Physical Properties of Aqueous Solutions of Ionic Liquid, 1-Propyl-3-methylimidazolium Methyl Sulfate, at T = (298.15 to 328.15) K

Osmotic coefficients, electrical conductances, densities, viscosities, and refractive indices of ionic liquid, 1-propyl-3-methylimidazolium methyl sulfate [PrMIm]MSO4, with water have been measured at T = (298.15 to 328.15) K and atmospheric pressure. Experimental osmotic coefficients have been measured using the vapor pressure osmometry (VPO) method and correlated with Pitzer-ion interaction and modified NRTL (MNRTL) electrolyte models. Molar conductances of this system have been correlated with the low concentration chemical model (IcCM) of conductance equation, and then ion association constants have been obtained at different temperatures. Ion association constant values increase with increasing temperature. The apparent molar volumes at infinite dilution are estimated by the Redlich-Mayer and Pitzer equations. Viscosity B coefficients have been calculated from Jones-Dole equation. It was found that in the investigated range of concentrations the values of viscosity B coefficients are positive. The B coefficient decreases with an increase in temperature. The results are explained in terms of hydrophobic hydration of ionic liquid.