Liquid–Liquid Separation of an Azeotropic Mixture (Hexane/Ethyl Acetate) with Imidazolium-Based Ionic Liquids

This work comprises the separation of an azeotropic mixture (hexane/ethyl acetate) with two different ionic liquids, viz, (1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF 4 ], and 1-ethyl-3-methylimidazolium dicyanamide, [EMIM][DCA]. The liquid–liquid equilibrium (LLE) data for the two ternary systems were obtained at T = 298.15 K and at p = 101 kPa. Ionic liquids with the same cation but different anions (1-ethyl-3-methylimidazolium tetrafluoroborate or dicyanamide) were used to determine the ability to separate ethyl acetate from hexane. The efficiency to separate hexane + ethyl acetate with the investigated ionic liquids was assessed by calculating distribution ratios (β) and selectivity ( S ) values for each system. These parameters revealed the influence of the effect of anions on the ionic liquids on LLE data. The ionic liquid containing dicyanamide [DCA] anions in comparison with tetrafluoroborate [BF 4 ] revealed high selectivity and distribution ratio. The experimental tie lines were successfully correlated using the thermodynamic nonrandom two-liquid equation and were also used to compute the phase composition error in the mole fraction for the two ternary mixtures.