Application of Pyrrolidinium-Based Ionic Liquid as Solvent for the Liquid Extraction of Benzene from Its Mixtures with Aliphatic Hydrocarbons

The ionic liquids 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMpyr][TfO], 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMpyr][NTf2], and 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr][DCA], have been studied as solvents for the extraction of benzene from its mixtures with several aliphatic hydrocarbons. The liquid-liquid equilibrium (LLE) of the ternary systems {octane (1) + benzene (2) + [BMpyr][TfO] (3)}, {decane (1) + benzene (2) + [BMpyr][TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr][TfO] (3)}, {dodecane (1) + benzene (2) + [BMpyr][NTf2] (3)}, and {dodecane (1) + benzene (2) + [BMpyr][DCA] (3)} at T = 298.15 K and atmospheric pressure was carried out. The solute distribution ratio and selectivity values derived from the tie-lines were used to evaluate if the studied ionic liquids can be used as extraction solvents, and the obtained values were compared with those found in the literature for the traditional organic solvents. Finally, experimental LLE data for the ternary mixtures were correlated by means of the non-random two-liquid (NRTL) thermodynamic model.