Heterogeneous Catalytic Ozonation of COD and Quinoline from Coal Gasification Wastewater Secondary Effluent with Carbon Supported Copper Oxides as Catalyst

Coal gasification wastewater (CGW) is a refractory and toxic wastewater. The secondary effluent quality usually cannot meet the discharge standards after conventional biological treatment processes. Heterogeneous catalytic ozonation is a promising technology for solving this problem. Two carbon materials were investigated as ozonation catalysts for the removal of the quinoline and COD in a real CGW secondary effluent. Results were indicated that CuOx /GAC presented a higher catalytic performance than granular activated carbon and single ozone, efficiency of removal of quinoline and COD were 69%, 92% respectively. Higher pH had positive effect on the degradation of quinoline due to the formation of hydroxyl radical (removal of quinoline rapidly reached above 90% in pH=10). The presence of the radical scavenger tert-butanol (TBA) evidenced the participation of hydroxyl radicals (•OH) in the oxidation mechanisms of quinoline. The stability of the catalysts was demonstrated by carrying repetitive experiments reusing catalysts sample.