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 chelat ed heavy metal compounds using electron beam and gamma radiation. Para meter analyses include the effect of dissolved oxygen and the influenc e 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 h ave also studied the radiation induced degradation of polychlorinated biphenyls (PCBs) in aqueous-organic and aqueous micellar systems. Rate s and extent of dechlorination have been quantified in different solut ion matrices; reaction byproducts and intermediate species have been i dentified; and the influences of dissolved oxygen and pH have been eva luated. The presence of a carbonate buffer was observed to significant ly enhance PCB dechlorination yields by reducing concentrations of H3O +. Ionizing radiation was effective in degrading PCBs in micellar solu tions but scavenging of e(aq)(-) by the surfactant lowered reaction ef ficiencies.