• Journal of Korean Society for Atmospheric Environment
• /
• 제23권E1호
• /
• pp.10-15
• /
• 2007

The gas hydrates are probably most sensitive to climate change since they are stable only under specific conditions of high pressure and low temperature. One of the main factors responsible for formation of gas hydrates is the saturation of the gases with water vapor. Quantitative phase equilibrium data and understanding of the roles of water component in the phase behavior of the heterogeneous water-hydrocarbon-hydrate mixture are of importance and of engineering value. In this study, the water content of ethylene gas in equilibrium with hydrate and water phases were analyzed by theoretical and experimental methods at temperatures between 274.15 up to 291.75 K and pressures between 593.99 to 8,443.18 kPa. The experimental and theoretical enhancement factors (EF) for the water content of ethylene gas and the fugacity coefficients of water and ethylene in gas phase were determined and compared with each other over the entire range of pressure carried out in this experiment. In order to get the theoretical enhancement factors, the modified Redlich-Kwong equation of state was used. The Peng-Robinson equations and modified Redlich-Kwong equations of state were used to get the fugacity coefficients for ethylene and water in the gas phase. The results predicted by both equations agree very well with the experimental values for the fugacity coefficients of the compressed ethylene gas containing small amount of water, whereas, those of water vapor do not in the ethylene rich gas at high temperature for hydrate formation locus.

• Environmental Analysis Health and Toxicology
• /
• 제22권4호
• /
• pp.299-304
• /
• 2007

This paper was studied to investigate the equilibrium state between organochlorine pesticides (OCPs) concentration of air and soil, and to know whether soil is a secondary pollution source of OCPs in air or not. The OCPs concentration of air ($C_{air}$) and soil ($C_{soil}$) is not related to molecular weight, vapor pressure ($P_L$) and octanol-air partition coefficient ($K_{oa}$). The slope of the regression line between soil-air partition coefficient ($K_{sa}$) and scavenging coefficient ($C_{soil}/C_{air}$) was 0.2952, which the OCPs concentration between air and soil did not reached to the equilibrium state. The soil/air fugacity quotients ($f_{soil}/f_{air}$) of p, p'-DDT/DDD/DDE and ${\beta}-HCH\;(0.30{\sim}0.67$), which is smaller than 1, means the deposit of OCPs from air to soil. However, $f_{soil}/f_{air}$ of heptachlor, heptachlor epoxide, ${\alpha}/{\gamma}-chlordane$, trans-nonachlor, endosulfan sulfate and ${\alpha}/{\gamma}-HCH\;(1.90{\sim}73.25)$, which is greater than 1, means that soil is secondary pollution source of OCPs in air.

• Journal of Korean Society for Atmospheric Environment
• /
• 제19권E1호
• /
• pp.1-9
• /
• 2003

The soil concentrations of polychlorinated biphenyls (PCBs) were measured at 12 sites in Ansung, Kyonggi province, Korea. Correlation coefficient (r) between total PCBs and organic matter content (OM) was significant (r=0.562, p< 0.05). It suggests that organic matter may be a key factor of soil absorption of PCBs. The PCB concentrations of low chlorinated congeners with high vapor pressure were relatively abundant in air but high chlorinated congeners with low vapor pressure were mainly dominated by soil. The results indicated the influence of physicochemical properties of PCBs such as vapor pressure, octanol - air partition coefficient ( $K_{OA}$ ). The calculated soil/air fugacity quotients suggested that the soil may be a source of heavier molecular PCBs (>penta-CBs) to the atmosphere, where lighter molecular PCBs appear to be affected by a movement from air to soil, especially tetra-CBs. Therefore, PCB homologs with low vapor pressure might have been influenced by revolatilization from soil.

• Bulletin of the Korean Chemical Society
• /
• 제16권5호
• /
• pp.432-436
• /
• 1995

The solubility of caffeine in compressed carbon dioxide has been measured to determine its fugacity coefficient between 330 and 410 K up to 500 bar. The result allows the calculation of the thermodynamic excess functions such as the molar excess enthalpy, the molar excess free energy, and the molar excess entropy. The pressure variations of the molar excess functions of caffeine in the caffeine-CO2 mixture were discussed and also compared them with those in the caffeine-NH3 mixture.

• 설비공학논문집
• /
• 제10권2호
• /
• pp.238-250
• /
• 1998

Vapor-liquid equilibrium apparatus is designed and set up. The vapor-liquid equilibrium data of the binary system HFC125/134a are measured in the range between 268.15 and 283.15K at five compositions. Twenty-five equilibrium data are obtained. To verify consistency of these data, they are tested for thermodynamic consistency. Based upon the present data, the binary interaction parameter for CSD and RKS equation of state is calculated at five isotherms and comparison with the data in the open literatures is made. Results of Nagel and Bier are in very good agreements with those from this study within 0.32∼1.11% for bubble point pressure and －0.66∼0.18% for vapor mole fraction.

• Korean Chemical Engineering Research
• /
• 제58권3호
• /
• pp.325-345
• /
• 2020

본 연구에서는 다매체 퓨가시티 모델을 기반으로 Volatile organic compounds (VOCs) 방지기술의 인체위해성·환경성·경제성 평가를 수행하여 석유화학 산업단지 내 VOCs 저감을 위한 최적가용기법(Best available technology, BAT)을 선정하였다. 다매체 퓨가시티 모델을 이용하여 U-city에 소재한 석유화학 산업단지에서 배출되는 VOCs 중 Benzene, Toluene, Ethylbenzene, Xylene (BTEX)의 다매체 거동 특성과 잔류농도 분포를 예측하였다. 매체 통합 인체위해성 평가 및 민감도 분석을 이용해 BTEX의 물질별 인체위해성을 예측하고 주요 영향 변수를 규명하였으며, 다매체 환경시스템 내 잔류농도 기준의 환경성 평가와 비용-편익 경제성 평가를 수행하여 우수환경관리기법군(BAT군)을 선정하였다. BTEX의 다매체 거동 분석 결과, 토양 매체에서 높은 잔류 분포 특성(60%, 61%, 64%, 63%)을 보였으며, Xylene은 모든 다매체 환경에서 가장 높은 잔류성을 보였다. BAT후보군 중에서 흡수법은 가장 높은 인체위해성을 보여 BAT 선정에서 제외하였으며, 민감도 분석 결과 대기 매체에서의 물질 반감기와 경로별 노출계수가 인체위해성과 높은 상관성이 있는 것으로 판단되었다. 환경성 평가와 비용-편익 경제성 평가를 고려하여, 재생 열산화법, 재생 촉매산화법, 바이오 필터법, UV 산화법, 활성탄 흡착법을 석유화학 산업단지 내 VOCs 저감을 위한 BAT군으로 선정하였으며, 본 연구에서 제시한 매체통합적 접근 방식의 BAT 선정 방법론은 사업장에서 오염물질 저감을 위한 최적의 배출시설 선정과 통합환경관리제도 운영에 기여할 수 있을 것으로 기대된다.

• 공업화학
• /
• 제8권2호
• /
• pp.220-229
• /
• 1997

펜탄용매를 이용하여 상압잔사유로부터 고급 경질 탄화수소의 추출실험을 수행하였다. 추출공정 계산에 앞서 복잡한 혼합물로 구성된 상압잔사유의 진비점을 계산하기 위하여 모사증류방법을 이용하였다. 추출공정 계산절차를 간단히 하기 위하여 재분류 방법을 이용하여 많은 성분을 포함하고 있는 상압잔사유를 성상이 유사한 몇 개의 가상성분으로 분류하였다. 상압잔사유-펜탄계 추출공정의 모사는 등온 플래시 방법에 기초를 두고 있으며, 계산과정 중 기상과 액상에서의 퓨개시티 계수를 계산하기 위하여 Peng-Robinson 상태방정식을 이용하였다. 복잡한 계산과정을 포함하고 있는 추출공정 모사에 비하여 실험치는 계산치와 잘 일치 하였다.

• Bulletin of the Korean Chemical Society
• /
• 제30권8호
• /
• pp.1749-1754
• /
• 2009

Solubilities of carbon dioxide (C$O_2$) in a series of fluorine-free room temperature ionic liquids (RTILs), dialkylimidazolium dialkylphosphates and dialkylimidazolium alkylphosphites, were measured at 313∼333 K and pressures up to 5 MPa. Henry’s law coefficients as the solubility parameter of C$O_2$ in RTILs were derived from the isotherm of fugacity versus C$O_2$ mole fraction. The C$O_2$ solubility in a phosphorus-containing RTIL was found to increase with the increasing molar volume of the RTIL. In general, dialkylimidazolium dialkylphosphate exhibited higher absorption capacity than dialkylimidazolium alkylphosphite as long as the RTILs possess an identical cation. Among RTILs tested, 1-butyl-3-methylimidazolium dibutylphosphate [BMIM][B$u_2PO_4$] and 1-butyl-3-methylimidazolium butylphosphite [BMIM][BuHP$O_3$] exhibited similar Henry’s law coefficients to 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide ([BMIM][T$f_2$N]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][B$F_4$]), respectively. The Krichevsky-Kasarnovsky equation was employed to derive the C$O_2$ solubility parameter (Henry’s law coefficient) from the solubility data measured at elevated pressures.