title: Enhancement effects of reducing agents on the degradation of tetrachloroethene in the Fe(II)/Fe(III) catalyzed percarbonate system.
abstract: In this study, the effects of reducing agents on the degradation of tetrachloroethene (PCE) were investigated in the Fe(II)/Fe(III) catalyzed sodium percarbonate (SPC) system. The addition of reducing agents, including hydroxylamine hydrochloride, sodium sulfite, ascorbic acid and sodium ascorbate, accelerated the Fe(III)/Fe(II) redox cycle, leading to a relatively steady Fe(II) concentration and higher production of free radicals. This, in turn, resulted in enhanced PCE oxidation by SPC, with almost complete PCE removal obtained for appropriate Fe and SPC concentrations. The chemical probe tests, using nitrobenzene and carbon tetrachloride, demonstrated that HO was the predominant radical in the system and that O2(-) played a minor role, which was further confirmed by the results of electron spin resonance measurements. PCE degradation decreased significantly with the addition of isopropanol, a HO scavenger, supporting the hypothesis that HO was primarily responsible for PCE degradation. It is noteworthy that Cl(-) release was slightly delayed in the first 20 min, indicating that intermediate products were produced. However, these intermediates were further degraded, resulting in the complete conversion of PCE to CO2. In conclusion, the use of reducing agents to enhance Fe(II)/Fe(III) catalyzed SPC oxidation appears to be a promising approach for the rapid degradation of organic contaminants in groundwater.
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China; Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, The University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Zhouwei
authors.initials: Z
authors.lastname: Miao
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Gu
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China. Electronic address: lvshuguang@ecust.edu.cn.
authors.forename: Shuguang
authors.initials: S
authors.lastname: Lu
authors.affiliation: Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, The University of Arizona, 429 Shantz Building, Tucson, AZ 85721, United States.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Brusseau
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: Ni
authors.initials: N
authors.lastname: Yan
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Zhaofu
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sui
mesh_terms: D002251:Carbon Tetrachloride / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D002384:Catalysis; D002712:Chlorides / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry; D060587:Groundwater; D009578:Nitrobenzenes / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D019163:Reducing Agents / Q000737:chemistry*; D013750:Tetrachloroethylene / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D002254:Carbonates; D002712:Chlorides; D005290:Ferric Compounds; D005296:Ferrous Compounds; D016166:Free Radical Scavengers; D009578:Nitrobenzenes; D017382:Reactive Oxygen Species; D019163:Reducing Agents; D014874:Water Pollutants, Chemical; D002251:Carbon Tetrachloride; C036077:nitrobenzene; D013750:Tetrachloroethylene; C034738:sodium percarbonate
keywords: Hydroxyl radical (HO); Reducing agents; Sodium percarbonate (SPC); Tetrachloroethene (PCE)