Project Summary (2005-2008)

Versatile technologies are required for the development of effective techniques for dechlorination of hazardous organics utilizing both oxidative and reductive pathways. Chlorinated organics range from chloroethylenes (such as the degreasing solvent, trichloroethylene, TCE), chlorophenols, polychlorinated biphenyls (PCBs), etc. Many chlorinated organics are toxic even at low concentrations, and exert a cumulative, deleterious effect on the environment. The overall objective of this project is to develop iron-based oxidative (with Fe(II) chelates) and reductive (zero valent Fe with dopants such as, Ni, Pd) platforms suitable for highly effective remediation strategies for selected chloro-organic detoxification (PCBs and TCE). Dr. Bhattacharyya's recent research has shown the benefits of chelate-modified hydroxyl radical-based oxidative reaction and nanosized zero valent metals for reductive dechlorination. The fundamental understanding of these reactive systems is critical for sustainable use involving remediation. For the oxidative systems, this research examines in-situ generation of hydrogen peroxide by enzymes, immobilization of polychelates (such as poly-acrylic acid) on inert particles for controlled release of Fe(ll), which is needed for hydroxyl radical formation, and control of dechlorination rates. The reductive platform examines synthesis of nanosized Fe/Ni and Fe/Pd bimetallic systems using chemical reductants (such as borohydride) and by a novel particle formation method using electrochemical technique within conducting polymers. This research requires several studies involving development of materials, reagent immobilization techniques, quantification of surface morphology, parent compound and intermediates analysis for establishing reaction rates and carbon balance closure, and reaction kinetic parameters for remediation needs. Because hazardous waste and Superfund sites often contain a mixture of organics, the simultaneous development of both oxidative and reductive remediation techniques should provide more flexibility and more tractable approaches.