Reduction of Nitrate by g-C3N4-TiO2 Photocatalyst on Electrode Coupled with Electricity Generating Bio-anode

Photocatalytic reduction of nitrate and/or nitrite is performed using g-C3N4-TiO2 as photocatalytic cathode combined with electricity generating bio-anode. Effect on photocatalytic reduction of nitrate is investigated from hole scavenger, aeration conditions and biological anode, respectively, and the reduction mechanism is analyzed. The result shows that the system has the best removal efficiency with a biological anode and exposure to nitrogen, while hole scavenger has the least effect on photocatalytic reduction. The removal of nitrate is 72.57% and the concentration of nitrite (by-product) is 0.31 mg L-1 after 210 min of reaction, while ammonia is not detected. The supported catalyst does not fall off and the catalyst activity remains essentially unchanged after repeated experiments, which means the catalyst and electrode can be reused.