Isobaric Vapor–Liquid Equilibria for Separation of the <i>n</i>-Propanol and Water Azeotropic System with the Addition of a Choline Chloride–Ethylene Glycol-Based Deep Eutectic Solvent as an Entrainer

This paper investigates the separation of n-propanol from an azeotropic aqueous solution by extractive distillation. A choline chloride–ethylene glycol (CC-EG) deep eutectic solvent (DES) was used as the green entrainer to shift the azeotropic point, while ethylene glycol (EG) was used as the comparison. Vapor–liquid equilibrium (VLE) data for n-propanol + water + EG and n-propanol + water + DES (CC-EG (1:3)/CC-EG (3:8)) were measured at 101.3 kPa using an ebulliometer. The Van Ness test proved that the experimental data of the ternary system were consistent, and NRTL and UNIQUAC models were used to fit the data. Binary interaction parameters were calculated; the AAD T range was 0.0017–0.0022, and the AAD y range was 0.0007–0.0055. The ranking of the entrainers to shift the azeotropic point was EG < CC-EG (1:3) < CC-EG (3:8) with azeotropic shifts of 0.458, 0.528, and 0.547 mole fractions, respectively.