Volumetric investigation of aqueous mixtures of the {choline chloride + phenol (1:4)} deep eutectic solvent

Abstract

In this study, the densities of the pseudo-binary systems of water and the deep eutectic solvent, 1 choline chloride + 4 phenol were measured and reported for the first time in literature, and a comprehensive investigation on the various volumetric properties was carried out. Nine mixtures, with different compositions of water, were prepared. The densities of the prepared mixtures, as well as pure water and pure deep eutectic solvent (DES) were measured within a temperature range of 293.15–333.15 K at atmospheric pressure. Various volumetric properties, such as excess molar volumes and isobaric volume expansions, partial molar volumes and excess partial molar volumes were calculated for the investigated compositions. Furthermore, partial molar volumes and excess partial molar volumes at infinite dilution were estimated for water and the DES. By analysing the calculated properties, the interstitial accommodation effect was suggested for the investigated mixtures. The stronger tendency of water to be solvated in the mixture, as compared to the DES, was observed for all investigated temperatures. This suggests that, most probably, hydrogen bonds in the investigated mixtures are established in a manner in which water molecules are located at central positions, surrounded by the DES pseudo-molecules.