The study of molecular interactions of aqueous solutions of Choline Acetate at different temperatures

Abstract

Thermophysical properties viz. density ρ, speed of sound u, refractive index nD, and specific conductivity κ for aqueous solution of ionic liquid; 2-hydroxyethyl-trimethylammonium Acetate; [(C2H4OH)-(CH3)3N] [Acetate] (Choline Acetate) have been studied over the whole concentration range at different temperature (293.15 to 323.15) K at atmospheric pressure in order to understand the molecular interactions between solvent and solute. To have more insight of solute–solvent interactions occurring in aqueous solutions of Choline Acetate, apparent molar volume Vφ, apparent molar volume at infinite dilution Vφ0, limiting apparent molar expansibilities φE0, apparent molar compressibility KSφ, limiting isentropic compression KSφ0, molar refraction RM and limiting molar conductance ∧omhave been calculated over the whole composition range as a function of ionic liquid concentration. Thermophysical results confirm the presence of strong solute-solvent interactions in the aqueous solutions of Choline Acetate, which gets stronger with increase in temperature. Also, computational studies have been carried out for deeper understanding of interactions of aqueous solutions of Choline Acetate at molecular level by using Density Functional Theory (DFT). These results show that solute-solute interactions in Choline Acetate decreases on addition of water solvent hence are in good agreement with thermophysical results.