title: Quantitative characterization of hydroxyl radical generation in a goethite-catalyzed Fenton-like reaction.
abstract: In order to find out the truth of influence of solution chemistry on the oxidation efficiency of a goethite-catalyzed Fenton-like reaction, the amount of hydroxyl radicals (OH) was quantified by using coumarin as its trapping agent to produce the only fluorescent derivative 7-hydroxycoumarin (7-HC), because OH was the reactive species responsible for the oxidation activity of Fenton reactions. The concentration of OH achieved maximum at solution pH of 3 and decreased with an increase of solution pH value. However, considerable amount of OH can also generate at near neutral pH (i.e. pH 6 and 7). The concentration of OH was increased both with increasing of goethite and H2O2 dosages, but H2O2 could compete with coumarin to scavenge OH to reduce the formation of 7-HC when the concentration of H2O2 was too high. Anions inhibited OH generation followed an order of H2PO4(-)>SO4(2-)>Cl(-)>NO3(-)>ClO4(-). Higher concentrations of Cl(-) and SO4(2-) resulted in greater inhibition of OH generation. Results of this study demonstrated that the influence of solution chemistry on the oxidation efficiency of the goethite-catalyzed Fenton-like reaction was greatly attributed to the effect of solution chemistry on the amount of OH formed in the process of reaction.
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Lin
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: zhaoling@issas.ac.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yuan-Hua
authors.initials: YH
authors.lastname: Dong
mesh_terms: D002384:Catalysis; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000032:analysis* / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D058085:Iron Compounds; D008903:Minerals; C094886:goethite; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D007501:Iron
keywords: 7-Hydroxycoumarin; Goethite; Heterogeneous Fenton-like reaction; Hydroxyl radical; Quantitative characterization