Local Structure Investigations of Sequential Sorption of U and Fe on Polyacrylamide Hydroxamic Acid Resins

Uranium- and iron-containing waste simulated effluent has been treated sequentially with a novel resin, viz., polyacrylamide hydroxamic acid (PAAHA). The motivation is to investigate the competitive interactions with transition metals during the removal of radiologically and chemically toxic uranium. The sequential sorption results indicate that the resin is more Fe selective compared to U and it retains more iron. X-ray absorption fine structure measurements, which comprise of both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques, have been carried out on the PAAHA resin at the Fe K-edge and U L₃-edge to probe the change in the local coordination environment on sequential sorption of uranium and iron. EXAFS measurements conclude that the U-O distances and coordination are modified when the treatment sequences of U and Fe are interchanged, whereas the Fe local structure remains intact. The results obtained from EXAFS measurements have been verified by detail analysis of XANES data.