Isobaric vapor-liquid equilibrium for 2-butanone + ethanol + acetate-based ionic liquids at 101.3 kPa

Three acetate-based ionic liquids (ILs) (tetraethylammonium acetate, [N2,2,2,2][AC]; 1‑butyl‑2,3-dimethylimidazolium acetate, [BMMIM][AC]; or tributyl-methylammonium acetate, [N4,4,4,1][AC]) were used to separate the 2-butanone-ethanol azeotropic mixture as entrainer. The separation abilities of the three ILs were compared by measuring isobaric vapor-liquid equilibrium (VLE) data of the 2-butanone + ethanol + IL ternary systems at 101.3 kPa. The VLE data were well correlated through the use of the nonrandom two-liquid (NRTL) model. The azeotrope of 2-butanone + ethanol binary system is entirely eliminated when the concentration of IL achieves a certain value. The minimum mole fractions of the three ILs to completely eliminate azeotropic phenomena are 0.0146, 0.0166 and 0.0240, respectively. The breaking azeotropic capacities of the three ILs are better than that previously reported in the literatures. According to the average relative volatility, after the azeotropic point is thoroughly eliminated, the order of the separation capability of the three ILs is as below: [N2,2,2,2][AC] > [BMMIM][AC] > [N4,4,4,1][AC]. The σ-profiles were used to further explore the separation mechanism.