This work focuses on the extension of group parameters of the UNIFAC model to systems with ionic liquids. The new group parameters for ionic liquids were obtained by means of correlating the activity coefficients of solutes at infinite dilution in ionic liquids at different temperatures. The group parameters for 12 main groups and 24 subgroups were added into the current UNIFAC parameter matrix. It was verified that the new group parameters can be used not only for predicting the vapor-liquid equilibria of the systems with ionic liquids at finite concentration, but also for screening the suitable ionic liquids in separation processes. Since there have been only a limited number of functional groups for ionic liquids included in the UNIFAC model, the future development of this predictive model will still require much more accurate experimental data.

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This work tries to explore the relation between molecular structures of ionic liquids (ILs) as entrainers and separation performance on ethyl acetate (1) and ethanol (2). The vapor-liquid equilibrium (VLE) data have been measured for ethyl acetate (1) + ethanol (2) containing ILs at 101.32 kPa. The ionic liquids investigated were 1-butyl-3-methylimidazolium tetrafluoroborate (that has been studied in our previous work. All the ILs could give rise to the salting-out effect. It was found that, at low IL concentration, the separation ability of ILs is in the order-, while at high IL concentration (x 3 ) 0.10-0.30) the separation ability of ILs is in the order]due to the difference of polarity of the three ILs and demixing effect. [EMIM] + [triflate]was included as entrainer and compared with the tetrafluoroboratebased ILs. The measured ternary data were correlated using the NRTL model.

Isobaric vapor-liquid equilibrium (VLE) data for the isopropanol (1) + water (2) system containing ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM] + [BF4] -) at atmospheric pressure (101.32 kPa) were measured with a modified Othmer still. The results showed that the VLE of isopropanol + water in the presence of different contents of IL was obviously different from that of the IL-free system. The IL studied showed a salting-out effect, which gave rise to a change of the relative volatility of isopropanol and even to the elimination of the azeotropic point. It was found that the salting-out effect followed the order of x 3 ′ ) 0.30 > x 3 ′ ) 0.20 > x 3 ′ ) 0.10, which was probably attributed to the interaction between the ions resulting from the dissociation of IL and water.