Goals of Project: We are developing multi-functional anion-exchange resins that facilitate anion uptake by carefully controlling the structure of the anion receptor site. We are attempting to determine if the precepts of "bite size," "preorganization," and "bidentate" have an appreciable impact upon electrostatic bonding as they do for covalent bonding. If these precepts do have a positive impact, we will develop new ion-exchange resins that interface the rapidly developing field of ionspecific

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... chelating ligands with robust, commercial ion-exchange technology. The overall objective of our research is to develop a predictive capability that will enable us to design and implement multi-functionalized anion-exchange materials which selectively sorb metal complexes of interest from targeted process, waste, and environmental streams. The following Focus Areas and Crosscutting Programs have described needs that would be favorably impacted by the new materials: Efficient Separations and Processing -radionuclide removal (Pu, U, Am) from aqueous phases Plutonium -Pu, Am or total alpha removal to <30 pCi/L before discharge to the environment Plumes -U and Tc in groundwater; U, Pu, Am, and Tc in soils Mixed Waste -radionuclide partitioning High-Level Tank Waste -actinide and Tc removal from supernatants and/or sludges Technical Description of Work: We determine actinide-complex speciation in specific media, then develop models for the metal complex/functional site interactions Synthesis of multi-functionalized extractants and ionexchange materials that implement key features of the optimized binding site, and testing of these materials, provide feedback to the modeling and design activities. To determine optimal binding site characteristics, we have combined empirical testing with theoretical modeling (applied in an iterative mode). Resin materials that actively facilitate the uptake of actinide complexes from solution should display both improved selectivity and kinetic properties. Our primary implementation of the bifunctionality concept involves N-derivatization of pyridinium units from a base poly(4vinylpyridine) resin with a second cationic site such that the two anion-exchange sites are linked by "spacer" arms of varying length and flexibility.