Synthesis of CdMoO4/g-C3N4 composites and the mechanism of photocatalytic degradation of metronidazole in aquaculture wastewater

In this study, a visible light-responsive CdMoO 4 /g-C 3 N 4 heterojunction photocatalyst was successfully prepared by hydrothermal synthesis for the efficient degradation of metronidazole pollutants in aquaculture wastewater. Systematic spectroscopic and electrochemical characterization of materials was performed by XRD, SEM, TEM, HRTEM, XPS, UV–vis DRS and electrochemical measurements. The results showed that the optimized CMCN4 composites (CdMoO 4 : g-C 3 N 4 mass ratio = 0.4:1) exhibited excellent photocatalytic performance, achieving over 90% MTZ degradation rate in 5 h, with a total organic carbon removal rate of 62%. This efficient degradation performance was mainly due to the Z-scheme-like mechanism of the heterojunction, which significantly facilitated the separation of photogenerated electron-hole pairs. XRD, SEM, and XPS analyses further revealed the tight interfacial contact formed between the CdMoO 4 nanorods and g-C 3 N 4 , while free radical trapping experiments confirmed that hydroxyl radicals were the main active species in the degradation process. In addition, the catalyst still maintained stable structure and catalytic activity after six cycles, showing good practical application potential and providing a feasible solution for the treatment of antibiotic wastewater.