title: New insights into atrazine degradation by cobalt catalyzed peroxymonosulfate oxidation: kinetics, reaction products and transformation mechanisms.
abstract: The widespread occurrence of atrazine in waters poses potential risk to ecosystem and human health. In this study, we investigated the underlying mechanisms and transformation pathways of atrazine degradation by cobalt catalyzed peroxymonosulfate (Co(II)/PMS). Co(II)/PMS was found to be more efficient for ATZ elimination in aqueous solution than Fe(II)/PMS process. ATZ oxidation by Co(II)/PMS followed pseudo-first-order kinetics, and the reaction rate constant (k(obs)) increased appreciably with increasing Co(II) concentration. Increasing initial PMS concentration favored the decomposition of ATZ, however, no linear relationship between k(obs) and PMS concentration was observed. Higher efficiency of ATZ oxidation was observed around neutral pH, implying the possibility of applying Co(II)/PMS process under environmental realistic conditions. Natural organic matter (NOM), chloride (Cl(-)) and bicarbonate (HCO3(-)) showed detrimental effects on ATZ degradation, particularly at higher concentrations. Eleven products were identified by applying solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC/MS) techniques. Major transformation pathways of ATZ included dealkylation, dechlorination-hydroxylation, and alkyl chain oxidation. Detailed mechanisms responsible for these transformation pathways were discussed. Our results reveal that Co(II)/PMS process might be an efficient technique for remediation of groundwater contaminated by ATZ and structurally related s-triazine herbicides.
authors.affiliation: College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: yuefeiji@njau.edu.cn.
authors.forename: Yuefei
authors.initials: Y
authors.lastname: Ji
authors.affiliation: College of Sciences, Nanjing Agricultural University,Nanjing 210095, China.
authors.forename: Changxun
authors.initials: C
authors.lastname: Dong
authors.affiliation: Nanjing Institute of Environmental Science, Ministry of Environmental Protection of PRC, Nanjing 210042, China.
authors.forename: Deyang
authors.initials: D
authors.lastname: Kong
authors.affiliation: College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: jhlu@njau.edu.cn.
authors.forename: Junhe
authors.initials: J
authors.lastname: Lu
mesh_terms: D001280:Atrazine / Q000737:chemistry*; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006540:Herbicides; D010545:Peroxides; D014874:Water Pollutants, Chemical; C038288:peroxymonosulfate; D003035:Cobalt; D001280:Atrazine
keywords: Atrazine; Cobalt catalyzed peroxymonosulfate; Degradation pathways; Sulfate radical; Transformation mechanism