Cobalt cross-linked ordered mesoporous carbon as peroxymonosulfate activator for sulfamethoxazole degradation

Ordered mesoporous carbons (OMCs) functionalized with catalytically-active metals have many potential applications in sulfate radical-based advanced oxidation processes for degrading antibiotics. Cobalt cross-linked ordered mesoporous carbon materials (OMC-Co-Tx) were synthesized through evaporation-induced self-assembly, calcinated at (600 to 800) oC. The OMC-Co-Tx materials were then employed as peroxymonosulfate (PMS) activators for removal of sulfamethoxazole (SMX) from aqueous solutions. OMC-Co-T800 prepared by calcination at 800 °C had a large specific surface area (449 m2/g), uniform pore structure (∼4.5 nm) and showed the best performance for activation of PMS. With a dosage of 0.1 g/L OMC-Co-T800 and 0.4 g/L PMS, the functionalized OMC material allowed SMX (10 mg/L) removal of up to 99% in 30 min. The increase of calcination temperature promoted the reduction of cobalt in OMC materials and increased the defects in their structure, resulting in better catalyst behavior. Quenching experiments and electron paramagnetic resonance analyses showed that reactive species of sulfamethoxazole degradation involved in the OMC-T800/PMS system were SO4•−, OH, O2•− and 1O2. HPLC-MS analyses of degradation intermediates formed in the OMC-Co-T800/PMS system allowed elucidation of four transformation pathways for SMX degradation.