乙腈+水+离子液体等压汽液平衡测定与计算

Determination and calculation of isobaric vapor equilibrium for acetonitrile+water+ionic liquid

采用改进的Ellis平衡蒸馏仪测定了乙腈+水+1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])、乙腈+水+{1-乙基-3-甲基咪唑醋酸盐([EMIM][OAC])+[EMIM][DEP]}常压(101.3 kPa)等压汽液平衡(VLE)数据。实验结果表明,备选离子液体可促进水+乙腈混合物的分离并消除其共沸点。借助NRTL模型成功关联了含离子液体的三元和四元VLE实验数据,获得了乙腈-[EMIM][DEP]、水-[EMIM][DEP]和[EMIM][OAC]-[EMIM][DEP]二元交互作用参数。应用COSMO-SAC预测了实验VLE,结果令人满意。量化计算表明可与水形成强相互作用的离子液体更易促进乙腈与水的分离。

Acetonitrile is easy to form an azeotropic mixture with water and it is impossible to separate them through ordinary distillation technology. In this work, ionic liquids (ILs) are employed as entrainer to separate acetonitrile and water. The isobaric vapor liquid equilibria (VLE) of acetonitrile + water + 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), acetonitrile + water +{1-ethyl-3-methylimidazolium acetate ([EMIM][OAC])+[EMIM][DEP]} are determined at atmospheric pressure (101.3 kPa) in a glass equilibrium still with a vapor cycle, indicating that the selected ILs can well improve the separation of acetonitrile and water mixture, and further eliminate its azeotropy. The VLE data of ternary and quaternary mixtures containing ILs are well correlated with NRTL model, and the binary interaction parameters of acetonitrile -[EMIM][DEP], water -[EMIM][DEP] and [EMIM][OAC]-[EMIM][DEP] are obtained. The experimental VLE was predicted using COSMO-SAC and the results were satisfactory. The interactions among different molecules are analyzed through quantum calculations showing that the interactions between water and ILs are stronger than ones between water and acetonitrile so that the used ILs here can improve the separation of acetonitrile and water.