396 results on '"Ultrasound-assisted"'
Search Results
202. Protein stabilized seabuckthorn fruit oil Nanoemulsion:Preparation, characterization and performance research.
- Author
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Zhang, Qiang, Zhang, Chengbao, Luo, Xiaomin, Wang, Zhong, Guo, Juan, and Bi, Yongguang
- Subjects
SODIUM caseinate ,FRUIT ,SEA buckthorn ,EDIBLE fats & oils ,ZETA potential ,OLIVE oil - Abstract
Protein-stabilized nanoemulsion was successfully prepared by ultrasound-assisted method under optimal ultrasound conditions, so as to improve the defects of sea buckthorn fruit oil (SBFO) and increase its bioavailability. This paper investigated the performance of nanoemulsion obtained by sodium caseinate (SC) and whey glycoprotein (WGP) at different concentrations, including polymer dispersity index (PDI), particle size, zeta potential (ZP). The SBFO nanoemulsion prepared under the optimal concentration of protein has good microstructure and rheological properties. Under different temperature (20–80 °C), pH (3–9), salinity (50–200 mM) and storage time (4 weeks), the performance of SBFO nanoemulsion has been measured to prove that SBFO nanoemulsion can maintain stable state in most cases. The safety of the SBFO nanoemulsion was evaluated by cytotoxicity (MTT) method and the results showed non-toxic to normal human embryonic kidney cells (HEK 293T). SBFO nanoemulsion preparation, principle and partial characterization schematic diagram. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
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203. Simultaneous adsorption of cobalt ions, azo dye, and imidacloprid pesticide on the magnetic chitosan/activated carbon@UiO-66 bio-nanocomposite: Optimization, mechanisms, regeneration, and application.
- Author
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Motaghi, Hamed, Arabkhani, Payam, Parvinnia, Mohammad, and Asfaram, Arash
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AZO dyes , *LEAD removal (Sewage purification) , *CHEMICAL process control , *ADSORPTION (Chemistry) , *PESTICIDES , *MALACHITE green , *CHITOSAN - Abstract
• The magnetic chitosan/activated carbon bio-nanocomposite was modified with UiO-66 MOFs. • Ultrasound-assisted simultaneous adsorption removal of cobalt (II) ions, malachite green dye, and imidacloprid pesticide from aqueous solution. • The maximum adsorption capacity of adsorbent in a ternary model were, 44.5, 62.1, and 25.2 mg g−1 for Co (II), MG, and IMI respectively. • The adsorption process parameters were optimized by response surface methodology based on central composite design (RSM-CCD). • Adsorption results have been analyzed by isotherm, kinetic, and thermodynamic studies. In this study, the modification of magnetic chitosan/activated carbon bio-nanocomposite (MCS/AC) with UiO-66 MOFs (MCS/AC@UiO-66) was carried out, and the obtained bio-nanocomposite was applied as an efficient adsorbent for the ultrasound-assisted simultaneous adsorption removal of cobalt (II) ions (Co (II)), malachite green (MG) dye, and imidacloprid (IMI) pesticide from aqueous solution. Assessing the possible interaction and optimization of process parameters including pH, sonication time, adsorbent mass and the concentration of adsorbates was carried out by response surface methodology based on central composite design (RSM-CCD). The isotherm experimental data were demonstrated to be great fitted with Langmuir isotherm model, and the maximum capacity values of adsorption in a ternary medium were 44.5 mg g−1, 62.1 mg g−1, and 25.2 mg g−1 for Co (II), MG, and IMI, respectively. A better description of the adsorption process was provided by using pseudo-second-order model, meaning that chemical adsorption controlled the process. In addition, the thermodynamic parameters illustrated that the adsorption of all contaminants occurred spontaneously and endothermically. MCS/AC@UiO-66 demonstrated to be a superb reusable adsorbent with a high adsorption capacity even after four adsorption–desorption cycles for the removal of all contaminants from various real wastewater samples. It was concluded that MCS/AC@UiO-66 with excellent properties, such as eco-friendly, easy synthesis, cost-effectiveness, fast adsorption kinetic, high adsorption efficiency, simple magnetic separation, and excellent reusability, could be considered as a promising candidate to remove a wide range of contaminants from wastewaters. [ABSTRACT FROM AUTHOR]
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- 2022
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204. Associating chitosan and nanoemulsion as a delivery system of essential oil; the potential on quality maintenance of minimally processed produce.
- Author
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Chen, Fangyuan, Kowaleguet, Marlyse Gianna Gloire Martha, Shi, Wanli, Zhang, Shuang, Dai, Jiujun, Ban, Zhaojun, Wang, Lijun, Wu, Yuanfeng, and Wang, Hongpeng
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ESSENTIAL oils , *CHITOSAN - Abstract
Plant-derived essential oil (EO) has gained more and more attentions resulted from its antioxidant, antiradical, and antimicrobial properties. The ginger EO delivery system based on chitosan nano-emulsion using ultrasound (US) was constructed and the application on the quality attributes of minimally processed cantaloupe was investigated in this paper. Results demonstrated that emulsions with small particle size and excellent stability were produced under US 60% conditions. The addition of 0.5% EO in emulsions enabled the polysaccharide-based coating to maintain the quality attributes during storage of minimally processed cantaloupe. The antioxidant capacity and vitamin C content in minimally processed cantaloupe were increased by more than 56%; whereas the total soluble solids and the weight loss were declined by 6.4% and 3.7%, respectively. Furthermore, the microbial development (the total bacterial count is 2 log CFU/g, and the yeast and mold count is 2 log CFU/g) were significantly inhibited after 10 days of storage. In summary, the delivery system of EO prepared with chitosan-based emulsion effectively contributed to the quality maintenance and the shelf-life extension of minimally processed cantaloupe. • Chitosan/Essential oil (EO) nanoemulsion prepared by ultrasonic assisted method. • Emulsion with 60% ultrasonic power showed low UV transmittance and high stability. • Chitosan-based ginger EO emulsion extend the shelf-life of fresh-cut cantaloupe. • Ginger EO emulsion coating can effectively inhibit the growth of microorganisms. • 0.5% ginger EO added can effectively maintain the quality of fresh-cut cantaloupe. [ABSTRACT FROM AUTHOR]
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- 2022
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205. EFFECT OF NITROGEN AND PHOSPHORUS LEVELS ON THE LIPID PRODUCTION OF CHLORELLA VULGARIS AND EVALUATION OF ULTRASOUND-ASSISTED LIPID EXTRACTION.
- Author
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Yuanxing Huang, Liang Li, and Cuihong Song
- Abstract
The effect of nitrogen and phosphorus levels on the lipid production and fatty acid composition of Chlorella vulgaris was investigated. In addition, ultrasound-assisted lipid extraction was evaluated based on its efficiency. Results showed that nitrogen concentration in the culture medium affected the lipid yield, biomass production and lipid composition significantly. The highest lipid yield of 34.4 g
lipid /100gbiomass was obtained under the initial NaNO3 concentration of 35 mg L-1 . The highest lipid production occurred when the initial NaNO3 concentration was 150 mg L-1 . The major fatty acids detected include C16:0, C18:0, C18:1, C18:2 and C18:3. Nitrogen limitation led to an increase of C18:1 and a decrease of C18:3. The phosphorus level did not influence the lipid production and composition obviously, while insufficient phosphorus caused poor biomass production. Ultrasoundassisted lipid extraction was effective for C. vulgaris, of which the ultrasonic treatment time was the most important parameter to affect the lipid yield. [ABSTRACT FROM AUTHOR]- Published
- 2013
206. Leaching kinetics of zinc residues augmented with ultrasound.
- Author
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Xin, Wang, Srinivasakannan, C., Xin-hui, Duan, Jin-hui, Peng, Da-jin, Yang, and shao-hua, Ju
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LEACHING , *CHEMICAL kinetics , *ZINC , *CHEMICAL affinity , *REACTIVITY (Chemistry) , *CHEMICAL processes - Abstract
Highlights: [•] The leaching kinetics of zinc residue is leached augmented with ultrasound is presented. [•] The best zinc recovery ratio can is showed at this paper. [•] The kinetics research of ultrasound-assisted leaching is researched using shrinking core model. [•] The rate controlling step of ultrasound-assisted leaching is identified to be the diffusion through the product layer. [Copyright &y& Elsevier]
- Published
- 2013
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207. Ultrasound-assisted emulsification microextraction combined with injection-port derivatization for the determination of some chlorophenoxyacetic acids in water samples.
- Author
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Yamini, Yadollah and Saleh, Abolfazl
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ACETIC acid analysis , *CHLOROPHENOXYACETIC acid , *DERIVATIZATION , *CHROMATOGRAPHIC analysis , *CONCENTRATION functions , *ORGANIC solvents - Abstract
An efficient method based on ultrasound-assisted emulsification microextraction followed by injection-port derivatization GC analysis was developed to determine 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) in natural water samples. In this procedure, 12.5 μL of 1-undecanol was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample of the analytes located inside an ultrasonic water bath. The resulting emulsion was centrifuged, and 1 μL of the separated organic solvent together with 1 μL of the derivatization reagent were injected into a GC equipped with a flame ionization detector. Several factors that influence the derivatization and extraction were optimized. Under the optimal conditions, the LODs were 0.33 and 1.7 μg/L for MCPA and 2,4-D, respectively. Preconcentration factors of 670 and 836 were obtained for MCPA and 2,4-D, respectively. The precision of the proposed method was evaluated in terms of repeatability, which was <5.7% ( n = 5). The applicability of the proposed method was evaluated by extraction and determination of chlorophenoxyacetic acids from some natural waters, which indicated that the matrices of natural waters have no significant effect on the extraction and derivatization efficiency of this method. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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208. Rapid analysis of six phthalate esters in wine by ultrasound-vortex-assisted dispersive liquid–liquid micro-extraction coupled with gas chromatography-flame ionization detector or gas chromatography–ion trap mass spectrometry
- Author
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Cinelli, Giuseppe, Avino, Pasquale, Notardonato, Ivan, Centola, Angela, and Russo, Mario Vincenzo
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PHTHALATE esters , *LIQUID-liquid extraction , *GAS chromatography/Mass spectrometry (GC-MS) , *FLAME ionization detectors , *STANDARD deviations , *PRECISION (Information retrieval) - Abstract
Abstract: An Ultrasound-Vortex-Assisted Dispersive Liquid–Liquid Micro-Extraction (USVADLLME) procedure coupled with Gas Chromatography-Flame Ionization Detector (GC-FID) or Gas Chromatography-Ion Trap Mass Spectrometry (GC-IT/MS) is proposed for rapid analysis of six phthalate esters in hydroalcoholic beverages (alcohol by volume, alcvol−1, ≤40%). Under optimal conditions, the enrichment factor of the six analytes ranges from 220- to 300-fold and the recovery from 85% to 100.5%. The limit of detection (LOD) and limit of quantification (LOQ) are ≥0.022μgL−1 and ≥0.075μgL−1, respectively. Intra-day and inter-day precisions expressed as relative standard deviation (RSD), are ≤8.2% and ≤7.0%, respectively. The whole proposed methodology has demonstrated to be simple, reproducible and sensible for the determination of trace phthalate esters in red and white wine samples. [Copyright &y& Elsevier]
- Published
- 2013
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209. Rapid determination of triclosan in personal care products using new in-tube based ultrasound-assisted salt-induced liquid–liquid microextraction coupled with high performance liquid chromatography-ultraviolet detection
- Author
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Chen, Ming-Jen, Liu, Ya-Ting, Lin, Chiao-Wen, Ponnusamy, Vinoth Kumar, and Jen, Jen-Fon
- Subjects
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TRICLOSAN , *HYGIENE products , *LIQUID-liquid extraction , *LIQUIDS , *HIGH performance liquid chromatography , *ULTRAVIOLET radiation , *ORGANIC solvents - Abstract
Abstract: This paper describes the development of a novel, simple and efficient in-tube based ultrasound-assisted salt-induced liquid–liquid microextraction (IT-USA-SI-LLME) technique for the rapid determination of triclosan (TCS) in personal care products by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. IT-USA-SI-LLME method is based on the rapid phase separation of water-miscible organic solvent from the aqueous phase in the presence of high concentration of salt (salting-out phenomena) under ultrasonication. In the present work, an indigenously fabricated home-made glass extraction device (8-mL glass tube inbuilt with a self-scaled capillary tip) was utilized as the phase separation device for USA-SI-LLME. After the extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus, the collection and measurement of the upper organic solvent layer was simple and convenient. The effects of various parameters on the extraction efficiency were thoroughly evaluated and optimized. Under optimal conditions, detection was linear in the concentration range of 0.4–100ngmL−1 with correlation coefficient of 0.9968. The limit of detection was 0.09ngmL−1 and the relative standard deviations ranged between 0.8 and 5.3% (n =5). The applicability of the developed method was demonstrated for the analysis of TCS in different commercial personal care products and the relative recoveries ranged from 90.4 to 98.5%. The present method was proven to be a simple, sensitive, less organic solvent consuming, inexpensive and rapid procedure for analysis of TCS in a variety of commercially available personal care products or cosmetic preparations. [Copyright &y& Elsevier]
- Published
- 2013
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210. Comparative study of ultrasound-assisted and conventional stirred dead-end microfiltration of grape pomace extracts
- Author
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Liu, Dan, Vorobiev, Eugène, Savoire, Raphaëlle, and Lanoisellé, Jean-Louis
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MICROFILTRATION , *GRAPES , *PLANT extracts , *COMPARATIVE studies , *ULTRASONICS , *SONICATION , *IRRADIATION - Abstract
Abstract: Ultrasound (US) was used to facilitate dead-end microfiltration (MF) of grape pomace (GP) extracts. The effects of ultrasonic power, sonication cycle time and ultrasonic probe height on filtration behaviour were investigated. Ultrasonic irradiation had a strong impact on the MF processes, especially with high output power and continuous mode. A comparative study of US-assisted and stirred MF was performed. The energy consumption and liquid flux enhancement of the two filtration systems were compared. Under the same dissipation power, the flux enhancement is much higher for the US-assisted MF. A correlation equation for predicting permeate flux was derived from resistance-in-series model. The flux predictions were confirmed with the experimental results. Finally, the characteristics of permeate after US-assisted and stirred filtration were evaluated. [Copyright &y& Elsevier]
- Published
- 2013
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211. Ultrasound-assisted acid hydrolysis of palm leaves (Roystonea oleracea) for production of fermentable sugars
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Werle, Leandro B., Garcia, Jardel C., Kuhn, Raquel C., Schwaab, Marcio, Foletto, Edson L., Cancelier, Adriano, Jahn, Sérgio L., and Mazutti, Marcio A.
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PALMS , *LEAVES , *HYDROLYSIS , *ULTRASONICS , *FERMENTATION , *SUGARS - Abstract
Abstract: This work is focused on the ultrasound-assisted hydrolysis of palm leaves to obtain fermentable sugars using phosphoric acid as catalyst. The effects of phosphoric acid concentration (5.0–20wt%) and temperature (30–65°C) on the hydrolysis and kinetic parameters were evaluated. The maximum amounts of fermentable sugar obtained were 0.55 and 0.59g sugarg−1 dry material, leading to maximum efficiencies of hydrolysis of 68.8 and 74.0% in the absence and presence of ultrasound, respectively. The kinetic parameters obtained from the overall reaction curves showed that the ultrasound intensified the releasing of fermentable sugars in the period of constant reaction rate, since 51% of total fermentable sugar was released in this period in comparison with 45% in the absence. [Copyright &y& Elsevier]
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- 2013
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212. Composition of ethanolic extracts of wood and bark from Acer saccharum and Betula alleghaniensis trees of different vigor classes
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St-Pierre, François, Achim, Alexis, and Stevanovic, Tatjana
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CHEMICAL composition of plants , *PLANT extracts , *ETHANOL , *SUGAR maple , *BARK , *YELLOW birch , *PLANT populations - Abstract
Abstract: The forest populations of Acer saccharum Marsh and Betula alleghaniensis Britton of south west Québec contain a significant proportion of low vigor trees, which are prioritized for harvesting as part of a forest restoration plan. Ethanol extractions of bark and wood collected from vigorous and non-vigorous trees were performed in order to compare their chemical compositions and thus evaluate the potential of adding value to the processing of low-vigor trees. Two methods – maceration and ultrasound assisted solvent extractions – were applied. Total content of phenols, proanthocyanidins, hydroxycinnamic acids and flavonoids were determined in the extracts by spectrophotometric methods. Concentrations of selected triterpenes and sterols were evaluated by GC–MS. While some variation in extract yields, polyphenol and lipophilic content was detected between vigorous and non-vigorous trees, the overall composition of extracts remained similar across vigor classes. The two extraction methods yielded very similar results while the advantage of the ultrasound assisted method was a much shorter extraction time. Ultrasound assisted ethanolic extraction of potentially valuable compounds could therefore be considered as an option to add value to the processing of low vigor A. saccharum and B. alleghaniensis trees. [Copyright &y& Elsevier]
- Published
- 2013
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213. Optimization of ultrasound-assisted ultrafiltration of Radix astragalus extracts with hollow fiber membrane using response surface methodology
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Cai, Ming, Wang, Sanju, and Liang, Han-hua
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ULTRAFILTRATION , *IRRADIATION , *HOLLOW fibers , *RESPONSE surfaces (Statistics) , *ANALYSIS of variance , *FOULING , *EXTRACTS - Abstract
Abstract: Response surface methodology (RSM) with a central composite rotatable design (CCRD) was employed to optimize the process of ultrasound-assisted ultrafiltration (UF) for Radix astragalus mixtures. The effects and mutual interaction of several parameters, namely ultrasonic power, ultrasonic irradiation mode, trans-membrane pressure (TMP) and temperature, on fouling degree (Y 1) and process duration (Y 2) were investigated simultaneously. The analysis of variance (ANOVA) demonstrates that the second order polynomial regression models were appropriate and significant, with R 2 of 0.9820 and 0.9581 for Y 1 and Y 2, respectively. The study also shows that TMP is the most significant factor, followed by the temperature, ultrasonic power and irradiation mode. The desirability function approach was used to find the optimum conditions to minimize fouling degree and process duration simultaneously. The optimum conditions were found to be at ultrasonic power of 120W, continuous ultrasonic irradiation mode, TMP of 0.60bar and temperature of 20°C. The predicted responses are 40.2% for fouling degree and 57min for process duration, which are in good agreement with the results obtained from the confirmation experiments, valued about 38.5–43% and 53–58min respectively. The results indicate that the regression models are adequate and RSM is an efficient optimization tool for multi-responses and multi-variables study. [Copyright &y& Elsevier]
- Published
- 2012
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214. A facile synthesis of novel benzofuran-2-yl(9-methyl-9 H-carbazol-3-yl)methanones.
- Author
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Zhang, Hong, Yan, Yan, Li, Yang, and Gao, Wentao
- Subjects
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BENZOFURAN , *CARBAZOLE , *ORGANIC synthesis , *ULTRASONICS , *ALDEHYDES , *CHEMICAL reactions - Abstract
A facile synthesis of hitherto unreported benzofuran-2-yl(9-methyl-9 H-carbazol-3-yl)methanones ( 3a- l) is described. The synthesis mainly relies on the ultrasound-assisted Rap-Stoermer reaction of 3-chloroacetyl-9-methyl-9 H-carbazole ( 1) with a variety of salicylaldehydes, as well as 2-hydroxy-1-naphthaldehyde ( 2) in CHCN, with the presence of PEG-400 as a catalyst. This procedure offers easy access to benzofuran-2-yl(carbazolyl)methanone derivatives in a short reaction time and the products are achieved in good yields. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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215. Synthesis of novel 2,6-bis(5- t-butylbenzo[ b]furan-2-ylcarbonyl)pyridines.
- Author
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Li, Yang, Tao, Xiyue, Lin, Guihai, and Gao, Wentao
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CHEMICAL synthesis , *PYRIDINE synthesis , *CHEMICAL reactions , *CATALYSTS , *CANCER cells , *DNA - Abstract
A facile synthesis of new 2,6-bis(5- t-butyl-benzo[ b]furan-2-ylcarbonyl)pyridines 3a-e is described. The synthesis mainly relies on the ultrasound-assisted Rap-Stoermer reaction of 2,6-bis(bromoacetyl)pyridine ( 1) with t-butyl substituted salicylaldehydes 2a-e in MeCN with the presence of PEG-400 as catalyst. This procedure is characterized by short reaction times and good yields. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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216. Ultrasound-assisted synthesis of aromatic 1,2-diketones from oximinoketones under neutral conditions in aqueous media
- Author
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Mehrabi, Hossein
- Subjects
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ULTRASONICS , *KETONES , *AROMATIC compound synthesis , *SODIUM sulfate , *NUCLEAR magnetic resonance , *MASS spectrometry - Abstract
Abstract: We report a convenient, neutral, and facile methodology for the synthesis of aromatic 1,2-diketones from the corresponding oximinoketones in the presence of I2/SDS/water system under ultrasound-assisted conditions. Furthermore, a series of compounds were synthesized and characterized by melting point, IR, NMR, MS, and elemental analysis. Utilization of easy reaction conditions, very high to excellent yields, and short reaction times makes this manipulation potentially very useful. [Copyright &y& Elsevier]
- Published
- 2012
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217. Determination of β-sitosterol and cholesterol in oils after reverse micelles with Triton X-100 coupled with ultrasound-assisted back-extraction by a water/chloroform binary system prior to gas chromatography with flame ionization detection
- Author
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Kardani, Fatemeh, Daneshfar, Ali, and Sahrai, Reza
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CHOLESTEROL , *REVERSED micelles , *EXTRACTION (Chemistry) , *CHLOROFORM , *BINARY metallic systems , *GAS chromatography , *IONIZATION (Atomic physics) , *SUNFLOWER seed oil - Abstract
Abstract: Ultrasonic back-extraction of Triton X-100 reverse micelles by a water/chloroform binary system and gas chromatography with flame ionization detection (GC-FID) was developed for extraction and determination of β-sitosterol and cholesterol in soybean and sunflower oil samples. After the homogenization of the oil samples with Triton X-100, an aliquot of 200μL of methanol was added to the samples to form two phases. The clear Triton X-100 extract obtained by centrifugation was treated with a mixture of water (1000μL) and chloroform (300μL) for back-extraction of the analytes into the chloroform phase by ultrasonication. After centrifugation, the sedimented chloroform layer was withdrawn easily by a microsyringe and directly injected into the GC-FID system. The influence of several important parameters on the extraction efficiencies of the analytes was evaluated. Under optimized experimental conditions, the calibration graphs were linear in the range of 1.0–30.0mgL−1 with coefficient of determination more than 0.994 for both analytes. The method detection limit values were in the range of 0.2–0.7mgL−1. The lower limit of quantification values were in the range of 0.7–2.4mgL−1. Intra-day relative standard deviations were in the range of 1.0–2.7%. This procedure was successfully applied with satisfactory results to the determination of β-sitosterol and cholesterol in spiked oil samples. The relative mean recoveries of oil samples ranged from 93.6% to 105.0%. [Copyright &y& Elsevier]
- Published
- 2011
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218. Comparison of Extraction Methods for Recovery of Astaxanthin from Haematococcus pluvialis.
- Author
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Ruen-ngam, Duangkamol, Shotipruk, Artiwan, and Pavasant, Prasert
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SOLVENT extraction , *ACETONE , *SOLVENTS , *ACETONITRILE , *CHEMICAL engineering , *MICROWAVES , *INDUSTRIAL chemistry - Abstract
Solvent extraction, ultrasound assisted extraction (UAE), and microwave assisted extraction (MAE) were examined for the extraction of astaxanthin from Haematococcus pluvialis. In all cases, acetone was found to give the highest astaxanthin recovery compared with other selected solvents, i.e., methanol, ethanol, and acetonitrile. Among the various methods, MAE at 75°C for 5 min resulted in the highest astaxanthin recovery (74 ± 4%). [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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219. Ultrasonic-assisted convenient chemical synthesis of battery grade potassium ferrate(VI)
- Author
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Wang, Suqin, Yang, Zhanhong, Liu, Dongren, and Wang, Shengwei
- Abstract
Abstract: An ultrasound-assisted convenient method was developed for the synthesis of battery grade potassium ferrate (K2FeO4) with high yield (53–59%). The purity of the synthesized salt was determined by chromite method to be 95–96.8%. It was found that sample of the solid potassium ferrate has a tetrahedral structure with a space group of D 2h (Pnma) from X-ray diffraction (XRD) spectrum. From the scanning electronic microscopy (SEM), the K2FeO4 powders were crystallized polyhedron-shaped stick, and the particles had dimensions on the order of 25–200μm in length and 1–10μm in width. The electrochemical performance of the K2FeO4 electrodes was studied by using cyclic voltammetry and galvanostatic discharge methods in 10mol/L KOH aqueous electrolyte. The synthesized product possesses a capacity of 302.4mAh/g and coulombic efficiency of 74.5%. [Copyright &y& Elsevier]
- Published
- 2010
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220. Physical-Mechanical Behavior and Water-Barrier Properties of Biopolymers-Clay Nanocomposites.
- Author
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Calambas, Heidy Lorena, Fonseca, Abril, Adames, Dayana, Aguirre-Loredo, Yaneli, and Caicedo, Carolina
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YOUNG'S modulus , *NANOCOMPOSITE materials , *HYDROGEN bonding interactions , *TENSILE strength , *SONICATION - Abstract
The preparation and characterization of biodegradable films based on starch-PVA-nanoclay by solvent casting are reported in this study. The films were prepared with a relation of 3:2 of starch:PVA and nanoclay (0.5, 1.0, and 1.5% w/v), and glycerol as plasticizer. The nanoclays before being incorporated in the filmogenic solution of starch-PVA were dispersed in two ways: by magnetic stirring and by sonication. The SEM results suggest that the sonication of nanoclay is necessary to reach a good dispersion along the polymeric matrix. FTIR results of films with 1.0 and 1.5% w/v of sonicated nanoclay suggest a strong interaction of hydrogen bond with the polymeric matrix of starch-PVA. However, the properties of WVP, tensile strength, percentage of elongation at break, and Young's modulus improved to the film with sonicated nanoclay at 0.5% w/v, while in films with 1.0 and 1.5% w/w these properties were even worse than in film without nanoclay. Nanoclay concentrations higher than 1.0 w/v saturate the polymer matrix, affecting the physicochemical properties. Accordingly, the successful incorporation of nanoclays at 0.5% w/v into the matrix starch-PVA suggests that this film is a good candidate for use as biodegradable packaging. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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221. Comparison of the effectiveness of solid-phase and ultrasound-mediated liquid–liquid extractions to determine the volatile compounds of wine
- Author
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Hernanz, Dolores, Gallo, Valeria, Recamales, Ángeles F., Meléndez-Martínez, Antonio J., and Heredia, Francisco J.
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SOLID phase extraction , *ALCOHOLS (Chemical class) , *EXTRACTION (Chemistry) , *WINES - Abstract
Abstract: Two ultrasound-assisted liquid–liquid extraction (LLE-I, LLE-II) methods were compared to a solid-phase extraction (SPE) protocol to assess their effectiveness for the analysis of up to 44 volatile compounds in a synthetic and several commercial white, red and “cream” wines produced in the southwest of Spain. Regardless of the extraction protocol used the highest recoveries corresponded to acids and terpene alcohols and the lowest to lactones and alcohols. In any case, it was concluded that one of the liquid–liquid extraction protocols evaluated led to higher recoveries for a greater number of odorants that could be implicated in the aroma of the wines than the solid-phase extraction. However, the SPE method also presented some advantages that should not be overlooked, like higher repeatability and throughput and lower solvent consumption. [Copyright &y& Elsevier]
- Published
- 2008
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222. Ultrasound-assisted extraction of oil from flaxseed
- Author
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Zhang, Zhen-Shan, Wang, Li-Jun, Li, Dong, Jiao, Shun-Shan, Chen, Xiao Dong, and Mao, Zhi-Huai
- Subjects
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FLAX , *FLAXSEED , *MEDICAL imaging systems , *CHROMATOGRAPHIC analysis - Abstract
Abstract: Flaxseed oil is the main component of the flaxseed and has many beneficial functions to human health. In this paper, the ultrasound-assisted extraction of oil from flaxseed is reported. The effects of some operating parameters such as ultrasonic power, extraction time, extraction temperature and solvent to solid ratio on the yield of flaxseed oil have been investigated and some of the results have been compared with that of conventional method. It has been found that ultrasound-assisted extraction requires a shorter extraction time and a reduced solvent consumption. The yield of flaxseed oil has been found to increase with the increase of the ultrasonic power and to decrease as the temperature is increased. Scanning electronic microscopy analysis was carried out on the flaxseed powder after the extraction. The images are powerful evidences to show the effect of ultrasound. The fatty acid compositions of the oils extracted by the ultrasound-assisted method and the conventional method have been analyzed using gas chromatography. It has been shown that the compositions of the flaxseed oils were not affected significantly by the application of ultrasound (p >0.05). The ultrasound-assisted extraction may be an effective method for lipid production. [Copyright &y& Elsevier]
- Published
- 2008
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223. New Advances in Liposuction Technology.
- Author
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Mann, Margaret W., Palm, Melanie D., and Sengelmann, Roberta D.
- Subjects
MEDICAL imaging systems ,MEDICAL equipment ,DIAGNOSTIC imaging ,MEDICAL photography - Abstract
Although suction-assisted liposuction under tumescent anesthesia remains the traditional method for body sculpting, newer technologies promise to increase efficiency, decrease surgeon fatigue, and minimize complication. Power-, ultrasound-, and laser-assisted devices are ideal in large volume cases and in areas of fibrous tissues as an adjunct to traditional liposuction. Although skepticism remains chemical lipolysis, more commonly termed mesotherapy or lipodissolve may be an alternative to surgical treatment of localized fat. This article reviews the recent advancements in the field of liposuction and the current literature which support their use. [Copyright &y& Elsevier]
- Published
- 2008
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224. Extraction optimization crocin pigments of saffron (Crocus sativus)
- Author
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Karasu, S, Bayram, Y, Ozkan, K, and Sagdic, O
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colorant ,Crocus sativus ,Ultrasound-assisted ,RSM ,Microencapsulation ,Natural - Abstract
This study aimed to determine optimal extraction parameters by using response surface methodology, examining the effect of microencapsulation on crocin retention, and evaluating the temperature and pH stability of crocin microcapsules. The effect of process variables on the crocin yield was successfully determined by quadratic models (R-2>0.99 and adj R-2>0.98). All variables significantly affected the crocin yield (P0.05). The thermal and pH stability of the crocin was determined at different temperatures (60, 70, 80, and 90 degrees C) and pH levels (2, 4.5, and 6). The crocin degradation showed first order kinetic, and degradation rate constant (k) were significantly affected by pH and temperature (P
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- 2019
225. Utilization of watermelon peel as a pectin source and the effect of ultrasound treatment on pectin film properties.
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Guo, Zonglin, Ge, Xiangzhen, Yang, Lihua, Gou, Qiaomin, Han, Ling, and Yu, Qun-li
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WATERMELONS , *PECTINS , *EDIBLE coatings , *HYDROGEN bonding interactions , *ULTRASONIC imaging , *TREATMENT effectiveness , *FRUIT skins - Abstract
The objectives of this study were to prepare a biofilm from watermelon peel pectin and to improve the commercial value and performance of the pectin film using ultrasound treatment. The results showed that ultrasound treatment decreased the particle size and turbidity of the film-forming solutions and changed the rheological properties, including a decrease in the viscosity, storage modulus (G ′), and loss modulus (G ″), and an increase in the phase angle. The digital photos and micrographs of films showed that the watermelon peel pectin had good film-forming properties. A low ultrasonic treatment time (<10 min) dispersed the pectin molecules and increased the hydrogen bonding interactions, as shown by Fourier-transform infrared spectroscopy (FTIR). This caused the thickness, oxygen permeability (OP), water vapor permeability (WVP), transmittance, and tensile strength (TS) to decrease and the density and elongation at break (EAB) to increase; however, the physical, barrier, and mechanical properties declined when the ultrasonic treatment time was increased to 15 min due to small cavities in the film matrix formed by cavitation effects. These results suggest that the developed biodegradable films can be used as food-grade edible films and may potentially replace existing conventional synthetic plastic packages. • Pectin extracted from watermelon peel can be used to prepare biofilms. • Performing an ultrasonic treatment before the film formation has a positive impact on the performance of the film. • Using physical methods constitute a new route to improve the performance of biofilms. [ABSTRACT FROM AUTHOR]
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- 2021
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226. Spent Grain from Malt Whisky: Assessment of the Phenolic Compounds.
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Chetrariu, Ancuța and Dabija, Adriana
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- *
PHENOLS , *MALTING , *WHISKEY , *HYDROXYCINNAMIC acids , *CAFFEIC acid , *FREE radicals - Abstract
In order to extract antioxidant phenolic compounds from spent grain (SG) two extraction methods were studied: the ultrasound-assisted method (US) and the Ultra-Turrax method (high stirring rate) (UT). Liquid to solid ratios, solvent concentration, time, and temperature/stirring rate were optimized. Spent grain extracts were analyzed for their total phenol content (TPC) (0.62 to 1.76 mg GAE/g SG DW for Ultra-Turrax pretreatment, and 0.57 to 2.11 mg GAE/g SG DW for ultrasound-assisted pretreatment), total flavonoid content (TFC) (0.6 to 1.67 mg QE/g SG DW for UT, and 0.5 to 1.63 mg QE/g SG DW for US), and antioxidant activity was measured using 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical (25.88% to 79.58% for UT, and 27.49% to 78.30% for UT). TPC was greater at a high stirring rate and high exposure time up to a certain extent for the Ultra-Turrax method, and at a high temperature for the ultrasound-assisted method. P-coumaric acid (20.4 ± 1.72 mg/100 SG DW for UT, and 14.0 ± 1.14 mg/100 SG DW for US) accounted for the majority of the phenolic found compounds, followed by rosmarinic (6.5 ± 0.96 mg/100 SG DW for UT, and 4.0 ± 0.76 mg/100 SG DW for US), chlorogenic (5.4 ± 1.1 mg/100 SG DW for UT, and non-detectable for US), and vanillic acids (3.1 ± 0.8 mg/100 SG DW for UT, and 10.0 ± 1.03 mg/100 SG DW for US) were found in lower quantities. Protocatechuic (0.7 ± 0.05 mg/100 SG DW for UT, and non-detectable for US), 4-hydroxy benzoic (1.1 ± 0.06 mg/100 SG DW for UT, and non-detectable for US), and caffeic acids (0.7 ± 0.03 mg/100 SG DW for UT, and non-detectable for US) were present in very small amounts. Ultrasound-assisted and Ultra-Turrax pretreatments were demonstrated to be efficient methods to recover these value-added compounds. [ABSTRACT FROM AUTHOR]
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- 2021
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227. Ultrasound-assisted alkanol-based nanostructured supramolecular solvent for extraction and determination of cadmium in food and environmental samples: Experimental design methodology.
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Altunay, Nail and Elik, Adil
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ENVIRONMENTAL sampling , *SOLVENT extraction , *EXPERIMENTAL design , *CADMIUM , *REVERSED micelles , *ATOMIC absorption spectroscopy - Abstract
• Important factors affecting the extraction efficiency of Cd(II) were successfully scrutinized. • Low LOD (0.3 ng mL−1), high EF (165), and good precision (RSD < 2.5%) were obtained. • An overview of the extraction of Cd(II) in real samples by the UA-alkanol-based-SUPRAS-ME was presented. • Consisting of spherical micelle of 1-tetradecanol, SUPRAS was easily prepared. • Current method was applied to water, vegetable, and food samples. Herein, a new and green analytical method was described for extraction and determination of cadmium in food and environmental samples using ultrasound assisted alkanol-based nano structured supramolecular solvent microextraction (UA-alkanol-based-SUPRAS-ME) coupled with flame atomic absorption spectrometry (FAAS) detection. The SUPRAS was easily prepared from reverse micelles of 1-tetradecanol (as extraction solvent) in tetrahydrofuran (THF as dispersive solvent). The Box-Behnken design based on the analysis of variance and the desirability function guide was used to optimize the key variables (pH, SUPRAS volume, ligand amount, ultrasonic time) of the UA-alkanol-based-SUPRAS-ME procedure. Under the optimum conditions, the calibration graphs were linear in the range of 50–3500 µg kg−1 and 1–400 ng mL−1 for foods and environmental samples, respectively. Acceptable limits of detection (LODs) of 15 µg kg−1 and 0.3 ng mL−1 were calculated for food and environmental samples, respectively. Inter day RSDs% lower than 4.9% with an average recovery of 99.8%, and intraday RSDs% lower than 4.1% with an average recovery of 97% were obtained. Total cadmium was determined in the range of 48.2–186.4 µg kg−1 and 35.4–124.6 ng mL−1 in food and environmental samples, respectively. [ABSTRACT FROM AUTHOR]
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- 2021
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228. An eco-compatible access to diversified bisoxazolone and bisimidazole derivatives
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Arafa, Wael Abdelgayed Ahmed, Abdel-Magied, Ahmed Fawzy, Arafa, Wael Abdelgayed Ahmed, and Abdel-Magied, Ahmed Fawzy
- Abstract
An efficient, straight-forward and eco-friendly synthetic strategy for the assembly of novel bisoxazolones via a four-component, sequential reaction of dialdehydes, glycine, benzoyl chloride and acetic anhydride, using ultrasound radiation, is described. Additionally, a diverse group of new bisimidazoles has been synthesized in good yields by the sonication of diamines and (Z)-4-arylidene-2-phenyloxazol-5(4H)-ones. These approaches have resulted in a number of successful routes for the facile synthesis of bis-oxazolone and bis-imidazole frameworks within minutes of irradiation. Excellent outcomes using these environmentally-friendly parameters make these synthetic schemes ideal, sustainable, green-chemistry procedures and provide simple access towards the preparation of bisheterocycles. [GRAPHICS] ., QC 20180802
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- 2018
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229. Utilization of water-contained surfactant-based ultrasound-assisted microextraction followed by liquid chromatography for determination of polycyclic aromatic hydrocarbons and benzene in commercial oil sample
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Amlashi, Nadiya Ekbatani and Hadjmohammadi, Mohammad Reza
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- 2016
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230. Ultrasound-assisted preparation of double nano-emulsions loaded with glycyrrhizic acid in the internal aqueous phase and skim milk as the external aqueous phase.
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Maghamian, Nafiseh, Goli, Mohammad, and Najarian, Afsaneh
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FOOD emulsions , *SKIM milk , *RESPONSE surfaces (Statistics) , *MANUFACTURING processes - Abstract
In this study, response surface methodology (RSM) based on central composite rotatable design applied to encapsulate glycyrrhizic acid (GA), within the ultrasound-assisted double emulsions. Three independent variables considered as the 10–30% weight of the internal aqueous phase (W 1) in the primary-emulsion (W 1 /O), 6–10% of polyglycerol-polyricinoleate (PGPR) as the surfactant in the oil phase, and 4–6 min sonication-time; dependent variables for optimal W 1 /O emulsion fabrication were droplet-size, poly-dispersity-index (PDI), and sedimentation-index. Then, 5–25% wt. of the W 1 /O emulsion dispersed into the skim milk as an external aqueous phase (W 2) to form double-emulsions (W 1 /O/W 2) through sonication for 1–5 min. The lowest droplet-size and sedimentation-index obtained for the W 1 /O emulsions formulated by 19% W 1 in the W 1 /O emulsion, 6% PGPR and a sonication time of 6 min. Two optimal-conditions for preparation of double-emulsions were determined based on the results of encapsulation efficiency, droplet-size, and viscosity as follows: the first optimum treatment (15% W 1 /O and 3 min sonication) and the second optimal conditions (24% W 1 /O and 4 min sonication). The encapsulation efficiency of GA in these double-emulsions was 92%. The emulsions stored for 7 days at 37 °C showed instability (2-phase separation). In addition, droplet-size and encapsulation-efficiency increased and decreased during storage, respectively. Image 1 • We optimized the experimental data of primary and double emulsions production process using GA and RSM. • The high encapsulation efficiency for GA in the stable emulsions was observed. • Particle size, viscosity, and encapsulation efficiency of double emulsions were studied during storage time. • Casein micelle as a perfect emulsifier successfully stabilized W 1 /O/W 2 nano-emulsion containing GA. • Skim milk fortified with encapsulated GA within W 1 /O/W 2 nano-emulsion. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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231. Synthesis, characterization, and photocatalytic performance of FeTiO3/ZnO on ciprofloxacin degradation.
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Núñez-Salas, Raisa Estefanía, Hernández-Ramírez, Aracely, Santos-Lozano, Verónica, Hinojosa-Reyes, Laura, Guzmán-Mar, Jorge Luis, Gracia-Pinilla, Miguel Ángel, and Maya-Treviño, María de Lourdes
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- *
CIPROFLOXACIN , *X-ray photoelectron spectroscopy , *REFLECTANCE spectroscopy , *TRANSMISSION electron microscopy , *SCANNING electron microscopy , *ZINC oxide - Abstract
• CPX was completely degraded using FeTiO 3 /ZnO under UV-Vis irradiation. • h + and OH reactive species were responsible for the degradation and mineralization of CPX. • FeTiO 3 /ZnO heterojunction, Fe 2 O 3 impurities, and oxygen-vacancies suppressed e−/h+ recombination enhancing CPX mineralization. The catalyst FeTiO 3 /ZnO was prepared by ultrasound-assisted chemical precipitation method. The material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). FeTiO 3 /ZnO (1, 5, and 10%wt. FeTiO 3) was evaluated on photocatalytic degradation of ciprofloxacin (CPX) in an aqueous solution (10 mg L−1) under UV-Vis irradiation. The heterojunction between FeTiO 3 and ZnO, the presence of Fe 2 O 3 impurities, and the formation of oxygen vacancies allowed the coupled material FeTiO 3 /ZnO (1%wt.) showed a better photocatalytic performance (100% degradation CPX and 27% of mineralization) than bare ZnO. Although ZnO also attained complete degradation of CPX, the antibiotic was not mineralized under the same operating conditions. A scavenger study determined that h+ and OH were the principal reactive species involved in the CPX photocatalytic degradation. The heterostructured material showed high stability and reusability during three cycles of use. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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232. Optimization and technoeconomic analysis of biooil extraction from Calophyllum inophyllum L. seeds by ultrasonic assisted solvent oil extraction.
- Author
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Rajendran, Naveenkumar, Gurunathan, Baskar, and I., Aberna Ebenezer Selvakumari
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- *
CALOPHYLLUM inophyllum , *SOLVENT extraction , *FREE fatty acids , *ULTRASONIC waves , *GALACTOMANNANS , *VEGETABLE oils , *PLANT extracts - Abstract
• The 82.8 % (w/w) of biooil yield was obtained from C. inophyllum L. seeds. • An equal ratio of diethyl ether and ethanol was found best for bioil extraction. • Biooil was characterized using GC–MS and FTIR and oil contains 22.11 % of FFA. • Technoecconomic analysis of oil extraction was investigated using SuperPro. In the present investigation, the bio-oil extraction from Calophyllum inophyllum seeds using an ultrasonic-assisted heterogeneous solvent technique has been carried out in order to avoid diminishing the oil property and quality by high temperature. The application of different combinations of solvent extraction has been examined using Diethyl ether:Ethanol, Chloroform:Methanol, and Isopropanol: Methanol. The results reveals that the equal ratio of Diethyl ether:Ethanol in assistance with ultrasonic waves yields maximum oil extraction. The other optimized process conditions determined by central composite design was found to be the seed kernel to the solvent ratio of 1:15 (w:v); time 45 min; temperature 36 °C and ultrasonication power of 54 % yields maximum bio-oil of 82.8 % (w/w). The kinetic study denotes that the oil extraction process follows first-order kinetics. The presence of different functional groups, as well as volatile compounds in the extracted oil, were confirmed by fourier-transform infrared spectroscopy and gas chromatography-mass spectrometry. This confirms the presence of 22.11 % of free fatty acid content in the extracted bio-oil. The techno-economic analysis of 4.4 million kg of oil extract plant was investigated. The annual revenue estimated from the oil is 2,097,000 $/yr and the payback period is 5.43 years. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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- View/download PDF
233. Preparation of magnetic double network nanocomposite hydrogel for adsorption of phenol and p-nitrophenol from aqueous solution.
- Author
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Nakhjiri, Mahdi Taghvay, Bagheri Marandi, Gholam, and Kurdtabar, Mehran
- Subjects
PHENOL ,AQUEOUS solutions ,ADSORPTION (Chemistry) ,LANGMUIR isotherms ,ADSORPTION capacity - Abstract
Collagen-(AMPS-MAA/AAm)-Fe 3 O 4 @SiO 2 magnetic double-network nanocomposite hydrogel (DNNH) was synthesized through in-situ free-radical copolymerization under ultrasound-assisted condition. The pure double-network hydrogels (PDNH) and their magnetic composite structure were systematically characterized through XRD, FTIR, SEM-EDS, VSM, DTG, and tensile tests. The DNNH exhibits more powerful mechanical attributes (σf of 0.33 MPa, εf of 26.5 mm/mm) than PDNH (σf of 0.314 MPa, εf of 31 mm/mm). The adsorption process, which is influenced by multiple factors, was examined and the results of the surveys illustrated that the adsorption capacity improved with the Fe 3 O 4 @SiO 2 nanoparticles. Adsorption behavior was checked for the adsorption of phenol and 4-nitrophenol and it was found to remove about 77% and 83% of phenol and 4-nitrophenol solutions at pH 7, respectively. The applicability of kinetic and isotherm studies for the adsorption of mentioned pollutions, especially the pseudo-second-order model and Langmuir model were proved (q m = 16.52 mg/g for phenol and q m = 19.20 mg/g for 4-nitrophenol). Thermodynamic studies proposed that the adsorption of phenol and 4-nitrophenol was spontaneous and endothermic. Reusability of the prepared hydrogel in the adsorption–desorption process was simply done for successive 4 times. As a result, the prepared hydrogel is known as a suitable adsorbent for phenol and 4-nitrophenol adsorption from aqueous solutions. ga1 • Collagen-(AMPS-MAA/AAm)-Fe 3 O 4 @SiO 2 magnetic double-network nanocomposite hydrogel was synthesized. • Swelling, as well as phenol and 4-nitrophenol adsorption properties of as-prepared hydrogel were studied. • Different kinetic and isotherm models were studied for adsorption of phenol and 4-nitrophenol. • Thermodynamic of the phenol and 4-nitrophenol adsorption on magnetic double-network nanocomposite hydrogel was studied. • Adsorption of phenol and 4-nitrophenol followed Langmuir isotherm and pseudo-second-order kinetic models. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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234. Surface processes at a polymetallic (Mn-Fe-Pb) sulfide subject to cyanide leaching under sonication conditions and with an alkaline pretreatment: Understanding differences in silver extraction with X-ray photoelectron spectroscopy (XPS).
- Author
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Larrabure, Gonzalo, Chero-Osorio, Sheyla, Silva-Quiñones, Dhamelyz, Benndorf, Carsten, Williams, Mackenzie, Gao, Fei, Gamarra, Carlos, Alarcón, Alejandro, Segura, Carlos, Teplyakov, Andrew, and Rodriguez-Reyes, Juan Carlos F.
- Subjects
- *
CYANIDES , *PYRITES , *X-ray photoelectron spectroscopy , *LEACHING , *SONICATION , *LEAD sulfide , *SULFIDES , *METAL sulfides - Abstract
Leaching of polymetallic sulfides is often challenging due to the complexity of these systems. The main issues are related to the formation of surface by-products or to the presence of different metals that require a greater consumption of chemicals compared to that needed to extract the target metal during leaching. This latter case is followed in the present work using X-ray photoelectron spectroscopy (XPS) during the leaching of a silver-containing polymetallic (Mn-Fe-Pb) sulfide under three different cyanidation procedures: (1) conventional leaching, (2) ultrasound-assisted leaching, and (3) leaching of a sample pretreated in alkaline media. In all cases, leaching results in the build-up of Pb compounds (oxides/hydroxides) on the surface of the minerals, suggesting a mechanism in which Pb is first leached by hydroxide and cyanide and later is re-adsorbed as an external layer on the minerals. On the other hand, the effect of each process on Mn was quite distinct: 1) Conventional leaching leads to the oxidation of the sulfide (pyrite) surface and a slight increase of surface Mn species; 2) Ultrasound-assisted leaching decreases surface Mn by dissolving oxidized species, which exposes fresh sulfide surfaces and increases Ag extraction; and 3) An alkaline pretreatment at high temperature exposed fresh sulfide surfaces and decreased the surface concentration of Mn. The fact that ultrasound-assisted leaching and leaching after an alkaline pretreatment allow for a higher Ag extraction (60% and 75% of total Ag, respectively, as opposed to the 25% extracted via conventional leaching), indicates that leaching is more efficient if the surface is not oxidized and if Mn is removed from the samples, either before or during leaching. Unlabelled Image • Surface level analysis was employed to understand 3 strategies for cyanide leaching. • Sonication was found to avoid surface oxidation and to expose fresh sulfide layers. • Lead was leached and re-adsorbed in all cases as the leaching reaction proceeded. • Alkaline pretreatment decreases the amount of surface manganese. • The removal of surface manganese enhances the extraction of silver. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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235. Improved photodegradation of p-nitrophenol from water media using ternary MgFe2O4-doped TiO2/reduced graphene oxide.
- Author
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Thinh, Doan Ba, Tien, Nguyen Tan, Dat, Nguyen Minh, Phong, Ha Huu Tan, Thi Huong Giang, Nguyen, Tai, Le Tan, Thi Yen Oanh, Doan, Nam, Hoang Minh, Phong, Mai Thanh, and Hieu, Nguyen Huu
- Subjects
- *
GRAPHENE oxide , *PHOTODEGRADATION , *FOURIER transform infrared spectroscopy , *THERMOGRAVIMETRY , *WATER use - Abstract
Herein, MgFe 2 O 4 -doped TiO 2 /reduced graphene oxide (MFO-TiO 2 /rGO) was synthesized via the ultrasound-assisted hydrothermal method and directly used for photodegradation p-nitrophenol from water. The characteristics of the catalyst material were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Scanning electron microscope, Transmission electron microscopy, Energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller specific surface area, thermal gravimetric analysis, and UV–vis spectroscopy. The photodegradation studies via the catalytic recovering property were also investigated with comparing to TiO 2 /rGO, TiO 2 , and MFO. The results showed that the MFO and TiO 2 nanoparticles were homogeneously distributed on the GO sheet with an average diameter of 5–14 nm. The empirical data indicated a good photocatalytic property under visible light of MFO-TiO 2 /rGO compared to others with the photodegradation yield 99.53% in 50 min via 40 mg amount of catalysts, 1 mL H 2 O 2 substitution, and a pH of 9. The kinetic studies exhibited that the reaction followed the pseudo-first order with a rate constant of 0.1011 min−1. Besides, it can be easily separated and reused with an insignificant change in photodegradation yield. According to the results, MFO-TiO 2 /rGO is highly promising for organic contaminant elimination in the effluent for the future wastewater treatment plant. ga1 Mechanism of p-nitrophenol adsorption and photodegradation. • MFO-TiO 2 /rGO nanocomposite was successfully synthesized by the ultrasound-assisted hydrothermal method. • MFO and TiO 2 with an average size of 5–14 nm were uniformly distributed on rGO sheets. • MFO-TiO 2 /rGO shows an extraordinary effect in photodegrading p-nitrophenol form water media. • The amount of H 2 O 2 added, the catalyst dosage and pH has a vital impact on enhancing the photocatalytic property of the material. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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236. Ultrasound-assisted alkali-urea pre-treatment of Miscanthus × giganteus for enhanced extraction of cellulose fiber.
- Author
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Singh, Singam Suranjoy, Lim, Loong-Tak, and Manickavasagan, Annamalai
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- *
MISCANTHUS , *MICROBUBBLE diagnosis , *CELLULOSE fibers , *DELIGNIFICATION , *SONICATION , *THERMAL stability , *CELLULOSE , *HIGH-intensity focused ultrasound - Abstract
• Ultrasound pre-treatment extracted up to 52 % cellulose-fiber from miscanthus biomass. • Thermal stability of cellulose-fiber and crystallinity index were enhanced due to pre-treatment. • Crystallite size of cellulose-fiber was reduced due to pre-treatment. • Process parameters were optimized using RSM to maximise cellulose & lignin extraction. Ultrasound-assisted-alkali-urea (UAAU) pre-treatment of miscanthus biomass was investigated for enhanced delignification and extraction of cellulose fiber. The effects of pre-treatment conditions investigated were: sonication time (10.0, 15.0 and 20.0 min), alkali (NaOH) concentration (2.0, 3.5 and 5.0 %, w/v) and urea-concentration (1.0, 1.75 and 2.5 %, w/v) on the delignification and cellulose content. The process parameters were studied and optimized using a response surface methodology (RSM) based on the Box Behnken Design (BBD). From the RSM-BBD analysis, he optimized pre-treatment conditions were 2.1 % NaOH, 1.7 % urea and 15.5-min sonication time with maximal cellulose and lignin contents of 47.8 % (w/w) and 27.5 % (w/w) respectively. The pre-treated samples were further characterized by FTIR, colorimeter, SEM, XRD, and TGA analyses. The UAAU pre-treated samples have higher delignification and cellulose contents than the AU pre-treatment without sonication. Furthermore, the ultrasound process allowed selective removal of lignin without substantially degrading the functionalities of cellulose fiber. The UAAU pre-treated samples exhibited higher thermal stability, fibrillation, crystallinity index and smaller crystallite size. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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237. Adsorption of malachite green dye using ultrasound modified corn straw
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Lima, Diana Ramos, Dotto, Guilherme Luiz, Salau, Nina Paula Gonçalves, and Pinto, Luiz Antonio de Almeida
- Subjects
Efluentes coloridos ,Ultrassom-assitido ,Corn straw ,Adsorção ,Palha de milho ,ENGENHARIAS::ENGENHARIA QUIMICA [CNPQ] ,Adsorption ,Colored effluents ,Ultrasound-assisted - Abstract
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Colored effluents containing dyes are generated in different industrial sectors, such as textiles, cellulose, paper, leather, paint, among others. The treatment of these effluents is a current environmental problem, since dyes are stable and recalcitrant molecules. In this way, to collaborate in the solution of this problem, the present work aimed the study of Malachite Green (MG )removal from aqueous solutions, by adsorption with raw corn straw (RCS) and ultrasonic modified corn straw (MCS). RCS and MCS were prepared and characterized by XRD, FT-IR, MEV and pHpcz. The adsorption study was performed by equilibrium isotherms, constructed at different temperatures(298 to 328 K), kinetic curves, thermodynamic parameters and application in real effluents composed of dye mixtures and inorganic compounds. The physicochemical interpretations were developed based on the principle of grand canonical ensemble in statistical physics, which considered the following models: multilayer with saturation, double-layer model with two energies and monolayer model with one energy, where thermodynamic functions like configurable entropy (Sa), free adsorption enthalpy (G) and internal energy (Eint) were assessed. The characterization indicated that RCS and MCS presented a favorable structure for malachite green adsorption, as well as that the ultrasonic treatment provided a disorganization of the crystalline regions of the adsorbent, and also, caused the formation of cavities and protuberances. The Elovich model was suitable for adsorption kinetics and the Freundlich model was appropriate to represent equilibrium. The maximum adsorption capacities were 200 mg g-1 for RCS and 210 mg g-1 for MCS, obtained at 328 K. MCS was more effective than RCS to treat real effluents, attaining around 92% of color removal. The double layer model with two energies was the more adequate to represent the adsorption process. The number of MG molecules per site (n) varied from 0.33 to 2.33 and the quantity adsorbed at saturation (Qasat) ranged from 164.15 to 528.19 mg g-1, both of which were increased with temperature. The density of the receptor sites (NM) ranged from 248.71 to 104.88 and decreased with temperature. For RCS and MCS, the first and second energies, ε1 and ε2 increased with temperature, being ε1 greater than ε2. The adsorption energy of MCS (7.77-11.19 kJ mol-1) was higher than the adsorption energy of RCS (6.17-10.88 kJ mol-1). The adsorption process occurred by physisorption and the disorder increased at low equilibrium concentrations but decreased at high concentrations. Free enthalpy and internal energy carefully described the spontaneity of the system studied Os efluentes líquidos contendo corantes em solução são gerados em diferentes setores industriais, tais como, têxtil, celulose, papel, couro, pintura, entre outros. O tratamento destes efluentes é uma problematica ambiental atual, uma vez que os corantes são moléculas estáveis e recalcitrantes.Dessa forma, buscando colaborar na solução dessa problemática, as pesquisas do presente trabalho tiveram como principal objetivo o estudoda remoção do corante Verde Malaquita (MG) de soluções aquosas através da adsorção com palha de milho “in natura” (RCS) e palha de milho modificadapor ultrassom (MCS). RCS e MCS foram preparados e caracterizados via XRD, FT-IR, MEV e pHpcz.O estudo de adsorção foi realizado por isotermas de equilíbrio construídas em diferentes temperaturas (298 a 328 K), curvas cinéticas, parâmetros termodinâmicos e aplicação em efluentes reais compostos por misturas de corantes e compostos inorgânicos. As interpretações físico-químicas foram desenvolvidas com base em física estatística, considerando os seguintes modelos: multicamadas com saturação, modelo de dupla camada com duas energias e modelo monocamada com uma energia, onde foram estudadas funções termodinâmicas como entropia configuracional (Sa), entalpia de adsorção (G) e energia interna (Eint). As caracterizações indicaram que RCS e MCS apresentam uma estrutura favorável para a adsorção de verde de malaquita, bem como, que o tratamento com ultrassom proporcionou uma desorganização das regiões cristalinas do adsorvente e também causou a formação de cavidades e protuberâncias. O modelo de Elovich foi adequado para a cinética de adsorção e o modelo de Freundlich foi apropriado para representar o equilíbrio. As capacidades máximas de adsorção experimentais foram de 200 mg g-1 para RCS e 210 mg g-1 para MCS, obtidas a 328 K. MCS foi mais eficaz do que RCS para tratar efluentes reais, atingindo cerca de 92% de remoção de cor.O modelo de dupla camada com duas energias foi o mais adequado para representar a operação de adsorção. O número de moléculas de MG por sítio (n) variou de 0,33 a 2,33 e a quantidade adsorvida na saturação (Qasat) variou de 164,15 a 528,19 mg g-1, sendo ambos crescentes com a temperatura. A densidade dos sítios receptores (NM) variou de 248,71 a 104,88 e diminuiu com a temperatura. Para RCS e MCS, as primeiras e segundas energias, ε1 e ε2 aumentaram com a temperatura, sendoε1 maior do que ε2. As energias de adsorção de MCS (7,77-11,19 kJ mol-1) foram superiores às energias de adsorção de RCS (6,17-10,88 kJ mol-1). A adsorção ocorreu por fisiossorção e a desordem aumentou em baixas concentrações de equilíbrio, mas diminuiu em altas concentrações. A entalpia livre e a energia interna comprovaram a espontaneidade do sistema estudado.
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- 2017
238. Ultrasound-assisted synthesis of hyper-dispersed type-II tubular Fe3O4@SiO2@ZnO/ZnS core/shell heterostructure for improved visible-light photocatalysis.
- Author
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Xu, Ting, Wang, Pengfei, Wang, Dandan, Zhao, Ke, Wei, Maobin, Liu, Xiaoyan, Liu, Huilian, Cao, Jian, Chen, Yanli, Fan, Hougang, and Yang, Lili
- Subjects
- *
ZINC sulfide , *BAND gaps , *ULTRAVIOLET radiation , *VISIBLE spectra , *ORGANIC dyes , *NANOCOMPOSITE materials - Abstract
Novel Datura inoxia-like Fe 3 O 4 @SiO 2 @ZnO/ZnS (FSZZ) core/shell nanocomposites were prepared via a simple ultrasound-assisted in situ surface sulfidation method. The samples displayed excellent uniformity and were highly dispersed. The effects of the sulfidation concentration on the morphological, structural, optical, photoelectrochemical and photocatalytic properties of the nanocomposites were systematically studied. Regulating the sulfidation concentration introduced abundant zinc defects into the nanocomposites, so the light absorption was successfully extended to the visible light region. The intrinsic tubular core/shell heterostructures and number of zinc defects at the heterointerface were the key elements for synergistically promoting the transfer and separation efficiency of photogenerated charge carriers and then improving the degradation efficiency. When the concentration of thioacetamide was 9 mM (FSZZ0.3), the prepared sample exhibited superior photocatalytic efficiency of up to 99% under ultraviolet light irradiation and higher than 80% within 180 min under visible light irradiation for antibiotics and organic dyes degradation. Type-II staggered band alignment formed in FSZZ0.3, and the probable photocatalytic mechanism was proposed and discussed in detail. This novel 3D tubular core/shell heterostructure is an effective and promising photocatalyst for the wastewater purification, and our synthesis process provides a new simple and rapid strategy for designing other hyper-dispersed materials for different practical applications. The novel hyper-dispersed 3D Datura inoxia-like Fe 3 O 4 @SiO 2 @ZnO/ZnS nano-photocatalysts with tubular ZnO/ZnS core/shell heterostructures were synthesized via a simple ultrasound-assisted in situ surface sulfidation method, which displayed excellent photocatalytic activity for antibiotics and organic dyes degradation under ultraviolet and visible light irradiation. Image 1 • Novel tubular Fe 3 O 4 @SiO 2 @ZnO/ZnS (FSZZ) core/shell heterostructure was prepared. • A defect energy level introduced in nanocomposites could narrow the band gap. • FSZZ0.3 showed excellent visible-light degradation of antibiotics and dyes. • Probable photocatalytic mechanism is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
239. Catalytic conversion of lignin to bio-oil over PTA/MCM-41 catalyst assisted by ultrasound acoustic cavitation.
- Author
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Du, Boyu, Chen, Changzhou, Sun, Yang, Yu, Mengtian, Yang, Ming, Wang, Xing, and Zhou, Jinghui
- Subjects
- *
LIGNINS , *CAVITATION , *INFRARED spectroscopy , *DEPOLYMERIZATION , *CATALYSTS , *MONOMERS - Abstract
The ultrasound-assisted depolymerization of lignin was successfully conducted over a synthesized PTA/MCM-41 catalyst under different reaction conditions. Firstly, the structure of the prepared PTA/MCM-41 catalyst was characterized by various techniques, and its acidity was determined using Fourier-transform infrared spectroscopy (FT-IR) of pyridine adsorption and temperature-programmed desorption of ammonia (NH 3 -TPD). Then, the effects of ultrasound frequency, reaction temperature, and reaction time on the distribution and yield of the products of the ultrasound-assisted depolymerization of lignin were studied. The optimum reaction conditions were obtained at an ultrasound frequency of 30%, a reaction temperature of 300 °C, and a reaction time of 6 h. Under the optimum reaction conditions, the conversion of lignin depolymerization was equal to 94.79%, and the yield of phenolic monomers (PM) and lignin bio-oil was 8.37% and 90.58% respectively. Unlabelled Image • The PTA/MCM-41 catalyst is prepared for ultrasonic-assisted depolymerization of lignin. • Lignin can be depolymerized in green ultrasound-assisted method. • Ultrasound acoustic cavitation can effectively promote the conversion of lignin. • Ultrasound-assisted depolymerization can effectively reduce the formation of bio-char. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
240. Pigmentation and Degradative Activity of TiO2 on Polyethylene Films Using Masterbatches Fabricated Using Variable-Frequency Ultrasound-Assisted Melt-Extrusion.
- Author
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Cabello-Alvarado, Christian J., Quiñones-Jurado, Zoe V., Cruz-Delgado, Víctor J., and Avila-Orta, Carlos A.
- Subjects
- *
POLYETHYLENE films , *ANIMAL coloration , *SCANNING electron microscopy - Abstract
Ultrasound-assisted melt-extrusion method (USME) is a high-quality process used to produce polymeric compounds with an adequate homogeneous dispersion. This study evaluates white-color films of linear low-density polyethylene (LLDPE) prepared using TiO2 masterbatch obtained by ultrasound-assisted melt-extrusion at variable frequencies (USME-VF). LLDPE with three different melt-flow indices (2, 20 and 50 g/10 min) were used as the polymer matrix. The films were obtained from the dilution of masterbatches of LLDPE (melt-flow index = 2) at a concentration of 7 wt% TiO2. The morphology, pigmentation, TiO2 reactivity, and the mechanical stability of the films were assessed. The masterbatch compounds were evaluated by melt-flow index (MFI) and scanning electron microscopy (SEM). The contrast ratio, yellowness index and mechanical properties of films were also measured. The properties of whiteness and elongation at break improved in the films prepared using masterbatches with higher dispersion. Though the reactivity of the TiO2 particles increased during accelerated aging, it did not affect the elongation to rupture. The yellowness index was moderately affected in films that included TiO2 particles processed using USME-VF. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
241. Ultrasound-assisted extraction optimization and validation of ultra-performance liquid chromatographic method for the quantification of miquelianin in Cuphea glutinosa leaves.
- Author
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Santos, Marí C., Koetz, Mariana, Mendez, Andreas S.L., and Henriques, Amélia T.
- Subjects
- *
FACTORIAL experiment designs , *PARTICLES , *STATISTICAL reliability , *FLAVONOIDS , *ULTRAVIOLET spectrophotometry - Abstract
Cuphea glutinosa is a medicinal species abundant in South of Brazil, known because of its flavonoids, which have pharmacological properties as antioxidant, anti-hypertensive, diuretic, and antimicrobial. The present study aimed to optimize the extraction and validate an ultra-performance liquid chromatographic method coupled to a photodiode array detector (UPLC-PDA) method for the quantification of a chemical marker miquelianin in C. glutinosa leaves. The optimum conditions for the extraction of miquelianin from leaves of C. glutinosa were determined using a fractional factorial design (FFD) and a central composite design (CCD). An UPLC-PDA method was validated, following the ICH guidelines and RDC 166/2017 of ANVISA (Brazil). The extraction-optimization methodology was obtained with the following parameters: plant:solvent 1:60 (w/v), percentage solvent 38% ethanol, 60 min time, five extractions and particle size ≤ 180 μm. The validation parameters of the quantification method were satisfactory. The results revealed a method with excellent selectivity, linearity, precision (repeatability and intermediate precision were below 2.18 and 1.40%, respectively) and accuracy (mean recovery 90.6%). The average content of miquelianin was 1.03%. Briefly, the optimization of the extractive method in the leaves of C. glutinosa increased the concentration of miquelianin in the crude extract and the method was validated according to the current legislation. Image 1 • Ultrasound-assisted extraction optimization and validation from Cuphea glutinosa. • Ultrasound extraction optimization and validation for miquelianin quantification. • Optimization and validation for the quantification of miquelianin in Cuphea glutinosa. • Optimization and validation for the quantification of miquelianin. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
242. A novel approach for fast and simple determination pyrrolizidine alkaloids in herbs by ultrasound-assisted dispersive solid phase extraction method coupled to liquid chromatography–tandem mass spectrometry.
- Author
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Kaczyński, Piotr and Łozowicka, Bożena
- Subjects
- *
SOLID phase extraction , *TANDEM mass spectrometry , *LIQUID chromatography-mass spectrometry , *PYRROLIZIDINES , *PLANT metabolites , *MATRIX effect , *FOOD contamination , *HERBS - Abstract
• Ultrasound-assisted QuEChERS method was used to extract pyrrolizidine alkaloids. • Graphene effectively reduced the matrix effects in herbs extracts. • Pyrrolizidine alkaloids (PAs) were determined by LC–MS/MS. • The proposed extraction method was rapidity, simplicity, high efficiency. • The validated procedure was applied to determine of PAs in real herb samples. Pyrrolizidine alkaloids (PAs) are secondary plant metabolites witch can contaminate food, especially herbs. Due to the fact that alkaloids have a strong adverse effect on human health, it is necessary to use sensitive and selective detection methods. In present study a modified method based on LC–MS/MS was developed and validated for the simultaneous determination of thirty pyrrolizidine alkaloids and their corresponding N-oxides (PANOs) in herbs samples. Sample extraction was based on ultrasound-assisted dispersive solid phase extraction and clean-up using graphene. Method validation showed that the proposed method hold good recoveries (61–128 %) for PAs/PANOs with RSD <15 %. Limits of quantification has been set at 1 μg kg−1 level for all targeted alkaloids. The optimized method yielded a small matrix effect (-20–20 %) for most PAs/PANOs. The uncertainty associated with the analytical method was not higher than 38 %. The method is operationally simple, time-saving, and can be applied to the analysis of real herb samples. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
243. Iron removal from ultra-fine silicon carbide powders with ultrasound-assisted and its kinetics.
- Author
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Feng, Dong, Ren, Quanxing, Ru, Hongqiang, Wang, Wei, Ren, Shiyuan, Jiang, Yan, Liu, Baoyou, Chang, Sixiao, Zhang, Cuiping, and Yang, Yitong
- Subjects
- *
SILICON carbide , *FIELD emission electron microscopy , *POWDERS , *X-ray emission spectroscopy , *ZERO-valent iron , *ANALYTICAL mechanics - Abstract
In the present work, the occurrence form of iron impurities of SiC crystals were analyzed using the field emission scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), and the leaching kinetics of iron from the ultra-fine SiC powders in the acid system with ultrasound-assisted was also examined. The effects of the different parameters such as the types of acid, acid concentration, leaching temperature, reaction time, stirring speed, ultrasound frequency and power affecting on the iron removal efficiency were comprehensively studied to obtain an optimum condition. The results indicated that iron impurities are determined to exist in the form of Fe x Si y and Fe x -Si y -Ti z phases in SiC crystals. Under the optimized conditions with ultrasound, the removal rate of iron can reach more than 92%. The leaching kinetics fit a homogeneous control model with the second order model as the rate-controlling step, and the activation energy of the ultrasound-assisted leaching process is determined to be 53.6 kJ/mol. The presence of the ultrasound can accelerate the leaching process and improve the iron removal efficiency, compared to conventional stirring. Image 10064 • The effect of main parameters on the iron removal rate is evaluated. • The removal rate of iron can reach more than 92% with ultrasound-assisted. • The ultrasound-assisted can greatly improve 2.4%–6.8% of the iron removal rate. • The leaching kinetics obeys a homogeneous control model with the second order model as the rate-controlling step. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
244. Ultrasound-assisted desolventizing of fragrant oil from red pepper seed by subcritical propane extraction.
- Author
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Liu, Hua-Min, Yao, Yong-Gang, Ma, Yu-Xiang, and Wang, Xue-De
- Subjects
- *
PEPPERS , *OLEIC acid , *PROPANE , *SEEDS , *PRODUCT quality - Abstract
• Ultrasonic treatment was firstly applied on desolventizing of fragrant oil. • Ultrasonic technique was an efficient and promising method for desolventizing. • The oil after ultrasonic treatment also had good quality. • Ultrasonic treatment by did not obviously remove the typical aroma. In the present study, ultrasound was used to remove the residual solvent from the fragrant oil of red pepper seed obtained by subcritical propane extraction. The physical and chemical characteristics, particularly the volatile flavor compounds present of the oil before and after ultrasound-assisted desolventizing were comprehensively analyzed to determine the effect of the desolventizing process on product quality. The results showed that the maximum loss of residual solvent was achieved at a temperature of 90 °C maintained for 70 min with ultrasound applied during the entire process. After this treatment only a small amount of solvent (2.3% based on the total residual solvent originally present) remained in the oil. Although it was hypothesized that ultrasound treatment could result in the loss of volatile components, the analytical results showed no obvious reduction in the components associated with the typical aroma of the oil. After ultrasonic treatment, the oil also had good oxidation stability and quality. Additionally, after ultrasonic desolventizing, the oil samples were more suitable for cooking because they could more effectively minimize oxidation. Thus, these results demonstrate that this new ultrasonic technique is an effective and efficient method for removing the solvent remaining in fragrant oil after subcritical propane extraction. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
245. Gas diffusion and adsorption capacity enhancement via ultrasonic pretreatment for hydrothermal synthesis of K-KFI zeolite with nano/micro-scale crystals.
- Author
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Tang, Xuan, Liu, Jiaqi, Shang, Hua, Wu, Luogang, and Yang, Jiangfeng
- Subjects
- *
DIFFUSION , *GAS absorption & adsorption , *ADSORPTION capacity , *MASS transfer , *ULTRASONIC effects , *GAS fields , *HYDROTHERMAL synthesis - Abstract
Small-pore zeolites have been a research hotspot in the field of gas adsorption and separation. Despite the high adsorption levels of these zeolites, the slow adsorption and desorption rate as well as desorption hysteresis are detrimental to the industrial applications. In this work, nano/micro-scale (~500 nm) K-KFI zeolite crystals were synthesized via hydrothermal and ultrasound-assisted (US) methods. The US-K-KFI zeolites obtained were characterized by means of X-ray diffraction, scanning electron microscopy, and nitrogen adsorption-desorption isotherms at 77 K. The effect of the ultrasonic treatment time on zeolite formation was investigated. The results revealed that the ultrasonic time had a significant effect on the morphology of the K-KFI zeolite, and the particle size was reduced from 1.5 μm to 500 nm. Furthermore, the sample ultrasonically treated for 3 h and crystallized for 1 day (US-K-KFI-3h/1d) exhibited the same high level of crystallinity as the sample hydrothermally crystallized for 3 days without ultrasonic treatment (HT-K-KFI-0h/3d). Compared with large-crystal (3 μm) zeolite (HT-K-KFI-0h/3d) at a given pressure, nano/micro-scale (500 nm) zeolite (US-K-KFI-10h/1d) was characterized by a shorter adsorption equilibrium time and exhibited enhanced mass transfer due to its shorter diffusion path. Moreover, compared with that of HT-K-KFI-0h/3d, the adsorption capacity of US-K-KFI-10h/1d for CO 2 , CH 4 , N 2 , and O 2 was 31%, 24%, 18%, and 26% higher, respectively, at room temperature (298 K) and 1 bar. The results of this work showed that the ultrasound-assisted method represents a rapid and controllable means of synthesizing nano/micro-scale zeolites. Image 1 • The first ever application of an ultrasonic pretreatment for the synthesis of nano/micro-scale K-KFI zeolites was described. • The crystallization time of K-KFI was shortened from 72 h to 24 h. • The mass transfer and adsorption capacity of the US-K-KFI sample improved significantly. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
246. Comparative study of ability of sonochemistry combined ZnS:Ni nanoparticles-loaded activated carbon in reductive of organic pollutants from environmental water samples.
- Author
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Dastkhoon, Mehdi, Ghaedi, Mehrorang, Asfaram, Arash, and Alipanahpour Dil, Ebrahim
- Subjects
- *
ACTIVATED carbon , *METHYLENE blue , *POLLUTANTS , *POINTS of zero charge , *ENVIRONMENTAL sampling , *WATER sampling - Abstract
Nickel-doped ZnS nanoparticle-loaded activated carbon was synthesized and used for the simultaneous removal of sunset yellow and methylene blue from their aqueous solution. The nanostructured adsorbent was characterized using Field emission scanning electron microscopy, X-ray diffraction, Energy-dispersive X-ray spectroscopy, Particle Size Distribution and Point of zero charge. Adsorption of dyes was conducted by using central composite design to evaluate the effect of five independent process variables such as pH, adsorbent mass, SY concentration, MB concentration and sonication time on the SY and MB removal percentages as responses. Nickel-doped ZnS nanoparticle-loaded activated carbon applied for the simultaneous removal of sunset yellow (SY) and methylene blue (MB) from their aqueous solution. The under study adsorbent characterization and properties were identified and recognized via field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), particle Size distribution (PSD) and point of zero charge (pH pzc). Detailed of dyes adsorption dependency to expected significant variable such as pH, adsorbent mass, SY concentration, MB concentration and sonication time in term of sole and combination part was checked by central composite design on their simultaneous removal percentages. The experimental results reveal that most effective parameter was sonication time. The predictive models and best performance were attributed to 16 mg.L−1, 6.0, 0.014 g and 4 min corresponding to the initial concentration of each dye, pH, adsorbent mass and sonication time, respectively, at which more than 98% of both dyes was adsorbed. The analysis of experimental equilibrium data by conventional approaches reveal better applicability of the Langmuir isotherm for fitting and explanation of experimental data. Meanwhile, the maximum ultrasound-assisted adsorption capacities for SY and MB were estimated to be 120.481 and 142.86 mg g−1, respectively. Besides, their adsorption described well correlated and represented by the pseudo-second-order model. At optimum conditions, where the ultrasound-assisted best adsorption method is highly superior to magnetic-stirring- and vortex-assisted methods in term of lower time and higher adsorption capacity. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
247. In situ ultrasound-assisted ion exchange synthesis of sphere-like AgCl x Br 1-x composites with enhanced photocatalytic activity and stability.
- Author
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Abulizi A, Kadeer K, Maimaitizi H, Tursun Y, and Talifu D
- Subjects
- Catalysis, Ciprofloxacin, Ion Exchange, Light, Silver Compounds
- Abstract
AgCl
x Br1-x composites with different halogen molar ratios (Cl/Br) were prepared by a facile ultrasound-assisted ion-exchange method. The formation of close contact between AgCl and AgBr facilitated the transportation of photoexcited charge carriers and contributed to the enhanced visible-light-driven photocatalytic degradation of different kinds of antibiotics. The AgClx Br1-x composites had a sphere-like morphology and tunable band gaps from 2.95 to 2.57 eV depending on Cl/Br mole ratios. Besides, the AgClx Br1-x composite was optimized by varying halogen mole ratios (Cl/Br) to achieve the highest photocatalytic activity. Results indicated that AgCl0.75 Br0.25 showed the best photocatalytic degradation performance, which was about 2.36 and 2.78 times that of the single AgCl towards ciprofloxacin (CIP) and metronidazole (MNZ) degradation, respectively. Meanwhile, a possible photocatalytic degradation mechanism was discussed, and results indicated that the holes (h+ ) and •OH were the dominant active species in the AgCl0.75 Br0.25 system.- Published
- 2020
- Full Text
- View/download PDF
248. Ultrasound-Assisted Synthesis of Sucrose and Fructooligosaccharides Esters as Bio-Plasticizers
- Author
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Panteley Denev, Nadezhda Petkova, Milena Koleva, Dragomir Vassilev, Dragomir Vassilev, Panteley Denev, and Nadezhda Petkova
- Subjects
Sucrose ,Chromatography ,antimicrobial activity ,Chemistry ,Materials Science (miscellaneous) ,Sucrose esters ,Plasticizer ,04 agricultural and veterinary sciences ,Environmental Science (miscellaneous) ,Ultrasound assisted ,040401 food science ,transesterification ,chemistry.chemical_compound ,0404 agricultural biotechnology ,fructooligosaccharides esters ,"green" plasticizer ,ultrasound-assisted - Published
- 2016
249. A novel and facile synthesis of 3-(2-benzofuroyl)- and 3,6-bis(2-benzofuroyl)carbazole derivatives
- Author
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Yang Li, Meiru Zheng, and Wentao Gao
- Subjects
PEG 400 ,Rap–Stoermer reaction ,Carbazole ,Organic Chemistry ,Ultrasound assisted ,Full Research Paper ,2-benzofuroyl ,salicylaldehydes ,Catalysis ,PEG-400 ,lcsh:QD241-441 ,Chemistry ,chemistry.chemical_compound ,lcsh:Organic chemistry ,chemistry ,carbazole ,Organic chemistry ,lcsh:Q ,ultrasound-assisted ,lcsh:Science - Abstract
A facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a–k, 3,6-bis(2-benzofuroyl)carbazoles 5a–k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a–k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH3CN with the presence of PEG-400 as catalyst. The procedure offers easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.
- Published
- 2011
250. Comparative evaluation of maceration, microwave and ultrasonic-assisted extraction of phenolic compounds from propolis.
- Author
-
Oroian M, Dranca F, and Ursachi F
- Abstract
The aim of this study was to compare different techniques in order to achieve a high extraction of phenolic compounds from propolis. For this purpose, it was investigated the use of double maceration (24 h at room temperature with continuous agitation at 250 rpm), double microwave treatments (1 min at 140 W) and double ultrasound-assisted extraction (15 min at 20 kHz) using 70% ethanol. The extraction efficiency was measured based on extraction yield, total phenolic content, flavones and flavonol content, and flavanone and dihydroflavonol content. The ultrasonic extraction had an extraction yield higher than microwave extraction and maceration. The yield of the propolis ranged between samples and between the years of propolis harvesting. Of the twelve quantified phenolic compounds, p -coumaric acid was the most abundant (271.65 mg/g propolis)., (© Association of Food Scientists & Technologists (India) 2019.)
- Published
- 2020
- Full Text
- View/download PDF
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