1-Alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids as solvents in the separation of azeotropic mixtures

Highlights: ► Density and refractive index were measured at T = 313.15 K for the ternary systems. ► Several ionic liquids were studied as solvent to extract ethanol from heptane. ► LLE data were measured at T = 298.15 K and atmospheric pressure. ► Experimental data were correlated using NRTL and UNIQUAC thermodynamic models. - Abstract: (Liquid + liquid) equilibrium data for the ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMim][NTf2], 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [PMim][NTf2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMim][NTf2], and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [HMim][NTf2], mixed with ethanol and heptane were studied at T = 298.15 K and atmospheric pressure. The ability of these ionic liquids as solvents for the extraction of ethanol from heptane was evaluated in terms of selectivity and solute distribution ratio. Moreover, density and refractive index values over the miscible region for the ternary mixtures were also measured at T = 313.15 K. Finally, the experimental data were correlated with the Non Random Two Liquids (NRTL) and UNIversal QUAsi Chemical (UNIQUAC) thermodynamic models, and an exhaustive comparison with available literature data of the studied systems was carried out.