Ternary liquid–liquid equilibria of trifluorotris(perfluoroethyl)phosphate based ionic liquids + methanol + heptane

Ionic liquids: (4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpyrrolidinium) trifluorotris(perfluoroethyl)phosphate have been investigated in separation of heptane/methanol mixture which form an azeotrope. Three systems of ternary liquid–liquid equilibria containing mentioned ionic liquids + methanol + heptane have been determined at T = 298.15 K. All systems show total miscibility of methanol in the ionic liquid and low solubility of heptane. The experimental results have been correlated using NRTL model. The selectivity and the solute distribution ratio have been calculated for all systems. High selectivities and solute distribution ratios have been obtained for all systems. Experimental tie-lines as well as selectivities and solute distribution ratios are compared with other ionic liquids. The influence of cation and anion structure on phase equilibria is discussed.