Abstract
Poly(acrylamidoxime) fibers are the current state-of-the-art adsorbent for mining uranium from seawater. However, the competition between uranyl (UO2 2+) and vanadium ions poses a challenge to mining on the industrial scale. In this work, we employ density functional theory and coupled-cluster methods in the restricted formalism to investigate potential binding motifs of the oxovanadium(IV) ion (VO2+) with the formamidoximate ligand. Consistent with experimental extended Xray absorption fine structure data, the hydrated six-coordinate complex is predicted to be preferred over the hydrated fivecoordinate complex. Our investigation of formamidoximate.VO2+ complexes universally identified the most stable binding motif formed by chelating a tautomerically rearranged imino hydroxylamine via the imino nitrogen and hydroxylamine oxygen. The alternative binding motifs for amidoxime chelation via a nonrearranged tautomer and ν2 coordination are found to be ~11 kcal/ mol less stable. Natural bond orbital analysis was performed to understand the nature of the interactions in the VO2+ complexes. The difference in the most stable VO2+ and UO2 2+ binding conformation has important implications for the design of more selective UO2 2+ ligands.
Original language | English |
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Pages (from-to) | 4231-4240 |
Number of pages | 10 |
Journal | Industrial and Engineering Chemistry Research |
Volume | 55 |
Issue number | 15 |
DOIs | |
State | Published - Nov 22 2015 |
Funding
*E-mail: [email protected]. Phone: (865) 576-4272. Fax: (865) 576-7956. Funding This research was sponsored by the U.S. Department of Energy, Office of Nuclear Energy under Contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed by UT-Battelle, LLC. This manuscript has been authored by UT-Battelle, LLC under Contract DE-AC05-00OR22725 with the U.S. Department of Energy. Notes The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The authors declare no competing financial interest. The authors thank Dr. J. Casey Johnson (ORNL) for valuable discussions. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231. This research was sponsored by the U.S. Department of Energy, Office of Nuclear Energy under Contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed by UT-Battelle, LLC. This manuscript has been authored by UTBattelle, LLC under Contract DE-AC05-00OR22725 with the U.S. Department of Energy.