Evaluation of Solute-Solvent Interactions in Aqueous Solutions Containing Cholinium Aminoate Ionic Liquids and Polyethylene Glycol Dimethyl Ether as a Nontoxic Solvent: Thermodynamic and Transport Studies

摘要

The goal of this work is to study thermodynamic and transport properties of cholinium aminoate ionic liquids a ([Ch] [AA]-ILs) including cholinium glycinate, cholinium valinate, and cholinium prolinate as green and biocompatible extractants in water media at temperatures of 288.15, 298.15, 308.15, and 318.15 K and in three mixed solvents of water polyethylene glycol dimethyl ether 250 (PEGDME(250)) (i.e., w/w = 0.025-0.075) at 298.15 K under atmospheric pressure. In this respect, density (rho), sound speed (u), and viscosity (eta) of the studied aqueous solutions were experimentally measured. From the experimental density and acoustic studies, the limiting values for apparent molar volume (V-phi(0)) and apparent molar isentropic compressibility (kappa(0)(phi)) and also the transfer molar volume (Delta V-tran(phi)0) and isentropic compressibility (Delta(tran)kappa(0)(phi)) of [Ch] [AA] from water to aqueous PEGDME(250) solutions were calculated. The measured viscosity data were correlated with the extended Jones Dole equation for obtaining viscosity B-coefficient, the transfer viscosity B-coefficient (Delta B-tran), and the free energies of activation per mole of solvent (Delta mu(0(sic))(1)) and solute (Ayr). Finally, the changes in the above-mentioned thermodynamic and transport properties for transferring the [Ch] [AA]-ILs from water to mixed solvent of water-PEGDME were utilized for the evaluation of the solute solvent interactions. The results showed that the IL-water interactions in the presence of PEGDME250 are stronger than that in the pure water on the order of [Ch][Gly] > [Ch] [L-Pro] > [Ch] [L-Val]; and above the critical concentrations, these ternary solutions can be split into two phases (i.e., PEGDME(250)-rich phase and [Ch] [AA]-rich phase).