Study on high efficiency extraction of phenolic-containingwastewater from coal chemical industry

Due to the problems of low extraction efficiency of polyphenols by MIBK and DIPE extractants commonly used in coal chemical phenol-containing wastewater, a new phenolic substance extractant-cyclohexanone was developed.The extraction effects of cyclohexanone and MIBK, DIPE were compared.The main influencing factors such as extraction ratio, extraction temperature, and pH were discussed, and the extractant recovery experiment was carried out.The results showed that the extraction effects of cyclohexanone on hydroquinone and phloroglucin were as high as 91.65% and 83.52% respectively, which were much higher than 74.05%, 49.77% of MIBK and 27.95%,7.84% of DIPE.Under the optimal conditions such as temperature of 40 ℃,extraction ratio of 1∶3, and pH value of 8, the extraction rate of cyclohexanone for four types typical phenol such as phenol, m-cresol, hydroquinone and phloroglucin were 98.30%,96.83%,96.31%, and 91.67% respectively.Under the optimal conditions, the cyclohexanone extraction was carried out on mixed waters with different initial concentrations of 750 mg/L and 1 000 mg/L, and the removal rates of unit phenol and polyphenol were as high as respectively 97.81%, 94.74%, 96.96%, 94.31%; The distillation of the mixed wastewater extract was carried out at a temperature of 155 ℃ and constant pressure, the results showed the recovery rate of cyclohexanone was over 95.5%.The development of the new high-efficiency dephenolization extractant cyclohexanone could effectively reduce the concentration of phenol in water and reduce the burden of subsequent biochemical treatment, providing a technical reference for the treatment and comprehensive utilization of such wastewater and the sustainable development of coal chemical industry.