You are here:
PRACTICAL APPROACHES TO REMEDIATION OF POLYCHLORINATED BIPHENYLS IN SEDIMENTS
Citation:
FANG, Y. AND S. R. AL-ABED. PRACTICAL APPROACHES TO REMEDIATION OF POLYCHLORINATED BIPHENYLS IN SEDIMENTS. Presented at American Chemical Society National Meeting, Chicago, IL, March 25 - 29, 2007.
Impact/Purpose:
to present information
Description:
Polychlorinated biphenyls (PCBs) are one group of persistent organic pollutants (POPs) of international concern because of global distribution, persistence, and toxicity. Removal of these compounds from the environment presents a very tough challenge because they are highly hydrophobic and have very low solubility in water and because they are recalcitrant to chemical and biological degradations. Although there are few promising technologies, such as dechlorination using palladium-modified granular graphite electrode, palladized zerovalent iron, nanoparticles of iron or iron-palladium bimetals, which demonstrate effective dechlorination of PCBs in water and water-solvent mixtures, application of these technologies to remediation of PCBs in sediment systems face significant challenges: (a) very slow desorption of PCBs from sediments to the aqueous phase; (b) untested effectiveness of the technologies in sediment slurry matrix; (c) the life time of the reactive media such Fe and Fe/Pd "nanoparticles in sediment systems. This paper presents experimental results of Fe/Pd catalyzed dechlorination of PCBs in sediment slurries - the rate of dechlorination of 2-chlorobiphenyl (a target PCB compound) in sediment slurries was much slower than the values observed in water and water-solvent mixtures and the dechlorination process was significantly affected by the concentration of dissolved organic matters (DOM). Theoretical analysis of dechlorination of PCBs in sediment slurry supernatants indicate that the overall rate constant is a function of desorption rate constant, DOM concentration, PCB partitioning coefficient, and dechlorination rate constant. The theoretical result provides a fundamental relationship for understanding the process of remediation of PCBs in sediment system, for selecting appropriate technologies, and for developing innovative processes to optimize the remediation process.