In this study, the effect of glycine on the thermodynamic properties of aqueous solutions containing ionic liquids 1-butyl-3-methylimidazolium chloride, [C4mim]Cl, 1-hexyl-3-methylimidazolium chloride, [C6mim]Cl, 1-butyl-3-methyl-imidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], has been studied. For this purpose, first with help of the vapor pressure osmometery (VPO) method the water activity measurements have been performed on the ternary aqueous systems of (glycine + [C4mim]Cl, [C6mim]Cl, and [C4mim][CF3SO3]) at T = 308.15 K. The influence of the IL nature on the vapor–liquid equilibria behavior of the investigated systems has been studied. The VPO measurements of these solutions show that due to the unfavorable IL-glycine interactions, the negative deviations from the semi-ideal state and in conclude the soluting-out effects have been observed in these solutions. The soluting-out phenomena appears by aqueous biphasic system formation in the case of aqueous [C4mim][CF3SO3] + glycine system and precipitation of the glycine from the solution in the case of ternary [C4mim]Cl/[C6mim]Cl + glycine + water systems. In the second part of this work, density and sound velocity of solutions of the ILs in pure water and aqueous glycine solutions have been measured at four different temperatures. These data were used to obtain the apparent molar volume, Vϕ, isentropic compressibility, Kϕ, and those in the infinite dilution.
