Thermophysical Properties and Liquid-Liquid Equilibria of Pseudoternary Systems {Toluene + n-Heptane + Deep Eutectic Solvents Based on Levulinic Acid}

Abstract

Three deep eutectic solvents (DESs), DES1-DES3, were prepared using levulinic acid and choline chloride with molar ratios of 3:1, 4:1, and 5:1, respectively. Another three DESs, DES4-DES6, were prepared using levulinic acid and acetylcholine chloride with the same molar ratio. The density and viscosity of all six DESs were experimentally measured at temperatures ranging from 293.2 to 323.2 K. Both the density and logarithmic value of viscosity of all DESs follow a linear tendency with respect to temperature and reciprocal temperature, respectively. The liquid-liquid equilibria (LLE) for the pseudobinary systems of both toluene and the DES and n-heptane and the DES were performed over a temperature range from 298.2 to 318.2 K with a 10 K interval. The solubilities of toluene in DESs were higher than those of n-heptane in DESs. The LLE of the pseudoternary systems of toluene, n-heptane, and DESs were obtained over a temperature range of 298.2-318.2 K with a 10 K interval. The distribution coefficient of toluene and selectivity were determined. The values of selectivity of toluene with DESs measured in this study were higher than those of other conventional solvents. Not only the mole fraction of toluene in the raffinate phase and temperature but also the mole ratio between the hydrogen bond acceptor and the hydrogen bond donor plays a role in determining both the distribution coefficient of toluene and selectivity. © 2022 American Chemical Society