Degradation of oxytetracycline hydrochloride using photocatalysis in the presence of Fe3O4/rGO/Co-doped ZnO/g-C3N4 nanocomposite particles: Experiment, modeling, optimization and mechanistic evaluation

In recent years, semiconductor materials have shown excellent potential in the field of photocatalytic degradation of antibiotics. To prepare a photocatalyst with excellent performance, an Fe3O4/rGO/Co-doped ZnO/g-C3N4 tetrameric hybrid photocatalyst was successfully prepared for the first time by means of chemical pre-cipitation using graphene oxide as the precursor. The developed quaternary photocatalyst was used for the degradation of oxytetracycline hydrochloride (OTC), and its photocatalytic activity was investigated. The structure and morphology of the composites were characterized by XRD, SEM, HR-TEM, ESR, N-2 adsorption, PL spectroscopy and UV-Vis DRS. The effects of different parameters on the degradation process were studied by the response surface method and artificial intelligence. The results showed that Fe3O4/rGO/Co-doped ZnO/g-C3N4 was successfully synthesized. Under optimal conditions, the degradation rate of OTC was approximately 82% (the Fe3O4/rGO/Co-doped ZnO/g-C3N4 dose was 0.16 g, the pH was 7.0, the initial concentration of OTC was 30 mg/L, and the visible light irradiation time was 70 min). pH is the most influential variable for OTC removal. At the same time, the degradation rate of OTC remained above 50% after 5 times of recycling, indicating that Fe3O4/rGO/Co-doped ZnO/g-C3N4 photocatalyst had good stability and recoverability. In addition, the results of ESR and radical trapping experiments showed that center dot O-2(-) and center dot OH were the main active species in the OTC removal process.