Influence of binary ionic liquid mixtures of [BMIM][Cl] and [BMIM][BF4] on isobaric vapor-liquid equilibrium of acetonitrile plus water at atmospheric pressure

The effects of ionic liquid mixtures on the phase behavior of azeotropic mixture of acetonitrile + water were presented through the experimental determinations of isobaric vapor-liquid equilibrium for acetonitrile + water + 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and acetonitrile + water + 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) + [BMIM][BF4] at atmospheric pressure (101.3 kPa). The mole ratios of [BMIM][Cl] to [BMIM][BF4] in the mixing ILs were fixed at 2:1, 1:1 and 1:2, respectively. The results showed that [BMIM][BF4] was ineffective in breaking the azeotropy of acetonitrile and water, which whereas could be broken when [BMIM]ICII reached a certain concentration in the mixing ILs. VLE data of ternary and quatemary mixtures were satisfactorily correlated and predicted with NRTL model and COSMO-SAC could give a reasonable prediction of VLE for the investigated mixtures. Additionally, the analysis of interactions among different molecules showed that the interactions between [BMIM][Cl] and water are strong while ones between [BMIM][BF4] and water weak. (C) 2019 Elsevier B.V. All rights reserved.