Influence of chemical speciation on enrofloxacin degradation by UV irradiation: Kinetics, mechanism and disinfection by-products formation

Solar Photodegradation of a Novel des-F(6)-Fluoroquinolone, Garenoxacin, and Ecotoxicity of Its Phototransformation Products

“…As FQs often contain one or more ionizable functional groups, such as carboxylic and amine, they can exist in various ionization states under environmental pH conditions. As a result, the photodegradation of zwitterionic FQs may exhibit strong dependence on their ionization state due to the varying ability of neutral and charged species to activate molecular oxygen by 3 FQ* de-excitation in self-sensitized photolysis, as well as their different reactivity under the attack of electrophilic reagents (i.e., reactive oxygen species, ROSs). − The ionization of antibiotics has been well observed to result in the apparent pH dependence of their photodegradation rate constants. − For instance, the zwitterionic species of gemifloxacin, balofloxacin, lomefloxacin, norfloxacin, and ofloxacin were found to photodegrade faster than the cationic and anionic ones. , In contrast, the cationic ciprofloxacin species was reported to have the highest photodegradation rate among all chemical forms . The quantum yields for photodegradation of lomefloxacin, norfloxacin, and ofloxacin decreased in the order of zwitterionic > anionic > cationic, and their pathways of photodegradation were found to depend strongly on the ionization state, with more significant defluorination occurring when lomefloxacin and norfloxacin existed in zwitterionic forms …”

Comparison of Organic Matter Properties and Disinfection By-Product Formation between the Typical Groundwater and Surface Water

“…On account of the non-negligible health risks and widespread occurrence of DBPs in drinking water, some countries and organizations have regulated some common DBPs including trihalomethanes (THMs) and haloacetic acid (HAAs) [3]. In addition, nitrogenous disinfection by-products, including haloacetonitriles (HANs) etc., have attracted much attention in recent years because they have higher cytotoxicity and genotoxicity than traditional carbonous disinfection by-products even though they emerge in lower concentrations than THMs and HAAs in drinking water [4,5].…”