Liquid−Liquid Extraction of Toluene from Heptane Using 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids

The good stability and suitable polarity of the 1-alkyl-3-methyl bis(trifluoromethylsulfonyl)imide ionic liquids have prompted their use as solvents for the extraction of mixtures of aromatic and aliphatic hydrocarbons. In this paper, aiming to extend the study of these ionic liquids, the liquid−liquid equilibrium for the systems toluene + heptane + [mmim][Tf2N], [emim][Tf2N], [bmim][Tf2N], or [hmim][Tf2N] at T = 313.2 K were determined. The experiments with [mmim][Tf2N] and [emim]Tf2N have shown good results in the separation of toluene from heptane compared with the distribution ratio and separation factor of sulfolane in the whole range of composition. The degree of consistency of the experimental LLE data was ascertained by applying the Othmer−Tobias correlation. The phase diagrams for the ternary systems were plotted, and the tie lines correlated with the NRTL model compare satisfactorily with the experimental data.