Elution of Uranium and Transition Metals from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater Horng-Bin Pan Li-Jung Kuo Chien M. Wai Naomi Miyamoto Ruma Joshi Jordana R. Wood Jonathan E. Strivens Christopher J. Janke Yatsandra Oyola Sadananda Das Richard T. Mayes Gary A. Gill 10.1021/acs.iecr.5b03307.s001 https://acs.figshare.com/articles/journal_contribution/Elution_of_Uranium_and_Transition_Metals_from_Amidoxime_Based_Polymer_Adsorbents_for_Sequestering_Uranium_from_Seawater/2104636 High-surface-area amidoxime and carboxylic acid grafted polymer adsorbents developed at Oak Ridge National Laboratory were tested for sequestering uranium in a flowing seawater flume system at the PNNL-Marine Sciences Laboratory. FTIR spectra indicate that a KOH conditioning process is necessary to remove the proton from the carboxylic acid and make the sorbent effective for sequestering uranium from seawater. The alkaline conditioning process also converts the amidoxime groups to carboxylate groups in the adsorbent. Both Na<sub>2</sub>CO<sub>3</sub>–H<sub>2</sub>O<sub>2</sub> and hydrochloric acid elution methods can remove ∼95% of the uranium sequestered by the adsorbent after 42 days of exposure in real seawater. The Na<sub>2</sub>CO<sub>3</sub>–H<sub>2</sub>O<sub>2</sub> elution method is more selective for uranium than conventional acid elution. Iron and vanadium are the two major transition metals competing with uranium for adsorption to the amidoxime-based adsorbents in real seawater. Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt, 1 M) can remove iron from the adsorbent very effectively at pH around 7. The coordination between vanadium­(V) and amidoxime is also discussed based on our <sup>51</sup>V NMR data. 2015-11-30 00:00:00 Oak Ridge National Laboratory 51 V NMR data carboxylic acid hydrochloric acid elution methods FTIR CO KOH conditioning process seawater flume system Uranium amidoxime sequestering uranium adsorbent vanadium