Liquid-liquid equilibrium of alcohol–ester systems with deep eutectic solvent on the base of choline chloride

Highlights: • The capability of deep eutectic solvents (DES) for the extractive separation was considered. • DES was composed from the mixture of choline chloride with malonic acid. • LLE for the mixtures of alcohols – esters of propionic acid – DES was studied. • The effect of the temperature and length of the alcohol alkyl chain on selectivity was discussed. • The NRTL model was applied for the correlation of LLE data. -- Abstract: The liquid-liquid equilibrium (LLE) for the mixtures of ethanol – ethyl propionate, n-propanol – n-propyl propionate and n-butanol – n-butyl propionate with deep eutectic solvents (DES) was studied. DES was used on the basis of choline chloride with malonic acid in a mole ratioof 1:1. The studies were carried out at two temperatures, 293.15 K and 313.15 K and atmospheric pressure. The compositions of the coexisting organic and DES phases were determined. On the basis of experimental data, alcohol distribution coefficient and selectivity were calculated and analysed. The effect of the temperature and length of the alcohol alkyl chain on the alcohol distribution coefficient and selectivity were established. Using the non-random two liquids model (NRTL), a thermodynamic simulation of obtained experimental data on the liquid-liquid phase equilibrium was carried out.