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: 4.53). 12/2004; 116(3):219-28. DOI: 10.1016/j.jhazmat.2004.09.005
Source: PubMed


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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    • "Some authors suggest that catalysts like Pd and Ni could absorb the H 2 produced by iron corrosion into its lattice to form a transitional compound that can accelerate the reductive dechlorination of the COCs (Xu et al., 2005, Wang et al., 2013). On the other hand, other researchers have advanced that the removal mechanism by bimetallic NP is based on the attack of the hydrogen produced by ZVI corrosion to the contaminant that is adsorbed onto the surface of the metal acting as a catalyst, resulting in the dechlorination of the COC (the parent compound and its chlorinated degradation compounds) (Cwiertny et al., 2007; Schrick et al., 2002; Lin et al., 2004). However, the studies to elucidate the mechanism of bimetallic NP operation are still scarce or plainly lacking. "
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    ABSTRACT: The objective of this work was to review efficient nanomaterials for chlorin-ated organic compounds (COCs) treatment, use of supports and stabilizers that improve the process, interactions of nanomaterials with the microorganisms involved. Also emerging fields such as efficient nanomaterials for COCs treatment, use of supports and stabilizers that improve the process, interactions of nanomaterials with the microorganisms involved, nanoparticles made by microorganism, inter alia, were critically reviewed. INTRODUCTION The chlorinated organic compounds (COCs) are classified as persistent organic compounds due to their physical chemical properties; their degradation is slow and tends to accumulate in fatty tissues of various animals throughout the food chain. The use of COCs in industrial processes started in the mid of the 20th century, in applications such as plastics manufacture (vinyl chloride), aerosols, cleaning and degreasing metals (perchlorethylene, trichloroethylene), chemical manufacturing (dichloromethane, chloroform), additives paints and adhesives (dichloromethane, trichloroethane), pulp and paper industry (dioxins, furans), manufacture of pesticides (hexachlorobenzene and others), etc. Chlorinated aliphatic compounds (CACs), with perchloroethylene (PCE) as the most significant representative, are also COCs of a great environmental significance. Their improper handling and storage have caused contamination of soil and aquifers. CACs are potentially toxic and carcinogenic; they have been linked to damages to liver, lungs, and nervous system (Aschergrau et al., 2003; OEHHA, 2001). The metal particles and nanoparticles (NPs), particularly Fe particles, have been used for treating organochlorine compounds due to the ability of these metals to reduce chlorinated compounds. So far, the main chlorinated compound that has been removed using this technology is PCE and its metabolites trichloroethylene (TCE), dichloroehtyl-ene (DCE), and vinyl chloride (VC). Thus, this work presents a review that encompasses topics such as efficient nano-materials for chlorinated compounds; supports and stabilizers that improve the process; interactions of nanomaterials with the microorganisms involved; and emerging fields.
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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. "
    Dataset: p2013i1

    Full-text · Dataset · May 2014
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    • "In 2004, the U.S. Environmental Protection Agency [6] reported that of the 976 National Priorities List (1982–2003), a large number of these sites contain both BTEX and chlorinated compounds. The most popular technologies used for BTEX and chlorinated solvents remediation are biodegradation (microbial oxidation, [1,7–11]) and zero-valent iron (ZVI, [12] [13] [14] [15] [16] [17]). These two technologies can be combined to treat the mixed plumes of BTEX and chlorinated compounds. "
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