Measurement, correlation, and prediction of vapor pressure for binary and ternary systems containing an ionic liquid 1,3-dimethylimidazolium methylsulfate

• Vapor pressure data for four binary systems and two ternary systems were measured.
• NRTL model was used to correlate binary vapor pressure and predict ternary vapor pressure.
• The interaction between IL and volatile solvents was assessed by the method of activity coefficient prediction and quantum chemical calculation.
• Isobaric VLE data were predicted to evaluate the feasibility of IL to separate azeotropic mixtures by extractive distillation.

Vapor pressure data for water, ethanol, 1-propanol, and 2-propanol, as well as the mixtures of {water + 1-propanol} and {water + 2-propanol}, were experimentally measured in the presence of an ionic liquid (IL) 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]) at varying IL-contents and temperatures using a quasi-static ebulliometric method. The experimental vapor pressure data for binary systems containing IL were correlated using NRTL model with an overall relative root mean square deviation (rRMSD) of 0.0055, and the obtained binary NRTL parameters were employed to predict the vapor pressure for two ternary systems with an overall rRMSD less than 0.0234. Moreover, the inter-molecular interaction between [MMIM][MS] and volatile solvent was assessed theoretically in terms of the predicted activity coefficients of solvents for binary systems and quantum chemical calculations with polarizable continuum model. Finally, isobaric VLE data were predicted for three ternary systems containing [MMIM][MS] with IL mole fraction of 0.05, 0.15, and 0.25 at 101.325 kPa, respectively. The results indicate that [MMIM][MS] might be applied as a promising entrainer to separate the azeotropic mixtures of {water + ethanol}, {water + 1-propanol}, and {water + 2-propanol} by extractive distillation.

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