Liquid–Liquid Equilibrium of Alcohol–Ester Systems with Deep Eutectic Solvents Based on Choline Chloride and Alkanediols (Ethylene Glycol or Propylene Glycol)

Deep eutectic solvents (DESs) formed by choline chloride and ethylene glycol or propylene glycol were tested for the separation of azeotropic mixtures containing alcohols (ethanol, n -propanol, and n -butanol) and acetates. For this purpose, the experimental data of coexisting liquid phases were obtained at temperatures 293.15 and 313.15 K and atmospheric pressure. Liquid–liquid equilibrium compositions were determined by 1 H NMR spectroscopy and further analyzed. Additionally, liquid density and dynamic viscosity for DESs studied in the temperature range of 293.15–323.15 K and atmospheric pressure were measured. The separation efficiency of DESs was characterized by distribution coefficients and selectivity values for alcohol. Comparison of selectivity values in systems containing alcohols and esters with other DESs consisting of choline chloride and various hydrogen-bond donors (malonic acid, glutaric acid, glycerol, and urea) was carried out. A local composition model (NRTL) was used for liquid–liquid equilibria data correlation, which provided rather good estimates for the selectivity values.