Treatment of high-concentration phenolic wastewater by pyridine-coal tar complexation extraction system

摘要

To effectively and economically separate and recycle the useful phenols from industrial effluents, as well as provide a comprehensive method for reutilization of coal tar to improve its economic value, the pyridine-coal tar originating from lignite gasification process was innovatively developed as a promising extractant. The extraction characteristics of the pyridine-coal tar were studied via treatment of 4,000mg/L phenolic wastewater. Maximum extraction power of phenol on the extractant was obtained with 8% pyridine, 1.4:1 of phase ratio, 160rpm of rotary speed at weak acid or neutral pH, which the dephenolization efficiency was as high as 90% within 5min at 50 degrees C. The extracted phenol in pyridine-coal tar could be recovered, and the regenerated extractant can be reused for at least 5 cycles with no obvious loss in the dephenolization efficiency. The pyridine-coal tar was also used to extract phenol from practical phenolic wastewater, and the dephenolization efficiency was 86.7%. Based on the above experimental results, an optimized dephenolization process is proposed. This study might pave the way toward designing novel complexation extraction system with great potential for environment remediation.