Article

Dechlorination of trichloroethylene in aqueous solution by noble metal-modified iron

Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan.
Journal of Hazardous Materials (Impact Factor: 4.33). 12/2004; 116(3):219-28. DOI: 10.1016/j.jhazmat.2004.09.005
Source: PubMed

ABSTRACT Bimetallic particles are extremely interesting in accelerating the dechlorination of chlorinated organics. Four noble metals (Pd, Pt, Ru and Au), separately deposited onto the iron surface through a spontaneous redox process, promoted the TCE dechlorination rate, and the catalytic activity of the noble metal followed the order of Pd>Ru>Pt>Au. This order was found to be dependent on the concentrations of adsorbed atomic hydrogen, indicating that the initial reaction was cathodically controlled. Little difference in the distribution of the chlorinated products for the four catalysts (cis-DCE: 51%; 1,1-DCE: 27%; trans-DCE: 15% and VC: 7%) was observed. The chlorinated by-products accumulated in both Pt/Fe and Au/Fe (10.3% and 2.5% of the transformed TCE, respectively), but did not accumulate in Pd/Fe and Ru/Fe. Ru/Fe was further examined as an economical alternative to Pd/Fe. The 1.5% Ru/Fe was found to completely degrade TCE within 80 min. Considering the expense, the yield of chlorinated products and the lifetime of a reductive material, Ru provides a potential alternative to Pd as a catalyst in practical applications.

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    • "permeable reactive barrier), high pH condition is typically developed in the reaction zone due to Fe(0) oxidation, but external pH control is not practically feasible once reaction is initiated . Some researchers have employed noble metals such as palladium , nickel, and platinum to promote rate of contaminants reduction by Fe(0) (Kim and Carraway, 2000; Lin et al., 2004; He and Zhao, 2008). Although contaminants can be reduced in bimetallic system more rapidly, high cost of noble metals limits its use in field-scale application. "
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    • "permeable reactive barrier), high pH condition is typically developed in the reaction zone due to Fe(0) oxidation, but external pH control is not practically feasible once reaction is initiated . Some researchers have employed noble metals such as palladium , nickel, and platinum to promote rate of contaminants reduction by Fe(0) (Kim and Carraway, 2000; Lin et al., 2004; He and Zhao, 2008). Although contaminants can be reduced in bimetallic system more rapidly, high cost of noble metals limits its use in field-scale application. "
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