Excess molar enthalpies for mixtures of supercritical CO₂ and ethyl acetate and their role in supercritical fluid applications

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• 作者：Fouad Zahran ; Concepció ; n Pando ; ^{pando@quim.ucm.es} ; Juan A.R. Renuncio ; Albertina Cabañ ; as
• 关键词：EA ; ethyl acetate ; DMSO ; dimethylsulfoxide ; SAS ; supercritical antisolvent precipitation ; GAS ; gas antisolvent ; DELOS ; Depressurization of an Expanded Liquid Organic Solution ; VLE ; (vapor  ; +  ; liquid) equilibrium ; SRK ; Soave&ndash ; Redlich&ndash ; Kwo
• 刊名：Journal of Chemical Thermodynamics
• 出版年：2012
• 期刊代码：123_00219614
• 类别：ch
• 出版时间：August, 2012
• 卷：51
• 期：Complete
• 页码：59-64
• 文件大小：354 K

摘要

Mixtures of supercritical CO₂ and ethyl acetate (EA) are very often involved in supercritical fluid applications and their thermodynamic properties are required to understand and design these processes. Excess molar enthalpies () for (CO₂ + EA) mixtures were measured using an isothermal high-pressure flow calorimeter under conditions of temperature and pressure typically used in supercritical processes: pressures from (9.00 to 18.00) MPa and temperatures from (313.15 to 333.15) K. Mixtures showed exothermic mixing; excess molar enthalpies exhibited a minimum in the CO₂-rich region. The effects of pressure and temperature on the excess molar enthalpy of (CO₂ + EA) are large. The most exothermic values were observed for a coincident CO₂ mole fraction value of 0.737 at T/K = (323.15 and 333.15) and P/MPa = 9.00: (鈭?489 and 鈭?407) J 路 mol^鈭?, respectively. Two-phase splitting was observed in the CO₂-rich region at T/K = 333.15 and P/MPa = 9.00; in this region varies linearly with CO₂ mole fraction. For a given mole fraction and temperature, mixtures become more exothermic as pressure decreases. These trends were analyzed in terms of molecular interactions, phase equilibria, density and critical parameters previously reported for (CO₂ + EA). Excess molar enthalpies here reported were correlated using the Soave-Redlich-Kwong and Peng-Robinson equations of state, and the classical mixing rule with two binary interaction parameters. The influence of the thermal effects on the phase behavior of (CO₂ + EA) mixtures formed in supercritical antisolvent precipitation experiments was discussed.