Activation of peroxydisulfate by endogenous nitrogen-doped carbon for efficient degradation of sulfamethoxazole

• Endogenous N-doped carbon materials (ENC) is conducted for peroxydisulfate (PDS) activation. • Surface-bound radicals and mediated electron transfer are pivotal for sulfamethoxazole (SMX) degradation. • C=O, pyridinic N and oxidized N are identified as the main active sites for the activation of PDS. • SO₄·⁻ and PDS/ENC* are the key active species in the oxidative decomposition of SMX. An endogenous nitrogen-doped carbon (ENC) was synthesized to activate peroxydisulfate (PDS) for Sulfamethoxazole (SMX) removal using graphitic carbon nitride as the raw material. The characterization of the surface properties of ENC demonstrated that ENC is rich in functional groups and mesoporous structure, coupled with a very large specific surface area (1034.6 m²·g −1 ). The ENC/PDS system demonstrated up to 98.5% degradation capability of SMX within 30 min and maintained over 80% in a complex aqueous environment. Further investigation of the intrinsic mechanism of SMX decomposition by ENC/PDS confirmed the dominant roles of surface-bound radicals and mediated electron transfer, with surface-bound SO₄ · ⁻ and a transient active complex (PDS/ENC*) identified as the key reactive species. This study significantly broadens the scope of nitrogen-doped carbon materials in environmental treatment by conducting an extensive investigation of the ENC/PDS/SMX system. The synthesis of endogenous N-doped carbon materials enables efficient degradation of sulfamethoxazole through two primary pathways: surface-bound radicals and mediated electron transfer, expanding the understanding of the activation mechanism for peroxydisulfate in N-doped carbon materials.