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Title: Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents

Abstract

Adsorbents developed for the recovery of uranium from seawater display poor selectivity over other transition metals present in the ocean, with vanadium particularly problematic. To improve selectivity, an indispensable step is the positive identification of metal binding environments following actual seawater deployment. In this work we apply x-ray absorption fine structure (XAFS) spectroscopy to directly investigate the vanadium binding environment on seawater-deployed polyamidoxime adsorbents. Comparison of the x-ray absorption near edge spectra (XANES) reveal marked similarities to recently a reported non-oxido vanadium (V) structure formed upon binding with cyclic imidedioxime, a byproduct of generating amidoxime functionalities. Density functional theory (DFT) calculations provided a series of putative vanadium binding environments for both vanadium (IV) and vanadium (V) oxidation states, and with both amidoxime and cyclic imidedioxime. Fits of the extended XAFS (EXAFS) data confirmed vanadium (V) is bound exclusively by the cyclic imidedioxime moiety in a 1:2 metal:ligand fashion, though a modest structural distortion is also observed compared to crystal structure data and computationally optimized geometries which is attributed to morphology effects from the polymer graft chain and the absence of crystal packing interactions. These results demonstrate that improved selectivity for uranium over vanadium can be achieved by suppressing the formationmore » of cyclic imidedioxime during preparation of polyamidoxime adsorbents for seawater uranium recovery.« less

Authors:
 [1];  [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]
  1. Lawrence Berkeley National Laboratory (LBNL)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE), Fuel Cycle Technologies (NE-5)
OSTI Identifier:
1410923
Report Number(s):
ORNL/TM-2017/470
102788
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zhang, Zhicheng, Rao, Linfeng, Abney, Carter W., Bryantsev, Vyacheslav, and Ivanov, Aleksandr. Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents. United States: N. p., 2017. Web. doi:10.2172/1410923.
Zhang, Zhicheng, Rao, Linfeng, Abney, Carter W., Bryantsev, Vyacheslav, & Ivanov, Aleksandr. Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents. United States. doi:10.2172/1410923.
Zhang, Zhicheng, Rao, Linfeng, Abney, Carter W., Bryantsev, Vyacheslav, and Ivanov, Aleksandr. Fri . "Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents". United States. doi:10.2172/1410923. https://www.osti.gov/servlets/purl/1410923.
@article{osti_1410923,
title = {Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents},
author = {Zhang, Zhicheng and Rao, Linfeng and Abney, Carter W. and Bryantsev, Vyacheslav and Ivanov, Aleksandr},
abstractNote = {Adsorbents developed for the recovery of uranium from seawater display poor selectivity over other transition metals present in the ocean, with vanadium particularly problematic. To improve selectivity, an indispensable step is the positive identification of metal binding environments following actual seawater deployment. In this work we apply x-ray absorption fine structure (XAFS) spectroscopy to directly investigate the vanadium binding environment on seawater-deployed polyamidoxime adsorbents. Comparison of the x-ray absorption near edge spectra (XANES) reveal marked similarities to recently a reported non-oxido vanadium (V) structure formed upon binding with cyclic imidedioxime, a byproduct of generating amidoxime functionalities. Density functional theory (DFT) calculations provided a series of putative vanadium binding environments for both vanadium (IV) and vanadium (V) oxidation states, and with both amidoxime and cyclic imidedioxime. Fits of the extended XAFS (EXAFS) data confirmed vanadium (V) is bound exclusively by the cyclic imidedioxime moiety in a 1:2 metal:ligand fashion, though a modest structural distortion is also observed compared to crystal structure data and computationally optimized geometries which is attributed to morphology effects from the polymer graft chain and the absence of crystal packing interactions. These results demonstrate that improved selectivity for uranium over vanadium can be achieved by suppressing the formation of cyclic imidedioxime during preparation of polyamidoxime adsorbents for seawater uranium recovery.},
doi = {10.2172/1410923},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 2017},
month = {Fri Sep 01 00:00:00 EDT 2017}
}

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