Natural Deep Eutectic Solvent-Mediated Extractive Distillation For Separation Of Acetonitrile Plus Water Azeotropic Mixture

Natural deep eutectic solvents (NADESs) are designer green solvents which share many properties with ionic liquids. The uncommon intermolecular adjustment in a NADES matrix shows exceptional solubilizing and stabilizing properties. These properties make them suitable to be used as an entrainer for extractive distillation. The present work investigates the synthesis of choline chloride-based NADES and its viability as an entrainer for separation of acetonitrile (ACN) + water mixture by extractive distillation. A NADES was prepared by employing two natural and biodegradable compounds, DL-malic acid and choline chloride in a 1:1 molar ratio (MC1:1). The vapor-liquid equilibria at isobaric condition were measured for pseudo-binary mixtures (water + MC1:1 and ACN + MC1:1) using an improved Othmer recirculation still at 101.3 kPa. Other than these, the vapor-liquid equilibrium data for ACN + water + MC1:1 pseudo-ternary mixture were also measured at different NADES concentrations. From the results, MC1:1 could successfully eliminate the ACN + water azeotrope. Further, the collected experimental results were validated by employing a nonrandom two-liquid model with minor deviations. The used NADES (MC1:1) was also retrieved successfully and reused until five cycles with no notable change in chemical properties but a slight decrease in performance.