Liquid–liquid equilibrium of ternary systems 1-butyl-3-methylimidazolium hexafluorophosphate + aromatic + aliphatic

Liquid–liquid equilibrium data for the ternary systems nonane + benzene + [bmim][PF6], nonane + toluene + [bmim][PF6], nonane + m-xylene + [bmim][PF6], undecane + benzene + [bmim][PF6], undecane + toluene + [bmim][PF6], undecane + m-xylene + [bmim][PF6]) were determined at 298.15 K. Binodal curves were obtained by the cloud point method, while tie-line compositions were obtained by density and UV spectrophotometry measurements. In all cases the two-phase region is large and wide. The values of distribution coefficients and selectivities indicate that the ionic liquid [bmim][PF6] is a good solvent for the extraction of aromatic from aliphatic compounds. The consistency of the tie-line data was ascertained by applying the Othmer–Tobias correlation. The experimental LLE data were correlated through the well-known NRTL model for the activity coefficient, with estimation of new interaction energy parameters, using the Simplex minimization method and a composition-based objective function. The results, analyzed in terms of root mean square deviations between experimental and calculated compositions, were considered satisfactory.