Separation of ethyl acetate and ethanol azeotrope mixture using dialkylphosphates-based ionic liquids as entrainers

Isobaric vapor-liquid equilibrium (VLE) data for the ternary systems of ethyl acetate + ethanol + 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), ethyl acetate + ethanol + 1-butyl-3-methylimidazolium diethylphosphate ([BMIM][DEP]) and ethyl acetate + ethanol + 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) were measured at 101.3 kPa. The results showed that all the three ionic liquids (ILs) produced remarkable salting-out effect, leading to the increase of the relative volatility of ethyl acetate to ethanol. Hence, the azeotropic point of ethyl acetate and ethanol could be eliminated with the addition of a certain content of ILs. The separation effect of the three ILs follows the order of [EMIM][DEP] > [BMIM][DEP] > [BMIM][DBP]. Then, the experimental VLE data were well correlated with the nonrandom two-liquid (NRTL) model. Finally, the σ-Profiles of solvents and ILs were used to analysis the micro-mechanism of the different separation performance of the three investigated ILs.