Dehydration of Aqueous Acetonitrile Solutions by Extractive Distillation Using Deep Eutectic Solvents

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 towards the development of novel green solvents . This growing demand for green solvents has spurred the development of environmentally benign solvents. Separation of azeotropic mixtures is of particular interest for scientific community because it represents separation limit by conventional distillation. Extractive distillation is the most applied technique for the separation of azeotropic/close boiling mixtures. Application of non-toxic and biodegradable solvents in extractive distillation is today s need, due to the environmental concern. From the last two decades, application of ionic liquids (ILs) as an entrainer for azeotropic mixture separation, significantly encouraged the researchers due to their distinctive prominent features. Gradually, the use of ILs for separation applications became restricted due to complex synthesis process, difficulties in purification, high cost, potential toxicity and poor degradability. Recently, Deep Eutectic Solvents (DESs) which are ionic liquids (ILs) analogues have appeared as a promising substitute to conventional volatile organic solvents. Unlike ILs, DESs offer inexpensive and easy synthesis, less toxicity and good biodegradability. Due to the multitasking nature of DESs, these have been applied to many chemical processes. DESs are combination of two (or more) components, commonly a hydrogen-bond acceptor (HBA) and a hydrogen-bond donor (HBD), which forms a eutectic mixture. Because of the strong hydrogenbonding impact, these have much lower melting temperature than those of starting original substances. Due to these unusual chemical and physical properties, DESs are currently getting remarkable attention as greener means for a wide variety of applications. This study focuses on the separation of a common industrial waste, acetonitrile (ACN) + water mixture via extractive distillation.