Title : Ferrocene – catalyzed heterogeneous fenton-like degradation mechanisms and pathways of antibiotics under simulated sunlight: a case study of sulfamethoxazole
Antibiotics are widely used in aquaculture, stockbreeding, and human medicine. They are of great concern as many of them can induce bacterial resistance and resistant genes even at environmental concentrations. Recently, antibiotics have been detected worldwide in surface waters as well as wastewaters with their concentration levels as high as mg/L. Therefore, advanced treatment and remediation technology of antibiotic pollution are urgently needed. -OH-based heterogeneous Fenton-like oxidation process has been proved to be an effective approach for the removal of organic pollutants. However, the complex preparation processes and high cost of catalyst restrict the practical application for the removal of pollutants. In this study, Ferrocene (Fe) was introduced to establish a heterogeneous photo-Fenton system for the degradation of sulfonamide antibiotics, taking sulfamethoxazole as a representative. The results showed that the removal of sulfamethoxazole was effective in Fc-catalyzed photo-Fenton system as compared to other control system (Fe, H2O2 or Fc/H2O2 under irradiation). Electron spin resonance and radical scavenging experiments verified that there was a photoindued electron transfer process from Fc to H2O2 and dissolved oxygen resulting in the formation of hydroxyl radical (-OH) that was primarily responsible for the degradation of sulfamethoxazole in the Fc-catalyzed photo-Fenton system. The reactions of -OH with substructure model compounds of sulfamethoxazole unveiled that aniline moiety was the preferable reaction site of sulfamethoxazole with -OH, which was verified by the formation of hydroxylated product and the dimer of sulfamethoxazole in Fc-catalyzed photo- Fenton system. This heterogeneous photo-Fenton system displayed an effective degradation efficiency even in a complex water matrix, and Fc represented a long-term stability by using the catalyst for multiple cycles. The observation that dissolved organic matter, HCO3−, and Cl−/Br− at environmentally relevant concentrations, -OH scavengers, did not dramatically retard the degradation, which is positive from an application viewpoint. These results demonstrate that Fe-catalyzed photo- Fenton oxidation may be an efficient approach for the remediation of wastewater containing antibiotics, and provides new remediation strategy for the organic wastewater.
Audience Take Away:
• The audience can identify radical species in photocatalyzed system using electron spin resonance and radical scavenging methods.
• A heterogeneous photo-Fenton system based on ferrocene (Fe) was developed for the elimination of organic pollutants in wastewater, which provides new remediation method for organic wastewater and is helpful for filling the knowledge gap of heterogeneous photo-Fenton theory.
• Even in a complex water matrix, this heterogeneous photo-Fenton system still manifests an effective degradation
efficiency, which is indicative of well application prospect.