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RISS 인기검색어
- 검색키워드
- 주제어 : Subcritical Carbon Dioxide (검색결과 3 건)
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Carbonation of Chrysotile under Subcritical Conditions
Ryu, Kyoung Won,Chae, Soo Chun,Jang, Young Nam The Japan Institute of Metals 2011 Materials transactions Vol.52 No.10
<P>The carbonation of chrysotile [Mg<SUB>3</SUB>Si<SUB>4</SUB>O<SUB>10</SUB>(OH)<SUB>4</SUB>] under subcritical conditions was experimentally investigated in alkali solution, and the chemical composition as well as the morphological and structural changes were discussed. The starting material was hydrothermally treated by aqueous direct carbonation at a temperature of 100°C and a CO<SUB>2</SUB> partial pressure range of 0.5 MPa∼4 MPa at pH 13. Highly crystalline magnesite was synthesized under a CO<SUB>2</SUB> partial pressure of 3 MPa. The carbonation rate increased at the proportional rate according to the applied CO<SUB>2</SUB> pressure to approximately 57%. The surface morphology of chrysotile changed from the fibrous form to a round or oval shape at the initial stage and subsequently to magnesite with well-faceted rhombohedral planes.The dissolution rate of Mg was higher than Si, such that the Mg:Si ratio of chrysotile decreased from 1.56 to 0.4∼0.6 as the reaction time increased. The resultant silica-rich layer of the reaction product ultimately changed through the Mg-depleted skeletal phase to the amorphous silica phase. The experimental results suggest that carbonation in alkali solution under subcritical conditions is of great significance because an excessive amount of acid and alkali reagents can be eliminated in the carbonation process.</P>
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오징어 내장의 초임계 이산화탄소 추출 잔류물로부터 인지질의 분리
유병욱 ( Pyoung Ook U ),전병수 ( Byung Soo Chun ) 한국화학공학회 2010 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.48 No.6
Phospholipids were recovered from squid viscera residues by ethanol extraction after supercritical carbon dioxide(SCO2) extraction and from squid viscera was not processed SCO2 by various organic solvent extraction. SCO2 extraction were performed at 45˚C and 20MPa for removal of non polar lipid molecules from freeze dried squid viscera sample. Phospholipids were extracted from freeze dried squid viscera sample by chloroform, hexane, methanol, and ethanol and from SCO2 extracted squid viscera sample by ethanol. The pH was fixed at 5.7 for all phospholipids extraction conditions. Phospholipid classes were analyzed by HPLC equipped with evaporative light scattering detector (ELSD). Phosphatidyl choline (PC) extracted by ethanol from SCO2 extracted residues was higher than that of extracted by ethanol from squid viscera. But phosphatidyl ethanolamine (PE) and phosphatidic acid (PA) were extracted higher percentage in raw squid viscera. The fatty acid compositions in phospholipids extract by ethanol extract from SCO2 extracted residues were analyzed by gas chromatography (GC). Docosahexanoic acid (DHA) was found in highest percentage in phospholipid extract.
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Jung-Nam Park,전병수,Abdelkader Ali-Nehari,우희철 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
We investigated the thermal stability of polyphenols and fatty acids from Laminaria japonica powder by subcritical water hydrolysis among the range of the experimental conditions. The experiment was carried out at temperatures and pressures ranging from 200 to 280 oC and 13 to 60 bar, respectively for 28 to 42 min. Polyphenol and fatty acids in hydrolysates obtained from different conditions were analyzed by GC and UV-spectrophotometer. The results were compared with those obtained from Laminaria japonica oils extracted by supercritical CO2. Polyphenol and several fatty acids in hydrolysates produced by subcritical water showed high thermal stability.
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