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

Thermophysical properties viz. density rho, speed of sound u, refractive index n(D), and specific conductivity kappa for aqueous solution of ionic liquid; 2-hydroxyethyl-trimethylammonium Acetate; [(C2H4OH)-(CH3)(3)N] [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 V-phi, apparent molar volume at infinite dilution V-phi(0), limiting apparent molar expansibilities phi(0)(E), apparent molar compressibility K-s phi, limiting isentropic compression K-s phi(0) molar refraction R-M and limiting molar conductance Lambda(o)(m) have 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. (C) 2019 Published by Elsevier B.V.