title: Concentration-dependent photodegradation kinetics and hydroxyl-radical oxidation of phenicol antibiotics.
abstract: Thiamphenicol and florfenicol are two phenicol antibiotics widely used in aquaculture and are ubiquitous as micropollutants in surface waters. The present study investigated their photodegradation kinetics, hydroxyl-radical (OH) oxidation reactivities and products. Firstly, the photolytic kinetics of the phenicols in pure water was studied as a function of initial concentrations (C0) under UV-vis irradiation (λ>200nm). It was found that the kinetics was influenced by C0. A linear plot of the pseudo-first-order rate constant vs C0 was observed with a negative slope. Secondly, the reaction between the phenicol antibiotics and OH was examined with a competition kinetic method under simulated solar irradiation (λ>290nm), which quantified their bimolecular reaction rate constants of (2.13±0.02)×10(9)M(-1)s(-1) and (1.82±0.10)×10(9)M(-1)s(-1) for thiamphenicol and florfenicol, respectively. Then the corresponding OH oxidated half-lives in sunlit surface waters were calculated to be 90.5-106.1h. Some main intermediates were formed from the reaction, which suggested that the two phenicols underwent hydroxylation, oxygenation and dehydrogenation when OH existed. These results are of importance to assess the phenicol persistence in wastewater treatment and sunlit surface waters.
authors.affiliation: College of Ocean Technology and Environment, Dalian Ocean University, Dalian 116023, China; Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China. Electronic address: lkge@nmemc.gov.cn.
authors.forename: Linke
authors.initials: L
authors.lastname: Ge
authors.affiliation: Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Ren
authors.affiliation: Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Yu
authors.affiliation: Institute of Environmental Resource & Soil Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Ocean Technology and Environment, Dalian Ocean University, Dalian 116023, China.
authors.forename: Yuanfeng
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D017665:Hydroxyl Radical / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010782:Photolysis; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry*; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D017665:Hydroxyl Radical; D013839:Thiamphenicol; D062065:Wastewater; C035534:florfenicol
keywords: Competition kinetics; Phenicol antibiotics; Photolysis; Photooxidation; Transformation products