Design of Continuous Fixed Plate Photo-Fenton Reactor Based on Fe3O4/TiO2@Al2SiO5 Fiber Board Photocatalyst and Application in Tetracycline Hydrochloride Degradation

To address the limitations of traditional photo-Fenton reactions in antibiotic wastewater treatment, this study designed a continuous flat-plate photo-Fenton reactor based on the Fe3O4/TiO2@Al2SiO5 fiberboard photocatalyst and applied it to the degradation of tetracycline HCl (TCH). The supported catalyst Fe3O4/TiO2@Al2SiO5 was prepared via a calcination method, using the Al2SiO5 fiberboard as the carrier. This not only effectively addresses the issue of catalyst recovery but also enhances the dispersion and stability of the Fe3O4/TiO2 catalyst as a support. Moreover, the catalyst mainly exhibited an amorphous structure. TiO2 and Fe3O4 were successfully loaded onto the surface of the carrier. The operating parameters of the reactor were systematically optimized, and the optimal conditions were determined as follows: TCH influent concentration of 50 mg/L, hydraulic retention time (HRT) of 120 min, initial pH of 4.5, H2O2 dosage of 10 mmol/L, and ultraviolet (UV) light intensity of 2.36 kW/m3. Under these conditions, the TCH removal efficiency could reach over 90%. Active species trapping experiments indicated that hydroxyl radicals (•OH) were the main active substances responsible for TCH degradation. With the assistance of HPLC-MS/MS and GC-MS analyses, 19 types of degradation intermediates were identified. It was proposed that the TCH degradation pathway mainly included •OH-mediated hydroxylation addition reactions and demethylation reactions initiated by •OH and h+. The toxicity assessment showed that the toxicity of the degradation intermediates gradually decreased with the progress of the reaction. This reactor features high efficiency, stability, and easy operation, providing a feasible solution for the large-scale treatment of antibiotic wastewater.