Treatment of high-salt phenol wastewater by high-gravity technology intensified Co-Mn/γ-Al2O3 catalytic ozonation: Treatment efficiency, inhibition and catalytic mechanism

Abstract

The treatment of high-salt phenol wastewater is still a challenging problem, and the effect of salt on the catalysts and active free radicals is still unclear. In this study, high-gravity technology intensified Co-Mn/γ-Al2O3 (CMA) catalytic ozonation is proposed for the treatment of high-salt phenol wastewater, and the effect of salt on catalysts and active free radicals is revealed. It is found that salt has little effect on the degradation of phenol in the high-gravity environment. The main reason for the poor mineralization of phenol is the accumulation of salt on the active sites of the catalyst rather than the scavenging of hydroxyl radicals (OH·). The CMA catalytic ozonation process follows OH· mechanism and was verified by electron paramagnetic resonance (EPR). Under the optimal conditions, the ηphenol reaches 98.40 % in 9 min and the ηTOC reaches 90.02 % in 80 min at a salt concentration of 10 g/L. Compared to the bubbling reactor (BR)/CMA/O3 (BCO) system, the ηphenol and ηTOC of the RPB/CMA/O3 (RCO) system are increased by 12.30 % and 15.90 %, respectively. This study not only provides a new method for the treatment of high-salt phenol wastewater, but also offers new insights into the effect of salt on active components.