Highly enhanced heterogeneous photo-Fenton process for tetracycline degradation by Fe/SCN Fenton-like catalyst

To suppress the electron–hole recombination and enhance the electron transfer on carbon nitride, an Fe-doped porous carbon nitride catalyst (Fe/SCN) was synthesized via supramolecular self-assembly method and applied in heterogeneous Fenton activation for efficient tetracycline (TC) degradation. Various characterizations revealed that the catalyst exhibited excellent visible light capture performance and electron transfer capacity. The highest degradation efficiency and mineralization rate of TC (10 mg L⁻¹) were achieved under neutral condition (90.3% and 61.2%, respectively) with the leaching of Fe less than 14 μg L⁻¹. Free radical quenching experiments and spin-resonance spectroscopy characterizations revealed the dominating role of [rad]OH in TC degradation, and density functional theory calculation confirmed the formation of Fe-N_X and revealed the interaction between Fe sites and H₂O₂. Three possible pathways of TC degradation were proposed, and the biological inhibition test revealed the potential of Fe/SCN/H₂O₂ system to reduce environmental risks caused by TC. This work provides a new insight into the design of metal-doped heterogeneous Fenton catalyst for the efficient degradation of antibiotic contaminants in water.