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

Abstract

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.

Keywords

• graphite carbon nitride
• coking wastewater
• advanced treatment
• photocatalytic