Isobaric vapor–liquid equilibrium for ethyl acetate + ethanol with ionic liquids [MMIM][DMP] and [OMIM][PF6] as entrainers

Isobaric vapor–liquid equilibrium data for the ternary system of ethyl acetate + ethanol + ionic liquids (ILs) were obtained at 101.3 kPa. The ILs used were 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF6]). The vapor–liquid equilibrium data were correlated using the nonrandom two-liquid model, and the results were well fitted with the experimental data, showing that the minimum concentration (mole fraction) of [MMIM][DMP] and [OMIM][PF6] to break the azeotrope of ethyl acetate + ethanol system was 0.048 and 0.141, respectively. [MMIM][DMP] brought about a monotonous “salting-out” effect on ethyl acetate, while [OMIM][PF6] brought about a crossover effect containing “salting-in” and “salting-out” on ethyl acetate. Finally, polarity of solvents and ions dissociated by ILs was analyzed through the σ-profiles, indicating the mechanism of various separation results using these two ILs. It is suggested that [MMIM][DMP] and [OMIM][PF6] can be used as good candidate entrainers in separating ethyl acetate and ethanol.