Liquid–Liquid Equilibrium Measurements and Interaction Explorations for Separation of Dimethyl Carbonate and Isopropyl Alcohol Using ChCl-Based Deep Eutectic Solvents

Deep eutectic solvents (DESs) were adopted to separate the azeotropes of dimethyl carbonate (DMC) and isopropyl alcohol (IPA). Liquid–liquid equilibrium (LLE) data plays a crucial role in designing the separation process. Three appropriate DESs (choline chloride (ChCl)-Urea, ChCl-Glycerol (Gly), ChCl-Ethylene glycol (EG)) were selected using the COMSO model. Then, the LLE data of DMC-IPA-(ChCl-Urea), DMC-IPA-(ChCl-EG), and DMC-IPA-(ChCl-Gly) were obtained through experiments at 298.15 K under 101.32 kPa, the binary interaction parameters were obtained by regressing the LLE data by the nonrandom two-liquid (NRTL) model, and the GUI-Matlab was adopted to verify the precision of the NRTL interaction parameters and the experimental data. Finally, the mechanism of formation of the combined structures (DES-IPA/DMC) was explored through ESP. To further explore the extraction capacities of the selected DESs, the extraction mechanism of three DESs was revealed. The interactions between DESs and IPA/DMC were explored through penetration distance and AIM analysis; the calculation results showed that (ChCl-EG) has the best extraction capacity, which is consistent with the experimental results. The results of experimental and theoretical calculations showed that the DES could effectively separate DMC and IPA.