• Title/Summary/Keyword: Supercritical Methanol

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Synthesis of Biodiesel Using Supercritical Fluid (초임계유체를 이용한 바이오디젤연료의 제조기술)

  • Lee, Youn-Woo;Song, Eun-Seok;Kim, Hwayong
    • Clean Technology
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    • v.11 no.4
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    • pp.171-179
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    • 2005
  • Biodiesel is synthesized by transesterification of vegetable or animal oils with alcohols. Since it has similar characteristic with diesel fuel, it can be used as a fuel by mixing with diesel fuel. Moreover, it is advantageous that biodiesel can reduce air pollution emitted from fuel combustion and is produced from sustainable energy, biomass. Recently, many researchers have investigated biodiesel synthesis using supercritical methanol since it is economical due to shorter reaction time and simple separation/purification process, compared with conventional alkali- or acid-catalyzed process. By the development of biodiesel production process from waste edible oil using supercritical methanol, it can be expected to utilize potential energy resources, reduce carbon dioxide emission, and improve environmental conditions.

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Detection of estrogenic hormone 17β-estradiol in soil samples by a recombinant yeast bioassay and supercritical fluid extraction

  • Shim, Jae-Han;Kim, Mi-Ra;Topp, Edward;Choi, Jeong-Heui;Mamun, Iqbal Rouf
    • Korean Journal of Environmental Agriculture
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    • v.27 no.4
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    • pp.447-455
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    • 2008
  • Recombinant yeast estrogenicity (YES) assay was used as a bioanalytical tool in order to screen $17{\beta}$-estradiol in the soil samples collected from different sites of South Korea. Solvent extraction and supercritical fluid extraction (SFE) methods were compared for the extraction of the estradiol from the soils. Most high detection of the estradiol based on YES assay was observed in the soils extracted with methanol. Different types of estrogenic hormones including $17{\beta}$-estradiol were suggested to be possibly exiting in the soils, since the methanol extracts of the soils showed an estrogenic activity that was not observed in the hexane extracts of the soil. SFE extracts showed estrogenic activity in some of the samples but methanol extract showed best activity.

Low Pressure Synthesis of Silica Aerogels by Supercritical Drying (초임계 건조에 의한 실리카 에어로겔의 저압 합성)

  • 김동준;현상훈
    • Journal of the Korean Ceramic Society
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    • v.33 no.5
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    • pp.485-494
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    • 1996
  • Silica Aerogels with the density and porosity of 0.1g/cm3 and 96% were synthesized by two different supercri-tical drying processes (i.e additional solvent and intial pressure methods) Isoptopanol was chosen as sol-gel and supercritical drying solvents in order to synthesize aerogels at the lower temperature and pressure because the critical values of isopropanol are lower than those of methanol and ethanol commonly used. The P-V-T relationship of isopropanol was experimentally described for optimizing supercritical drying conditions such as the amount of extra solvent and supercritical drying temperature and pressure. In the addional solvent method monolithic and transparent aerogels were obtained by supercritical drying at 25$0^{\circ}C$ and 900 psing after 40% of the reactor volume was filled with isopropanol. Crack-free aerogels were synthesized at 25$0^{\circ}C$ and 1100~1200 psig by the initial pressure method with an intial nitrogen gas pressure of 400 psig and the isopropanol amount of 5% of the reactor volume.

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Optimum process conditions for supercritical fluid and co-solvents process for the etching, rinsing and drying of MEMS-wafers (초임계 유체와 공용매를 이용한 미세전자기계시스템 웨이퍼의 식각, 세정을 위한 최적공정조건)

  • Noh, Seong Rae;You, Seong-sik
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.3
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    • pp.41-46
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    • 2017
  • This study aims to select suitable co-solvents and to obtain optimal process conditions in order to improve process efficiency and productivity through experimental results obtained under various experimental conditions for the etching and rinsing process using liquid carbon dioxide and supercritical carbon dioxide. Acetone was confirmed to be effective through basic experiments and used as the etching solution for MEMS-wafer etching in this study. In the case of using liquid carbon dioxide as the solvent and acetone as the etching solution, these two components were not mixed well and showed a phase separation. Liquid carbon dioxide in the lower layer interfered with contact between acetone and Mems-wafer during etching, and the results after rinsing and drying were not good. Based on the results obtained under various experimental conditions, the optimum process for treating MEMS-wafer using supercritical CO2 as the solvent, acetone as the etching solution, and methanol as the rinsing solution was set up, and MEMS-wafer without stiction can be obtained by continuous etching, rinsing and drying process. In addition, the amount of the etching solution (acetone) and the cleaning liquid (methanol) compared to the initial experimental values can be greatly reduced through optimization of process conditions.

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Debinding Process Using Supercritical Fluids in Metal Powder Injection Molding (분말사출성형에서 초임계유체를 이용한 탈지공정)

  • 김용호;임종성;이윤우;박종구
    • Journal of Powder Materials
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    • v.10 no.1
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    • pp.6-14
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    • 2003
  • The purpose of the present study is to investigate the method decreasing debinding time as well as lowering operation condition than pure supercritical $CO_2$ debinding by using cosolvent or binary mixture of propane + $CO_2$. First method is to add cosolvent, such as n-hexane, DCM, methanol, 1-butanol, in supercritical $CO_2$. In case of adding cosolvent, we were found the addition of non-polar cosolvent (n-hexane) improves dramatically the binder removal rate (more than 2 times) compared with pure supercritical $CO_2$ debinding, second method is to use mixture of supercritical propane + $CO_2$, as solvent. In case of using mixture of supercritical propane + $CO_2$, the rate of debinding speeded up with increasing of pressure and concentration of propane at 348.15 K. It was found that addition of cosolvent (e.g., n-hexane, DCM) and binary mixture propane + $CO_2$ for supercritical solvent remarkably improved binder removal rate for the paraffin wax-based binder system, in comparison with using pure supercritical $CO_2$.

Structural Characteristics of Graphene Prepared in Supercritical Fluids and Thermal Conductivity of Graphene/Epoxy Composites (초임계유체 조건에서 제조된 그래핀의 구조분석과 그래핀/에폭시 수지조성물의 열전도 특성)

  • Oh, Weontae;Choi, Gyuyeon
    • Composites Research
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    • v.34 no.5
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    • pp.277-282
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    • 2021
  • Graphene oxide can be reduced to graphene under supercritical fluid condition even without using a specific reducing agent or applying a high thermal process. In this study, a process for converting graphene oxide into graphene was studied under supercritical fluid conditions in methanol and ethanol solvents. When the structure of asprepared graphene was analyzed by using FE-SEM and XRD, the reduction of graphene oxide in supercritical fluid condition was more affected by the change of solvent than other variables such as concentration of graphene oxide and reaction time. The use of ethanol showed better results for the reduction than the use of methanol. The graphene prepared in this study was mixed with epoxy resin up to 20 wt.% to make composites, and the thermal conductivity of the composites were analyzed. Thermal conductivity of the composite increased proportionally with graphene loadings. The graphene prepared in supercritical ethanol condition was more effective on the thermal conductivity of the composite.

Residue Analysis of Quinclorac in Soil by Supercritical Fluid Extraction and Fluorogenic Derivatization Coupled with High Performance Liquid Chromatography (초임계추출과 형광유도체를 이용한 HPLC 에서의 Quinclorac 의 토양중 잔류분석)

  • Kim, Yong-Whan
    • Applied Biological Chemistry
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    • v.40 no.5
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    • pp.442-446
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    • 1997
  • A new analytical method was developed by HPLC after supercritical fluid extraction and fluorogenic derivatization for the determination of quinclorac (3,7-dichloro-8-quinoline carboxylic acid) in soil. The graminicide quinclorac was extracted from soil by supercritical fluid extraction. Supercritical carbon dioxide at 7000 psi $(80^{\circ}C)$ modified with 30% of methanol extracted quinclorac from soil samples at the level of $0.1ng\;g^{-1}$ with 96% recovery. Extracted quinclorac was determined by HPLC as a fluorescent derivative. Derivatization was made with 4-bromomethyl-7-methoxycoumarin (4-Br-Mmc) using 18-crown-6-ether as a catalyst. The conversion was completed within 30 min and the limit of detection was 0.5 ppb to prove that the procedure could be used in the residue analysis of the pesticides containing carboxylic acid group.

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Comparison of Antioxidant and Antimicrobial Activities of Supercritical Fluid Extracts and Marc Extracts from Cinnamomum verum (계피 초임계 추출물 및 박 추출물의 항균·항산화 활성 비교)

  • Park, Sung-Jin;Yu, Mi-Hee;Kim, Ji-Eun;Lee, Sam-Pin;Lee, In-Seon
    • Journal of Life Science
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    • v.22 no.3
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    • pp.373-379
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    • 2012
  • This study was performed to evaluate the antioxidant and antimicrobiological effects of supercritical fluid extracts (SFEs) and Marc methanol extracts (SFMs) from Cinnamomum verum. Reducing effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and ABTS radical scavenging were investigated. SFM exhibited higher antioxidant activities in DPPH and ABTS radical scavenging assay. Measurements of the antimicrobial activity were used for Gram-positive bacteria (four strains) and Gram-negative bacteria (four strains). The antimicrobial activities of the SFE and SFM against gram-positive and gram-negative bacteria revealed that SFE had a higher inhibition zone than SFM. Cinnamaldehyde, the active compound of C. verum, had a higher content in SFM (35% at 300 bar, $30^{\circ}C$) than methanol extracts from C. verum (0.5%). These results indicate that not only SFE oil, but also SFM, could be a good source for the food industry.

Effects of Modifiers on the Supercritical $CO_2$ Extraction of Licorice (Glycyrrhiza glabra) and the Morphology of Licorice Tissue

  • Kim, Hyun-Seok;Lim, Gio-Bin;Kim, Byung-Yong
    • Food Science and Biotechnology
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    • v.14 no.1
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    • pp.6-10
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    • 2005
  • Optimal extraction conditions such as pressures, temperatures, and modifiers on glycyrrhizin extraction from licorice were investigated using supercritical $CO_2\;(SC-CO_2)$ at 3 mL/min flow rate. Morphology of licorice tissue, after glycyrrhizin extraction, was examined by SEM, and absolute density ($g/cm^3$) measurement and glycyrrhizin content were determined by HPLC. Pure $SC-CO_2$ had no effect on glycyrrhizin extraction, but recovery of glycyrrhizin ($32.66{\pm}0.77%$) was enhanced when water was used as modifier. The highest recovery was $97.22{\pm}2.17%$ when 70% (v/v) aqueous methanol was added to 15% (v/v) $SC-CO_2$ at 50 MPa and $60^{\circ}C$. Under optimal extraction conditions, 30 MPa pressure and $60^{\circ}C$ heating temperature, glycyrrhizin recovery reached maximum ($102.67{\pm}1.13%$) within 60 min. Licorice tissue was severely damaged by excessive swelling, and absolute density of licorice residues was highest when aqueous methanol was used as a modifier.