title: Trichloroethylene degradation by persulphate with magnetite as a heterogeneous activator in aqueous solution.
abstract: Iron oxide-magnetite (Fe3O4) as a heterogeneous activator to activate persulphate anions (S2O8(2-)) for trichloroethylene (TCE) degradation was investigated in this study. The experimental results showed that TCE could be completely oxidized within 5 h by using 5 g L(-1) magnetite and 63 mM S2O8(2-), indicating the effectiveness of the process for TCE removal. Various factors of the process, including. (S2O8(2-) and magnetite dosages, and initial solution pH, were evaluated, and TCE degradation fitted well to the pseudo-first-order kinetic model. The calculated kinetic rate constant was increased with increasing S2O8(2-) and magnetite dosages, but it was independent of solution pH. In addition, the changes of magnetite morphology examined by scanning electron microscopy and X-ray powder diffraction, respectively, confirmed the slight corrosion with α-Fe2O3 coated on the magnetite surface. The probe compounds tests clearly identified the generation of the reactive oxygen species in the system. While the free radical quenching studies further demonstrated that •SO4- and •OH were the major radicals responsible for TCE degradation, whereas •O2- contributed less in the system, and therefore the roles of reactive oxygen species on TCE degradation mechanisms were proposed accordingly. To our best knowledge, this is the first time the performance and mechanism of magnetite-activated persulphate oxidation for TCE degradation are reported. The findings of this study provided a new insight into the heterogeneous catalysis mechanism and showed a great potential for the practical application of this technique in in situ TCE-contaminated groundwater remediation.
authors.affiliation: a State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process , East China University of Science and Technology , Shanghai 200237 , People's Republic of China.
authors.forename: Xiaoxin
authors.initials: X
authors.lastname: Ruan
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Gu
authors.forename: Shuguang
authors.initials: S
authors.lastname: Lu
authors.forename: Zhaofu
authors.initials: Z
authors.lastname: Qiu
authors.forename: Qian
authors.initials: Q
authors.lastname: Sui
mesh_terms: D052203:Ferrosoferric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry*; D014241:Trichloroethylene / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017382:Reactive Oxygen Species; D013431:Sulfates; D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; D052203:Ferrosoferric Oxide
keywords: groundwater remediation; magnetite; persulphate activation; reactive oxygen species; trichloroethylene