A dual entrainer approach with ionic liquids for enhanced recovery of ethanol and isopropyl alcohol from wastewater

This study proposes a novel dual entrainer approach using 1-ethyl-3-methylimidazolium dicyanamide ([EMIM] [DCA]) and ethylene glycol (EG) to enhance the recovery of ethanol and isopropanol (IPA) from wastewater. The method effectively addresses the challenges of binary azeotropes between ethanol/water and IPA/water, while also improving the separation of near-boiling ethanol/IPA mixtures. A comprehensive energy-economicenvironmental analyses show that the dual entrainer configuration significantly outperforms traditional single-entrainer processes, reducing energy consumption, total annual costs (TAC), and gas emissions by 10.4 %- 64.1 %, 11.1 %-27.4 %, 10.4 %-64.1 %, respectively. Additionally, integrating heat pump-assisted pre-concentration with the extractive distillation process further enhances performance, leading to additional reductions of 4.3 %-69.9 % in energy use, 10.6 %-43.9 % in TAC, and 3.8 %-72.7 % in gas emissions. This work underscores the potential of dual entrainer systems for achieving sustainable and economically viable separation processes, offering a promising solution for industries dealing with high water content in their feedstocks.