Experimental investigation on the volumetric properties of mixtures of the deep eutectic solvent of Ethaline and methanol in the temperature range of 283.15 to 323.15 K

In this study, a comprehensive investigation on the volumetric properties of mixtures of a deep eutectic solvent (DES) and an alcohol was carried out. Ethaline (1 choline chloride + 2 ethylene glycol), which is one of the more common DESs, and methanol were chosen to make the desired mixtures. Nine different mixture compositions of Ethaline + methanol, over the full range of concentrations, were prepared. Densities of pure Ethaline and methanol, and also nine mixture samples, were measured at five temperatures from 283.15 to 323.15 K and atmospheric pressure. The excess volumes of the investigated mixtures were calculated and modeled with the Redlich-Kister model. All of the calculated values of excess volumes were negative, which probably shows stronger hydrogen bond contributions and better interstitial accommodations in the mixtures with respect to the pure states. Furthermore, other volumetric properties, such as partial molar volumes and excess partial molar volumes at each composition and at infinite dilution were calculated. By analyzing the calculated volumetric properties, the greater tendency of Ethaline for solvation in the mixture was observed as compared to methanol. Therefore, it is suggested that probably the hydrogen bond networks in the mixture are created in a pattern in which mostly Ethaline occupies central positions, being surrounded largely by methanol molecules. © 2020 Elsevier Ltd