High performance of heterogeneous catalytic ozonation for tetracycline removal by a N-doped biochar derived from co-pyrolysis of sludge and water hyacinth

Enhancing the performance of heterogeneous catalytic ozonation (HCO) for contaminant removal using biochar that is both cost-effective and stable is of great significance. In this research, a novel nitrogen-doped biochar (HSBC) was synthesized through the co-pyrolysis of sludge and water hyacinth. The presence of pyrrolic N, pyridinic N and graphitic N in HSBC as well as the high-temperature co-pyrolysis process, conferred a high degree of graphitization to the biochar. The graphitic N species facilitated the generation of free radicals, while the graphitic structure enhanced electron transfer between the catalyst and tetracycline (TC). HSBC demonstrated exceptional efficiency in TC removal via HCO, achieving a 93% removal rate within just 130 min. Moreover, the biodegradability of actual printing and dyeing wastewater with a chemical oxygen demand (COD) of (9900 mg/L) was increased sevenfold after HCO treatment. This study offers new perspectives on the preparation of N-doped biochar and its practical application in the treatment of industrial wastewater through HCO processes.