Boosting activation of peracetic acid by Co@mZVI for efficient degradation of sulfamethoxazole: Interesting two-phase generation of reactive oxidized species

Developing a cost-effective, easy-recycled, pH-independent and efficient activator is promising for the practical application of peracetic acid (PAA) based advanced oxidation process (AOP). In this study, [email protected] was synthesized to activate PAA for successful degradation of 96% sulfamethoxazole (SMX) within 30 min, while only 40% of the SMX could be removed in the mZVI/PAA system. Co-doping of Co extended the pH tolerance of mZVI as indicated by 90%-98% SMX removal efficiency at the initial pH range of 3.0–9.0. Reactive oxidized species (ROS) including organic radicals, hydroxyl radical (•OH) and Fe(IV) were produced from the [email protected]/PAA system. It’s found that the co-doped Co can 1) work as a catalyst to activate PAA with the generation of ROS dominated by CH3CO2• and CH3CO3• in the period of 0–10 min; 2) boost the production of iron ions by accelerating the corrosion of mZVI in the following 10–30 min, in which •OH played a main role in contaminant degradation. The eight intermediate degradation products of SMX resulted from the attack of •OH, CH3CO2• and CH3CO3• were detected and the possible degradation pathways were proposed. The biological acute toxicity of the [email protected] system during the treatment of SMX decreased over the reaction time. Additionally, [email protected] has good recovery ability and stability, suggesting the potential applicability of the [email protected]/PAA system in degrading antibiotics.