Vapor–Liquid Equilibrium Study of Binary Mixtures of Chloroform, 2‑Ethylhexanoic Acid, and Propylene Glycol Methyl Ether at Atmospheric Pressure

To separate the minimum-boiling azeotrope (propylene glycol methyl ether + water) in the production process of propylene glycol methyl ether, two extractive agents of chloroform and 2-ethylhexanoic acid were selected. The isobaric vapor–liquid phase equilibrium (VLE) data for three systems (chloroform + 2-ethylhexanoic acid), (propylene glycol methyl ether + 2-ethylhexanoic acid), and (chloroform + propylene glycol methyl ether) were measured at 101.3 kPa. Thermodynamic consistency of the measured VLE data was validated by the Herington and van Ness tests. The measured VLE data were well fitted with Hayden-O’Connell (HOC) thermodynamic models: nonrandom two-liquid-HOC, Wilson-HOC, and universal quasichemical-HOC with regressed parameters, respectively

Isobaric Vapor–Liquid Equilibrium for Binary Systems of 2,2,3,3-Tetrafluoro-1-propanol + 2,2,3,3,4,4,5,5-Octafluoro-1-pentanol at 53.3, 66.7, 80.0 kPa

In this work, the isobaric vapor–liquid equilibrium (VLE) data for binary mixtures of 2,2,3,3-tetrafluoro-1-propanol (TFP) + 2,2,3,3,4,4,5,5-octafluoro-1- pentanol (OFP) were determined at pressures of 53.3, 66.7, and 80.0 kPa by a modified Rose type recirculation still. The thermodynamic consistency of all the VLE data was checked by Herington and Van Ness test to confirm the reliability of the experimental data. No azeotropic behavior was observed for the binary systems at different pressures. Meanwhile, the VLE data were correlated by Wilson and nonrandom two-liquid (NRTL) activity coefficient models, which the calculated results were in good agreement with the experimental data. Also, the binary interaction parameters of the activity models were regressed

Separation of heterocyclic nitrogen compounds from coal tar fractions via ionic liquids: COSMO-SAC screening and experimental study

Ionic liquids (ILs) have been applied as a promising solvent for the separation of different kinds of compounds. But the enormous combination possibilities of the cations and anions make it a challenging task to screen an appropriate IL for a specific application. Thus, the method for screening IL candidates based on the COSMO-SAC model is presented and illustrated to extract heterocyclic nitrogen compounds, indole and carbazole, from coal tar fractions. Also, the σ-profile analysis is used to evaluate the effect of different types of cations and anions, and systematically confirmed the structure–activity relationships for the extraction process. Then, 22 cations and 19 anions are screened as the initial structures of the potential extractants from a σ-profile database (containing 39 cations and 29 anions). Along with the rigorous evaluation criterion proposed in this work, three IL extractants are adopted. Afterwards, the extractive ability of the candidates is experimentally investigated.</p

Vapor–Liquid Phase Equilibrium for Separation of Isopropanol from Its Aqueous Solution by Choline Chloride-Based Deep Eutectic Solvent Selected by COSMO-SAC Model

To separate isopropanol from its aqueous solution by distillation, the deep eutectic solvents (DESs) with choline chloride, which were screened using the COSMO-SAC mode, were applied to eliminate the azeotropic point. The charge density distribution over the molecular surface was calculated for isopropanol, water, and DESs to analyze the interactions between different species. Based on the screening results, a DES consisting of choline chloride and triethylene glycol in a molar ratio of 1:3 was selected. To validate the selected DES for the separation of isopropanol from its aqueous solution, the isobaric vapor–liquid equilibrium (VLE) data for the system of isopropanol + water + DES were measured at a pressure of 101.3 kPa. According to the measured VLE data, the azeotropic point of isopropanol and water can be eliminated by the DES at a concentration of 10 wt %. Meanwhile, the thermodynamic consistency of the VLE data was checked by the van Ness test. The non-random two-liquid model was employed to correlate the VLE data, which were in agreement with the measured VLE data

Liquid–Liquid Equilibrium of Isobutyl Acetate + Isobutyl Alcohol + Imidazolium-Based Ionic Liquids at 298.15 and 308.15 K

For separation of the azeotrope isobutyl acetate and isobutyl alcohol, imidazolium-based ionic liquids 1-hexyl-3-methyl­imidazolium hexa­fluoro­phosphate [Hmim]­[PF6] and 1-octyl-3-methyl­imidazolium hexafluoro­phosphate [Omim]­[PF6] were applied as the extractants in the extraction process. The liquid–liquid equilibrium (LLE) data for the ternary systems isobutyl acetate + isobutyl alcohol + ([Hmim]­[PF6]/[Omim]­[PF6]) were determined at temperature of 298.15 and 308.15 K. To evaluate extraction performance of the ILs, the selectivity and distribution coefficient were calculated from the experimental data. The effect of the alkyl chain length of the cations and the temperature on the LLE for the systems were explored. In addition, the experimental LLE data were correlated by the NRTL model, and the binary interaction parameters of the NRTL model were optimized

Isobaric Vapor–Liquid Equilibrium for Binary Systems of Thioglycolic Acid with Water, Butyl Acetate, Butyl Formate, and Isobutyl Acetate at 101.3 kPa

The isobaric vapor–liquid equilibrium (VLE) data for the systems (thioglycolic acid + water), (thioglycolic acid + butyl acetate), (thioglycolic acid + butyl formate), and (thioglycolic acid + isobutyl acetate) were measured at <i>P</i> = 101.3 kPa by using a vapor recirculating type (modified Rose) equilibrium still. The thermodynamic consistency test of the experimental data for the four binary systems were confirmed by the method of Van Ness. The experimental VLE data were correlated by the three activity coefficient models of Wilson, nonrandom two-liquid (NRTL), and universal quasi-chemical (UNIQUAC). The results show that all the calculated data by the Wilson, NRTL, and UNIQUAC models are in good agreement with the measured VLE data. Meanwhile, the binary interaction parameters of the three models for the binary systems were regressed

Liquid–Liquid Equilibrium for Ternary Mixture Water + (n-Propanol/Isopropanol) + Cyclohexanone at 298.15 and 308.15 K

For separation of the azeotropes of n-propanol (NPA) + water and isopropanol (IPA) + water by liquid–liquid extraction, cyclohexanone was selected as the extraction solvent. The liquid–liquid equilibrium (LLE) behavior of the two mixtures (water + NPA + cyclohexanone) and (water + IPA + cyclohexanone) was investigated at temperatures 298.15 and 308.15 K. The LLE phase diagrams of the two mixtures belong to Treybal’s type I. According to the measured data, distribution ratio and separation factor obtained by calculation were used to analyze the extraction effect of cyclohexanone. In addition, the NRTL and UNIQUAC models were used to fit the LLE experimental data, and the values of root mean square deviation are smaller than 0.007. Lastly, the analysis of Gibbs energy surfaces was applied to validate the coherence of the fitted binary interaction parameters for the thermodynamic models

Liquid–Liquid Equilibrium for Ternary Systems 2,2,2-Trifluoroethanol + Water + (Ethyl Acetate/Isopropyl Acetate/Isobutyl Acetate) at 308.15 K under 101.3 kPa

2,2,2-Trifluoroethanol (C2H3F3O, TFE) is a useful fluorine-containing alcohol. During the synthesis and application of TFE, TFE, and water can form an azeotropic mixture. To recover TFE from the mixture of TFE and water by liquid–liquid extraction (LLET), in the current work, three organic solvents, isobutyl acetate (C6H12O2), isopropyl acetate (C5H10O2), and ethyl acetate (C4H8O2), were chosen as the extractants. The liquid–liquid equilibrium (LLE) behavior for the three mixtures (water + TFE + ethyl acetate/isopropyl acetate/isobutyl acetate) was investigated at 101.3 kPa and 308.15 K. Selectivity (S) and distribution constant (D) were calculated as indexes to evaluate the extraction capacity of the three extractants. The results indicated that isobutyl acetate has better extraction ability in extracting TFE from its aqueous solution of TFE compared to the esters. The NRTL model was used to regress the determined tie-line data. The coherence of the fitted parameters of the NRTL model with the experimental data was checked by topological analysis

Separation of Dimethyl Carbonate and Methanol by Deep Eutectic Solvents: Liquid–Liquid Equilibrium Measurements and Thermodynamic Modeling

To separate the mixture of dimethyl carbonate and methanol, two deep eutectic solvents (DESs), choline chloride with glycerol and ethylene glycol, with the molar ratio of 1:2 were prepared to separate dimethyl carbonate from the mixture by liquid–liquid extraction. The liquid–liquid equilibrium (LLE) data for the ternary systems of dimethyl carbonate + methanol + DESs were determined at temperature of 298.15 and 308.15 K under 101.3 KPa. The measured tie-line data were validated by the Bachman equation, and the correlation coefficients (<i>R</i>²) were all close to 1. Meanwhile, the distribution coefficient and selectivity were calculated from the experimental results. The LLE experimental data were correlated using the nonrandom two-liquid (NRTL) model, and the correlated results agree well with the LLE experimental data. Also, the parameters of the NRTL model were regressed