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NANO-SCALE PALLADIUM DOPED MAGNESIUM BIMETALLICS FOR DECHLORINATING PCBS
Citation:
AGARWAL, S., S. R. AL-ABED, AND D. D. DIONYSIOU. NANO-SCALE PALLADIUM DOPED MAGNESIUM BIMETALLICS FOR DECHLORINATING PCBS. Presented at American Chemical Society National Meeting, Chicago, IL, March 25 - 29, 2007.
Impact/Purpose:
to present information
Description:
Polychlorinated biphenyls (PCBs) are toxic and recalcitrant pollutants found in rivers; coastal waters and in 500 of the nation's 1598 Superfund waste sites. According to an EPA estimate, the existing 525 million tons of PCB wastes will cost $394 billion to be incinerated, currently the most commonly used treatment technique for PCBs. A promising remediation technology is catalytic dechlorination using bimetallic systems wherein the enhanced corrosion of a reactive metal is combined with the catalytic hydrogenation properties of a noble metal to drive the reduction of PCBs at the bimetallic interface. Pd/Fe bimetallic systems have been widely researched. In this study, we tested Mg as a substrate in Pd doped bimetallic systems for dechlorinating 2-chlorobiphenyl (2-ClBP), a model PCB. Mg is a promising substrate owing to its high oxidation potential and unique corrosion properties. For this investigation, Pd/Mg particles were synthesized using a novel wet-chemistry procedure which produced bimetallic particles with nano-scaled Pd-islands. Aqueous 2-ClBP matrices were effectively degraded using these particles. The dechlorination kinetics was determined to be directly proportional to the total Pd content of the system. Experiments were also conducted to assess the potential of the particles to dechlorinate PCBs in sediment and clays. The results suggest that Pd/Mg bimetallic particles work well not only in soil-water slurry systems aided by enhanced extraction using organic solvents, but in stand-alone water-slurry systems as well. Results from these studies will be presented. A proposed mechanism for PCB dechlorination in Pd/Mg systems will also be discussed.