Isobaric vapour-liquid equilibrium of methanol + tetrahydrofuran + imidazolium-based ionic liquids at 101.3 kPa

Abstract The work studied the separation of imidazolium-based ionic liquids (ILs, 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4] and 1-hexyl-3-methylimidazolium trifluoromethylsulfonate [HMIM][OTF]) in the methanol + tetrahydrofuran azeotropic mixtures. The experimental vapour-liquid equilibrium (VLE) data demonstrated that both ILs could serve as nonvolatile entrainers to break the azeotrope of the methanol + tetrahydrofuran mixture. Calculated by the NRTL model, the azeotropic phenomenon of the methanol + tetrahydrofuran system was eliminated when the minimum molar fraction of [HMIM][BF4] and [HMIM][OTF] was 0.139 and 0.113, respectively. Then the effect was analysed in terms of separation ability and σ-Profiles. As a result, [HMIM][OTF] was the suitable entrainer to separate methanol + tetrahydrofuran azeotrope.