Sulfonate-Based Ionic Liquids in the Liquid–Liquid Extraction of Aromatic Hydrocarbons

The liquid–liquid equilibrium (LLE) data for the systems heptane + toluene + 1-ethyl-3-methylimidazolium methanesulfonate ([emim][CH3SO3]), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][CF3SO3]), or 1-ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate ([emim][CHF2CF2SO3]) at T = 313.2 K and atmospheric pressure were determined. To evaluate the suitability of these three ionic liquids for the extraction of aromatics from their mixtures with aliphatic hidrocarbons, the distribution ratios and separation factor curves from the LLE data were plotted and compared to those for the conventional solvent sulfolane. The degree of quality of the experimental LLE data was ascertained by applying the Othmer–Tobias correlation. In addition, the phase diagrams for the ternary systems were plotted, and the experimental tie lines were satisfactorily correlated with the nonrandom two-liquid (NRTL) model.