Efficient deep eutectic solvents selection based on the mechanism of hydrogen bonding for dephenolisation by liquid-liquid extraction

Highly efficient separation of phenolic compounds from coal tar can significantly enhance its quality. Herein, we proposed an effective method to screen the extractants of liquid-liquid extraction (LLE) for the separation of phenol +m-cresol/ toluene. The screening of nine deep eutectic solvents (DESs) was carried out by conducted with quantum chemical (QC) calculations and molecular dynamics (MD) simulations. The results of QC calculations and MD simulations revealed that all nine DESs interacted strongly with phenol and m-cresol; the DES with lowest neutral oil entrainment was choline chloride- ethylene glycol (ChCl-EG); ChCl-EG exhibited the best extraction performance for model oil containing <= 20 wt% at 30 C-degrees. Based on the screening process mentioned above, LLE experiments revealed that the extraction efficiency of ChCl-EG (molar ratio 1:3) on a low concentration (10 %-20 %) phenol and m-cresol model oil at 30 C-degrees could reach > 97 % and 93 %, respectively; the toluene entrainment was only 1.6 %. Moreover, the results were fully consistent with that of QC calculations and MD simulations, verifying the reliability and effectiveness of the DES screening method proposed in this study, which provided a theoretical reference for resolving similar problems.