Development of synergistic extraction process for highly efficient removal of phenols from coal gasification wastewater

Due to the limitation of the existing solvents, the phenols recovery process cannot control phenols concentration to less than 300 mg/L. Therefore, this study presented a synergistic phenols extraction process by using optimal design solvent mixture. The solvent mixture was proposed with the volume ratio of methyl isobutyl ketone (MIBK) to n-pentanol 6:4. The synergistic extraction process was simulated to acquire the parameters with treatment 130 t/h coal gasification wastewater. The removal efficiencies of phenols and treatment costs for the synergistic extraction process had been addressed. The removal efficiency of total phenols can reach to 97.0% after two-stage extraction, and the concentration of total phenols can be decreased from 6273 mg/L to 190 mg/L. Compared with single solvent MIBK, the reduction of phenols emissions is 47.2% by proposed solvent mixture. The operation cost and income of crude phenols showed that synergistic extraction process realized profit about 3.35 CNY/t. Given the removal efficiencies and treatment costs, the solvent mixture (60% MIBK, 40% n-pentanol) is very promising for phenols removal.