Isobaric vapor–liquid equilibrium for water + acetic acid + 1-butyl-3- methylimidazolium dibutylphosphate at 101.32 kPa

The removal and recycling of acetic acid from acetic acid + water mixture has a great significance for environmental protection and resource utilization. After the addition of ionic liquid (IL) 1-butyl-3-methylimidazolium dibutylphosphate [BMIM][DBP], the boiling point difference of the water + acetic acid system increased from 17.88 K (0 mass % IL) to 41.13 K (about 59 mass % IL), and the relative volatility (x1′ = 0.9) increased from 1.60 (0 mass % IL) to 9.81 (about 57 mass % IL). [BMIM][DBP] showed a remarkable entrainer performance for the separation of acetic acid from aqueous solution. In this work, Isobaric vapor-liquid equilibrium (VLE) data of the systems water + acetic acid, water + [BMIM][DBP], acetic acid + [BMIM][DBP], and water + acetic acid + [BMIM][DBP] were determined at 101.32 kPa by using an improved Rose–Williams equilibrium still. Based on the chemical theory and Hayden–O’Connell (HOC) method, the parameters of NRTL model for the binary systems were obtained, and the predicted values of the ternary systems of water + acetic acid + [BMIM][DBP] fitted the experimental VLE data well.