nZVI-biochar derived from Fe3O4-loaded rabbit manure for activation of peroxymonosulfate to degrade sulfamethoxazole

The pollution problem of livestock manure generated by the rapid development of farming industry is becoming more and more serious, and its conversion into functional materials through a new way is of great practical significance for its resource utilization. For the first time, nano zero-valent iron (nZVI)/biochar composites (Fe-RMC-850) were prepared by carbonizing Fe3O4-rabbit dung and used to activate PMS for degradation of sulfamethoxazole (SMX). The results showed that Fe-RMC-850 had high catalytic activity due to its rich pore, high graphitization and defective structure. When the dosage of Fe-RMC-850 and PMS were 0.3 g/L and 0.25 g/L respectively, the degradation rate of SMX could reach 100% within 20 min, and it still showed good catalytic stability after 5 cycles of experiments. The radical quenching, EPR and XPS results showed that radical and nonradical pathways acted synergistically in the degradation of SMX, in which nZVI, Fe2+-biochar and pyridinic N were used as the main active sites of the radical pathway. The nonradical pathway was attributed to the generation of C-O and COO by the oxygen-containing functional groups on the biochar surface. Moreover, the inherent P atoms formed PC and CPO3/C2PO2, thereby producing defective structures, while the graphitic carbon layer provided good electron transfer sites. Consequently, this study provides a nZVI-rabbit manure biochar composite PMS catalytic material with high organic pollutant degradation efficiency and offers a new option for the resource utilization of manure sources.