Measurement and correlation of ternary phase equilibrium of (hexane + ethyl acetate) with four ILs

- Liquid-liquid equilibria data of hexane + ethyl acetate + IL systems was measured.
- Influence of alkyl chain length and anion on the liquid-liquid equilibria was discussed.
- The NRTL and UNIQUAC models were applied to correlate the studied system.
- The UNIFAC model was used to predict these systems.

The ternary liquid-liquid phase equilibria (LLE) for four systems including {hexane + ethyl acetate + 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF4])}, 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim][BF4]), 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([Hmim][OTf]), and 1-octyl-3-methylimidazolium trifluoromethanesulfonate ([Omim][OTf])} were determined at 298.15 K and atmospheric pressure. All the investigated systems exhibited Treybal type I behaviour. The solute distribution ratio (β) and the selectivity (S) were calculated for each system to estimate the efficiency of the separation of a hexane + ethyl acetate mixture using ionic liquids as the solvent. The influence of the anion and substituent group of the cation imidazolium rings of the ionic liquid on the LLE was revealed. Two models, NRTL and UNIQUAC, were used to correlate the experimental LLE results for which the binary interaction parameters were obtained. The UNIFAC model was used to predict the LLE data of the ternary systems, and the results were compared with experimental data.