Effects of key reaction parameters on the reductive dechlorination of chloroform with Pd/Fe<sup>0</sup>bimetal in aqueous solution

Xuan, Xiaoli; Li, Xiang-zhong; Wang, Chuan; Liu, Hong

doi:10.1080/10934520903538608

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Procedures to exclude oxygen increases corresponding observed rate constants 3–4 times (Table ). Similarly, the efficiency of chloroform degradation by ZVI/Pd increased 2–4 times with solutions bubbled with O 2 , air, and N 2 . Oxygen should oxidize iron particles (eq ) and compete with debromination, as well as water reduction which generates H 2 on the Pd or Fe surface (eq ). Fe 0 + 1 2 normalO 2 + 2 normalH 2 normalO → Fe 2 + + normalH 2 normalO + 2 OH −- Fe 0 + 2 normalH 2 normalO → Fe 2 + + normalH 2 + 2 OH − Both iron corrosion and reduction reactions contribute to an increase of pH.…”

Section: Resultsmentioning

confidence: 99%

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Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Zhuang

Ahn

Seyfferth

et al. 2011

Environ. Sci. Technol.

171

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Nanoscale zerovalent iron particles (nZVI), bimetallic nanoparticles (nZVI/Pd), and nZVI/Pd impregnated activated carbon (nZVI/Pd-AC) composite particles were synthesized and investigated for their effectiveness to remove polybrominated diphenyl ethers (PBDEs) and/or polychlorinated biphenyls (PCBs). Palladization of nZVI promoted the dehalogenation kinetics for mono- to tri-BDEs and 2,3,4-trichlorobiphenyl (PCB 21). Compared to nZVI, the iron-normalized rate constants for nZVI/Pd were about 2-, 3-, and 4-orders of magnitude greater for tri-, di-, and mono-BDEs, respectively, with diphenyl ether as a main reaction product. The reaction kinetics and pathways suggest an H-atom transfer mechanism. The reaction pathways with nZVI/Pd favor preferential removal of para-halogens on PBDEs and PCBs. X-ray fluorescence mapping of nZVI/Pd-AC showed that Pd mainly deposits on the outer part of particles, while Fe was present throughout the activated carbon particles. While BDE 21 was sorbed onto activated carbon composites quickly, debromination was slower compared to reaction with freely dispersed nZVI/Pd. Our XPS and chemical data suggest about 7% of the total iron within the activated carbon was zero-valent, which shows the difficulty with in-situ synthesis of a significant fraction of zero-valent iron in the micro-porous material. Related factors that likely hinder the reaction with nZVI/Pd-AC are the heterogenous distribution of nZVI and Pd on activated carbon and/or immobilization of hydrophobic organic contaminants at the adsorption sites thereby inhibiting contact with nZVI.

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Section: Resultsmentioning

confidence: 99%

“…Similarly, the efficiency of chloroform degradation by ZVI/Pd increased 2À4 times with solutions bubbled with O 2 , air, and N 2 . 16 Oxygen should oxidize iron particles (eq 1) and compete with debromination, as well as water reduction which generates H 2 on the Pd or Fe surface (eq 2).…”

Section: Articlementioning

confidence: 99%

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Zhuang

Ahn

Seyfferth

et al. 2011

Environ. Sci. Technol.

171

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“…[1][2][3][4] The degradation products of TCE for ZVI were found to be ethane, ethylene, vinyl chloride (VC), 1,1-dichloroethylene (1,1-DCE), and cis-1,1-dichloroethylene (cis-1,1-DCE). [4] First-order degradation rate constants were found to be directly proportional to the surface area of the zero-valent iron.…”

Section: Introductionmentioning

confidence: 99%

Degradation of trichloroethylene using iron, bimetals and trimetals

Chao

Ong

Fryzek

et al. 2012

Journal of Environmental Science and Health, Part A

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A cold, electrodeless method was used to prepare bimetals (Fe/Cu, Fe/Ni) and trimetals (Fe/Cu/Ni) for the treatment of trichloroethylene (TCE). With Fe/Cu, the degradation of TCE was observed to increase with increasing copper content up to 9.26 % (w/w) with a first-order degradation rate constant approximately 10 times faster than that of zero-valent iron (ZVI) alone. For copper content greater than 9.26 %, the TCE degradation rate decreased. Dechlorinated compounds were initially observed but they were transitory and accounted for no more than 9 % of initial TCE mass on a carbon molar basis. Ethylene was the primary end product of TCE reduction. Similarly for Fe/Ni, increasing rates of degradation were observed with increasing amounts of nickel with a maximum degradation rate constant of about 30 times higher than that of ZVI alone. However, the amount of nickel needed to reach the maximum rate was only 0.25 %. When copper and nickel were plated onto iron, the maximum reaction rate constant was approximately 50 times higher than that of ZVI. The maximum degradation of TCE was observed for a copper and nickel content of 4.17 % and 0.40 %, respectively. The experimental results indicated that TCE degradation was enhanced by more than one order of magnitude when copper and/or nickel was plated onto the zero-valent iron. However, copper or nickel plated onto iron by the elctrodeless process was found to leach out during the reaction which may, in turn, impact the contaminated water.

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Perfluorooctane sulfonate (PFOS) removal with Pd0/nFe0 nanoparticles: Adsorption or aqueous Fe-complexation, not transformation?

Park

Zenobio

Lee

2018

Journal of Hazardous Materials

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Effects of key reaction parameters on the reductive dechlorination of chloroform with Pd/Fe⁰bimetal in aqueous solution

Abstract: This is the Pre-Published Version.

Cited by 5 publications

References 24 publications

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Degradation of trichloroethylene using iron, bimetals and trimetals

Perfluorooctane sulfonate (PFOS) removal with Pd0/nFe0 nanoparticles: Adsorption or aqueous Fe-complexation, not transformation?

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Effects of key reaction parameters on the reductive dechlorination of chloroform with Pd/Fe0bimetal in aqueous solution

Abstract: This is the Pre-Published Version.

Cited by 5 publications

References 24 publications

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyl by Bimetallic, Impregnated, and Nanoscale Zerovalent Iron

Degradation of trichloroethylene using iron, bimetals and trimetals

Perfluorooctane sulfonate (PFOS) removal with Pd0/nFe0 nanoparticles: Adsorption or aqueous Fe-complexation, not transformation?

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Effects of key reaction parameters on the reductive dechlorination of chloroform with Pd/Fe⁰bimetal in aqueous solution