On the positive role of doping Cu and N2 on TiO2 in improving dye degradation efficiency: Providing reaction mechanisms

This paper reports an investigation into the effect of a number of operating factors on the removal of Ponceau 4R (Acid Red 18) from an aqueous solution through photodegradation in the presence of nitrogen. N-2 was doped in situ on Cu-TiO2. The photocatalyst was UV/TiO2-Cu applied in suspension to the solution to achieve a larger catalyst surface area. The optimal values of photocatalyst dose, dye concentration, and pH were found to be 0.8mg L-1, 20mg L-1, and 7, respectively. The nitrogen gas was found to have a highly positive role in degradation. The aqueous solution was characterized for its COD. Photocatalyst efficiency was evaluated using XRD, SEM, and EPR techniques. The post-treatment product was characterized using FT-IR, HPLC, and GC-MS studies, intermediate compounds were detected, and a pathway was proposed for the degradation of the dye.