Isobaric Phase Equilibrium of Isopropyl Acetate–Isopropanol–Imidazolium-Based Ionic Liquids at 101.3 kPa

This study investigates the phase equilibrium behavior of the isopropyl acetate (IAC)-isopropanol (IPA) azeotrope system at 101.3 kPa in the presence of three different imidazolium-based ionic liquids (ILs) as entrainers, 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf₂]), and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf₂]). First, according to the measured vapor–liquid equilibrium (VLE) data of the binary system IAC(1)-IPA(2) and the ternary system IAC(1)-IPA(2)-ILs(3), [BMIM][Ac] in the ternary system produces a strong salting-in effect on IPA, while [BMIM][NTf₂] and [HMIM][NTf₂] produces a salting-in effect on IAC, and the effect of [BMIM][Ac] is much stronger than [BMIM][NTf₂] and [HMIM][NTf₂]. This work uses the nonrandom (local) two-liquid equation to correlate the VLE data. The mole fractions of [BMIM][Ac], [BMIM][NTf₂], and [HMIM][NTf₂] required to exactly eliminate the azeotropic point of the IAC-IPA system are 0.035, 0.144, and 0.206, respectively.