Synthesis of Fe3O4 Derived from Acid Mine Drainage (AMD) Sludge and Catalytic Degradation of Tetracycline.

Acid mine drainage (AMD) sludge is waste generated in the process of acid mine wastewater treatment, and the use of AMD sludge to prepare Fe₃O₄ to activate H₂O₂ degradation pollutants is an effective means of resource utilization. In this study, the heterogeneous catalyst Fe₃O₄-based composites were synthesized by a one-step method using AMD sludge as a raw material, and the Fe₃O₄-based materials before and after catalysis were characterized by powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of several key factors (pH values, H₂O₂ content, TC concentration, and Fe₃O₄ content) of tetracycline (TC) degradation were evaluated. The results revealed that the TC removal rate reached up to 95% within 120 min under optimal conditions (pH 3; H₂O₂, 5 mmol/L; TC concentration, 25 mg/L; Fe₃O₄ content, 1g/L). Moreover, ^•OH and ^•O₂^- radicals were generated during the Fenton-like degradation process, and the plausible degradation mechanism was discussed. Besides, the Fe₃O₄ catalyst exhibited fantastic stability after five cycles. In conclusion, this study is expected to promote the resource utilization of industrial sludge and provide a new material for the treatment of antibiotic-contaminated wastewater.