High-efficiency removal of tetracycline by carbon-bridge-doped g-C3N4/Fe3O4 magnetic heterogeneous catalyst through photo-Fenton process

Carbon-bridge-modified malonamide (MLD)/g-C3N4 (CN) was prepared by copolymerization of MLD with urea and melamine and loaded with Fe3O4 for the high-efficiency removal of tetracycline (TC) in water under photo-Fenton. The prepared catalysts were characterized by SEM, TEM, N-2 adsorption-desorption analysis, XPS, XRD, and FTIR, which proved that the modification method successfully introduced the C bridge into the carbon nitride molecular system and increased the structural defects of the catalyst. The Carbon-bridge-modified MLD/CN/Fe3O4 also had good visible-light response and charge-separation and transport abilities in the photo-electrochemical test. Degradation results showed that the photo-Fenton degradation of TC reached 95.8%, and the mineralization rate was 55.7% within 80 min at 80 mM H2O2 dosage, 0.5 g/L catalyst dosage, and near-neutral pH by 0.8MLD/CN/Fe3O4. Moreover, the oxidation products and mineralization pathways of TC were explored by LC-MS. Toxicity analysis indicated low environmental threat of the intermediates in TC minerali-zation. EPR analysis and H2O2 decomposition efficiency analyses showed an improvement in the H2O2 decom-position performance of 0.8MLD/CN/Fe3O4. This work could provide a valuable insight for the application of heterogeneous photo-Fenton technology in wastewater treatment.

Automated summary

The carbon-bridge-modified malonamide/g-C3N4/Fe3O4 catalyst was prepared for efficient removal of tetracycline in water, showing good performance and environmental friendliness.