A Glycerol-Based Deep Eutectic Solvent as an Effective Extractant for the Separation of Alcohols from Esters: A Liquid-Liquid Equilibrium Study

This study investigated the use of a deep eutectic solvent (DES) for separating azeotropic mixtures of alcohol–ester systems. The DES was composed of choline chloride and glycerol. Experimental liquid–liquid equilibrium (LLE) data were acquired for several pseudoternary systems. The studied systems consisted of an alcohol (ethanol, n-propanol, or n-butanol), an ester (n-propyl acetate, n-butyl acetate, ethyl propionate, n-propyl propionate, ethyl acetate, or n-butyl propionate), and the DES as the solvent. The experimental measurements were conducted at 293.15 and 313.15 K and 101.3 kPa. A comparative analysis revealed structure–property relationships, demonstrating how separation performance is affected by the alkyl chain length of both the alcohol and the ester. The efficiency of the separation was evaluated by calculating selectivity and distribution coefficients from the determined tie-line data. This work offers important findings on the viability of using a choline chloride-based DES as an effective agent for breaking azeotropes in alcohol–ester mixtures.