Roles of singlet oxygen and dissolved organic matter in self-sensitized photo-oxidation of antibiotic norfloxacin under sunlight irradiation
MetadataShow full item record
Many fluoroquinolone (FLQ) antibiotics undergo rapid photodegradation in sunlit waters and form multifaceted photo-products. The high photodegradation rate is primarily ascribed to their photosensitizing properties. Though widely studied, the photo-reaction pathways are not completely revealed; photo-products mediated by different reactive oxygen species are not identified. In our study, photo-degradation of fluoroquinolone norfloxacin was investigated. A rapid degradation in buffered water was observed with a first-order rate constant of 2.45/hr and a quantum yield of 0.039. After light screening correction, selected DOMs (5 mg C/L) slightly enhanced the photodegradation rate with the exception of Suwannee river hydrophobic organic matter (SR-HPO). Three major photo-products were identified using high resolution mass spectrometry (HRMS). With 1O2 dark formation and competitor experiments, norfloxacin self-sensitized 1O2 was found to oxidize norfloxacin by inducing its piperazine chain cleavage. DOMs exhibited a dual role by inhibiting the 1O2-mediated reaction while enhancing the heterolytic defluorination pathway. DOMs were proposed to enhance heterolytic defluorination by donating electron to triplet state FLQ, this proposal was supported with specific UV absorbance (SUVA) as an indicator for the abundance of p bonds. Fluoride formation indicated a 79% elimination ratio of fluorine, an important functional group for antimicrobial activity. This work provides important new insights into the photochemical fate of fluoroquinolone antibiotics in natural water.
Showing items related by title, author, creator and subject.
Research progress of perovskite materials in photocatalysis- and photovoltaics-related energy conversion and environmental treatmentWang, Wei; Tadé, M.; Shao, Zongping (2015)Meeting the growing global energy demand is one of the important challenges of the 21st century. Currently over 80% of the world's energy requirements are supplied by the combustion of fossil fuels, which promotes global ...
Black NiO-TiO2 nanorods for solar photocatalysis: Recognition of electronic structure and reaction mechanismLiu, J.; Li, Y.; Ke, J.; Wang, Shaobin; Wang, L.; Xiao, H. (2018)This work provides an engineering guide to construct active sites on TiO 2 nanorods (NRs) by coupling p-type black NiO nanoclusters (E g = 1.42 eV) with rich crystal defects and match-up band structure for excellent solar ...
Photodegradation of sulfathiazole under simulated sunlight: Kinetics, photo-induced structural rearrangement, and antimicrobial activities of photoproductsNiu, X.; Glady-Croué, J.; Croue, Jean-Philippe (2017)© 2017 Elsevier Ltd Photolysis is a core natural process impacting the fate of some sulfonamide antibiotics in sunlit waters. In this study, sunlight-induced phototransformation of sulfathiazole was investigated. A ...