Degradation of ofloxacin by activation of persulfate with metal-N co-doped modified peanut shell biochar: The key role of cobalt doping

Recently, pollution caused by the extensive use of ofloxacin (OFX) antibiotics has had a profound impact on human health and environmental ecosystems. Herein, two types of biochar materials, namely cobalt‑nitrogen and iron‑nitrogen co-doped modified peanut shell biochar (Co-N-BC and Fe-N-BC, respectively), were synthesized using a hydrothermal pyrolysis method and then employed to activate persulfate (PS) for OFX degradation. The results showed that Co/Fe and N atoms were successfully loaded onto the surface and inside the biochar. Under optimal conditions, the degradation rate of OFX by Co-N-BC/PS was 93.99 %, whereas that of Fe-N-BC/PS reached 77.37 % within 120 min. After three cycles, the OFX degradation rate remained notably high, exceeding 60 % for both the Co-N-BC/PS and Fe-N-BC/PS samples. Hydroxyl radicals, sulfate radicals, and singlet oxygen were involved in both systems during OFX degradation. Four pathways for OFX degradation were proposed for the Co-N-BC/PS system, whereas the Fe-N-BC/PS system included three pathways. The Toxicity Evaluation Software Tool (T.E.S.T.) estimation showed that the toxicity of the OFX degradation intermediates decreased after treatment with Co-N-BC/PS and Fe-N-BC/PS. Overall, this study showed that these novel biochar catalysts can provide a new direction for the purification of wastewater laden with OFX antibiotics.