<i>PVT</i> Properties of Choline Chloride-Based Deep Eutectic Solvents with Polyols and Water under Extreme Conditions

In this study, the PVT properties of choline chloride-based deep eutectic solvents (DESs) with two polyols were measured using a high-pressure densitometer from 298.15 to 348.15 K and up to 50 MPa at two different molar ratios and various water content. The high-pressure densities experimental data were used to determine the excess molar volumes and isothermal compressibilities, which were also evaluated using the modified Redlich–Kister model. The binary interactions between DESs and water were calculated using the FOV and Schotte equations of state (EOS). Results show that the density of DESs decreases as the temperature increases and increases as the pressure and the DES mole fraction increase. The isothermal compressibility of the DES–water mixture increases with increasing temperature and decreases with pressure. Deviations in the correlation of densities with the Tait equation are less than 0.09%. The excess molar volumes were calculated using a modified Redlich–Kister equation with deviations between 0.01 and 0.1. The deviations in the binary interactions between DES and water are less than 0.2% and 0.29% for the FOV and Schotte EOS, respectively. These findings suggest that choline chloride has strong interactions with water, reducing densities over a wide range of temperatures and pressures.