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황경엽,이윤용,이병철,김재덕 한국화학공학회 1989 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.27 No.4
20-50℃, 100-307bar의 초임계 이산화탄소에 대한 달맞이꽃씨유의 용해도를 측정하고 추출수율에 미치는 온도와 압력의 영향 및 물질전달속도를 구하였다. 용해도는 온도를 일정하게 유지하면 압력이 높아짐에 따라 증가하였다. 그러나 용해도에 미치는 온도의 영향은 압력에 따라 다르게 나타남을 알 수 있었다. 107-200bar일 때는 온도가 높아짐에 따라 용해도는 감소하였고 250bar일 때는 거의 일정하다가 300bar에서는 온도가 높아짐에 따라 증가하였다. 추출수율에 미치는 온도와 압력의 영향도 용해도에서의 경향과 일치하였다. 이산화탄소의 유량이 3.5-4.0ℓ/min(STP)일 때, 본 연구의 실험범위에서 최적 추출조건은 50℃, 300bar이며, 이때 추출수율은 약 2l wt%였다. 유지기준 추출수율이 약 50%될 때까지 loading량은 거의 일정하였고, 그 후 급격한 감소가 일어났으며, 평균 loading량은 체류시간에 따라 증가하였다. 또한 물질전달 parameter, k_(c)a는 이산화탄소의 선속도에 따라 선형적으로 증가하였다. Solubilities of evening primrose oil(EPO) in supercritical carbon dioxide were measured at temperatures of 20-50℃ and pressures of 100 to 300 bars. Solubilities of EPO were found to increase with increasing pressure at constant temperature. When pressure vas kept constant. solubilities of EPO decreased with increase in temperature at pressures of 100 to 200 bars, while they increased with higher temperatures at 300 bar. Solubilities at 250 bar were of a constant value. The effects of temperature and pressure on the extraction yield coincided with the tendency in solubility. Under the range covered in this study the highest yield of extraction was 21 wt% at the temperature of 50℃ and the pressure of 300 bar with the flow rate of carbon dioxide of 3.5-4.0 ℓ/min (STP). Loading of oil in supercritical carbon dioxide was constant until the extraction yield based on available oil was less than about 50%, and then it decreased sharply. The average loadings increased with increase in residence time. Mass transfer parameter, k_(c)a, increased linearly with the superficial velocity of carbon dioxide in the extractor.
MgO 기반 고화제를 이용하여 처리한 중금속 오염 준설토의 고형화/탄산염화 특성
황경엽,서정윤,판 꽝 후이 호앙,안준영,황인성,Hwang, Kyung-Yup,Seo, Jeong-Yun,Phan, Hoang Quang Huy,Ahn, Jun-Young,Hwang, Inseong 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.1
A novel MgO-based binder was developed and applied to treat the anoxic sediment that was collected from Seonakdong river, Korea and was contaminated with heavy metals. The treated sediment was evaluated by measuring compressive strength, expansion, leaching of heavy metals and storage characteristics for $CO_2$. Initially, an optimal blending ratio of lime (L)/fly ash (FA)/blast furnace slag (BFS) that was to be mixed with MgO was screened to be $L_{0.3}-FA_{0.1}-BFS_{0.6}$. Long-term strengths of the sediments that were treated by various mixtures of MgO and $L_{0.3}-FA_{0.1}-BFS_{0.6}$ were then evaluated and the blending ratios between 4 : 6 and 6 : 4 were found optimal, which yielded a compressive strength of 4.09 MPa. On this basis, the optimal MgO-based binder was selected to be a 5 : 5 mixture of MgO and $L_{0.3}-FA_{0.1}-BFS_{0.6}$. The good performance of the MgO-based binder was believed to be due to the formation of Mg $(OH)_2$, which filled the micropores and also increased the density of the solidified matrices. The MgO-based binder exhibited an average stabilizing capacities for heavy metals of 92.9%, which was similar to or higher than that of Portland cement. It was found that 69.1 kg of carbon dioxide could be sequestrated after 365 days of curing when treating a ton of anoxic sediments.