Understanding the solvation behavior of SO3H functionalized Brønsted acidic ionic liquids in water and DMSO: Volumetric and acoustic approach

Abstract

In the present work, density, ρ and speed of sound, u measurements have been performed, for binary mixtures of two synthesized Brønsted-acidic ionic liquids namely N,N,N-triethyl-4-sulfobutaneammonium hydrogensulfate, [N222(C4SO3H)][HSO4] and N,N,N-triethyl-4-sulfobutaneammonium trifluoromethanesulfonate, [N222(C4SO3H)][CF3SO3] with water and DMSO as solvents. Experimental measurements have been carried out at variable concentrations of ILs in the temperature range of (293.15 to 328.15) K with the constant interval of 5 K and at atmospheric pressure. Using experimentally measured density and speed of sound data, apparent molar volume, Vϕ and apparent molar isentropic compressibility, Ks, ϕ and limiting apparent molar expansion, Eϕ∞ have additionally been derived for the studied binary solutions. Apparent molar property data were fitted to the Redlich-Mayer type equation from which corresponding derived properties i.e. apparent molar volume and apparent molar isentropic compressibility at infinite dilutions, Vϕ∞ and κs, ϕ∞ were attained. Magnitude of these derived properties and corresponding empirical parameters were evaluated in the scope of understanding the nature of interactions prevailing among ions of ILs as well as ions and solvents.