Experimental Measurement and Modeling of Ternary Vapor–Liquid Equilibrium for Water + 1‑Propanol + 1‑Butyl-3-methylimidazolium Chloride

Isobaric vapor–liquid equilibrium (VLE) data for the ternary system water + 1-propanol + 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) are reported. Complete T, x, y data were measured over a relatively wide range of ionic liquid (IL) mass fractions up to 0.8. The experimental pressure varied from (30 to 100) kPa, depending on the IL mass fraction. Six data sets were obtained in which the 1-propanol liquid-phase mole fraction on an IL-free basis (x 2 ′) was fixed at a value in the range from 0.1 to 0.98. With the addition of [bmim][Cl], the azeotrope of water + 1-propanol was removed at an IL mass fraction of 0.5. The electrolyte nonrandom two-liquid (eNRTL) activity coefficient model was used for correlation and found to be adequate for the ternary system over the experimental composition range. The ternary VLE behavior was also modeled by correlation of two data sets in which the mole fractions of the volatile quasi-binary pair were set at the two diluted ends. In this way, the six data sets were reproduced satisfactorily, with root-mean-square deviations of 0.93 K for temperature and 0.0082 for the vapor-phase mole fractions.