Photocatalytic treatment of coking wastewater by cerium oxide loading with nitrogen-doping co-modified graphite carbon nitride

Coking wastewater contains over 500 species toxic substances, and is recognized as the most intractable treated wastewater. Currently, most domestic coking twastewater is treated by biochemical-physicochemical method,and the final effluent water quality is still difficult to meet the “Discharge Standard for Coking Chemical Industry Pollutants”(GB 16171-2012). Thus, the deep treatment and reuse of coking wastewater has become a hot topic in the industry. In order to make up for the shortage of g-C3N4 monomer, CeO2/N-doped g-C3N4(CeO2/NGCN) composite photocatalysts co-modified with nitrogen doping and CeO2 loading were designed and synthesized with expanding visible light absorption and promoting photogenerated carrier separation. The CeO2/NGCN(mass fraction of 1%) exhibited excellent photodegradation performance, the removal rate of COD and UV254 in the coking wastewater after biological treatment reached 49.79% and 69.37% within 120 min, respectively, which was much higher than that of g-C3N4 and N-doped g-C3N4. This work proved that N-doping and CeO2 loading could effectively broaden the photoresponse range of g-C3N4, facilitate the separation of photogenerated electron-hole pairs, which provided a reference for the construction of g-C3N4-based photocatalyst with high-efficiency photodegradation activity.