Applications of ionizing radiation to the remediation of materials contaminated with heavy metals and polychlorinated biphenyls

We have investigated the removal from water of heavy metals and chelated heavy metal compounds using electron beam and gamma radiation. Parameter analyses include the effect of dissolved oxygen and the influence of adding various buffers and radical scavengers. Complete removal (>99%) of mercury, lead and cadmium ions, both free and chelated within EDTA, was achieved using radiation doses ranging from 3–100 kGy. We have also studied the radiation induced degradation of polychlorinated biphenyls (PCBs) in aqueous-organic and aqueous micellar systems. Rates and extent of dechlorination have been quantified in different solution matrices; reaction by-products and intermediate species have been identified; and the influences of dissolved oxygen and pH have been evaluated. The presence of a carbonate buffer was observed to significantly enhance PCB dechlorination yields by reducing concentrations of H₃O⁺. Ionizing radiation was effective in degrading PCBs in micellar solutions but scavenging of e_aq⁻ by the surfactant lowered reaction efficiencies.