Nitrogen-doped Fe-MOFs derived carbon as PMS activator for efficient degradation of tetracycline

Tetracycline (TC) poses a significant threat to ecosystems and human health. Advanced oxidation techniques based on persulfates are increasingly investigated for their environmental friendliness and efficiency. Co-pyrolysis of melamine (MA) and Fe-MOFs can avoid the accumulation of MOFs and produce structural nitrogen and defective structures, thus enhancing the catalytic activity of the catalyst. Fe-NPC was prepared by co-pyrolysis using MIL-101-Fe and MA. The effects of MA/MIL-101-Fe ratio, dosages of catalyst and PMS, initial pH and co-existing ions were discussed. The catalysts were characterized by XRD, SEM, BET, and VSM, and the degradation mechanism was analyzed using EPR, LC-MS, and XPS characterization of the catalysts before and after use. Results showed that approximately 90% of TC was removed within 20 min using 15 mg Fe-NPC, 30 mg PMS at 25℃. Co-existing ions and humic acid had no apparent effect on TC degradation efficiency in the Fe-NPC-600/PMS system. The Fe species and pyridinic N played significant roles in activating PMS and therefore achieving high efficiency of TC degradation. 1O2 was identified as the dominant reactive species in the Fe-NPC-600 system. Four possible TC degradation pathways were confirmed. The catalyst maintains a good circulation effect after five cycles.