Rational selection and evaluation of ionic liquid as extractant for efficient separation of hexane and methyl ethyl ketone azeotrope

Abstract

Efficient separation of azeotropic mixtures is of great importance for the recovery of valuable substances but poses significant challenges. In this study, we present an intensified separation of the methyl ethyl ketone and hexane azeotrope by liquid–liquid extraction using ionic liquids (ILs). A systematic framework combining thermodynamic model screening, experimental validation, and comprehensive process evaluation is proposed to investigate the industrial applicability of ILs for azeotrope separation. The pre-selection of promising IL candidates was guided by thermodynamic model predictions. Subsequent liquid–liquid equilibrium experiments demonstrated that 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) exhibits superior selectivity and distribution coefficient compared to traditional organic solvent. Entire process simulation further indicated a significant 81.2 % reduction in energy consumption and a 71.6 % decrease in solvent usage, rendering the separation process using ILs more cost-effective and environmentally sustainable. These findings provide a critical reference for separating other alkane and ketone azeotropes.