Carbonized poly(dopamine)@Co0 composites for the high-efficient removal of sulfamethoxazole: Role of direct electron-transfer and adsorption

[Display omitted] •A novel CPDA@Co0 catalyst was synthesized via a simple and green approach.•CPDA@Co0/PS system was efficient over a wide pH range.•There was synergistic effect between adsorption and catalysis.•Core-shell structure could efficiently protect inner Co0 core from leaching.•CPDA@Co0 could be easily separated and reused at least 5 times. It is great challenge to design a simple approach to prepare Co-based N-doped carbon catalysts with high activity and minimum impact to the environment. Here, a novel carbonized poly(dopamine)-coated cobalt nanocomposite (CPDA@Co0) was synthesized via a simple and “zero-organic solvents” approach and employed to activate persulfate (PS) for sulfamethoxazole (SMX) degradation. The CPDA@Co0/PS system exhibited outstanding performance on SMX degradation over a wide pH range (3.0–8.5), and facilitated by acidic conditions and Cl-. For fair comparison, CPDA@Co0 under slightly acidic pH exhibited a much higher rate constant (0.121 min−1) than many reported catalysts. A direct electron-transfer pathway played a leading role in the oxidation, while adsorption of SMX on the surface of CPDA@Co0 might be the determining step. Since the synergistic effect between adsorption and catalysis, 10 mg/L SMX could be completely removed within 25 min, which provided a new strategy for removing organic pollutants from wastewater. Besides, the special core–shell structure could efficiently protect inner Co0 core from leaching. CPDA@Co0 could be easily separated via a permanent magnet and reused at least 5 times. This study might inspire others to develop effective and green PS activation processes for application in SMX treatment.