Parts of This Report Contain Proprietary Information Disclosed in a Patent Disclosure to Colorado State

The goals of this program have been to develop a series of new compounds that act as redoxrecyclable heavy metal ion selective materials. This has been a preliminary exploration into the viability of creating materials that act as selective exchange media. We have historically been involved in the separation of ionic pollutants such as radionuclides or toxic heavy metal ions from water by designing extractants with high selectivities and large capacities. We have also recognized that there is a more urgent need to develop processes that allow the target pollutants to be recovered in a minimal volume of secondary waste and that allow the extractants to be reused or recycled. We have been studying redoxactive transition-metal-containing extractants that undergo reversible electron transfer activation and deactivation as the target ions are extracted and recovered or that undergo .efficient, selective ion exchange. The redox-recyclable extractants investigated so far include molecular organometallic complexes such as substituted ferrocenes and layered metal chalcogenides or oxochalcogenides such as MoS, and Zr(HSPO&. The molecular complexes can be dissolved in water-immiscible organic solvents for solvent-extraction processes or can be immobilized on inert supports for ion-exchange chromatography. The bulk metal chalcogenide solids themselves function as redox-recyclable or ion-exchangeable materials. We have thus demonstrated in the laboratory the viability of design and function of new compounds that are ion-selective solids or selective composites. The proposed work herein will demonstrate the applicability that these materials possess and will study the effectiveness of these and newly developed materials in complex mixtures of ions and organics. Using activated MoS,, greater than 99% of mercury was selectively extracted from an aqueous phase containing 1 M HNO, and 10m3 M Hg2”, reducing the mercury concentration to ppt levels (kn = 10’). Greater than 94% of the mercury could be recovered in elemental form after stripping giving an overall reduction in waste volume of more than 104. These are just a few examples of how we have been able to effectively design and test materials for selective ion removal from simulated contaminated waste streams. New compounds developed in our laboratories provide clear-cut evidence that continued efforts in new materials design and synthesis are effective means to solving mixed waste problems. For example, the reaction between aqueous solutions of zirconium or hafnium chlorides and Na,SPO, result in the formation of a high surface-area gel that can be dried into a powder with a composition M(HSPO,), where M = Zr or Hf. These layered materials provide a surface of HSwithin the interlayer gallery of the solids that are selective for soft metal cations such as lead, mercury or cadmium when in competition with alkali or alkaline earth ions. A view of these layered galleries is shown in Fig 1.