title: Mechanism of Intrinsic Chemiluminescence Production from the Degradation of Persistent Chlorinated Phenols by the Fenton System: A Structure-Activity Relationship Study and the Critical Role of Quinoid and Semiquinone Radical Intermediates.
abstract: We found recently that intrinsic chemiluminescence (CL) could be produced by all 19 chlorophenolic persistent organic pollutants during environmentally friendly advanced oxidation processes. However, the underlying mechanism for the structure-activity relationship (SAR, i.e., the chemical structures and the CL generation) remains unclear. In this study, we found that, for all 19 chlorophenol congeners tested, the CL increased with an increasing number of chlorine atoms in general; and for chlorophenol isomers (such as the 6 trichlorophenols), the CL decreased in the order of meta- > ortho-/para-Cl-substituents with respect to the -OH group of chlorophenols. Further studies showed that not only chlorinated quinoid intermediates but also, more interestingly, chlorinated semiquinone radicals were produced during the degradation of trichlorophenols by the Fenton reagent; and the type and yield of which were determined by the directing effects, hydrogen bonding, and steric hindrance effect of the OH- and/or Cl-substitution groups. More importantly, a good correlation was observed between the formation of these quinoid intermediates and CL generation, which could fully explain the above SAR findings. This represents the first report on the structure-activity relationship study and the critical role of quinoid and semiquinone radical intermediates, which may have broad chemical and environmental implications for future studies on remediation of other halogenated persistent organic pollutants by advanced oxidation processes.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.|Science and Technology College, North China Electric Power University , Baoding, P.R. China 071051.
authors.forename: Hui-Ying
authors.initials: HY
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Li
authors.initials: L
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Lin-Na
authors.initials: LN
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Jie
authors.initials: J
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.
authors.forename: Bo
authors.initials: B
authors.lastname: Shao
authors.affiliation: Department of Biophysics, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States.
authors.forename: Balaraman
authors.initials: B
authors.lastname: Kalyanaraman
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences and University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing, P.R. China 100085.|Linus Pauling Institute, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Ben-Zhan
authors.identifier: 0000-0001-5484-4290
authors.initials: BZ
authors.lastname: Zhu
mesh_terms: D002733:Chlorophenols / Q000737:chemistry; D049449:Luminescence; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D002733:Chlorophenols; D010636:Phenols