Explorations of Liquid–Liquid Phase Equilibrium for the Mixture (Isopropanol + Water) with Pyridinium-Based Ionic Liquids

Three pyridinium-based ionic liquids (ILs) were adopted to extract isopropanol (IPA) from its aqueous mixture for investigating the potential of these ILs in the separation of a (water + IPA) azeotropic mixture. The liquid–liquid equilibrium values for the mixtures (water + IPA + ILs) was determined at 298.15 K. The selectivity and distribution coefficient were computed, which indicates that the IL n-hexylpyridinium bis(trifluoromethyl sulfonyl)imide displays a better extraction effect to separate the mixture of IPA and water. Besides, the NRTL model was applied to regress the determined tie-line values, and the coherence of the optimized binary parameters was examined using the Gibbs energy surfaces analysis.