Sequential doping of exogenous iron and nitrogen to prepare Fe-N structured biochar to enhance the activity of OTC degradation

In order to prepare high-performance biochar for application in the treatment of antibiotic wastewater by persulfate oxidation, the feasibility of preparing Fe-N biochar from waste chestnut shells by sequential doping of exogenous iron, nitrogen was investigated. Biochar containing Fe-N structure (Fe3N-BC) was successfully prepared by using K2FeO4 as the iron source and urea as the nitrogen source. It can effectively activate PS and remove 98% of oxytetracycline (OTC) within 20 min. The main mechanism of PS activation by Fe3N-BC for OTC degradation is a non-radical pathway dominated by 1O2 generation and direct electron transfer. The formation of Fe-N structure in biochar changed the electron distribution on the catalyst surface and improved the electron transfer efficiency while inhibiting the leaching of iron ions, verifying the unique role of heteroatoms in iron-based catalysts. The study also identified the degradation intermediates of OTC and suggested possible degradation pathways. Showing that demethylation, deamidation and dehydroxylation are the prior steps for degradation. This study provides a new idea for the preparation of Fe-N structured biochar for OTC degradation.