Role of pH on photolytic and photocatalytic degradation of antibiotic oxytetracycline in aqueous solution under visible/solar light:Kinetics and mechanism studies
In this study,the photochemical degradation of the antibiotic oxytetracycline (OTC) at different pH values was investigated in aqueous solution under visible andsolar light irradiation.Particular emphasis was given to the kinetics and mechanism during the photolytic and photocatalytic degradation of OTC.A comparative study of the photolysis of OTC under solar light,with different initial concentrations and in the presence of scavengers of reactive oxygen species (ROS),revealed a self-photosensitization pathway with evidenceof singlet oxygen generation at pH 8.5 and 11.0 during OTC photolysis.The three-dimensional fluorescence spectra of OTC at different pH values demonstrate that OTC only exhibits significant emission spectra at pH 8.5 and 11.0.The change of the internal electrostatic force between the electron withdrawing group and the dehydrogenation moiety of OTC as a fimction of solution pH values was proposed as a critical factor influencing the energy states and observed reaction pathways of OTC under light irradiation.
Chun Zhao Miguel Pelaez Xiaodi Duan Huiping Deng Kevin O Shea Despo-Fatta Kassinos Dionysios D.Dionysiou
Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shangha Environraental Engineering & Science Program, University of Cincinnati, Cincinnati, OH, 45221-0071, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shangha Department of Chemistry and Biochemistry, Florida International University, University Park, Miami, Nireas-lnternational Water Research Centre, University of Cyprus, 20537 Nicosia, Cyprus Environraental Engineering & Science Program, University of Cincinnati, Cincinnati, OH, 45221-0071,