Acetylperoxyl radical-mediated dual polymerization and mineralization pathways for selective sulfonamide antibiotics removal in pharmaceutical wastewater: A combined experimental and DFT study

Given that the pollution problem of sulfonamide antibiotics (such as sulfamethoxazole, SMX) in pharmaceutical wastewater is particularly prominent, traditional free radical advanced oxidation technologies are limited in practical application due to their susceptibility to matrix interference and the difficulty in recovering powdered catalysts. This study proposes a strategy for the simultaneous decomposition and polymerization of sulfonamide antibiotics based on an electron transfer-mediated peracetic acid (PAA) advanced oxidation system, and systematically investigates the removal mechanism of SMX mediated by CH₃C(O)OO• oxidation. Experimental results show that this system exhibits excellent removal effects on sulfonamide antibiotics such as SMT, SMR, SDZ, and STZ (SDZ > STZ > SMR > SMT, k  = 0.057–0.099 min - 1 ). To achieve engineering application, a CuCoNi-NF/PAA catalytic reactor was developed, maintaining a SMX removal rate of approximately 70% during 20 h of continuous operation, with excellent reusability (effectively regenerated by calcination after 10 consecutive cycles) and low metal ion leaching rate. Overall, this study reports for the first time a heterogeneous PAA activation system based on CuCoNi-NF, which enables the simultaneous polymerization and mineralization of SMX without the addition of external organic small molecules, presenting an electron transfer-mediated advanced oxidation process with strong anti-interference performance and unveiling a previously neglected polymerization pathway in SMX-related AOPs.