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IMPACT OF VEGETATION ON HEAVY METAL MOVEMENT

Current remediation generally revolves around precipitation techniques, generally using amorphous iron(III) oxyhydroxides. Our recent work has focused on the incorporation of heavy metals into a magnetite (Fe304)matrix. Removal by this technique not only provides the cost effectiveness of using iron compounds for precipitation, but it also avails itself to magnetic separation techniques for waste removal.

Specifically, our work has entailed the removal of actinides and transition metals from water in the presence of potential organic chelators. The metals studied include silver, lead, mercury, cadmium, chromium as well as uranium and thorium. Excellent removal was found for each of these metals in the absence of organics.

The chelating agents selected for study are those commonly found in industrial cleansers. These include EDTA, NTA, ethanolamine, and as well as common long chain oxysurfactants. As would be expected, certain organics do supress metal ion removal from aqueous media. It is assumed that the metal-ligand complexes formed prevent incorporation of the metal ion into the magnetite matrix. Surprisingly however, the presence of certain organics actually enhanced the removal efficiencies. The results of these studies will be discussed in this presentation.

Key words: heavy metals, precipitation techniques, chelating agents, metal ion removal, aqueous media