Application of 1-alkyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquids for the ethanol removal from its mixtures with alkanes

In this work, two ionic liquids 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, [EMpy][NTf2], and 1-methyl-3-propylpyridinium bis(trifluoromethylsulfonyl)imide, [PMpy][NTf2], were investigated as possible solvents in the extraction processes for the ethanol removal from its mixtures with heptane and hexane. Hence, the experimental determination of the (liquid + liquid) equilibrium (LLE) for the ternary systems {heptane (1) + ethanol (2) + [EMpy][NTf2] (3)}, {hexane (1) + ethanol (2) + [EMpy][NTf2] (3)}, {heptane (1) + ethanol (2) + [PMpy][NTf2] (3)} and {hexane (1) + ethanol (2) + [PMpy][NTf2] (3)} at T = 298.15 K and atmospheric pressure was carried out. The solute distribution ratio and selectivity were calculated to evaluate the capability of these ionic liquids for the extraction of ethanol. Moreover, comparisons with other ILs taken from the literature were made. Finally, the experimental LLE values were compared with the correlated values obtained by means of the NRTL thermodynamic model.

► LLE data for two pyridinium ionic liquids mixed with ethanol and alkanes were studied at T = 298.15 K. ► The effect of the alkyl chain length of the ionic liquids on the extraction process was evaluated. ► Results of selectivity and solute distribution ratio were compared with available literature. ► The NRTL model satisfactorily correlates the LLE data.