Isobaric Vapor–Liquid\nEquilibria for Separation\nof the <i>n</i>‑Propanol and Water Azeotropic System\nwith the Addition of a Choline Chloride–Ethylene Glycol-Based\nDeep Eutectic Solvent as an Entrainer

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