Photocatalytic Degradation of Metronidazole Using D‐g‐C 3 N 4 ‐Bi 5 O 7 I Composites Under Visible Light Irradiation: Degradation Product, and Mechanisms

Abstract Herein, the efficiency of a number of D‐g‐C 3 N 4 ‐Bi 5 O 7 I composites for the photocatalytic degradation of metronidazole (MNZ) was investigated under visible‐light irradiation. Initially, the operating parameters, intermediate products and related mechanisms were thoroughly assessed. The photocatalytic performance of D‐g‐C 3 N 4 ‐Bi 5 O 7 I composites containing 40 wt% D‐g‐C 3 N 4 (D‐CNBi‐40) was almost 4.3 times more efficient than that of the D‐g‐C 3 N 4 . Then, the effects of pH and D‐CNBi‐40 dosage on the photocatalytic degradation of MNZ were also studied and the optimum values were set. The optimum photocatalytic efficiency were achieved at pH 10, and carrier dosage of 0.8 g L −1 . In another development, it was revealed that the variations in the catalyst performance were negligible over at least four consecutive cyclic runs. The photocurrent response of D‐CNBi‐40 was 0.7μA.cm −1 under visible light irradiation, which was 1.5 and 2.18 times higher than that of Bi 5 O 7 I, and D‐g‐C 3 N 4 , respectively. The results regarding the radical quenching process demonstrated that • O 2 – , and h + were the dominant active species in the degradation of MNZ, whilst •OH played no major role in the respective degredation. In addition, the products generated from the degredation of MNZ were identified by GC/MS. The utiliziation of D‐CNBi‐40 in various water matrices for the degradation of MNZ disclosed that it has a great potential for practical application. Finally, it is thought that this study could be a step forward toward establishing an effective and recycable photocatalytic system in wide variety of aquatic samples.