NEW BIFUNCTIONAL ANION-EXCHANGE RESINS FOR NUCLEAR WASTE TREATMENT

Several new types of bifunctional anion-exchange resin have been desig ned, synthesized, and tested for their ability to remove Pu(TV) from n itric acid. The functional group present in all of these resins is a p yridinium unit derived from the host poly(4-vinylpyridine) resin. Bifu nctionality was achieved by adding a second anion-exchange site to the pyridine nitrogen via an alkylene spacer that encompassed ethylene th rough hexylene. The attached anion-exchange sites include trimethylamm onium, pyridinium, and trimethylphosphonium. The sorption kinetics and distribution coefficients of Pu(IV) from 5 to 9 M nitric acid general ly were best when the two anion-exchange sites were separated by a fiv e-carbon spacer. The order of affinity for Pu(TV) from 7 M nitric acid was pyridinium>phosphonium>trimethylammonium. Replacing the central m ethylene unit in a five-carbon spacer with an ether-oxygen further enh anced the sorption of Pu(IV) onto the trimethylammonium-containing res in. Because these bifunctional resins are modifications of existing co mmercial Reillex(TM) resins, they are much easier to prepare than resi ns that require complete synthesis. We plan to evaluate these and rela ted bifunctional resin structures for their ability to selectively rem ove other targeted anions from groundwater and industrial waste stream s.