Engineering molten salt‐treated biochar to facilitate periodate activation for sulfamethoxazole degradation through an electron transfer pathway

Abstract Antibiotics pose significant risks to human health and ecosystems due to their environmental persistence and high hydrophilicity. In this study, sulfamethoxazole (SMX) was selected as a target contaminant, and a molten copper chloride‐modified sludge‐derived biochar (Cu‐SBC) was developed to activate periodate (PI) for the efficient removal of antibiotics from water. The results indicated that the introduction of copper significantly altered the surface chemistry of the biochar, thereby simultaneously enhancing its adsorption capacity for SMX and its activation performance toward PI. The Cu‐SBC/PI system achieved complete degradation of SMX within 50 min and exhibited strong environmental adaptability and good reusability. Quenching experiments and electrochemical analyses revealed that SMX degradation predominantly occurred via a non‐radical pathway facilitated by an electron transfer mechanism. Moreover, seed germination tests confirmed the effective detoxification capability of the Cu‐SBC/PI system toward SMX degradation. This study provides a novel strategy for designing sludge‐based biochar catalysts and offers a promising technical approach for the efficient degradation of antibiotics in aquatic environments.