Density, Viscosity, and CO<sub>2</sub> Solubility of a Deep Eutectic Solvent Comprising Choline Chloride and Ethylene Glycol
Yuto Ainai, Ayaka Taniguchi, Chiaki Yokoyama, Daisuke Kodama
Abstract
We investigated the densities, viscosities at atmospheric pressure, high-pressure densities, and CO 2 solubilities of a deep eutectic solvent comprising choline chloride (ChCl) and ethylene glycol (EG) at a 1:2 molar ratio (ChCl2EG). The measured CO 2 solubility of ChCl2EG was compared with several references. The saturated densities of the vapor and liquid phases of the CO 2 + ChCl2EG system were measured using a static-circulation-type apparatus equipped with two vibrating-tube densimeters. The saturated densities of the liquid phase were expressed using a newly developed density-correlated equation. The present study proposes a method for calculating the liquid density of the homogeneous phase for asymmetric mixtures composed of a nonvolatile solvent and gaseous or supercritical CO 2 . The liquid density of the homogeneous phase obtained using the density-correlated equation could be used to calculate the excess and partial molar volumes, which are essential properties for analyzing liquid structures.