Measurement and Prediction of Vapor Pressure of Binary and Ternary Systems Containing 1-Ethyl-3-methylimidazolium Ethyl Sulfate

Abstract

Vapor pressure data were measured for water, methanol, and ethanol as well as their binary mixtures in the presence of the ionic liquid (IL) 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][ES]) at different temperatures and IL-content ranging from mass fraction of (0.10 to 0.70) using a quasi-static ebulliometer method. The vapor pressure data of the IL-containing binary systems were correlated by the NRTL equation with an average absolute relative deviation (ARD) within 0.0068. The binary NRTL parameter was used for the prediction of vapor pressure of ternary systems with fair accuracy. Furthermore, the isobaric vapor−liquid equilibrium data for water + ethanol and methanol + ethanol binary mixtures at 101.3 kPa and mass fraction of [EMIM][ES] of 0.5 were predicted. It is shown that the relative volatility of ethanol in both binaries is enhanced and that the azeotrope of the water + ethanol mixture was eliminated completely since the interaction energy between different solvents and IL follows the order water > methanol ≫ ethanol, manifested by the infinite dilution activity coefficients of the solvent in the IL [EMIM][ES].