Multiscale Screening of Deep Eutectic Solvents for Efficient Extraction of m-Cresol from Model Coal Tar

Screening of suitable deep eutectic solvents (DESs) as extractants is vitally important in an extraction process. In this study, a multiscale method combining conductor-like screening model for real solvents (COSMO-RS) calculation, experimental validation, and process simulation is presented. This method was applied to screen DESs for extracting m-cresol from cumene. First, the COSMO-RS model was performed to calculate the phase equilibrium of different ternary systems at different feed compositions, thereby prescreening DESs by investigating the effects of DES structures on the extraction performance. Then, the prescreened DESs were studied by extraction experiments to further validate their extraction performance. The extraction mechanism was investigated through FT-IR characterization. Afterward, continuous process simulation by Aspen Plus was employed to identify more promising DESs. The COSMO-RS calculation and experimental results showed that both choline chloride (ChCl)/ethylene glycol (EG) (1:2) and ChCl/glycerol (Gly) (1:2) demonstrated a high extraction performance, which were selected as two suitable DESs. Considering the mass purity and recovery ratio of m-cresol and cumene products in industrial applications, as well as the extractant dosage and equipment costs, ChCl/Gly (1:2) is considered a more promising DES in industrial application.