Ionic liquid extractive distillation for the recovery of diisopropyl ether and isopropanol from industrial effluent: Experiment and simulation

To recover diisopropyl ether (DIPE) and isopropyl alcohol (IPA) from industrial wastewater through extractive distillation (ED), the most suitable extrainer 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) was screened out by comparing the selectivity of DIPE to IPA and IPA to water in ionic liquids (ILs) composed of 9 common cations and 12 common anions. Theoretical insight at the molecular level based on surface charge-density (σ-profiles) and excess enthalpy (HE) was provided to analyze the hydrogen bonding and separation mechanism between IL and the azeotrope. Isobaric vapor-liquid equilibrium (VLE) experiment of DIPE + IPA + [EMIM][OAc] and IPA + water + [EMIM][OAc] further validated the predicted results. After inputting the binary interaction parameters, the ternary ED configuration with [EMIM][OAc] as entrainer was simulated, and the thermal integration scheme was further explored. Comprehensive evaluation demonstrated that when compared to ethylene glycol (EG), the energy-integrated ED scheme with [EMIM][OAc] as entrainer saves energy consumption and the total annual cost (TAC) of 27.71% and 12.29%, respectively. This separation method provides a more energy-efficient and environmentally friendly choice for clean production of IPA.