Ternary Liquid–Liquid Equilibrium of Azeotropes (Ester + Alcohol) with Different Ionic Liquids at T = 298.15 K

The liquid–liquid equilibria (LLE) for ternary systems of n-propyl acetate (PAC) + 1-propanol (NPA) + 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]­[PF6]) or 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim]­[PF6]) and n-butyl acetate (NBAC) + n-butanol (NBA) + [Bmim]­[PF6] or [Hmim]­[PF6] were measured at 298.15 K and 101.325 kPa. All the studied systems containing ionic liquids (ILs) show Treybal type I behavior of the LLE. The solute distribution coefficient (β) and the selectivity (S) were used to investigate the effect of the number of carbon atoms of cations, esters, and alcohols of ionic liquids on the liquid–liquid phase behavior for ester-alcohol-ILs. The measured data were correlated using both the NRTL model and the UNIQUAC model. Results indicate that all these systems can be correlated with reasonable accuracy by using both the NRTL model and the UNIQUAC model.