Experimental Measurement and Modeling of Vapor−Liquid Equilibrium for Ternary Systems Containing Ionic Liquids: A Case Study for the System Water + Ethanol + 1-Hexyl-3-methylimidazolium Chloride

Abstract

Vapor−liquid equilibrium (VLE) data were measured for the ternary system water (1) + ethanol (2) + 1-hexyl-3-methylimidazolium chloride ([hmim]Cl) (3) at p = 100 kPa. Six sets of complete T, x, y data were reported. While the mole fraction of ethanol on an ionic liquid (IL)-free basis was fixed, respectively, at 0.1, 0.2, 0.4, 0.6, 0.8, and 0.98, measurements were performed in a way in which the IL mass fraction varied from 0.8 to 0.1, in an interval of 0.1. The NRTL equation was used for correlation and was revealed as adequate for the ternary system in the experimental composition range. The quality of correlation appeared to be sensitive to the parameters used for water + ethanol. The ternary VLE behavior was also modeled by correlation of two data sets, in which the ethanol mole fraction on an IL-free basis is, respectively, at 0.1 and 0.98. In this way, the six data sets were reproduced satisfactorily, with root-mean-square deviations of 0.49 K for temperature and 0.0042 for vapor phase mole fraction. Owing to the regular distribution of the experimental compositions, the feasibility of the correlation−prediction procedure was graphically presented, and in some sense visualized, in terms of relative volatility, activity coefficient, and bubble temperature, showing good agreement between experiment and calculation.