Antibiotics are acknowledged micropollutants in wastewaters and surface waters. They are of particular concern because they can trigger an increase in resistant bacteria. Therefore, novel and efficient technology for the removal of antibiotics is urgently needed. In this study, heterogeneous Fenton-like reaction based on ferrocene (Fc) had been constructed, sulfamethazine (SMZ) was selected as target compound due to its abundance in water. The degradation kinetics, transformation pathway, and degradation products of SMZ in this system were investigated. The results showed that Fc+H2O2+UV had better degradation efficiency for SMZ than did Fc, Fc+UV, H2O2, and H2O2+UV, Fc+H2O2 systems. Radical scavenger experiments confirmed that the photogenerated OH was largely responsible for the photolytic enhancement of SMZ in the Fc+H2O2+UV system. Additionally, the electron spin resonance technique revealed that photogenerated O2- was found in the system, indicating that Fc can generate electrons under light conditions. H2O2 underwent electron disproportionation to produce OH, which promoted the degradation of SMZ. The degradation products of SMZ in the Fc+H2O2+UV system were identified by LC/LTQ-Orbitrap MS. The hydroxylation of SMZ, the removal of SO2, and the products of breaking C-S, S-N, and N-C bonds were observed. Common soluble components (such as DOM, Cl-, and Br-) in water can quench OH, thus inhibiting the photodegradation of SMZ. However, the ionic strength had no significant effect on the degradation of SMZ in the Fc+H2O2+UV system, which showed that this technique positively affected the treatment of wastewater containing high-salinity antibiotics.
Keywords: ferrocene; heterogeneous Fenton-like reaction; hydroxyl radicals; photodegradation behavior; sulfamethazine.