Soluting Effect in Ternary Aqueous Solutions of Ionic Liquids by Isopiestic Equilibrium Studies and Applying the Linear Isopiestic Relations for Estimating Their Speed of Sound, Density, and Surface Tension Data

Abstract

In the present study, to investigate the soluting effect in ternary aqueous solutions of ionic liquids (ILs), experimental studies have been carried out on ionic liquid 1 + ionic liquid 2 + water systems that are in isopiestic equilibrium. The imidazolium-based ionic liquids 1-ethyl-3-methyl-imidazolium bromide ([C2MIM]­Br), 1-butyl-3-methylimidazolium bromide ([C4MIM]­Br), and 1-hexyl-3-methylimidazolium bromide ([C6MIM]­Br) were selected, and the vapor–liquid equilibria (VLE) of {[C2MIM]Br + [C6MIM]Br + water}, {[C2MIM]Br + [C4MIM]Br + water}, and {[C4MIM]Br + [C6MIM]Br + water} were investigated by the isopiestic method. The equations derived from the Zdanovskii–Stokes–Robinson rule were applied to predict the thermodynamic properties (density, speed of sound, and surface tension) of ternary solutions from the corresponding data of binary subsystems with the same water activity data, and the calculated thermodynamic properties were compared to the experimental data.

Isopiestic Studies on Mixed Ionic Liquid Aqueous Solutions at 298.15 K

“…33 The VLE data of IL1 + IL2 + water is rare in the literature. 32,34 In fact, in the present work, for the first time, the effect of anion on the VLE behavior of IL + IL + water systems was investigated by the isopiestic method. The imidazolium class of ionic liquid is the most studied because of its air and moisture stability.…”

“…As a continuation of that work, in the present study, ionic liquids with the same cations and different anions were selected and the improved isopiestic method was used to obtain the water activity of the aqueous solutions of ternary IL1 + IL2 mixtures as well as their binary subsystems . The VLE data of IL1 + IL2 + water is rare in the literature. , In fact, in the present work, for the first time, the effect of anion on the VLE behavior of IL + IL + water systems was investigated by the isopiestic method. The imidazolium class of ionic liquid is the most studied because of its air and moisture stability.…”

“…Vapor–liquid equilibria, VLE, can provide useful information about the interactions that exist in these systems. In our previous work, vapor–liquid equilibria of three IL1 + IL2 + water systems in which the ionic liquids have same anion and different cations ([C 2 MIM]Br + [C 6 MIM]Br + water, [C 2 MIM]Br + [C 4 MIM]­Br + water, and [C 4 MIM]Br + [C 6 MIM]Br + water) were investigated by the isopiestic method. As a continuation of that work, in the present study, ionic liquids with the same cations and different anions were selected and the improved isopiestic method was used to obtain the water activity of the aqueous solutions of ternary IL1 + IL2 mixtures as well as their binary subsystems .…”

“…Vapor−liquid equilibria, VLE, can provide useful information about the interactions that exist in these systems. In our previous work, 32 continuation of that work, in the present study, ionic liquids with the same cations and different anions were selected and the improved isopiestic method was used to obtain the water activity of the aqueous solutions of ternary IL1 + IL2 mixtures as well as their binary subsystems. 33 The VLE data of IL1 + IL2 + water is rare in the literature.…”