title: Degradation of trichloroethene by siderite-catalyzed hydrogen peroxide and persulfate: Investigation of reaction mechanisms and degradation products.
abstract: A binary catalytic system, siderite-catalyzed hydrogen peroxide (H2O2) coupled with persulfate (S2O82-), was investigated for the remediation of trichloroethene (TCE) contamination. Batch experiments were conducted to investigate reaction mechanisms, oxidant decomposition rates, and degradation products. By using high performance liquid chromatography (HPLC) coupled with electron paramagnetic resonance (EPR), we identified four radicals (hydroxyl (HO·), sulfate (SO4-·), hydroperoxyl (HO2·), and superoxide (O2-·)) in the siderite-catalyzed H2O2-S2O82-system. In the absence of S2O82-(i.e., siderite-catalyzed H2O2), a majority of H2O2was decomposed in the first hour of the experiment, resulting in the waste of HO·. The addition of S2O82-moderated the H2O2decomposition rate, producing a more sustainable release of hydroxyl radicals that improved the treatment efficiency. Furthermore, the heat released by H2O2decomposition accelerated the activation of S2O82-, and the resultant SO4-· was the primary oxidative agent during the first two hours of the reaction. Dichloroacetic acid was firstly detected by ion chromatography (IC). The results of this study indicate a new insight to the reaction mechanism for the catalytic binary H2O2-S2O82-oxidant system, and the delineation of radicals and the discovery of the chlorinated byproduct provide useful information for efficient treatment of chlorinated-solvent contamination in groundwater.
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering/School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China ; Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Ni
authors.initials: N
authors.lastname: Yan
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering/School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering/School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xue
authors.affiliation: Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Brusseau
authors.affiliation: Beijing Key Laboratory of Water Resources and Environmental Engineering/School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Yali
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Development Research Center of the Ministry of Water Resources, Beijing 100038, PR China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Wang
keywords: Advanced oxidation; Byproduct; Chlorinated solvent; Radical identification