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Keywords:

  • extractive distillation;
  • ionic liquids;
  • solid inorganic salts;
  • mathematical model;
  • theoretical analysis

The use of the mixture of ionic liquid (IL) and solid inorganic salt in place of the single IL as entrainers for extractive distillation, which integrates the advantages of a liquid solvent, that is, IL (easy operation and nonvolatility) and a solid salt (high separation ability) has been proposed in this work. The vapor–liquid equilibrium experiments indicated that the combination of [EMIM]+[Ac] and KAc is the most promising for the separation of ethanol and water among all of the entrainers investigated. Based on the thermodynamic study, the conceptual process design was developed to evaluate the competitiveness of the suggested entrainers for the separation of ethanol and water. It was determined that the overall heat duty on reboilers in the extractive distillation process using the new mixed entrainers decreases 19.04% compared with the benchmark entrainer [EMIM]+[Ac]. Moreover, the density functional theory and COSMO-RS model were used to achieve theoretical insights at the molecular level. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2994–3004, 2014