Dialkylphosphate-Based Ionic Liquids as Solvents to Extract Toluene from Heptane

In this work, the ability of ionic liquids (ILs) 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) as alternative solvents used in liquid removal of toluene from its combination with heptane was studied. The liquid–liquid equilibrium (LLE) data in relation to ternary systems {toluene + heptane + [MMIM][DMP], [EMIM][DEP], or [BMIM][DBP]} calibrated at T = 298.2 K and atmospheric pressure. The LLE results studied in relation to ternary systems were fitted by the thermodynamic nonrandom two-liquid (NRTL) model. The toluene solute distribution ratios and toluene/heptane selectivities, derived from the experimental LLE data, were compiled and analyzed to determine the extraction capacity of the studied ILs.