Efficient separation of phenols from phenols-containing oil mixtures via forming hydrogen bonds

In this work, the separation of phenol from oil mixtures was proposed by using mildronate (THP), Girard's Reagent T, and Girard's Reagent P. The results showed that the mentioned separation agents could form deep eutectic solvent (DES) with phenol and then separate phenol. The highest separation efficiency of phenol was 96.5% by THP, and the residual phenol content in oil was as low as 1.3 g/L; the separation could be finished in 10 min; the initial phenol content had no effect on the minimum residual phenol content (about 8.8 g/L) in oil after separation. An n-hexane washing method was used to remove the neutral oil entrained in DES. The results showed that the mass ratio of neutral oil to phenol in DES was reduced to 0.04, indicated that the purity of phenol product was greatly improved. THP was renewable and its properties remained unchanged after be reused for 5 times. Finally, FT-IR spectra showed that hydrogen bonds were formed between THP and phenol.