ranging from 60 to 150 s at an interval of 15 s with a view to determine the suitable combination of dosage in order to get the maximum yield with little change in colour. Related changes in properties were also studied. It was observed that the surface temperature of the grain increased with the increase in microwave power level from 450 to 810 W as well as exposure time from 60 to 150 s in the range from 58 to 123 °C while the dehulling time reduced from 445 to 170 s. The dehulling yield increased with increasing microwave dosage in the beginning and reached to the maximum value followed by decreasing trend. The colour of the dehulled grain changed slowly up to a microwave dosage of 972 J/g after that it changed vividly darker than the control. The dehulling and dhal yields and colour change were polynomial functions of microwave dosage. The highest yield of 73.7 % was achieved at about 972 J/g with a little change in colour (CIELAB ΔE* value of 2.58). The corresponding dehulling time, cooking time and losses during dehulling were respectively 185 s, 10 min and 15.1 % as compared to 492 s, 20 min and 31.5 % for control respectively. It is concluded that a dosage of about 972 J/g was the best for the black gram dehulling at a rate of 630 W or higher power level.

  11. 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.

  12. 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

  13. Microwave-assisted synthesis of transition metal phosphide

    Science.gov (United States)

    Viswanathan, Tito

    2014-12-30

    A method of synthesizing transition metal phosphide. In one embodiment, the method has the steps of preparing a transition metal lignosulfonate, mixing the transition metal lignosulfonate with phosphoric acid to form a mixture, and subjecting the mixture to a microwave radiation for a duration of time effective to obtain a transition metal phosphide.

  14. Microwave-Assisted Hydantoins Synthesis on Solid Support

    Science.gov (United States)

    Coursindel, Thibault; Martinez, Jean; Parrot, Isabelle

    2010-01-01

    In this laboratory activity, students are introduced to a three-step synthesis of hydantoin (imidazolidine-2,4-dione), a moiety that is found in many biologically active compounds. Using a microwave oven and solid-support technology, this synthetic experiment is designed for masters-degree candidates working in organic chemistry or upper-level…

  15. Microwave-Assisted Synthesis of Nanomaterials and Nanocomposites

    Science.gov (United States)

    The aqueous preparation of nanoparticles using vitamins B1 and B2, and vitamin C which can function both as reducing and capping agents prompted us accomplished the bulk syntheses of Ag and Fe nanorods using polyethylene glycol (PEG) under microwave (MW) irradiation conditions; t...

  16. Complex-mediated microwave-assisted synthesis of polyacrylonitrile nanoparticles

    Directory of Open Access Journals (Sweden)

    Trinath Biswal

    2010-10-01

    Full Text Available Trinath Biswal, Ramakanta Samal, Prafulla K SahooDepartment of Chemistry, Utkal University, Vani Vihar, Bhubaneswar 751004, IndiaAbstract: The polymerization of acrylonitrile (AN is efficiently, easily, and quickly achieved in the presence of trans-[Co(IIIen2Cl2]Cl complex in a domestic microwave (MW oven. MW irradiation notably promoted the polymerization reaction; this phenomenon is ascribed to the acceleration of the initiator, ammonium persulfate (APS, decomposition by microwave irradiation in the presence of [Co(IIIen2Cl2]Cl. The conversion of monomer to the polymer was mostly excellent in gram scale. Irradiation at low power and time produced more homogeneous polymers with high molecular weight and low polydispersity when compared with the polymer formed by a conventional heating method. The interaction of reacting components was monitored by UV-visible spectrometer. The average molecular weight was derived by gel permeation chromatography (GPC, viscosity methods, and sound velocity by ultrasonic interferometer. The uniform and reduced molecular size was characterized by transmission electron microscopy, the diameter of polyacrylonitrile nanoparticles (PAN being in the range 50–115 nm and 40–230 nm in microwave and conventional heating methods respectively. The surface morphology of PAN prepared by MW irradiation was characterized by scanning electron microscope (SEM. From the kinetic results, the rate of polymerization (Rp was expressed as Rp = [AN]0.63 [APS]0.57 [complex (I].0.88Keywords: microwave, complex catalyst, nanoparticle, kinetics

  17. Optimum Conditions for Microwave Assisted Extraction for Recovery of Phenolic Compounds and Antioxidant Capacity from Macadamia (Macadamia tetraphylla Skin Waste Using Water

    Directory of Open Access Journals (Sweden)

    Adriana Dailey

    2015-12-01

    Full Text Available This study aimed to develop optimal microwave assisted extraction conditions for recovery of phenolic compounds and antioxidant properties from the macadamia skin, an abundant waste source from the macadamia industry. Water, a safe, accessible, and inexpensive solvent, was used as the extraction solvent and Response Surface Methodology (RSM was applied to design and analyse the conditions for microwave-assisted extraction (MAE. The results showed that RSM models were reliable for the prediction of extraction of phenolic compounds and antioxidant properties. Within the tested ranges, MAE radiation time and power, as well as the sample-to-solvent ratio, affected the extraction efficiency of phenolic compounds, flavonoids, proanthocyanidins, and antioxidant properties of the macadamia skin; however, the impact of these variables was varied. The optimal MAE conditions for maximum recovery of TPC, flavonoids, proanthocyanidins and antioxidant properties from the macadamia skin were MAE time of 4.5 min, power of 30% (360 W and sample-to-water ratio of 5 g/100 mL. Under these conditions, an extract could be prepared with TPC of 45 mg/g, flavonoids of 29 mg RUE/g of dried macadamia skin.

  18. Effects of Assistant Solvents and Mixing Intensity on the Bromination Process of Butyl Rubber

    Institute of Scientific and Technical Information of China (English)

    王伟; 邹海魁; 初广文; 向阳; 彭晗; 陈建峰

    2014-01-01

    A slow bromination process of butyl rubber (IIR) suffers from low efficiency and low selectivity (S) of target-product. To obtain suitable approach to intensify the process, effects of assistant solvents and mixing inten-sity on the bromination process were systemically studied in this paper. The reaction process was found constantly accelerated with the increasing dosage and polarity of assistant solvent. Hexane with 30%(by volume) dichloro-methane was found as the suitable solvent component, where the stable conversion of 1,4-isoprene transferring to target product (xA1s) of 80.2%and the corresponding S of 91.2%were obtained in 5 min. The accelerated reaction process was demonstrated being remarkably affected by mixing intensity until the optimal stirring rate of 1100 r·min-1 in a stirred tank reactor. With better mixing condition, a further intensification of the process was achieved in a ro-tating packed bed (RPB) reactor, where xA1s of 82.6% and S of 91.9% were obtained in 2 min. The usage of the suitable solvent component and RPB has potential application in the industrial bromination process intensification.

  19. 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.

  20. Synthesis of Cycloveratrylene Macrocycles and Benzyl Oligomers Catalysed by Bentonite under Microwave/Infrared and Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Manuel Salmón

    2013-10-01

    Full Text Available Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.

  1. Solvent-free and catalyst-free method for the synthesis of 2,4,5-triarylimidazoles under microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    Jian Feng Zhou; Gui Xia Gong; Hui Qin Zhu; Feng Xia Zhu

    2009-01-01

    A facile procedure for the synthesis of 2,4,5-triarylimidazoles is being reported starting from benzil, aromatic aldehyde and ammonium acetate. The reactions were carried out with catalyst-free, solvent-free and under microwave irradiation conditions in high yield (80-99%) with short time (3-5 min) and environmental benign, as well as convenient operation. The structures of the compounds have been confirmed on the basis of their IR, ~1H NMR, and/or ~(13)C NMR, MS, and elemental analyzer.

  2. 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.

  3. Photonic crystal nanocavity assisted rejection ratio tunable notch microwave photonic filter

    Science.gov (United States)

    Long, Yun; Xia, Jinsong; Zhang, Yong; Dong, Jianji; Wang, Jian

    2017-01-01

    Driven by the increasing demand on handing microwave signals with compact device, low power consumption, high efficiency and high reliability, it is highly desired to generate, distribute, and process microwave signals using photonic integrated circuits. Silicon photonics offers a promising platform facilitating ultracompact microwave photonic signal processing assisted by silicon nanophotonic devices. In this paper, we propose, theoretically analyze and experimentally demonstrate a simple scheme to realize ultracompact rejection ratio tunable notch microwave photonic filter (MPF) based on a silicon photonic crystal (PhC) nanocavity with fixed extinction ratio. Using a conventional modulation scheme with only a single phase modulator (PM), the rejection ratio of the presented MPF can be tuned from about 10 dB to beyond 60 dB. Moreover, the central frequency tunable operation in the high rejection ratio region is also demonstrated in the experiment.

  4. 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.

  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 (N2H4·H2O) 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 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)

  7. 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.

  8. 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

  9. 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.

  10. 微波辅助溶剂热法合成烟酸锌配位聚合物%Microwave-assisted Solvothermal Synthesis of Bis(nicotinate) zinc

    Institute of Scientific and Technical Information of China (English)

    高飞; 王颖; 刘晓旸

    2011-01-01

    采用微波辅助溶剂热法合成了烟酸锌配位聚合物,并对其性质进行了表征.讨论了时间、温度、底物浓度、加热方法及溶剂等因素对产物的结晶情况和生长过程中粒径大小的影响.通过结合微波溶剂热与传统溶剂热两种方法,既使合成反应具备了微波加热反应速度快的优点,同时又使晶体成核均匀,利用该法合成获得了适于晶体结构解析的单晶体.%Bis( nicotinate)zinc was successfully synthesized in 10 min under microwave-assisted solvothermal condition, the influences of reaction time, temperature, solvent, substrate concentration and heating method on the crystallization of the complexes were disscussed. Microwave heating not only shorten the reaction time significantly and improve the yield and purity of product, but also has good reproducibility and stability of the amplification. The combination of the microwave-assisted solvothermal method and the conventional solvothermai method not only has the advantages of microwave heating, but also can obtain crystals with large particle size that suitable for structural analysis.

  11. 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.

  12. 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

  13. Improved conventional and microwave-assisted silylation protocols for simultaneous gas chromatographic determination of tocopherols and sterols: Method development and multi-response optimization.

    Science.gov (United States)

    Poojary, Mahesha M; Passamonti, Paolo

    2016-12-09

    This paper reports on improved conventional thermal silylation (CTS) and microwave-assisted silylation (MAS) methods for simultaneous determination of tocopherols and sterols by gas chromatography. Reaction parameters in each of the methods developed were systematically optimized using a full factorial design followed by a central composite design. Initially, experimental conditions for CTS were optimized using a block heater. Further, a rapid MAS was developed and optimized. To understand microwave heating mechanisms, MAS was optimized by two distinct modes of microwave heating: temperature-controlled MAS and power-controlled MAS, using dedicated instruments where reaction temperature and microwave power level were controlled and monitored online. Developed methods: were compared with routine overnight derivatization. On a comprehensive level, while both CTS and MAS were found to be efficient derivatization techniques, MAS significantly reduced the reaction time. The optimal derivatization temperature and time for CTS found to be 55°C and 54min, while it was 87°C and 1.2min for temperature-controlled MAS. Further, a microwave power of 300W and a derivatization time 0.5min found to be optimal for power-controlled MAS. The use of an appropriate derivatization solvent, such as pyridine, was found to be critical for the successful determination. Catalysts, like potassium acetate and 4-dimethylaminopyridine, enhanced the efficiency slightly. The developed methods showed excellent analytical performance in terms of linearity, accuracy and precision. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. 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.

  15. 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.

  16. Microwave-Assisted Synthesis of Poly(Aspartic Acid-Itaconic Acid) Copolymer and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    Zhang Yuling; Jiang Yijian; Hu Zhiguang; Wei Hanxiao; Guo Jun; Wang Jilong

    2016-01-01

    Poly(aspartic acid-itaconic acid) copolymer was synthesized from aspartic acid (Asp) and itaconic acid (Ita) un-der microwave irradiation. The effects of microwave power, microwave irradiation time, molar ratio of itaconic acid and aspartic acid, catalyst type, catalyst and organic solvent content on copolymer yield, and the performance for inhibition of CaCO3 fouling were investigated. It was found that the product yield achieved a highest record of 95% when the amount of catalyst NaH2PO4was 0.012 mol, the amount of organic solvent propylene carbonate was 16 mL, the molar ratio of Asp/Ita was 3:1, the microwave output power was 1200 W and the irradiation time was 5.5 min. And the product performance for inhibition of calcium carbonate also reached a highest value of 94.38%. Structural characterization of the product showed that the product was the aspartic acid-itaconic acid copolymer.

  17. Rapid method for the determination of 16 organochlorine pesticides in sesame seeds by microwave-assisted extraction and analysis of extracts by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Papadakis, Emmanouil N; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

    2006-09-15

    A method for the multiresidue analysis of 16 organochlorine insecticides in sesame seeds has been developed. The method is based on the microwave-assisted extraction (MAE) of the sesame seeds by the use of a water-acetonitrile mixture followed by Florisil clean-up of the extracts and subsequent analysis by gas chromatography-mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. MAE operational parameters (extraction solvent, temperature and time, extractant volume) were optimized with respect to extraction efficiency of the target compounds from sesame seeds with 46% oil content. Recoveries >80% with relative standard deviations (RSD) seed samples imported to Greece.

  18. The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

    Science.gov (United States)

    Tajti, Ádám; Ádám, Anna; Csontos, István; Karaghiosoff, Konstantin; Czugler, Mátyás; Ábrányi-Balogh, Péter

    2017-01-01

    Summary A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair.

  19. The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

    Directory of Open Access Journals (Sweden)

    Erika Bálint

    2017-01-01

    Full Text Available A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair.

  20. Parallel microwave-assisted synthesis of ionic liquids and screening for denitrogenation of straight-run diesel feed by liquid-liquid extraction.

    Science.gov (United States)

    Ceron, Miguel A; Guzman-Lucero, Diego J; Palomeque, Jorge F; Martínez-Palou, Rafael

    2012-06-01

    Fifty-six ionic liquids were efficiently synthesized in parallel format under one-pot, solvent-free microwave-assisted synthesis. These compounds were evaluated as extracting agents of nitrogen-containing compounds from a real Diesel feed before being submitted to the hydrodesulfurization process to obtain ultralow sulfur Diesel. Our results showed that halogenated ionic liquids are an excellent alternative due to these ionic liquids are relatively inexpensive, presenting a high selectivity for the extraction of nitrogen-containing compounds and can be regenerated and recycled.

  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. 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.

  3. Magnetic carbon nanostructures: microwave energy-assisted pyrolysis vs. conventional pyrolysis.

    Science.gov (United States)

    Zhu, Jiahua; Pallavkar, Sameer; Chen, Minjiao; Yerra, Narendranath; Luo, Zhiping; Colorado, Henry A; Lin, Hongfei; Haldolaarachchige, Neel; Khasanov, Airat; Ho, Thomas C; Young, David P; Wei, Suying; Guo, Zhanhu

    2013-01-11

    Magnetic carbon nanostructures from microwave assisted- and conventional-pyrolysis processes are compared. Unlike graphitized carbon shells from conventional heating, different carbon shell morphologies including nanotubes, nanoflakes and amorphous carbon were observed. Crystalline iron and cementite were observed in the magnetic core, different from a single cementite phase from the conventional process.

  4. 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...

  5. 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...

  6. 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.

  7. Microwave-Assisted Chemistry: Synthetic Applications for Rapid Assembly of Nanomaterials and Organics

    Science.gov (United States)

    The magic of microwave (MW) heating technique, termed as the Bunsen burner of the 21th Century, has emerged as valuable alternative in synthesis of organics, polymers, inorganics, and nanomaterials. Important innovations in MW-assisted chemistry now enable chemists to prepare cat...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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...

  15. Characteristics of the microwave pyrolysis and microwave CO2-assisted gasification of dewatered sewage sludge.

    Science.gov (United States)

    Chun, Young Nam; Jeong, Byeo Ri

    2017-07-28

    Microwave drying-pyrolysis or drying-gasification characteristics were examined to convert sewage sludge into energy and resources. The gasification was carried out with carbon dioxide as a gasifying agent. The examination results were compared with those of the conventional heating-type electric furnace to compare both product characteristics. Through the pyrolysis or gasification, gas, tar, and char were generated as products. The produced gas was the largest component of each process, followed by the sludge char and the tar. During the pyrolysis process, the main components of the produced gas were hydrogen and carbon monoxide, with a small amount of hydrocarbons such as methane and ethylene. In the gasification process, however, the amount of carbon monoxide was greater than the amount of hydrogen. In microwave gasification, a large amount of heavy tar was produced. The largest amount of benzene in light tar was generated from the pyrolysis or gasification. Ammonia and hydrogen cyanide, which are precursors of NOx, were also generated. In the microwave heating method, the sludge char produced by pyrolysis and gasification had pores in the mesopore range. This could be explained that the gas obtained from the microwave pyrolysis or gasification of the wet sewage sludge can be used as an alternative fuel, but the tar and NOx precursors in the produced gas should be treated. Sludge char can be used as a biomass solid fuel or as a tar removal adsorbent if necessary.

  16. One-step microwave-assisted colloidal synthesis of hybrid silver oxide/silver nanoparticles: characterization and catalytic study

    Science.gov (United States)

    Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    This study reports the characterization and catalytic activities of silver-oxide/silver nanoparticles (Ag2O/Ag NPs) synthesized by microwave-assisted colloidal method in the presence of anionic sodium dodecyl sulfate (SDS) surfactant. To promote different contents of silver in silver oxide, the volume ratio (VR) of ethylene glycol (EG) was varied (VR: 10% to 14%) in relation to the total volume of distilled water solvent. The plasmonic resonance of Ag2O/Ag NPs could be detected around a wavelength of 350 nm, and it is suggested that Ag2O/Ag NPs were successfully formed in the colloid solution following exposure to microwaves. Additionally, the growth rate for each crystal phase within Ag2O and Ag was influenced by an increase of EG as revealed by x-ray diffraction patterns. The morphology, average diameter, and uniformity of Ag2O/Ag NPs were studied simultaneously by transmission electron microscopy. Infrared absorption measurement of Ag2O/Ag NPs confirmed the existence of SDS surfactant as a protective agent. Based on the characterization data, Ag2O/Ag NPs synthesized using this technique exhibited good properties, with high-yield production of NPs. The photocatalytic experiments demonstrate the key role of the crystal phase of Ag2O/Ag NPs in photocatalytic efficiency.

  17. 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.

  18. One-step microwave-assisted synthesis of water-dispersible Fe3O4 magnetic nanoclusters for hyperthermia applications

    Science.gov (United States)

    Sathya, Ayyappan; Kalyani, S.; Ranoo, Surojit; Philip, John

    2017-10-01

    To realize magnetic hyperthermia as an alternate stand-alone therapeutic procedure for cancer treatment, magnetic nanoparticles with optimal performance, within the biologically safe limits, are to be produced using simple, reproducible and scalable techniques. Herein, we present a simple, one-step approach for synthesis of water-dispersible magnetic nanoclusters (MNCs) of superparamagnetic iron oxide by reducing of Fe2(SO4)3 in sodium acetate (alkali), poly ethylene glycol (capping ligand), and ethylene glycol (solvent and reductant) in a microwave reactor. The average size and saturation magnetization of the MNC's are tuned from 27 to 52 nm and 32 to 58 emu/g by increasing the reaction time from 10 to 600 s. Transmission electron microscopy images reveal that each MNC composed of large number of primary Fe3O4 nanoparticles. The synthesised MNCs show excellent colloidal stability in aqueous phase due to the adsorbed PEG layer. The highest SAR value of 215 ± 10 W/gFe observed in 52 nm size MNC at a frequency of 126 kHz and field of 63 kA/m suggest the potential use of these MNC in hyperthermia applications. This study further opens up the possibilities to develop metal ion-doped MNCs with tunable sizes suitable for various biomedical applications using microwave assisted synthesis.

  19. 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

  20. 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.

  1. 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.

  2. Synthesis of new pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8,11-dione (PCU) cyanosilylated derivatives using sulphated zirconia and hydrotalcite as catalysts in microwave-assisted reactions under solvent free conditions.

    Science.gov (United States)

    Guerra-Navarro, Nahí Adriana; Palacios-Grijalva, Laura Nadxieli; Angeles-Beltrán, Deyanira; Negrón-Silva, Guillermo E; Lomas-Romero, Leticia; González-Zamora, Eduardo; Gaviño-Ramírez, Rubén; Navarrete-Bolaños, Juan

    2011-08-04

    A comparison was made of the effectiveness of the functionalization reactions of pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8,11-dione (PCU) using sulphated zirconia in protection-deprotection reactions and Mg/Al hydrotalcite in a cyanosilylation reaction, under classical thermal conditions and imposing microwave radiation; improved yields and reaction times were considered.

  3. Analysis of niflumic acid prepared by rapid microwave-assisted evaporation.

    Science.gov (United States)

    Radacsi, Norbert; Stefanidis, Georgios D; Szabó-Révész, Piroska; Ambrus, Rita

    2014-09-01

    Evaporative crystallization is widely applied in several industrial processes, including the pharmaceutical industry. Microwave irradiation can significantly speed up solvent evaporation in these crystallization processes, resulting in reduced particle size due to rapid crystallization. A single-mode microwave setup was used for evaporative crystallization of the model active pharmaceutical ingredient, niflumic acid, and the polymer, polyvinylpirrolidone (PVP). Production of crystals by microwave irradiation offers a modern way for drug formulation, and by reducing the particle size the dissolution rate and bioavailability of the active pharmaceutical ingredient can be enhanced. In this study, a 2.5-fold increase in the dissolution rate of the produced niflumic acid crystals was observed compared to the dissolution rate of the original drug in 120min. When niflumic acid was produced together with the PVP in the microwave system, an amorphous solid dispersion was created with particles in the nano-size range, which showed a 5-fold increase in dissolution rate in 120min compared to the dissolution of the crystalline niflumic acid samples created by the microwave irradiation in the absence of PVP.

  4. 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.

  5. Kinetics of Solvent Blue and Reactive Yellow removal using microwave radiation in combination with nanoscale zero-valent iron.

    Science.gov (United States)

    Mao, Yanpeng; Xi, Zhenqian; Wang, Wenlong; Ma, Chunyuan; Yue, Qinyan

    2015-04-01

    We investigated the efficiency and kinetics of the degradation of soluble dyes over the pH range 5.0-9.0 using a method employing microwave radiation in combination with nanoscale zero-valent iron (MW-nZVI). The nZVI particles (40-70 nm in diameter) were prepared by a liquid-phase chemical reduction method employing starch as a dispersant. Compared to the removal of Solvent Blue 36 and Reactive Yellow K-RN using only nZVI, more rapid and efficient dye removal and total organic carbon removal were achieved using MW-nZVI. The dye removal efficiency increased significantly with decreasing pH, but was negligibly affected by variation in the microwave power. The kinetics of dye removal by MW-nZVI followed both an empirical equation and the pseudo first-order model, while the kinetics of dye removal using nZVI could only be described by an empirical equation. It was also concluded that microwave heating of the dye solutions as well as acceleration of corrosion of nZVI and consumption of Fe(II) were possible reasons behind the enhanced dye degradation.

  6. Nanoscale physical properties of polymer glasses formed by solvent-assisted laser deposition

    Science.gov (United States)

    Shepard, Kimberly; Arnold, Craig; Priestley, Rodney

    2015-03-01

    High-energy, low-density nanostructured polymer glasses are formed via the solvent-assisted laser deposition technique MAPLE (Matrix Assisted Pulsed Laser Evaporation). During film deposition, micro- to nano-size polymer/solvent clusters are ejected via laser ablation from a frozen dilute polymer solution. During flight to the substrate under vacuum, the clusters experience rapid cooling and solvent stripping, forming polymer nanoglobules. Bulk polymer films are formed via the gradual assembly of these spherical-like nanostructured building blocks (i.e. nanoglobules). The MAPLE process thus enables investigation of the exceptional properties of glasses formed under extreme processing conditions. In the bulk state, we probe the effect of process parameters and chemical identity of the thermal behavior of a series of methacrylate polymers. We also employ multiple techniques to directly measure the properties of the polymer nanoglobules and connect the results to the global film properties. This talk will address nanoscale dilatometry via AFM, in which the volume of an individual polymer nanoglobule is tracked as it is heated through its glass transition, as well as Flash DSC analysis of the thermal properties of nanogram size MAPLE-deposited polymer glasses. We then discuss these findings in the context of the material's unconventional route to the glassy state.

  7. Microwave assisted click chemistry on a conductive polymer film

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Hansen, Thomas S.; Larsen, Niels Bent

    2011-01-01

    Microwave (MW) irradiation has been used to accelerate the functionalization of an azide functional poly(3,4-ethylenedioxythiophene) film by click chemistry. The absorption of MW energy by the conductive polymer has been exploited for localized activation of the reaction on the polymer surface....... The method has been applied for anchoring of the chelating agent nitrilotriacetic acid (NTA) on the conductive polymer. The chelating linkage ability of NTA on the surface was investigated through a sandwich ELISA study confirming the selective bonding of a histidine tagged protein....

  8. 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.

  9. Microwave-assisted extraction versus Soxhlet extraction for the analysis of short-chain chlorinated alkanes in sediments.

    Science.gov (United States)

    Parera, J; Santos, F J; Galceran, M T

    2004-08-13

    Microwave-assisted extraction (MAE) was evaluated as a possible alternative to Soxhlet extraction for analysing short-chain chlorinated alkanes (commonly called short-chain chlorinated paraffins, SCCPs) in river sediment samples, using gas chromatography coupled to negative chemical ionisation mass spectrometry. For MAE optimisation, several extraction parameters such as solvent extraction mixture, extraction time and extraction temperature were studied. Maximum extraction efficiencies for SCCPs (90%) and for 12 polychlorinated biphenyl (PCB) congeners (91-95%) were achieved using 5 g of sediment sample, 30 ml of n-hexane-acetone (1:1, v/v) as solvent extraction, and 15 min and 115 degrees C of extraction time and temperature, respectively. Activated Florisil was used to clean-up the extracts, allowing highly selective separation of SCCPs from other organic contaminants such as PCBs. MAE was compared with a conventional extraction technique such as Soxhlet and good agreement in the results was obtained. Quality parameters of the optimised MAE method such as run-to-run (R.S.D. 7%) and day-to-day precision (R.S.D. 9%) were determined using spiked river sediment samples, with LODs of 1.5 ng g(-1). This method was successfully applied to the analysis of SCCPs in river sediment samples at concentrations below the ng g(-1) level. O 2004 Elsevier B.V. All rights reserved.

  10. Microwave and blanch-assisted drying of white yam (Dioscorea rotundata).

    Science.gov (United States)

    Abano, Ernest Ekow; Amoah, Robert Sarpong

    2015-11-01

    The effect of microwave and blanch pretreatments on the drying kinetics and quality of white yam (Dioscorea rotundata) was investigated. Yam cubes destined for hot air drying at temperatures 70-90°C were predried in a domestic microwave or blanched in hot water for 1-5 min. Microwave pretreatment time had a positive significant effect on drying rate but both pretreatments had a negative influence on the ascorbic acid content and the nonenzymatic browning. The optimum drying conditions were a microwave pretreatment time of 5 min and a temperature of 70°C and a blanching time of 1 min at a temperature of 80°C. Among the models fitted, the Midilli et al. and the Page models gave the best fits for yam cubes predried with microwave and blanch, respectively. The effective moisture diffusivity for microwave-assisted drying increased from 1.05 × 10(-8 )m(2 )s(-1) to 2.00 × 10(-8) m(2 )s(-1) while the hot water blanched samples decreased from 1.53 × 10(-8) to 8.81 × 10(-9 )m(2 )s(-1) with time. The study demonstrates that microwave-assisted drying could be used to enhance heat and mass transfer processes to produce better quality dried yam products.

  11. 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.

  12. 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

  13. Polyol synthesis of nanosized Pt/C electrocatalysts assisted by pulse microwave activation

    Energy Technology Data Exchange (ETDEWEB)

    Lebegue, E.; Baranton, S.; Coutanceau, C. [Laboratoire de Catalyse en Chimie Organique (LACCO), UMR 6503 CNRS, Universite de Poitiers, 40 av recteur Pineau, F-86000 Poitiers (France)

    2011-02-01

    A polyol process assisted by pulse microwave activation was used to prepare efficient Pt/C electrocatalysts for PEMFC applications with reducing cost. Catalysts from pulsed microwave method were compared with a catalyst issued from a classical method, in terms of active surface area, platinum loading and activity towards the oxygen reduction reaction. A design of experiments (DOE derived from the Taguchi method) has been implemented to optimize experimental parameters only related to pulse microwave activation, the intrinsic synthesis parameters (concentration of platinum salt, platinum/carbon weight ratio and pH) being kept constant. Controlled parameters were duration of microwave pulse, maximum temperature and total duration of the synthesis. Considered responses were catalyst active surface area and the Pt/C loading. An optimized configuration of synthesis parameter was proposed. The confirmation experiment revealed a trend in agreement with that expected. Three catalysts (two from pulsed microwave synthesis method and one prepared by the classical method) were characterized by transmission electron microscopy, cyclic voltammetry and CO stripping. Catalysts from pulsed microwave method display higher characteristics than the one prepared by the classical method. The Pt/C catalyst from the confirmation experiment displays the highest catalytic activity toward oxygen reduction reaction. (author)

  14. 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.

  15. Microwave assisted antibacterial chitosan-silver nanocomposite films.

    Science.gov (United States)

    Raghavendra, Gownolla Malegowd; Jung, Jeyoung; Kim, Dowan; Seo, Jongchul

    2016-03-01

    In the current approach, antibacterial chitosan-silver nanocomposite films were fabricated through microwave irradiation. During the process, by utilizing chitosan as reducing agent, silver nanoparticles were synthesized within 11 min by microwave irradiation. Further, films were fabricated within 90 min. It involved an energy consumption of just 0.146 kWh to synthesize silver nanoparticles. This is many times less than the energy consumed during conventional methods. The silver nanoparticles were examined through UV-vis spectrum and transmission electron microscopy (TEM). The fabricated films were characterized by using scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and contact angle (CA) measurements. The films exhibited antibacterial properties against both Gram-negative micro-organisms (Escherichia coli; E. coli) and Gram-positive micro-organisms (Staphylococcus aureus; S. aureus). In overall, the procedure adopted for fabricating these antibacterial films is environmental friendly, time-saving and energy-saving.

  16. A novel microwave synthesis of calcium hydroxyapatite. Optimisation and investigation of a microwave assisted reaction route

    CERN Document Server

    Zawahreh, Y

    2001-01-01

    Hydroxyapatite is a bioactive calcium phosphate used in non-load bearing applications, such as space-filling in maxillofacial reconstruction. As a coating, hydroxyapatite is used on load-bearing orthopaedic metal prostheses to improve fixation and/or biocompatibility. Conventional synthesis processes for the production of hydroxyapatite are time-consuming and labour-intensive. Microwave irradiation was investigated as a means to enhance the synthesis reaction using calcium hydroxide (Ca(OH) sub 2) and orthophosphoric acid (H sub 3 PO sub 4) as reactants. An initial set of reactions indicated the feasibility of the microwave synthesis route. Optimisation reactions were then performed followed by investigation sets of reactions. Parameters such as microwave power, irradiation time, and reactant concentrations were varied. Using 0.5M Ca(OH) sub 2 and 0.3M H sub 3 PO sub 4 , a phase-pure hydroxyapatite powder with a stoichiometric molar Ca/P ratio of 1.67 was produced in 60 seconds at 450W and 2.45GHz. The microw...

  17. Degradation of Transformer Oil (PCB Compounds by Microwave Radiation, Ethanol Solvent, Hydrogen Peroxide and Dioxide Titanium for Reducing Environmental Hazards

    Directory of Open Access Journals (Sweden)

    Reza Tajik

    2013-02-01

    Full Text Available Background: Poly chlorinated biphenyls (PCBs are a class of chlorinated organic chemicals that do not easily degrade in the environment. This study was conducted to determine the effect of microwave rays, hydrogen peroxide, dioxide titanium and ethanol solvent on the degradation of PCBs. Methods: A 900w domestic MW oven with a fixed frequency of 2450 MHZ was used to provide MW irradiation. Ray powers were used in 540, 720, and 900w. A hole was made on the top portion of the oven and a Pyrex vessel reactor (250ml volume was connected to condensing system with a Pyrex tube connector. The PCBs were analyzed by GC-ECD. Results: The degradation of total PCBs was 54.62%, 79.71%, and 95.76% in terms of their ratio to solvent with transformer oil at 1:1, 2:1, and 3:1, respectively. The degradation of total PCBs was 84.27%, 89.18%, and 96.1% when using 540, 720, and 900W microwave radiation, respectively. The degradation of total PCBs was 70.72%, 93.02%, 94.16, 95.23% and 96.1% when not using H2O2/ Tio2 and using 20% H2O2 and 0.05, 0.1, 0.15, and 0.2g Tio2, respectively. Conclusion: In the present study, the optimum conditions to decompose PCBs efficiently included 50 ml volume of ratio to solvent with transformer oil (3:1, sodium hydroxide solution (0.2N 1 cc, use of 20% hydrogen peroxide of total volume of samples, dioxide titanium (0.2g, and irradiation for 9 minutes. Under these optimum conditions, efficiency of PCBs decomposition increased.

  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. 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.

  20. 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.

  1. 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.

  2. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS.

    Science.gov (United States)

    Ye, Qing

    2013-06-01

    In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. 微波辅助丙酮提取大蒜油工艺的研究%Study on the Microwave-Assisted Acetone Extraction of Garlic Oil

    Institute of Scientific and Technical Information of China (English)

    邵金华; 陈莫林; 董加宝; 胡娜

    2013-01-01

    In order to increase the garlic oil yield and add value of garlic,this article made a study on the extraction technology of garlic oil by using microwave-assisted acetone extraction method.Through single factor and orthogonal design of microwave power,garlic and acetone ratio,microwave extraction time and acetone concentration on garlic oil extraction rate effects.The results showed that the optimal conditions for the extraction of garlic oil were the microwave power of 100W,microwave extraction time of 75s,ratio of solvent to material of 25∶1 and acetone concentration of 90%,and the highest rate of the garlic oil was 3.85%,and the ratio of solvent to material was a major influence factor for the extraction yield of garlic oil.%为提高大蒜油的得率,增加大蒜的附加值,采用微波辅助、丙酮提取的方法进行大蒜油提取工艺.通过单因素和正交试验考察微波的功率、大蒜和丙酮的配比、微波提取的时间和丙酮的浓度对大蒜油提取得率的影响.结果表明,大蒜和丙酮的配比为大蒜油提取工艺的最显著影响因素;最佳的工艺条件是,微波功率100 W、微波提取时间75 s、液料比25∶1、丙酮体积分数为90%时,大蒜油的提取率最高,提取率为3.85%.

  4. Fast analysis of volatile components of Achillea tenuifolia Lam with microwave distillation followed by headspace single-drop microextraction coupled to gas chromatography-mass spectrometry (GC-MS).

    Science.gov (United States)

    Piryaei, Marzieh; Nazemiyeh, Hossein

    2016-01-01

    This article investigates the effect of microwaves on the amount of volatile compounds Achillea tenuifolia Lam with two methods, headspace single-drop microextraction and microwave-assisted headspace single-drop microextraction (MA-SDME), for the analysis of essential oil. Solvent selection, solvent volume, microwave power, irradiation time and sample mass were optimised by the simplex method.

  5. Rapid extraction of PCDD/Fs from soil and fly ash samples. Pressurized fluid extraction (PFE) and microwave-assisted extraction (MAE)

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, P.; Fabrellas, B. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain)

    2004-09-15

    The main reference extraction method in the analysis of polychlorinated dibenzop- dioxins and dibenzofurans (PCDD/Fs) is still the Soxhlet extraction. But it requires long extraction times (up to 24 hs), large volumes of hazardous organic solvents (100-300 ml) and its automation is limited. Pressurized Fluid Extraction (PFE) and Microwave-Assisted Extraction (MAE) are two relatively new extraction techniques that reduce the time and the volume of solvent required for extraction. However, very different PFE extraction conditions are found for the same enviromental matrices in the literature. MAE is not a extraction technique very applied for the analysis of PCDD/Fs yet, although it is used for the determination of other organic compounds, such as PCBs and PAHs. In this study, PFE and MAE extraction conditions were optimized to determine PCDDs y PCDFs in fly ash and soil/sediment samples. Conventional Soxhlet extraction with toluene was used to compare the extraction efficiency of both techniques.

  6. Explicit solvent molecular dynamics simulations of chaperonin-assisted rhodanese folding

    Institute of Scientific and Technical Information of China (English)

    Ying Ren; Jian Gao; Ji Xu; Wei Ge; Jinghai Li

    2009-01-01

    Chaperonins are known to facilitate the productive folding of numerous misfolded proteins, Despite their established importance, the mechanism of chaperonin-assisted protein folding remains unknown. In the present article, all-atom explicit solvent molecular dynamics (MD) simulations have been performed for the first time on rhodanese folding in a series of cavity-size and cavity-charge chaperonin mutants. A compromise between stability and flexibility of chaperonin structure during the substrate folding has been observed and the key factors affecting this dynamic process are discussed.

  7. 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.

  8. 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.

  9. 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.

  10. Green synthesis of silver nanoparticles using extract of Parkia speciosa Hassk pods assisted by microwave irradiation

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2016-11-01

    Full Text Available This paper reports an investigation of the microwave-assisted synthesis of silver nanoparticles (Ag NPs using extract of stinky bean (Parkia speciosa Hassk pods (BP. The formation of Ag NPs was identified by instrumental analysis consists of UV–vis spectrophotometry, Fourier-transform infrared (FTIR spectrophotometry, scanning electron microscopy (SEM, transmission electron microscopy (TEM and particle size analysis. Furthermore, Ag NPs were used as antibacterial agents against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The results indicate rapid formation of Ag NPs during microwave irradiation with similar properties to those obtained through the aging method. In general, the use of microwave irradiation yields larger particles, and it is affected by volume ratio of the extract to the AgNO3 solution. The prepared materials demonstrated antibacterial activity.

  11. Microwave-Assisted Extraction Followed by Solid-Phase Extraction for the Chromatographic Analysis of Alkaloids in Stephania cepharantha.

    Science.gov (United States)

    Liu, Ying; Xie, Daotao; Kang, Yun; Wang, Yaqin; Yang, Ping; Guo, Jixian; Huang, Jianming

    2016-04-01

    A procedure involving microwave-assisted extraction (MAE) followed by solid-phase extraction (SPE) was established for the extraction and purification of three bisbenzylisoquinoline alkaloids from Stephania cepharantha, and a reversed-phase high-performance liquid chromatography (HPLC) method was developed for the quantification of the target alkaloids. Chromatographic separation was achieved on a Phenomenex Luna Phenyl-Hexyl column. Prior to the HPLC analysis, the alkaloids were rapidly extracted by an optimized MAE process using 0.01 mol/L hydrochloric acid as the solvent. The MAE extract was subsequently purified by SPE using a cation-exchange polymeric cartridge. The MAE-SPE procedure extracted the three alkaloids with satisfactory recoveries ranging from 100.44 to 102.12%. In comparison with the MAE, Soxhlet and ultrasonic-assisted extractions, the proposed MAE-SPE method showed satisfactory cleanup efficiency. Thus, the validated MAE-SPE-HPLC method is specific, accurate and applicable to the determination of alkaloids in S. cepharantha.

  12. Facile and efficient one-pot solvothermal and microwave-assisted synthesis of stable colloidal solutions of MFe{sub 2}O{sub 4} spinel magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Solano, Eduardo; Perez-Mirabet, Leonardo [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Martinez-Julian, Fernando; Guzman, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC (Spain); Yanez, Ramon [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Pomar, Alberto; Ricart, Susagna, E-mail: ricart@icmab.es [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC (Spain); Ros, Josep [Universitat Autonoma de Barcelona, Departament de Quimica (Spain)

    2012-08-15

    Well-defined synthesis conditions of high quality MFe{sub 2}O{sub 4} (M = Mn, Fe, Co, Ni, Zn, and Cu) spinel ferrite magnetic nanoparticles, with diameters below 10 nm, have been described based on facile and efficient one-pot solvothermal or microwave-assisted heating procedures. Both methods are reproducible and scalable and allow forming concentrated stable colloidal solutions in polar solvents, but microwave-assisted heating allows reducing 15 times the required annealing time and leads to an enhanced monodispersity of the nanoparticles. Non-agglomerated nanoparticles dispersions have been achieved using a simple one-pot approach where a single compound, triethyleneglycol, behaves at the same time as solvent and capping ligand. A narrow nanoparticle size distribution and high quality crystallinity have been achieved through selected nucleation and growth conditions. High resolution transmission electron microscopy images and electron energy loss spectroscopy analysis confirm the expected structure and composition and show that similar crystal faceting has been formed in both synthetic approaches. The spinel nanoparticles behave as ferrimagnets with a high saturation magnetization and are superparamagnetic at room temperature. The influence of synthesis route on phase purity and unconventional magnetic properties is discussed in some particular cases such as CuFe{sub 2}O{sub 4}, CoFe{sub 2}O{sub 4}, and ZnFe{sub 2}O{sub 4}.

  13. Optimization of Microwave-Assisted Extraction of Curcumin From Curcuma longa L. (Turmeric and Evaluation of Antioxidant Activity in Multi-Test Systems

    Directory of Open Access Journals (Sweden)

    Mustafa Bener

    2016-03-01

    Full Text Available Turmeric ( Curcuma longa L. is a medicinal plant, and its biological activities mainly arise from the main constituent, known as diferuloylmethane or curcumin. In the present paper, microwave-assisted extraction (MAE was investigated for the recovery of curcumin from turmeric in comparison to conventional heat-assisted extraction (CHAE technique. Various experimental conditions, such as solvent concentration (0-100%, v/v, MAE temperature (30-130 oC and MAE time (0-20 min were investigated to optimize the extraction of curcumin from turmeric. The identification and quantification of curcumin in extracts were performed by HPLC-DAD system. Antioxidant potential and radical scavenging abilities of microwave-assisted extract and conventional heat-assisted extract of turmeric (MAET and CHAET were evaluated using different systems including total phenolic content (TPC, total antioxidant capacity (TAC, and radical scavenging activities. MAET and CHAET showed high antioxidant activity in all test systems, but the antioxidant properties of MAET were stronger than those of CHAET.

  14. 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.

  15. SOLVENT-FREE PREPARATION OF IONIC LIQUIDS USING A HOUSEHOLD MICROWAVE OVEN

    Science.gov (United States)

    An efficient solventless protocol for the preparation of a wide variety of ionic liquids is described which requires a simple exposure of admixed 1-methylimidazole and alkyl halides to microwave irradiation in open glass containers. The details of this clean process using a commo...

  16. SOLVENT-FREE PREPARATION OF IONIC LIQUIDS USING A HOUSEHOLD MICROWAVE OVEN

    Science.gov (United States)

    An efficient solventless protocol for the preparation of a wide variety of ionic liquids is described which requires a simple exposure of admixed 1-methylimidazole and alkyl halides to microwave irradiation in open glass containers. The details of this clean process using a commo...

  17. Negative Feedback Effect of Microwave Irradiation in the Microwave—assisted Hydrothermal Synthesis of Bi2S3 Nanorods

    Institute of Scientific and Technical Information of China (English)

    陶秀成; 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 effcet which increases the degree of crystallinity in the reaction.

  18. Efficient three-wave mixing in a three-level atomic medium with an assisting microwave driven field

    Institute of Scientific and Technical Information of China (English)

    Li Jia-Hua; Luo Jin-Ming; Yang Wen-Xing; Zhan Zhi-Ming

    2006-01-01

    The potential for nonlinear conversion between two laser pulses in a three-level V-type medium with assistance of an auxiliary microwave resonant radiation is studied. The results show that microwave driven field can lead to the parametric generation of a new laser pulse with high conversion efficiency when a weak pump laser pulse is applied.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Microwave-assisted extraction and large-volume injection gas chromatography tandem mass spectrometry determination of multiresidue pesticides in edible seaweed.

    Science.gov (United States)

    García-Rodríguez, D; Carro, A M; Cela, R; Lorenzo, R A

    2010-09-01

    A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection gas chromatography-tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g(-1) and the limits of quantification were between 2.3 and 76.9 pg g(-1), far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed samples.

  4. 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

  5. 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.

  6. 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

  7. Microwave-Assisted Synthesis of Alginate-Stabilized Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Foliatini Foliatini

    2014-12-01

    Full Text Available An efficient and rapid method for preparation of Au nanoparticles (Au-NP has been developed by direct microwave irradiation of metal precursor and alginate mixed solution in a single step. Here, alginate molecules act as both the reducing and stabilizing agents of Au-NP. The obtained nanoparticles were characterized by ultraviolet-visible (UV-Vis spectroscopy, particle size analyzer, fourier transform infrared spectroscopy, and transmission electron microscopy. The nanoparticles have a spherical form and perfectly capped with alginate when using alginate and chloro auric acid (HAuCl4 precursor in the concentration range of 0.50 to 0.75% (w/v and 0.40 mM, respectively. The use of a lower concentration of alginate and/or higher concentration of HAuCl4 caused agglomeration to occur, thereby resulting in a bigger size of Au-NP and red shifting of surface plasmon resonance (SPR peak to a higher wavelength.

  8. Microwave-Enhanced Sulphated Zirconia and SZ/MCM-41 Catalyzed Regioselective Synthesis of β-Amino Alcohols Under Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Eduardo González-Zamora

    2008-04-01

    Full Text Available A solvent-free approach for the regioselective synthesis of β-amino alcohols inshorter reaction times and higher yields, compared to conventional heating is described. Itinvolves microwave (MW exposure of undiluted reactants in the presence of sulphatedzirconia (SZ or sulphated zirconia over MCM-41 (SZM as catalyst. Both acid materialscan be easily recovered and reused.

  9. 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%...

  10. 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

  11. 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...

  12. 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...

  13. Microwave assisted convenient synthesis of quino[2,3-b][1,5]benzoxazepines

    Institute of Scientific and Technical Information of China (English)

    Swapnil S.Sonar; Sandip A.Sadaphal; Shivaji S.Pawar; Bapurao B.Shingate; Murlidhar S.Shingare

    2009-01-01

    A convenient synthesis of quino[2,3-b][1,5]benzoxazepines from substituted 2-chloroquinoline-3-carbaldehyde and 2-hydroxy-aniline by using stable,non-toxic and inexpensive catalyst 1,8-diazabicyclo-undecan-7-ene (DBU)/silica gel is described.This method affords the quino[2,3-b][1,5]benzoxazepines under the influence of microwave irradiation (360 W) in solvent-free conditions within short reaction times (2-3 min),giving high yields of products (93-96%).

  14. Rapid microwave assisted synthesis and antimicrobial bioevaluation of novel steroidal chalcones.

    Science.gov (United States)

    Kakati, Dwipen; Sarma, Rupak K; Saikia, Ratul; Barua, Nabin C; Sarma, Jadab C

    2013-03-01

    A novel class of chalconoyl pregnenolones has been prepared via Claisen-Schmidt condensation under microwave activation and solvent free reaction conditions. The compounds were screened for antimicrobial activity against two bacterial strains Bacillus subtilis and Escherichia coli and two fungal strains Aspergillus niger and Candida albicans. Some of the compounds exhibited significant inhibitory activity against the microbial strains. Presence of the α,β-unsaturated carbonyl moiety in the synthesized compounds was found to be essential for the activity as manipulation of the same through epoxidation of the double bond diminished the activity.

  15. An Efficient Microwave-assisted Synthesis of Pyrido[2,3-d]pyrimidine Derivatives

    Institute of Scientific and Technical Information of China (English)

    TU Shujiang; WU Shanshan; HAN Zhengguo; HAO Wenjuan

    2009-01-01

    A series of new pyrido[2,3-d]pyrimidine derivatives were synthesized by multi-component reactions of equi-molar amount of aromatic aldehydes with barbituric acids (barbituric acid or 1,3-dimethylbarbituric acid) and 5-amino-2-methylbenzo[d]thiazol in mixed solvent of glacial acetic acid and ethylene glycol without catalyst under microwave irradiation. This one-pot method has the advantage of good yields (90%-93%), simple workup proce-dure and short reaction time (5 min).

  16. Microwave-irradiation-assisted hybrid chemical approach for titanium dioxide nanoparticle synthesis: microbial and cytotoxicological evaluation.

    Science.gov (United States)

    Ranjan, Shivendu; Dasgupta, Nandita; Rajendran, Bhavapriya; Avadhani, Ganesh S; Ramalingam, Chidambaram; Kumar, Ashutosh

    2016-06-01

    Titanium dioxide nanoparticles (TNPs) are widely used in the pharmaceutical and cosmetics industries. It is used for protection against UV exposure due to its light-scattering properties and high refractive index. Though TNPs are increasingly used, the synthesis of TNPs is tedious and time consuming; therefore, in the present study, microwave-assisted hybrid chemical approach was used for TNP synthesis. In the present study, we demonstrated that TNPs can be synthesized only in 2.5 h; however, the commonly used chemical approach using muffle furnace takes 5 h. The activity of TNP depends on the synthetic protocol; therefore, the present study also determined the effect of microwave-assisted hybrid chemical approach synthetic protocol on microbial and cytotoxicity. The results showed that TNP has the best antibacterial activity in decreasing order from Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. The IC50 values of TNP for HCT116 and A549 were found to be 6.43 and 6.04 ppm, respectively. Cell death was also confirmed from trypan blue exclusion assay and membrane integrity loss was observed. Therefore, the study determines that the microwave-assisted hybrid chemical approach is time-saving; hence, this technique can be upgraded from lab scale to industrial scale via pilot plant scale. Moreover, it is necessary to find the mechanism of action at the molecular level to establish the reason for greater bacterial and cytotoxicological toxicity. Graphical abstract A graphical representation of TNP synthesis.

  17. 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.

  18. 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.

  19. Stable Isotope-Assisted Evaluation of Different Extraction Solvents for Untargeted Metabolomics of Plants

    Directory of Open Access Journals (Sweden)

    Maria Doppler

    2016-06-01

    Full Text Available The evaluation of extraction protocols for untargeted metabolomics approaches is still difficult. We have applied a novel stable isotope-assisted workflow for untargeted LC-HRMS-based plant metabolomics , which allows for the first time every detected feature to be considered for method evaluation. The efficiency and complementarity of commonly used extraction solvents, namely 1 + 3 (v/v mixtures of water and selected organic solvents (methanol, acetonitrile or methanol/acetonitrile 1 + 1 (v/v, with and without the addition of 0.1% (v/v formic acid were compared. Four different wheat organs were sampled, extracted and analysed by LC-HRMS. Data evaluation was performed with the in-house-developed MetExtract II software and R. With all tested solvents a total of 871 metabolites were extracted in ear, 785 in stem, 733 in leaf and 517 in root samples, respectively. Between 48% (stem and 57% (ear of the metabolites detected in a particular organ were found with all extraction mixtures, and 127 of 996 metabolites were consistently shared between all extraction agent/organ combinations. In aqueous methanol, acidification with formic acid led to pronounced pH dependency regarding the precision of metabolite abundance and the number of detectable metabolites, whereas extracts of acetonitrile-containing mixtures were less affected. Moreover, methanol and acetonitrile have been found to be complementary with respect to extraction efficiency. Interestingly, the beneficial properties of both solvents can be combined by the use of a water-methanol-acetonitrile mixture for global metabolite extraction instead of aqueous methanol or aqueous acetonitrile alone.

  20. Highly efficient, quick and green synthesis of biarlys with chitosan supported catalyst using microwave irradiation in the absence of solvent.

    Science.gov (United States)

    Baran, Talat; Açıksöz, Eda; Menteş, Ayfer

    2016-05-20

    The aim of this study was to develop a quick reaction that had high activity with a small amount of catalyst, which could be an eco-friendly alternative technique for the synthesis of biarlys in Suzuki coupling reactions. First, a novel chitosan Schiff base supported Pd(II) catalyst was synthesized, and its structure was illuminated with FTIR, (1)H NMR, (13)C NMR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV-vis, magnetic moment, and molar conductivity techniques. Subsequently, the catalytic activity of the catalyst was tested in Suzuki C-C reactions under microwave irradiation using a solvent-free reaction condition. The catalytic tests showed an excellent activity with a small load of the catalyst (0.02 mol%) in 4 min. The catalyst showed seven runs without loss of activity, and high values of turnover numbers (TON) and turnover frequency (TOF) were obtained. The novel biopolymer supported Pd(II) catalyst provided much faster reaction times, higher yields, and reusability under microwave heating compared to classic heating methods.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Intensification of marrubiin concentration by optimization of microwave-assisted (low CO2 yielding) extraction process for Marrubium vulgare using central composite design and antioxidant evaluation.

    Science.gov (United States)

    Mittal, Vineet; Nanda, Arun

    2017-12-01

    Marrubium vulgare Linn (Lamiaceae) was generally extracted by conventional methods with low yield of marrubiin; these processes were not considered environment friendly. This study extracts the whole plant of M. vulgare by microwave assisted extraction (MAE) and optimizes the effect of various extraction parameters on the marrubiin yield by using Central Composite Design (CCD). The selected medicinal plant was extracted using ethanol: water (1:1) as solvent by MAE. The plant material was also extracted using a Soxhlet and the various extracts were analyzed by HPTLC to quantify the marrubiin concentration. The optimized conditions for the microwave-assisted extraction of selected medicinal plant was microwave power of 539 W, irradiation time of 373 s and solvent to drug ratio, 32 mL per g of the drug. The marrubiin concentration in MAE almost doubled relative to the traditional method (0.69 ± 0.08 to 1.35 ± 0.04%). The IC50 for DPPH was reduced to 66.28 ± 0.6 μg/mL as compared to conventional extract (84.14 ± 0.7 μg/mL). The scanning electron micrographs of the treated and untreated drug samples further support the results. The CCD can be successfully applied to optimize the extraction parameters (MAE) for M. vulgare. Moreover, in terms of environmental impact, the MAE technique could be assumed as a 'Green approach' because the MAE approach for extraction of plant released only 92.3 g of CO2 as compared to 3207.6 g CO2 using the Soxhlet method of extraction.

  6. Rapid, efficient and solvent free microwave mediated synthesis of aldo- and ketonitrones

    Directory of Open Access Journals (Sweden)

    Loredana Maiuolo

    2016-01-01

    Full Text Available A library of C-alkyl and C-aryl nitrones has been obtained by direct condensation of primary N-substituted hydroxylamine hydrochlorides with various aldehydes and ketones without catalysts or base. The synthetic procedure, performed under MW irradiation in the absence of solvent, does not require the presence of a base, is fast, clean, high-yielding and characterized by simple work-up.

  7. Extraction and characterization of polysaccharides from Semen Cassiae by microwave-assisted aqueous two-phase extraction coupled with spectroscopy and HPLC.

    Science.gov (United States)

    Chen, Zhi; Zhang, Wei; Tang, Xunyou; Fan, Huajun; Xie, Xiujuan; Wan, Qiang; Wu, Xuehao; Tang, James Z

    2016-06-25

    A novel and rapid method for simultaneous extraction and separation of the different polysaccharides from Semen Cassiae (SC) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) in a one-step procedure. Using ethanol/ammonium sulfate system as a multiphase solvent, the effects of MAATPE on the extraction of polysaccharides from SC such as the composition of the ATPS, extraction time, temperature and solvent-to-material ratio were investigated by UV-vis analysis. Under the optimum conditions, the yields of polysaccharides were 4.49% for the top phase, 8.80% for the bottom phase and 13.29% for total polysaccharides, respectively. Compared with heating solvent extraction and ultrasonic assisted extraction, MAATPE exhibited the higher extraction yields in shorter time. Fourier-transform infrared spectra showed that two polysaccharides extracted from SC to the top and bottom phases by MAATPE were different from each other in their chemical structures. Through acid hydrolysis and PMP derivatization prior to HPLC, analytical results by indicated that a polysaccharide of the top phases was a relatively homogeneous homepolysaccharide composed of dominant gucose glucose while that of the bottom phase was a water-soluble heteropolysaccharide with multiple components of glucose, xylose, arabinose, galactose, mannose and glucuronic acid. Molar ratios of monosaccharides were 95.13:4.27:0.60 of glucose: arabinose: galactose for the polysaccharide from the top phase and 62.96:14.07:6.67: 6.67:5.19:4.44 of glucose: xylose: arabinose: galactose: mannose: glucuronic acid for that from the bottom phase, respectively. The mechanism for MAATPE process was also discussed in detail. MAATPE with the aid of microwave and the selectivity of the ATPS not only improved yields of the extraction, but also obtained a variety of polysaccharides. Hence, it was proved as a green, efficient and promising alternative to simultaneous extraction of polysaccharides from SC.

  8. 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.

  9. The Production of Biodiesel and Bio-kerosene from Coconut Oil Using Microwave Assisted Reaction

    Science.gov (United States)

    SAIFUDDIN, N.; SITI FAZLILI, A.; KUMARAN, P.; PEI-JUA, N.; PRIATHASHINI, P.

    2016-03-01

    Biofuels including biodiesel, an alternative fuel, is renewable, environmentally friendly, non-toxic and low emissions. The raw material used in this work was coconut oil, which contained saturated fatty acids about 90% with high percentage of medium chain (C8-C12), especially lauric acid and myristic acid. The purpose of this research was to study the effect of power and NaOH catalyst in transesterification assisted by microwave for production of biofuels (biodiesel and bio-kerosene) derived from coconut oil. The reaction was performed with oil and methanol using mole ratio of 1:6, catalyst concentration of 0.6% with microwave power at 100W, 180W, 300W, 450W, 600W, and 850W. The reaction time was set at of 3, 5, 7, 10 and 15 min. The results showed that microwave could accelerate the transesterification process to produce biodiesel and bio-kerosene using NaOH catalyst. The highest yield of biodiesel was 97.17 %, or 99.05 % conversion at 5 min and 100W microwave power. Meanwhile, the bio-kerosene obtained was 65% after distillation.

  10. 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.

  11. Microwave Assisted Enzymatic Kinetic Resolution of (±-1-Phenyl-2-propyn-1-ol in Nonaqueous Media

    Directory of Open Access Journals (Sweden)

    Saravanan Devendran

    2014-01-01

    Full Text Available Kinetic resolution of 1-phenyl-2-propyn-1-ol, an important chiral synthon, was studied through trans-esterification with acyl acetate to investigate synergism between microwave irradiation and enzyme catalysis. Lipases from different microbial origins were employed for the kinetic resolution of (R/S-1-phenyl-2-propyn-1-ol, among which Candida antarctica lipase B, immobilized on acrylic resin (Novozym 435, was found to be the best catalyst in n-hexane as solvent. Vinyl acetate was the most effective among different acyl esters studied. The effect of various parameters was studied in a systematic manner. Definite synergism between microwave and enzyme was observed. The initial rate was improved around 1.28 times under microwave irradiation than conventional heating. Under optimum conditions, maximum conversion (48.78% and high enantiomeric excess (93.25% were obtained in 2 h. From modeling studies, it is concluded that the reaction follows the Ping-Pong bi-bi mechanism with dead end alcohol inhibition. Kinetic parameters were obtained by using nonlinear regression. This process is green, clean, and easily scalable as compared to the chemical process.

  12. Combination of microwave-assisted extraction and ultrasonic-assisted dispersive liquid-liquid microextraction for separation and enrichment of pyrethroids residues in Litchi fruit prior to HPLC determination.

    Science.gov (United States)

    Wang, Ke; Xie, Xiujuan; Zhang, Yi; Huang, Yuanxiang; Zhou, Shiyu; Zhang, Wei; Lin, Yuyang; Fan, Huajun

    2018-02-01

    A novel method for simultaneous determination of pyrethroids residues in Litchi fruit has been developed by HPLC-UV detection using microwave-assisted extraction (MAE) coupled with ultrasonic-assisted dispersive liquid-liquid microextraction (UADLLME). Extraction conditions of MAE and UADLLME were respectively investigated by single-factor experiments and response surface methodology. Optimized experimental conditions included 310μL of chlorobenzene as extraction solvent, 1.3mL of ethanol as dispersive solvent and 3min of extraction time for UADLLME. In the case of MAE, extraction temperature of 70°C, extraction time of 4min and solvent-to-materials ratio of 40:1 were adopted. Results demonstrated that the proposed method had good performance with linearity of 0.0050-4.98mg/L, recovery of 83.3-91.5%, RSDs below 5.6% and detection limit (LOD) of 1.15-2.46μg/L for six pyrethroids, offering higher extraction efficiency and larger enrichment factor. MAE-UADLLME provided a sensitive and efficient alternative to determination of trace amounts of pesticides residues in food samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Microwave-Assisted Synthesis and Biological Evaluation of Dihydropyrimidinone Derivatives as Anti-Inflammatory, Antibacterial, and Antifungal Agents

    Directory of Open Access Journals (Sweden)

    Anjna Bhatewara

    2013-01-01

    Full Text Available A simple protocol for the efficient preparation of aryl and heteroaryl substituted dihydropyrimidinone has been achieved via initial Knoevenagel, subsequent addition, and final cyclization of aldehyde, ethylcyanoacetate, and guanidine nitrate in the presence of piperidine as a catalyst in solvent-free under microwave irradiation. The synthesized compounds showed a good anti-inflammatory, antibacterial, and antifungal activity.

  20. Microwave-assisted Green and Efficient Synthesis of N6-(2-Hydroxyethyl)adenosine and its Analogues

    Institute of Scientific and Technical Information of China (English)

    Gui Rong QU; Ming Wei GENG; Su Hui HAN; Zhi Guang ZHANG; Feng XUE

    2006-01-01

    An efficient protocol for the synthesis of N6-(2-Hydroxyethyl)adenosine and its analogues through nucleophilic substitution was developed. All the reactions were completed in 10 min under microwave irradiation. Using water as solvent makes our method eco-friendly and easy to handle with.

  1. Solvent-Assisted Gel Printing for Micropatterning Thin Organic-Inorganic Hybrid Perovskite Films.

    Science.gov (United States)

    Jeong, Beomjin; Hwang, Ihn; Cho, Sung Hwan; Kim, Eui Hyuk; Cha, Soonyoung; Lee, Jinseong; Kang, Han Sol; Cho, Suk Man; Choi, Hyunyong; Park, Cheolmin

    2016-09-27

    While tremendous efforts have been made for developing thin perovskite films suitable for a variety of potential photoelectric applications such as solar cells, field-effect transistors, and photodetectors, only a few works focus on the micropatterning of a perovskite film which is one of the most critical issues for large area and uniform microarrays of perovskite-based devices. Here we demonstrate a simple but robust method of micropatterning a thin perovskite film with controlled crystalline structure which guarantees to preserve its intrinsic photoelectric properties. A variety of micropatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically prepatterned elastomeric poly(dimethylsiloxane) (PDMS) mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. The key materials development of our solvent-assisted gel printing is to prepare a thin precursor film with a high-boiling temperature solvent, dimethyl sulfoxide. The residual solvent in the precursor gel film makes the film moldable upon microprinting with a patterned PDMS mold, leading to various perovskite micropatterns in resolution of a few micrometers over a large area. Our nondestructive micropatterning process does not harm the intrinsic photoelectric properties of a perovskite film, which allows for realizing arrays of parallel-type photodetectors containing micropatterns of a perovskite film with reliable photoconduction performance. The facile transfer of a micropatterned soft-gel precursor film on other substrates including mechanically flexible plastics can further broaden its applications to flexible photoelectric systems.

  2. Study on Microwave-Assisted Extraction of Coix Seed Oil from Coix lachrymajobi L.%微波法提取薏苡仁油的研究

    Institute of Scientific and Technical Information of China (English)

    金宏; 朱庆书; 赵文英; 公衍玲; 蒋艳霞

    2009-01-01

    The method of microwave-assisted extraction (MAE) was used to extract coix seed oil from Coix lachrymajobi L.. The main influential factors including microwave irradiation power, sample size, microwave irradiation time and ratio of material to solvent were investigated with the extraction rate of coix seed oil as index. Optimum conditions for MAE of coix seed oil were determined as follows:using ethanol as solvent, the microwave irradiation time was 7 min,the microwave irradiation power was 300 W, the ratio of material to solvent was 1∶5, and the particle size of sample was 60 meshes. Under above conditions,extraction rate of coix seed oil was 6.87%. The MAE saved a lot of time, but had little influence on constituent of coix seed oil compared with traditional extraction method.%以薏苡仁油的提取率为指标,考察了微波法提取薏苡仁油的主要影响因素微波辐射功率、微波辐射时间、料液比和药材粒度;采用气相色谱法考察微波对薏苡仁油成分的影响,并与加热回流法进行了比较.结果表明,微波法提取薏苡仁油的优化工艺条件为:采用无水乙醇作溶剂、药材粒度60目、微波辐射功率300 W、微波辐射时间7 min、料液比1∶5,在此条件下薏苡仁油的提取率为6.87%;气相色谱分析表明,微波法与加热回流法提取的薏苡仁油的主要化学成分基本相同,微波辐射对薏苡仁油成分无影响.

  3. Microwave-Assisted Superheating and/or Microwave-Specific Superboiling (Nucleation-Limited Boiling of Liquids Occurs under Certain Conditions but is Mitigated by Stirring

    Directory of Open Access Journals (Sweden)

    Anthony Ferrari

    2015-12-01

    Full Text Available Temporary superheating and sustained nucleation-limited “superboiling” of unstirred liquids above the normal atmospheric boiling point have been documented during microwave heating. These phenomena are reliably observed under prescribed conditions, although the duration (of superheating and magnitude (of superheating and superboiling vary according to system parameters such as volume of the liquid and the size and shape of the vessel. Both phenomena are mitigated by rapid stirring with an appropriate stir bar and/or with the addition of boiling chips, which provide nucleation sites to support the phase-change from liquid to gas. With proper experimental design and especially proper stirring, the measured temperature of typical organic reaction mixtures heated at reflux will be close to the normal boiling point temperature of the solvent, whether heated using microwave radiation or conventional convective heat transfer. These observations are important to take into consideration when comparing reaction rates under conventional and microwave heating.

  4. 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.

  5. Application of microwave-assisted micro-solid-phase extraction for determination of parabens in human ovarian cancer tissues.

    Science.gov (United States)

    Sajid, Muhammad; Basheer, Chanbasha; Narasimhan, Kothandaraman; Choolani, Mahesh; Lee, Hian Kee

    2015-09-01

    Parabens (alkyl esters of p-hydroxybenzoic acid) are widely used as preservatives in food, cosmetics and pharmaceutical products. However, weak estrogenicity of some parabens has been reported in several studies, which provided the impetus for this work. Here, a simple and efficient analytical method for quantifying parabens in cancer tissues has been developed. This technique involves the simultaneous use of microwave-assisted solvent extraction (MASE) and micro-solid phase extraction (μ-SPE), in tandem with high performance liquid chromatography (HPLC/UV) analysis for the determination of parabens. The pollutants studied included four parabens (methyl, ethyl, propyl and butyl parabens). Optimization of the experimental parameters for MASE and μ-SPE was performed. Good relative standard deviation (%RSD) ranged from 0.09 to 2.81% and high enrichment factors (27-314) were obtained. Coefficients of determination (r(2)) up to 0.9962 were obtained across a concentration range of 5.0-200ngg(-1). The method detection limits for parabens ranged from 0.005 to 0.0244ngg(-1). The procedure was initially tested on prawn samples to demonstrate its feasibility on a complex biological matrix. Preliminary studies on human ovarian cancer (OC) tissues showed presence of parabens. Higher levels of parabens were detected in malignant ovarian tumor tissues compared to benign tumor tissue samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Extraction of bioactive carbohydrates from artichoke (Cynara scolymus L.) external bracts using microwave assisted extraction and pressurized liquid extraction.

    Science.gov (United States)

    Ruiz-Aceituno, Laura; García-Sarrió, M Jesús; Alonso-Rodriguez, Belén; Ramos, Lourdes; Sanz, M Luz

    2016-04-01

    Microwave assisted extraction (MAE) and pressurized liquid extraction (PLE) methods using water as solvent have been optimized by means of a Box-Behnken and 3(2) composite experimental designs, respectively, for the effective extraction of bioactive carbohydrates (inositols and inulin) from artichoke (Cynara scolymus L.) external bracts. MAE at 60 °C for 3 min of 0.3 g of sample allowed the extraction of slightly higher concentrations of inositol than PLE at 75 °C for 26.7 min (11.6 mg/g dry sample vs. 7.6 mg/g dry sample). On the contrary, under these conditions, higher concentrations of inulin were extracted with the latter technique (185.4 mg/g vs. 96.4 mg/g dry sample), considering two successive extraction cycles for both techniques. Both methodologies can be considered appropriate for the simultaneous extraction of these bioactive carbohydrates from this particular industrial by-product. To the best of our knowledge this is the first time that these techniques are applied for this purpose.

  7. Special Effect of Ionic Liquids on the Extraction of Flavonoid Glycosides from Chrysanthemum morifolium Ramat by Microwave Assistance

    Directory of Open Access Journals (Sweden)

    Ying Zhou

    2015-04-01

    Full Text Available A microwave-assisted extraction approach based on ionic liquids of different chain lengths was successfully applied to the extraction of ten flavonoid glycosides from the flowering heads of Chrysanthemum morifolium Ramat. The pretreated sample was quantified by HPLC-ESI-MSn. The main components were identified as flavonoid glycosides, including three luteolin glycosides, three apigenin glycosides, three kaempferide glycosides, and one acacetin glycoside according to the characteristics of the corresponding CID mass spectrometric patterns. Eight ionic liquids from the imidazolium family with different chain lengths, namely, 1-alkyl-3-methylimidazolium bromide, [Cnmim]Br, (n = 2–16 were studied as extraction medium in water. Results indicated that alkyl chain length had an irregular impact on the extraction efficiency. Moreover, the best extraction efficiency was achieved by 1-dodecyl-3-methylimidazolium bromide aqueous solution ([C12mim]Br. Besides the alkyl chain length of the cations, other factors influencing extraction efficiency were systematically investigated, including concentration of the IL solutions, extraction time, matrix-to-solvent ratio and irradiation power.

  8. Simultaneous extraction, identification and quantification of phenolic compounds in Eclipta prostrata using microwave-assisted extraction combined with HPLC-DAD-ESI-MS/MS.

    Science.gov (United States)

    Fang, Xinsheng; Wang, Jianhua; Hao, Jifu; Li, Xueke; Guo, Ning

    2015-12-01

    A simple and rapid method was developed using microwave-assisted extraction (MAE) combined with HPLC-DAD-ESI-MS/MS for the simultaneous extraction, identification, and quantification of phenolic compounds in Eclipta prostrata, a common herb and vegetable in China. The optimized parameters of MAE were: employing 50% ethanol as solvent, microwave power 400 W, temperature 70 °C, ratio of liquid/solid 30 mL/g and extraction time 2 min. Compared to conventional extraction methods, the optimized MAE can avoid the degradation of the phenolic compounds and simultaneously obtained the highest yields of all components faster with less consumption of solvent and energy. Six phenolic acids, six flavonoid glycosides and one coumarin were firstly identified. The phenolic compounds were quantified by HPLC-DAD with good linearity, precision, and accuracy. The extract obtained by MAE showed significant antioxidant activity. The proposed method provides a valuable and green analytical methodology for the investigation of phenolic components in natural plants.

  9. Simultaneous determination of salidroside and tyrosol in extracts of Rhodiola L. by microwave assisted extraction and high-performance liquid chromatography.

    Science.gov (United States)

    Mao, Yu; Li, Yan; Yao, Ning

    2007-11-05

    Rhodiola L. has a long history of use in traditional Chinese medicine (TCM) and has shown great promise in recent clinical trials. Salidroside and tyrosol are two important active compounds present in this TCM. In this work, microwave-assisted extraction (MAE) followed by high performance liquid chromatography (HPLC) with a photodiode array detector (DAD) was developed for quantitative analysis of salidroside and tyrosol in Rhodiola L. samples. After systematical investigation, the optimal experimental parameters of soak time (60 min), extraction solvent volume (1g sample, 5 mL), extract solvent composition (50% methanol/water), microwave power (400 W) and extraction time (5 min) were investigated. The optimized method provided satisfactory precision (R.S.D. values less than 7.5%), good recovery (from 94.4 to 123%), and good linear relation in the range of 5.0-500 microg/mL for salidroside and 1.0-100 microg/mL for tyrosol (R2>0.999). The proposed method was applied to quantitative analysis of salidroside and tyrosol in Rhodiola L. samples from five different growing areas. To demonstrate the method feasibility, recirculation was also used to analyze salidroside and tyrosol in Rhodiola L. samples. The proposed MAE-HPLC-DAD is a simple, rapid and low-cost method for quantitative analysis of salidroside and tyrosol, and a potential tool for quality assessment of Rhodiola L. sample.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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 synthesis of CdSe quantum dots: can the electromagnetic field influence the formation and quality of the resulting nanocrystals?

    Science.gov (United States)

    Moghaddam, Mojtaba Mirhosseini; Baghbanzadeh, Mostafa; Keilbach, Andreas; Kappe, C Oliver

    2012-12-07

    Microwave-assisted syntheses of colloidal nanocrystals (NCs), in particular CdSe quantum dots (QDs), have gained considerable attention due to unique opportunities provided by microwave dielectric heating. The extensive use of microwave heating and the frequently suggested specific microwave effects, however, pose questions about the role of the electromagnetic field in both the formation and quality of the produced QDs. In this work a one-pot protocol for the tunable synthesis of monodisperse colloidal CdSe NCs using microwave dielectric heating under carefully controlled conditions is introduced. CdSe QDs are fabricated using selenium dioxide as a selenium precursor, 1-octadecene as a solvent and reducing agent, cadmium alkyl carboxylates or alkyl phosphonates as cadmium sources, 1,2-hexadecanediol to stabilize the cadmium complex and oleic acid to stabilize the resulting CdSe QDs. Utilizing the possibilities of microwave heating technology in combination with accurate online temperature control the influence of different reaction parameters such as reaction temperature, ramp and hold times, and the timing and duration of oleic acid addition have been carefully investigated. Optimum results were obtained by performing the reaction at 240 °C applying a 5 min ramp time, 2 min hold time before oleic acid addition, 90 s for oleic acid addition, and a 5 min hold time after oleic acid addition (8.5 min overall holding at 240 °C). By using different cadmium complexes in the microwave protocol CdSe QDs with a narrow size distribution can be obtained in different sizes ranging from 0.5-4 nm by simply changing the cadmium source. The QDs were characterized by TEM, HRTEM, UV-Vis, and photoluminescence methods and the size distribution was monitored by SAXS. Control experiments involving conventional conductive heating under otherwise identical conditions ensuring the same heating and cooling profiles, stirring rates, and reactor geometries demonstrate that the

  17. Microwave-assisted synthesis of CdSe quantum dots: can the electromagnetic field influence the formation and quality of the resulting nanocrystals?

    Science.gov (United States)

    Moghaddam, Mojtaba Mirhosseini; Baghbanzadeh, Mostafa; Keilbach, Andreas; Kappe, C. Oliver

    2012-11-01

    Microwave-assisted syntheses of colloidal nanocrystals (NCs), in particular CdSe quantum dots (QDs), have gained considerable attention due to unique opportunities provided by microwave dielectric heating. The extensive use of microwave heating and the frequently suggested specific microwave effects, however, pose questions about the role of the electromagnetic field in both the formation and quality of the produced QDs. In this work a one-pot protocol for the tunable synthesis of monodisperse colloidal CdSe NCs using microwave dielectric heating under carefully controlled conditions is introduced. CdSe QDs are fabricated using selenium dioxide as a selenium precursor, 1-octadecene as a solvent and reducing agent, cadmium alkyl carboxylates or alkyl phosphonates as cadmium sources, 1,2-hexadecanediol to stabilize the cadmium complex and oleic acid to stabilize the resulting CdSe QDs. Utilizing the possibilities of microwave heating technology in combination with accurate online temperature control the influence of different reaction parameters such as reaction temperature, ramp and hold times, and the timing and duration of oleic acid addition have been carefully investigated. Optimum results were obtained by performing the reaction at 240 °C applying a 5 min ramp time, 2 min hold time before oleic acid addition, 90 s for oleic acid addition, and a 5 min hold time after oleic acid addition (8.5 min overall holding at 240 °C). By using different cadmium complexes in the microwave protocol CdSe QDs with a narrow size distribution can be obtained in different sizes ranging from 0.5-4 nm by simply changing the cadmium source. The QDs were characterized by TEM, HRTEM, UV-Vis, and photoluminescence methods and the size distribution was monitored by SAXS. Control experiments involving conventional conductive heating under otherwise identical conditions ensuring the same heating and cooling profiles, stirring rates, and reactor geometries demonstrate that the

  18. 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.

  19. 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.

  20. 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.

  1. Development of an ionic liquid-based microwave-assisted method for simultaneous extraction and distillation for determination of proanthocyanidins and essential oil in Cortex cinnamomi.

    Science.gov (United States)

    Liu, Ye; Yang, Lei; Zu, Yuangang; Zhao, Chunjian; Zhang, Lin; Zhang, Ying; Zhang, Zhonghua; Wang, Wenjie

    2012-12-15

    Cortex cinnamomi is associated with many health benefits and is used in the food and pharmaceutical industries. In this study, an efficient ionic liquid-based microwave-assisted simultaneous extraction and distillation (ILMSED) technique was used to extract cassia oil and proanthocyanidins from Cortex cinnamomi; these were quantified by gas chromatography/mass spectrometry (GC-MS) and the vanillin-HCl colorimetric method, respectively. 0.5M 1-butyl-3-methylimidazolium bromide ionic liquid was selected as solvent. The optimum parameters of dealing with 20.0 g sample were 230 W microwave irradiation power, 15 min microwave extraction time and 10 liquid-solid ratio. The yields of essential oil and proanthocyanidins were 1.24 ± 0.04% and 4.58 ± 0.21% under the optimum conditions. The composition of the essential oil was analysed by GC-MS. Using the ILMSED method, the energy consumption was reduced and the extraction yields were improved. The proposed method was validated using stability, repeatability, and recovery experiments. The results indicated that the developed ILMSED method provided a good alternative for the extraction of both the essential oil and proanthocyanidins from Cortex cinnamomi.

  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. 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.

  4. 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)

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. Heterogeneous Phase Microwave-Assisted Reactions under CO2 or CO Pressure

    Directory of Open Access Journals (Sweden)

    Emanuela Calcio Gaudino

    2016-02-01

    Full Text Available The present review deals with the recent achievements and impressive potential applications of microwave (MW heating to promote heterogeneous reactions under gas pressure. The high versatility of the latest generation of professional reactors combines extreme reaction conditions with safer and more efficient protocols. The double aims of this survey are to provide a panoramic snapshot of MW-assisted organic reactions with gaseous reagents, in particular CO and CO2, and outline future applications. Stubborn and time-consuming carbonylation-like heterogeneous reactions, which have not yet been studied under dielectric heating, may well find an outstanding ally in the present protocol.

  11. 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.

  12. 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.

  13. Gain-assisted superluminal microwave pulse propagation via four-wave mixing in superconducting phase quantum circuits

    CERN Document Server

    Sabegh, Z Amini; Maleki, M A; Mahmoudi, M

    2015-01-01

    We study the propagation and amplification of a microwave field in a four-level cascade quantum system which is realized in a superconducting phase quantum circuit. It is shown that by increasing the microwave pump tones feeding the system, the normal dispersion switches to the anomalous and the gain-assisted superluminal microwave propagation is obtained in this system. Moreover, it is demonstrated that the stimulated microwave field is generated via four-wave mixing without any inversion population in the energy levels of the system (amplification without inversion) and the group velocity of the generated pulse can be controlled by the external oscillating magnetic fluxes. We also show that in some special set of parameters, the absorption-free superluminal generated microwave propagation is obtained in superconducting phase quantum circuit system.

  14. 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.

  15. 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.

  16. 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.)

  17. Application of microwave-assisted desorption/headspace solid-phase microextraction as pretreatment step in the gas chromatographic determination of 1-naphthylamine in silica gel adsorbent.

    Science.gov (United States)

    Yan, Cheing-Tong; Jen, Jen-Fon; Shih, Tung-Sheng

    2007-03-30

    Pretreatment of silica gel sample containing 1-naphthylamine by microwave-assisted desorption (MAD) coupled to in situ headspace solid phase microextraction (HS-SPME) has been investigated as a possible alternative to conventional methods prior to gas chromatographic (GC) analysis. The 1-naphthylamine desorbs from silica gel to headspace under microwave irradiation, and directly absorbs onto a SPME fiber located in a controlled-temperature headspace area. After being collected on the SPME fiber, and desorbed in the GC injection port, 1-naphthylamine is analyzed by GC-FID. Parameters that influence the extraction efficiency of the MAD/HS-SPME, such as the extraction media and its pH, the microwave irradiation power and irradiation time as well as desorption conditions of the GC injector, have been investigated. Experimental results indicate that the extraction of a 150mg silica gel sample by using 0.8ml of 1.0M NaOH solution and a PDMS/DVB fiber under high-powered irradiation (477W) for 5min maximizes the extraction efficiency. Desorption of 1-naphthylamine from the SPME fiber in GC injector is optimal at 250 degrees C held for 3min. The detection limit of method is 8.30ng. The detected quantity of 1-naphthylamine obtained by the proposed method is 33.3 times of that obtained by the conventional solvent extraction method for the silica gel sample containing 100ng of 1-naphthylamine. It provides a simple, fast, sensitive and organic-solvent-free pretreatment procedure prior to the analysis of 1-naphthylamine collected on a silica gel adsorbent.

  18. 微波辅助提取芒果皮黄酮工艺研究%Microwave-assisted Extraction Technology of Flavonoid from Mango Peel

    Institute of Scientific and Technical Information of China (English)

    白雪莲; 沈淑雅; 陈怀玉; 吴亮亮; 吕多多

    2015-01-01

    More and more mango peel is generated by mango processing factories. It has been reported that mango peel is a rich source of flavonoid, which have a broad spectrum of bioactivities. In order to effectively extract flavonoid compounds from mango peel, investigation of microwave-assisted extraction is carried out. The whole experiments are carefully designed and optimized with single-factor experiment. Factors, such as microwave power, extraction time, extraction temperature, ethanol concentration, and ratio of solvent to pomace are investigated. Results show that the optimized extraction conditions are microwave power 500 W, extraction time 20 min, extraction temperature 30 ℃, ratio of solvent to peel 1∶30, ethanol concentration 80%.%芒果营养价值高,除鲜食外,常被加工成果脯、果干等,其加工副产物果皮多被废弃。而芒果皮富含黄酮类化合物,采用微波辅助溶剂法从不同品种的芒果皮中提取具有生理活性的黄酮。用微波辅助溶剂法提取,采用单因素设计试验,对芒果皮黄酮的工艺进行研究,最佳工艺条件为微波功率500 W,提取时间20 min,提取温度30℃,料液比1∶30,乙醇体积分数80%。

  19. 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.

  20. Microwave-assisted synthesis of ZnO and its photocatalytic activity in degradation of CTAB

    Science.gov (United States)

    Song, Hua; Zhu, Kenan; Liu, Yanxiu; Zhai, Xiaoqing

    2017-01-01

    Nanosized zinc oxide (nano-ZnO) was prepared by a microwave irradiation method using zinc nitrate and triethanolamine as starting materials and distilled water as a solvent. The as-prepared powder was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic degradation of cetyltrimethylammonium bromide (CTAB) using the prepared material under UV irradiation was studied.The effects of ZnO dosage and initial pH on the photodegradation of CTAB were investigated. As the ZnO load increased, the CTAB degradation first increased and then decreased. The optimum ZnO dosage was 3 g L-1. Photodegradation of CTAB is more efficient in slightly alkaline media (pH 9).

  1. High speed synthesis of pyrazolones using microwave-assisted neat reaction technology

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Sarbani; Mareddy, Jyoti; Devi, Nalla Suneetha Devi [Post Graduate College, Kukatpally, Hyderabad (India). Dept. of Chemistry]. E-mail: sarbani277@yahoo.com

    2008-07-01

    A high speed, solvent-free, and practical synthesis of pyrazolones under microwave irradiation is described. This greener synthetic methodology involves the reaction of {beta}-keto ester with substituted or unsubstituted hydrazine and provides a simple and straightforward one-pot approach for the synthesis of a variety of pyrazolone derivatives with high regioselectivity. These pyrazolones can exist in different tautomeric forms in solution and the aryl ring of 2-aryl pyrazol-3-ones remain twisted with respect to the pyrazole plane in the crystal state. Mechanism of the reaction accounting the regioselectivity has been proposed. One of the pyrazolones obtained via this process was utilized to prepare a spirocyclohexanone derivative of potential biological significance. (author)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 微波辅助提取鸡眼草中的黄酮类物质%Microwave-assisted Extraction of Flavoniods from the Kummerowia striata (Thunb.) Schindl.

    Institute of Scientific and Technical Information of China (English)

    许海棠; 欧小辉; 陈其锋; 李家璇

    2013-01-01

    [目的]优化鸡眼草中黄酮类化合物的提取条件.[方法]以鸡眼草的总黄酮提取率为评价指标,通过单因素试验对微波辅助提取鸡眼草黄酮类化合物的工艺条件进行了研究,再运用正交分析法确定最佳提取条件.[结果]微波辅助提取鸡眼草中的黄酮类物质的最佳条件为:乙醇浓度为50%、料液比1∶30(W/V,g/ml,下同)、微波功率300W,微波处理时间25 min;在此条件下,鸡眼草的总黄酮提取率为3.28%.[结论]微波辅助提取鸡眼草中的黄酮类物质,操作简单易行,提取率较高,是一种理想的提取方法.%[Objective]To study the optimal conditions for extracting total flavonoids from Kummerowia striata ( Thunb. )' Schindl.. [ Method] The technological conditions of microwave-assisted extraction of flavoniods were investigated by the single factor and orthogonal experiments, and were assessed according to the extraction rate of tatol flavonoids. [Result] The optimum conditions of microwave-assisted extraction were 50% ethanol as solvent, 1:30 ( W/V, g/ml) of solid-liquid ratio, 300 W of microwave power and 25 min of microwave extraction time. Under the conditions, the extraction rate of total falconoid was 3.28%. [ Conclusion] The microwave-assisted extraction extracting flavoniods in Kummerowia striata (Thunb. ) Schindl. is a simple and ideal extraction method with high efficiency.

  10. Aqueous enzymatic process assisted by microwave extraction of oil from yellow horn (Xanthoceras sorbifolia Bunge.) seed kernels and its quality evaluation.

    Science.gov (United States)

    Li, Ji; Zu, Yuan-Gang; Luo, Meng; Gu, Cheng-Bo; Zhao, Chun-Jian; Efferth, Thomas; Fu, Yu-Jie

    2013-06-15

    In this study, aqueous enzymatic process (AEP) assisted by microwave extraction (ME) of oil from yellow horn (Xanthoceras sorbifolia Bunge.) seed kernel was investigated. Central composite design (CCD) and response surface methodology (RSM) were used to optimise an enzyme cocktail (cellulase, hemicellulase, pectinase) for AEP. The main factors of ME were also studied. A maximal oil extraction yield of 55.8% was achieved under optimal conditions. Moreover, scanning electron microscope (SEM) was applied to characterise the extraction process. Analysing chemical composition of the extracted oil by GC-MS showed that the content of unsaturated fatty acids by this emerging method (91.18%) was similar to that by conventional organic solvent extraction (88.76%). In addition, the main physicochemical properties and antioxidant activities of yellow horn oil were measured to evaluate its quality. The present research supported necessary data for the green extraction method of edible oil in food industry.

  11. An improved facile method for extraction and determination of steroidal saponins in Tribulus terrestris by focused microwave-assisted extraction coupled with GC-MS.

    Science.gov (United States)

    Li, Tianlin; Zhang, Zhuomin; Zhang, Lan; Huang, Xinjian; Lin, Junwei; Chen, Guonan

    2009-12-01

    An improved fast method for extraction of steroidal saponins in Tribulus terrestris based on the use of focus microwave-assisted extraction (FMAE) is proposed. Under optimized conditions, four steroidal saponins were extracted from Tribulus terrestris and identified by GC-MS, which are Tigogenin (TG), Gitogenin (GG), Hecogenin (HG) and Neohecogenin (NG). One of the most important steroidal saponins, namely TG was quantified finally. The recovery of TG was in the range of 86.7-91.9% with RSDTribulus terrestris from different areas of occurrence. The difference in chromatographic characteristics of steroidal saponins was proved to be related to the different areas of occurrence. The results showed that FMAE-GC-MS is a simple, rapid, solvent-saving method for the extraction and determination of steroidal saponins in Tribulus terrestris.

  12. One pot three components microwave assisted and conventional synthesis of new 3-(4-chloro-2-hydroxyphenyl)-2-(substituted) thiazolidin-4-one as antimicrobial agents.

    Science.gov (United States)

    Pansare, Dattatraya N; Mulla, Nayeem A; Pawar, Chandrakant D; Shende, Vikas R; Shinde, Devanand B

    2014-08-01

    A one-pot, three-component, microwave assisted and conventional synthesis of new 3-(4-chloro-2-hydroxyphenyl)-2-(substituted) thiazolidin-4-one (4a-n) was carried out by using N,N-dimethylformamide as a solvent with high product yield. Among these synthesized compounds (4f, 4g, 4l and 4m) were found to be a broad spectrum molecule active against all bacterial and fungus strains tested, except fungus Aspergillus niger. Amongst the compounds (4g, 4l and 4m) were found to be more potent than respective standard drugs used in the experiment against Candida albicans, Staphylococcus aureus and Aspergillus flavus, respectively. All synthesized compounds were also tested for their cytotoxic activity against HeLa and MCF-7 cell lines by the sulforhodamine B (SRB) assay. This study shows that all compounds were non-cytotoxic in nature, and confirmed their antimicrobial specificity apart from any general cytotoxicity.

  13. Determination of nonylphenol and octylphenol in paper by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Latorre, A; Lacorte, S; Barceló, D; Montury, M

    2005-02-18

    A novel and simple method for the determination of active endocrine disrupter compounds (octylphenol OP, and nonylphenol NP) in paper using microwave-assisted extraction (MAE) and headspace solid-phase microextraction, coupled with gas chromatography-mass spectrometry has been developed. Parameters affecting the efficiency in the MAE process such as exposure time and extraction solvent were studied in order to determine operating conditions. The optimised method was linear over the range studied (1.25-125 microg kg(-1) for OP and 9.50-950 microg kg(-1) for NP) and showed good level of precision, with a RSD lower than 10% and detection limits at 0.10 and 4.56 microg kg(-1) for OP and NP, respectively. The results obtained from six different types of paper revealed the presence of the target compounds in all samples analysed, at levels ranging between 3 and 211 microg kg(-1).

  14. A simultaneous, direct microwave/ultrasound-assisted digestion procedure for the determination of total Kjeldahl nitrogen.

    Science.gov (United States)

    Domini, Claudia; Vidal, Lorena; Cravotto, Giancarlo; Canals, Antonio

    2009-04-01

    Simultaneous direct irradiation with microwaves and ultrasound was used to determine total Kjeldahl nitrogen. The method involves chemical digestion in two steps, mineralization with sulfuric acid and oxidation with H(2)O(2). The most influential variables for the microwave/ultrasound (MW/US)-assisted digestion were optimized using tryptophan as the model substance. The optimum conditions were: H(2)SO(4) volume, 10 mL; H(2)O(2) volume, 5 mL; weight of sample, 0.05 g; MW power, 500 W; US power, 50 W; digestion time, 7 min (i.e., 5 min mineralization and 2 min oxidation). A modification of the classical Kjeldahl (Hach) method and an US-assisted digestion method were used for comparison. The latter was also optimized; the optimum conditions were: H(2)SO(4) volume, 10 mL; H(2)O(2) volume, 5 mL; sonication time with H(2)SO(4), 15 min; sonication time with H(2)O(2),10 min; US power, 50 W; weight of sample, 0.05 g. Five pure amino acids and two certified reference materials (NIST standard reference materials 1547 (peach leaves), and soil, NCS DC 73322) were analyzed to assess the accuracy of our new MW/US-assisted digestion method, that was successfully applied to five real samples. The significant reduction in digestion time (being 30 min and 25 min for classical Kjeldahl and US-assisted digestion methods, respectively) and consumption of reagents show that simultaneous and direct MW/US irradiation is a powerful and promising tool for low-pressure digestion of solid and liquid samples.

  15. Determination of triazine herbicides in fresh vegetables by dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction high performance liquid chromatography.

    Science.gov (United States)

    Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Yu, Cui; Zhang, Yupu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-02-01

    A novel extraction method, dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction, was developed for the determination of triazine herbicides, including desmetryn, terbumeton, propazine, terbuthylazine, dimethametryn, and dipropetryn in fresh vegetable samples by high performance liquid chromatography (HPLC). In the developed method, 120 μL of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) was added to 10 mL of aqueous solution containing 0.3 g of NaCl to obtained the extraction solvent. Six triazines could be extracted completely within 4 min by the present method. Then, [NH4][PF6] was added into the extract to form a water-insoluble ionic liquid [C4MIM][PF6] via a simple metathesis reaction, and the analytes were enriched into the ionic liquid phase. After centrifugation and dilution with acetonitrile, the resulting solution was analyzed directly by HPLC. The effects of some experimental parameters, including type and volume of ionic liquid, volume of extraction solvent, amount of ion-pairing agent [NH4][PF6], salt concentration, microwave power, and flow rate of extraction solvent on the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 2.50-250.00 μg kg(-1), with the correlation coefficients ranging from 0.9989 to 0.9999. When the present method was applied to the analysis of vegetable samples, satisfactory recoveries were obtained in the range of 76.8%-106.9%, and relative standard deviations were lower than 9.8%.

  16. 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

  17. Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L. Seed at Subcritical Conditions with Statistical Analysis

    Directory of Open Access Journals (Sweden)

    N. I. Yusoff

    2017-01-01

    Full Text Available Roselle seeds are the waste product of roselle processing, but they are now labeled as a polyphenol source with great herbal quality. In this work, polyphenols were extracted using ethanol-water (70% (v/v in a closed vessel under microwave irradiation. The main objective was to determine the optimal parameters statistically. The influence of extraction time (4–10 min, microwave power (100–300 W, and solvent/solid ratio (25–100 mL/g was studied. The total phenolic and flavonoids content were determined using Folin-Ciocalteu and aluminum chloride methods, respectively. Without temperature control, the subcritical conditions could occur and the highest flavonoid content (14.4251 mg QE/g was achieved at 158°C and 16.4 bar. Although the optimum MAE conditions (10 min, 300 W, and 97.7178 mL/g resulted in the highest yield (65.0367% and phenolic content (18.2244 mg GAE/g, low flavonoids content (6.4524 mg QE/g was unexpectedly obtained due to degradation at 163°C.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. [Simultaneous determination of six organophosphorous flame retardants in textiles by gas chromatography-tandem mass spectrometry combined with microwave assisted extraction].

    Science.gov (United States)

    Wang, Chengyun; Li, Lixia; Xie, Tangtang; Zhang, Weiya; Liu, Caiming; Zhu, Naiqing

    2011-08-01

    An effective method was established for the simultaneous determination of six banned organophosphorous flame retardants in textiles by gas chromatography-tandem mass spectrometry (GC-MS/MS) combined with microwave assisted extraction (MAE). By investigating the extraction efficiency of 12 different extraction solvents for the target analytes, the optimal conditions were that the sample was extracted by microwave assisted extraction using acetone as the solvent at 76 degrees C for 30 min. Then the extract was analyzed by GC-MS/MS in multiple reaction monitoring (MRM) mode, and the concentration of each analyte was calibrated by external standard method. The linear ranges of tris-(1-aziridinyl) phosphine oxide (TEPA), tris-(2-chloroethyl) phosphate (TCEP), tris-(1,3-dichloropropyl) phosphate (TDCP), bis-(2,3-dibromopropyl) phosphate (DDBPP), tri-o-cresyl phosphate (TOCP) and tris-(2,3-dibromopropyl) phosphate (TRIS) were 9.17 - 366.80, 0.95 - 75.98, 1.04 - 83.20, 41.60 - 832.00, 3.80 - 75.90, and 40.48 - 809.60 microg/L, respectively, the correlation coefficients were not less than 0.997 5, while the limits of quantification (LOQ) (S/N = 10) were 3.0, 0.2, 0.3, 25.0, 2.5 and 29.0 microg/kg, respectively. The spiked recoveries varied from 82.62% to 96.88% with the relative standard deviations of 3.80% to 8.79%. The proposed method was successfully applied to the determination of organophosphorous flame retardants in eight commercial textiles. The experimental results demonstrated that the method developed is simple, rapid, sensitive and accurate, which could satisfy the demand of the analysis of banned organophosphorous flame retardants in textiles.

  4. 响应面法优化微波辅助提取姜黄中姜黄素工艺的研究%Optimization of microwave-assisted extraction of curcumin from turmeric by response surface methodology

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 李坚柱; 刘彩琴

    2012-01-01

    The optimization of extraction technology of curcumin from turmeric with microwave-assisted method was examined by curcumin yield,using ethanol as extracting solvent based on response surface methodology. Results showed that the optimum microwave extraction parameters were:solid- liquid ratio of 1:43,microwave power for 540W,microwave treatment time for 30s and solvent 73% ethanol solution. Under these conditions, curcumin yield was 0.2045%.%采用微波辅助提取技术提取姜黄中的姜黄素,以姜黄素提取率为指标,通过响应面优化实验,考察了料液比、处理时间、微波功率、乙醇浓度等因素对提取率的影响。结果表明,微波提取的最佳工艺参数是:料液比为1:43、微波功率为540W,处理时间为30s,溶剂为73%乙醇溶液,在此参数下,姜黄素提取率为0.2045%。

  5. 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.

  6. The determination of organochlorine pesticides based on dynamic microwave-assisted extraction coupled with on-line solid-phase extraction of high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ligang [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ding Lan [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)]. E-mail: analchem@jlu.edu.cn; Jin Haiyan [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Song Daqian [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhang Huarong [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Li Jiantao [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhang Kun [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Wang Yutang [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

    2007-04-25

    A rapid technique based on dynamic microwave-assisted extraction coupled with on-line solid-phase extraction of high-performance liquid chromatography (DMAE-SPE-HPLC) has been developed. A TM{sub 010} microwave resonance cavity built in the laboratory was applied to concentrate the microwave energy. The sample placed in the zone of microwave irradiation was extracted with 95% acetonitrile (ACN) aqueous solution which was driven by a peristaltic pump at a flow rate of 1.0 mL min{sup -1}. The extraction can be completed in a recirculating system in 10 min. When a number of extraction cycles were completed, the extract (1 mL) was diluted on-line with water. Then the extract was loaded into an SPE column where the analytes were retained while the unretained matrix components were washed away. Subsequently, the analytes were automatically transferred from the SPE column to the analytical column and determined by UV detector at 238 nm. The technique was used for determination of organochlorine pesticides (OCPs) in grains, including wheat, rice, corn and bean. The limits of detection of OCPs are in the range of 19-37 ng g{sup -1}. The recoveries obtained by analyzing the four spiked grain samples are in the range of 86-105%, whereas the relative standard deviation (R.S.D.) values are <8.7% ranging from 1.2 to 8.7%. Our method was demonstrated to be fast, accurate, and precise. In addition, only small quantities of solvent and sample were required.

  7. Enhanced esterification of oleic acid and methanol by deep eutectic solvent assisted Amberlyst heterogeneous catalyst.

    Science.gov (United States)

    Pan, Ying; Alam, Md Asraful; Wang, Zhongming; Wu, Jingcheng; Zhang, Yi; Yuan, Zhenhong

    2016-11-01

    In present study, esterification of oleic acid with methanol using deep eutectic solvent (DES) assisted Amberlyst heterogeneous catalyst was investigated to produce biodiesel. Results showed that esterification efficiency was enhanced by the DES. The combined effect of DES on Amberlyst BD20 (BD20) is better than Amberlyst 15 (A-15) due to different structure. The optimal reaction conditions were 12:1M ratio of methanol to oleic acid, 20%(wt/wt) catalyst (BD20-DES (2:8) and A-15-DES (8:2)) at 85°C for 100min with agitating at 200rpm. The mechanism involved in catalysis and their capacity to reuse were studied. We proposed, Choline chloride-glycerol (Chcl-gly) DES could enhance the Amberlyst function due to the hydrogen bond effect on both DES and water. BD20 has fewer pores than A-15, have desirable performance in decreasing the inhibition the water during esterification of high FFA content and provide better performance in reuse.

  8. Ultrasound assisted enzyme catalyzed hydrolysis of waste cooking oil under solvent free condition.

    Science.gov (United States)

    Waghmare, Govind V; Rathod, Virendra K

    2016-09-01

    The present work demonstrates the hydrolysis of waste cooking oil (WCO) under solvent free condition using commercial available immobilized lipase (Novozyme 435) under the influence of ultrasound irradiation. The process parameters were optimized using a sequence of experimental protocol to evaluate the effects of temperature, molar ratios of substrates, enzyme loading, duty cycle and ultrasound intensity. It has been observed that ultrasound-assisted lipase-catalyzed hydrolysis of WCO would be a promising alternative for conventional methods. A maximum conversion of 75.19% was obtained at mild operating parameters: molar ratio of oil to water (buffer pH 7) 3:1, catalyst loading of 1.25% (w/w), lower ultrasound power 100W (ultrasound intensity - 7356.68Wm(-2)), duty cycle 50% and temperature (50°C) in a relatively short reaction time (2h). The activation energy and thermodynamic study shows that the hydrolysis reaction is more feasible when ultrasound is combined with mechanical agitation as compared with the ultrasound alone and simple conventional stirring technique. Application of ultrasound considerably reduced the reaction time as compared to conventional reaction. The successive use of the catalyst for repetitive cycles under the optimum experimental conditions resulted in a loss of enzymatic activity and also minimized the product conversion. Copyright © 2016. Published by Elsevier B.V.

  9. Solvent-Assisted Preparation of High-Performance Mesoporous CH₃NH₃Pbl₃ Perovskite Solar Cells.

    Science.gov (United States)

    Li, Zhi-Hua; Liu, Jie; Ma, Jing-Yuan; Jiang, Yan; Ge, Qian-Qing; Ding, Jie; Hu, Jin-Song; Wan, Li-Jun

    2016-01-01

    Organometal trihalide perovskite based solar cells have attracted great attention worldwide since their power conversion efficiency (PCE) have risen to over 15% within only 3 years of development. Comparing with other types of perovskite solar cells, mesostructured perovskite solar cells based on CH₃NH₃Pbl₃ as light harvesting material have already demonstrated remarkable advance in performance and reproducibility. Here, we reported a mesoscopic TiO₂/CH₃NH₃Pbl₃ heterojunction solar cell with uniform perovskite thin film prepared via solvent-assisted solution processing method. The best performing device delivered photocurrent density of 20.11 mA cm⁻², open-circuit voltage of 1.02 V, and fill factor of 0.70, leading to a PCE of 14.41%. A small anomalous hysteresis in the J-V curves was observed, where the PCE at forward scan was measured to be 84% of the PCE at reverse scan. Based on a statistical analysis, the perovskite solar cells prepared by the reported method exhibited reproducible and high PCE, indicating its promising application in the fabrication of low-cost and high-efficiency perovskite solar cells.

  10. 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.

  11. Dual ultrasonic-assisted dispersive liquid-liquid microextraction coupled with microwave-assisted derivatization for simultaneous determination of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol by ultra high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Zhao, Xian-En; Lv, Tao; Zhu, Shuyun; Qu, Fei; Chen, Guang; He, Yongrui; Wei, Na; Li, Guoliang; Xia, Lian; Sun, Zhiwei; Zhang, Shijuan; You, Jinmao; Liu, Shu; Liu, Zhiqiang; Sun, Jing; Liu, Shuying

    2016-03-11

    This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20(S)-protopanaxadiol (PPD) and 20(S)-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4'-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma.

  12. 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.

  13. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions.

    Science.gov (United States)

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η(coup)) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  14. 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.

  15. 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.

  16. Microwave assisted synthesis and characterization of unsymmetrical tetradentate Schiff base complexes of VO(IV) and MoO(V).

    Science.gov (United States)

    Thaker, B T; Barvalia, R S

    2011-12-15

    Microwave synthesis, is green chemical method, simple, sensitive, reducing solvent amount and reaction time. The attempt was made to synthesize the unsymmetrical tetradentate N(2)O(2) ligands and their VO(IV) and MoO(V) unsymmetrical tetradentate Schiff base complexes by classical and microwave techniques using domestic microwave oven. The resulting unsymmetrical Schiff base ligands L(1)-L(3) characterized by different spectral methods. Their complexes with oxocations of VO(IV) and MoO(V) have been synthesized and characterized by elemental analyses, conductometric measurements, infrared and electronic absorption, (1)H NMR spectra, mass spectrometry, ESR spectra, magnetic susceptibility measurement and thermal study. The study suggests that the oxo metal ion is bonded to the ligand through the oxygen and imino nitrogen and the geometry around metal ion is distorted octahedral.

  17. Study on the microwave assistant extraction technique of roselle seed oil%微波辅助提取玫瑰茄籽油工艺的研究

    Institute of Scientific and Technical Information of China (English)

    黎冬明; 上官新晨; 杨武英; 郑国栋; 沈勇根

    2011-01-01

    Microwave assisted extraction method was used in drying treatment of roselle seed.Using reflux extraction with petroleum ether as solvent to extracted oils from roselle seed.The effect of microwave treatment temperature,microwave treatment time,ultrasonic temperature,extraction time,extraction temperature,solid-liquid ratio on the oil extraction efficiency were investigated by orthogonal experiments.The results showed that the primary and secondary order of the factors influencing oil extraction efficiency were as follows:solid-liquid ratio microwave treatment temperatureextraction temperaturemicrowave treatment timeextraction time.The maximum extraction efficiency of roselle seed oil could reach 14.08% and the extraction rate could reach 85.5% under the solid-liquid ratio of 1:9,microwave treatment temperature of 90℃,extraction temperature of 50℃,microwave treatment time of 150s and the extraction time was 3h.%应用微波加热技术,对玫瑰茄籽进行干燥处理;以石油醚为溶剂,采用回流法提取玫瑰茄籽油。利用正交实验探讨微波处理温度、微波处理时间、提取时间、提取温度和料液比对玫瑰茄籽油提取得率的影响。结果表明,影响玫瑰茄籽油提取得率的因素主次顺序为:料液比〉微波处理温度〉提取温度〉微波处理时间〉提取时间;最佳提取工艺条件:料液比为1:9、微波处理温度为90℃、提取温度为50℃、微波处理时间为150s、提取时间为3h,得率为14.08%,提取率为85.5%。

  18. 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

  19. 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.

  20. 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.