Plutonium(IV) sorption by soluble anion-exchange polymers

Soluble anion-exchange polymers have been designed, synthesized, and evaluated for their ability to take up Pu(IV) from nitric acid solutions. These polymers, based on linear poly(4-vinylpyridine) (PVP) and polyethyleneimine (PEI) are soluble in aqueous and strong acid solutions. Weak-base sites on the polymers are protonated under experimental conditions, and, in most cases, have been converted by alkylation to form mono- and bifunctional strong-base anion-exchange sites. Distribution of Pu(IV) onto these polymers was determined by comparing visible spectroscopic data in the presence and absence of the soluble polymer. Overall plutonium affinity for the anion-exchange sites in the soluble materials is found to be much lower than for comparable solid resins, but the distribution behavior follows similar trends in that bifunctionalized materials are superior to monofunctionalized and a five-atom "spacer" between the two cationic sites is superior to other spacer lengths.