Acetonitrile Dehydration via Extractive Distillation Using Low Transition Temperature Mixtures as Entrainers

Low transition temperature mixtures (LTTMs) are versatile alternatives to ILs. They share many properties with ILs, so they become a suitable choice for entrainers in extractive distillation processes. In this study, glycolic acid and choline chloride in a 3:1 molar ratio (GC3:1) were synthesized and explored as entrainers for separation of acetonitrile + water azeotropic mixtures. Isobaric vapor-liquid equilibrium data for the pseudobinary mixtures of ACN + GC3:1 and water + GC3:1 were measured at atmospheric pressure (101.32 kPa). For the pseudoternary system ACN + water + GC3:1, also VLE data were measured at different GC3:1 mole fractions of 0.05, 0.1, and 0.15. The thermodynamic modeling of these systems was performed using the nonrandom two-liquid (NRTL) model. Furthermore, a study was conducted for synthesized GC3:1 recoverability. A good agreement were found between experimental data and predicted values for these systems. Results showed that LTTM (GC3:1) eliminated the acetonitrile + water azeotrope by manipulating the relative volatility of the acetonitrile + water mixture. Therefore, LTTM (GC3:1) can be concluded as an efficient entrainer for the separation of an acetonitrile + water azeotropic mixture by extractive distillation.