Proposed mechanisms for the dechlorination of PCBs using microscale Mg/Pd in methanol.
The combination of zero-valent metals and hydrogenation catalysts, specifically mechanically alloyed, palladized magnesium (Mg/Pd) has been proven effective in the remediation of polychlorinated biphenyls (PCBs), although the exact mechanism of degradation has yet to be elucidated. Knowing the exact mechanism of dechlorination could prove useful in optimizing the bimetallic Mg/Pd for use in field-scale applications. A variety of experiments have been performed on individual PCB congeners in an attempt to determine the mechanism by which the degradation occurs. Studies have focused on experiments carried out in methanol, however, several studies have also been carried out in water to examine solvent specificity. Results of these studies have suggested three possible solvent specific mechanisms, all of which include the removal of the chlorine atom by hydrogen as the rate limiting step, varying only in the exact nature of the hydrogen species (radical, hydride, or "hydride-like" radical).
American Chemical Society
DeVor, R., Maloney, P., Clausen, C.A., Elsheimer, S., Carvalho-Knighton, K., & Geiger, C.L. (2009). Proposed mechanisms for the dechlorination of PCBs using microscale Mg/Pd in methanol. In C.L. Geiger & K.M. Carvalho-Knighton (Eds.), Environmental Applications of Nanoscale and Microscale Reactive Metal Particles, (pp. 55-74). Washington DC: American Chemical Society. doi: 10.1021/bk-2009-1027.ch004
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