Rapid charge transfer and non-radical pathways induced by nanoconfined Fe species/S(IV) system realized complete sulfadiazine degradation

A nanoconfinement strategy was employed to encapsulate iron species within carbon nanotubes (Fe-CCNTs) in this study, enabling rapid degradation of sulfadiazine (SDZ) through sulfite (S(IV)) activation. The Fe-CCNTs catalyst enhanced the generation of reactive species during the S(IV) activation process. Nearly complete SDZ degradation was achieved within 10 min, with a reaction rate constant 1.8 times higher than that of the non-confined system. Fe-CCNTs shifted the mechanism from a radical pathway (SO 4 • − and •OH) to a non-radical pathway ( 1 O 2 and Fe IV =O), thereby improving SDZ degradation efficiency. The nanoconfinement effect increased the local charge density, accelerating electron transfer and promoting the formation of reactive species. This system exhibited strong catalytic performance, high reusability, and resistance to interference. Furthermore, the Fe-CCNTs/S(IV) treatment reduced the abundance of intestinal pathogenic bacteria and the toxicity of byproducts. The Fe-CCNTs/S(IV) system offers a promising and low-toxicity solution for antibiotic removal in water treatment.