Ammonium-based deep eutectic solvent as entrainer for separation of acetonitrile–water mixture by extractive distillation

Abstract

The increasing concern about environmental issues and the requirement to reduce the negative influence of industrial processes has directed the attention of scientific community toward the development of new green solvents. Recently, Deep Eutectic Solvents (DESs), which are ILs analogues have appeared as a promising substitutes to conventional volatile organic solvents. Unlike ILs, DESs offer inexpensive and easy synthesis, less toxicity and good biodegradability. In this study, ammonium-based deep eutectic solvent was synthesized and its feasibility was assessed as extracting agent for acetonitrile dehydration using extractive distillation. Glycolic acid and tetramethylammonium chloride (TMAC) based DES was prepared in 3:1 M ratio (GTM3:1) due to its well-known advantages over ionic liquids or organic molecular solvents. Isobaric vapor–liquid equilibrium data for pseudo-binary mixtures (acetonitrile–GTM3:1 & water–GTM3:1) were determined at 101.32 kPa. The pseudo-ternary VLE data of acetonitrile–water–GTM3:1 were also determined by keeping the concentration of DES nearly constant (x3 = 0.05, 0.10, and 0.15). The experimental data for these systems, were fitted using nonrandom two-liquid (NRTL) model and good correlation between predicted values and experimental data were obtained. From the results, GTM3:1 was capable of improving the relative volatility of the studied azeotropic mixture and successfully eliminated the azeotrope. The recoverability of used GTM3:1 was also investigated and the chemical properties of recovered GTM3:1 were found stable.