Osmotic Coefficients and Refractive Indices of Aqueous Solutions of Ionic Liquids Containing 1-Butyl-3-methylimidazolium Halide at T = (298.15 to 328.15) K

Abstract

Experimental results of the osmotic coefficients and refractive indices of aqueous solutions of ionic liquids containing 1-butyl-3-methylimidazolium chloride, [BMIm]Cl, and 1-butyl-3-methylimidazolium iodide, [BMIm]I, have been measured over the composition range of 3 mol·kg−1 at T = (298.15 to 328.15) K. The determination of experimental osmotic coefficients was performed by the vapor pressure osmometry method. The results show that osmotic coefficients increase when the concentration of ionic liquid and temperature increase. The osmotic coefficients were correlated to the Pitzer ion interaction and modified NRTL (MNRTL) models. From these data, mean activity coefficients and excess Gibbs free energies have been calculated. The results have been interpreted in terms of ion−solvent and ion−ion interactions and structural factors of the ionic liquid. Experimental results of refractive indices for the binary system are reported and have been fitted by a polynomial expansion.