title: Ozonation of indomethacin: Kinetics, mechanisms and toxicity.
abstract: Ozonation of a commonly used non-steroidal anti-inflammatory drug indomethacin (IM) was studied. Kinetic constants of IM with ozone and hydroxyl radicals were measured at an order of magnitude of 105M-1s-1and 109M-1s-1, respectively. IM was degraded within 7min under the lowest ozone dose, but TOC removal was only 50% even under the highest ozone dose used in the experiments. Ozone rather than hydroxyl radicals was found to be the main oxidant during reaction, with a contribution rate of 80% under pH 7. Six intermediates were identified by high resolution mass spectrometer. Nitrogen atom, CC double bond and benzene ring were found to be the main reaction sites. Electrophilic attack or Criegee cyclo-addition were proved to be the most probable pathways at the first step. The formation mechanism of one of the ozone products was first proposed during the experiment, then confirmed by the density functional theory (DFT) calculation. Acetic acid, formic acid and oxalic acid were detected as small molecule organic products. The toxicity change during ozonation was measured by luminescent bacterium with results showing that the toxicity can be reduced to zero when ozone dose was high enough.
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Jiangmeng
authors.initials: J
authors.lastname: Kuang
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, and Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, China.
authors.forename: Siyu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Shubo
authors.initials: S
authors.lastname: Deng
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
authors.forename: Yujue
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China. Electronic address: yg-den@mail.tsinghua.edu.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
mesh_terms: D004350:Drug Residues / Q000737:chemistry / Q000633:toxicity; D007213:Indomethacin / Q000737:chemistry* / Q000633:toxicity*; D007700:Kinetics; D009584:Nitrogen / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D010776:Photobacterium / Q000187:drug effects; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D010126:Ozone; D009584:Nitrogen; D007213:Indomethacin
keywords: Kinetics; Mechanism; Ozonation; Pharmaceuticals and personal care products; Toxicity