Pine needle biochar loaded with iron-nickel bimetal composite as heterogeneous catalysts to activate peroxymonosulfate for efficient degradation of oxytetracycline

Residual antibiotics in the environment pose a serious threat to the environment. To solve the problems of inter-particle agglomeration, metal ion leaching and difficult recovery of transition metal oxides as catalysis in advanced oxidation processes for the treatment of antibiotic wastewater, pine needle biochar loaded with iron-nickel bimetals (Fe/Ni@PNBC) were successfully produced by the impregnation-co-precipitation method to activate peroxymonosulfate (PMS) for degradation of oxytetracycline (OTC). The Fe/Ni@PNBC catalyst has good surface properties, abundant functional groups and catalytic stability. Under the optimal conditions, the degradation efficiency of OTC with initial concentration of 10 similar to 60 mg/L is close to 90%. In addition, O-1(2) and O-2(center dot-) played a major role in OTC degradation. The reaction mechanism for generation of active species and OTC degradation in the reaction system was proposed from two perspectives including redox of iron and nickel ions in different valence states and interconversion between the active substances. After 5 cycles, Fe/Ni@PNBC still maintained a high catalytic activity for OTC degradation. This study provides a new method to prepare an economical and environmentally friendly catalyst for activating PMS to treat antibiotic wastewater.