N-Propanol (NPA) and n-propyl acetate (NPAC) can form an azeotrope under normal pressure, so their separation cannot be carried out by conventional distillation. Therefore, 1-butyl-3-methylimidazole acetate ([BMIM][OAC]) and ethylene glycol (EG) were selected as entrainers for extractive distillation of the two substances. Isobaric vapor–liquid equilibrium data were obtained by experiments of NPA + NPAC, NPA + NPAC + [BMIM][OAC], and NPA + NPAC + EG at normal pressure; the experimental results showed that the separation effect of [BMIM][OAC] is significantly better than that of EG. Finally, the data were fitted and correlated with the NRTL model. The ARD (average relative deviation) of NPA + NPAC, NPA + NPAC + [BMIM][OAC], and NPA + NPAC + EG is less than 5%, indicating that the NRTL model has good applicability to the vapor–liquid system.

Vapor−liquid phase equilibrium experiments for the binary system of methyl acetate + ethanol and ternary systems of methyl acetate + ethanol + 1-ethyl-3-methylimidazole acetate ([EMIM][OAC]), methyl acetate + ethanol + 1-butyl-3-methylimidazole acetate ([BMIM][OAC]), and methyl acetate + ethanol + 1-ethyl-3methylimidazolium methanesulfonate ([EMIM][MeSO 3 ]) were conducted at 101.3 kPa. The results show that all three extractants can effectively break the azeotrope of methyl acetate + ethanol. The ILs produce a salting-out effect on methyl acetate and increase the relative volatility of methyl acetate to ethanol. The NRTL model has been chosen to correlate the experimental data. The ARD (average relative deviation) of the activity coefficient of NRTL for the binary system of methyl acetate + ethanol and ternary systems of methyl acetate + ethanol + [EMIM][OAC], methyl acetate + ethanol + [BMIM][OAC], and methyl acetate + ethanol + [EMIM][MeSO 3 ] is 1.22, 1.88, 1.64, and 1.57%, respectively, indicating the good applicability of NRTL.

Due to the azeotrope between ethanol and isopropyl acetate, separating them and meeting the separation requirements is challenging. In this study, ethylene glycol (EG), dimethyl sulfoxide (DMSO), and 1-butyl-3-methyl-imidazole acetate ([BMIM][OAC]) were selected as entrainers, and the vapor−liquid equilibrium data of ethanol−isopropyl acetate, ethanol + isopropyl acetate + EG, ethanol + isopropyl acetate + DMSO, and ethanol-isopropyl acetate + [BMIM][OAC] were measured at atmospheric pressure. The thermodynamic NRTL model was able to fit these experimental results. It showed that the model could correctly describe the influence of these entrainers on this azeotropic system. According to the VLE data, three entrainers caused different effects on the relative volatility of ethanol−isopropyl acetate. The azeotropic point would be completely eliminated, while the mole fraction of [BMIM][OAC] added is 0.1, which performs better than EG and DMSO.

The solubility of trans-3-hydroxycinnamic acid in pure solvents (methanol, ethanol, n-propanol, isopropanol, nbutanol, isobutanol, methyl acetate, ethyl acetate, and n-propyl acetate) and (ethanol + ethyl acetate) cosolvent mixtures was measured by the gravimetric method from 293.15 to 333.15 K in normal pressure. The experimental results show that the solubility of 3-HCA(E) in alcohol solvents is greater than in ester solvents, which conforms to "like dissolves like". On this basis, the experimental result was correlated with semiempirical models (the modified Apelblat, van't Hoff, λh, Jouyban−Acree−van't Hoff equation, and combined model) and activity coefficient models (Wilson, NRTL, and UNIQUAC equation). The modified Apelblat model has the best correlation of the experimental data, with an ARD of less than 0.5% for pure solvents and cosolvent mixtures. The solvent effect was calculated by the KAT-LSER equation, showing that the hydrogen bond alkalinity of solvents−solutes (β) and the solvent self-association (δ H ) significantly influence the solubility of 3-HCA(E), accounting for 32.46 and 55.02%, respectively. Finally, the thermodynamic parameters (ΔH mix , ΔS mix , ΔG mix ,%ξ H , and %ξ TS ) were calculated. Negative values of both ΔH mix and ΔG mix indicate that the mixing process of 3-HCA(E) is exothermic and spontaneous. The Gibbs energy of the mixing process is jointly contributed by enthalpy and entropy.

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