A Review on Eco-Friendly Solvents in Extractive Distillation: Ionic Liquids and Deep Eutectic Solvents

Extractive distillation(ED) is one of the most effective methods to separate azeotropic mixtures. This method entails adding an entrainer to the original azeotropic mixture. This entrainer alters the relative volatility of the mixture’s components by different interactions, which aids the separation process. Currently, volatile organic compounds (VOC) are majorly used as entrainers in the industry. However, VOCs are highly toxic, carcinogenic, mutagenic, and flammable. This calls for the introduction of environment-friendly and non-toxic entrainers which also helps in decarbonizing distillation while reducing operating costs and enhancing component recovery. This study reviews two such entrainers, namely: Ionic liquids (ILs) and Deep eutectic solvents (DES). This study also aims to compare both of these solvents and discuss an algorithm to select an appropriate solvent based on the process requirements.