Measurement and correlation of (liquid + liquid) equilibrium of the azeotrope (cyclohexane + 2-butanone) with different ionic liquids at T = 298.15 K

Experimental densities, speeds of sound, and refractive indices of the binary mixtures of 2-butanone with cyclohexane and OMIM PF₆ (1-methyl-3-octylimidazolium hexafluorophosphate) were determined from T = (293.15 to 303.15) K, since they are necessary to determine the (liquid + liquid) equilibrium. Excess molar volumes, changes of refractive index on mixing, and deviations in isentropic compressibility for the above systems were calculated. Experimental (liquid + liquid) equilibrium of the ternary mixtures {cyclohexane + 2-butanone + 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM PF₆)} and (cyclohexane + 2-butanone + OMIM PF₆) were carried out to assess the suitability of HMIM PF₆ and OMIM PF₆ as azeotrope breaker of the mixture cyclohexane and 2-butanone. Selectivity and distribution ratio values, derived from the tie lines data, were presented in order to analyze the best separation solvent in a liquid extraction process. Experimental (liquid + liquid) equilibrium data were compared with the correlated values obtained by means of the NRTL and UNIQUAC models.