Uranium exists uniformly as uranyl carbonate at a concentration of ~3.3 ppb in seawater. Because of the vast volume of the oceans, the total estimated amount of uranium in seawater is 4.5×10<sup>9</sup> tonnes, approximately 1000 times larger than the terrestrial resources. Thus, the extraction of uranium from seawater presents a very attractive alternative source of uranium for nuclear fuel needs. However, a significant challenge remains for making the extraction of uranium from seawater a commercially viable alternative technology. In this study, we have developed an alternative chemical grafting method for adsorbent preparation for uranium recovery from seawater using atom-transfer radical polymerization (ATRP) with post modification as opposed to a conventional method, radiation-induced graft polymerization (RIGP). The ATRP method provides a much higher degree of grafting (d.g.) on the adsorbents than that achieved by RIGP alone. Such a high d.g. and tunability of the graft-chain length and composition (e.g., block copolymers) suggest that this ATRP approach is a promising strategy. This work demonstrated that both amidoxime ligand density and hydrophilicity were crucial for optimal performance. The graft polymerization chemistry and uranium adsorption results were significantly altered depending on the fiber precursors (trunk materials) and graft chain composition. Moreover, the location of a hydrophilic block on the graft chain also affected the uranium adsorption capacity in seawater, unveiling the importance of grafted polymer chain conformation for uranium recovery from seawater. The survey of trunk materials among the fiber adsorbents prepared via ATRP and the effect of graft chain composition and conformation for uranium adsorption in seawater will be discussed in this presentation.<br/>Acknowledgement: This work was sponsored by the US Department of Energy, Office of Nuclear Energy, under contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed by UT-Battelle, LLC.

Advanced fiber adsorbents for recovery of uranium from seawater prepared via controlled radical polymerization

249th National Meeting (2015)

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