Mechanism of the degradation of individual PCB congeners using mechanically alloyed Mg/Pd in methanol

    Authors

    R. Devor; K. Carvalho-Knighton; B. Aitken; P. Maloney; E. Holland; L. Talalaj; S. Elsheimer; C. A. Clausen;C. L. Geiger

    Comments

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    Abbreviated Journal Title

    Chemosphere

    Keywords

    Polychlorinated biphenyls; PCB; Zero-valent metals; Mechanism; Hydrogen; POLYCHLORINATED-BIPHENYLS; RAPID DECHLORINATION; IRON; WATER; PARTICLES; ORGANICS; PD/FE; Environmental Sciences

    Abstract

    Polychlorinated biphenyls (PCBs) are a continuing concern in the environment, although legislation restricting the production and use of PCBs was introduced more than 30 years ago. The combination of zero-valent metals and hydrogenation catalysts has been proven effective in the remediation of PCBs, although the exact mechanism of degradation is not known as of yet. The use of mechanically alloyed zero-valent magnesium and palladium (on graphite) has shown great success in the dechlorination of PCBS. Knowing the mechanism for this dechlorination would be helpful in optimizing the bimetallic Mg/Pd for use in the field. A variety of experiments have been performed on a single PCB congener (PCB-151, 2,2',3,5,5',6-polychlorobiphenyl) in an attempt to determine the mechanism by which the degradation occurs. The studies are carried out in methanol to mimic the solvent system which will be used in field applications. Results of these studies have suggested three possible mechanisms, all of which include the removal of the chlorine atom by a hydrogen as the rate-limiting step, varying only in the exact nature of the hydrogen species (radical, hydride, or "hydride-like" radical). Brief. A series of studies has suggested three possible mechanistic pathways for the degradation of PCBs in methanol by Mg/Pd. (C) 2009 Elsevier Ltd. All rights reserved.

    Journal Title

    Chemosphere

    Volume

    76

    Issue/Number

    6

    Publication Date

    1-1-2009

    Document Type

    Article

    Language

    English

    First Page

    761

    Last Page

    766

    WOS Identifier

    WOS:000269243900006

    ISSN

    0045-6535

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