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Title: Probing the interaction of U (VI) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy

The fundamental interaction of U (VI) with diethylphosphatoethyl triethoxysilane functionalized SBA-15 mesoporous silica is studied by macroscopic batch experiments and solid-state NMR spectroscopy. DPTS-functionalized silica has been shown to extract U (VI) from nitric acid solutions at or above pH 3. Extraction is dependent on pH and ionic strength. Single-pulse 31P NMR on U (VI) contacted samples revealed that U (VI)only interacts with a fraction of the ligands present on the surface. At pH 4 the U (VI) extraction capacity of the material is limited to 27ā€“37% of the theoretical capacity, based on ligand loading. We combined single pulse 31P NMR on U (VI)-contacted samples with batch studies to measure a ligand-to-metal ratio of approximately 2 : 1 at pH 3 and 4. Batch studies and cross-polarization NMR measurements reveal that U (VI) binds to deprotonated phosphonate and/or silanol sites. We use 31Pā€“ 31P DQ-DRENAR NMR studies to compare the average dipolar coupling between phosphorus spins for both U (VI)-complexed and non-complexed ligand environments. Furthermore, these measurements reveal that U (VI) extraction is not limited by inadequate surface distribution of ligands, but rather by low stability of the surface phosphonate complex.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1]
  1. Univ. of California, Berkeley, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-689079
Journal ID: ISSN 1477-9226; ICHBD9
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Dalton Transactions
Additional Journal Information:
Journal Volume: 45; Journal Issue: 25; Journal ID: ISSN 1477-9226
Publisher:
Royal Society of Chemistry
Research Org:
Lawrence Livermore National Lab., Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
OSTI Identifier:
1281682

Uribe, Eva C., Mason, Harris E., Shusterman, Jennifer A., Bruchet, Anthony, and Nitsche, Heino. Probing the interaction of U(VI) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy. United States: N. p., Web. doi:10.1039/C6DT01200K.
Uribe, Eva C., Mason, Harris E., Shusterman, Jennifer A., Bruchet, Anthony, & Nitsche, Heino. Probing the interaction of U(VI) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy. United States. doi:10.1039/C6DT01200K.
Uribe, Eva C., Mason, Harris E., Shusterman, Jennifer A., Bruchet, Anthony, and Nitsche, Heino. 2016. "Probing the interaction of U(VI) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy". United States. doi:10.1039/C6DT01200K. https://www.osti.gov/servlets/purl/1281682.
@article{osti_1281682,
title = {Probing the interaction of U(VI) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy},
author = {Uribe, Eva C. and Mason, Harris E. and Shusterman, Jennifer A. and Bruchet, Anthony and Nitsche, Heino},
abstractNote = {The fundamental interaction of U(VI) with diethylphosphatoethyl triethoxysilane functionalized SBA-15 mesoporous silica is studied by macroscopic batch experiments and solid-state NMR spectroscopy. DPTS-functionalized silica has been shown to extract U(VI) from nitric acid solutions at or above pH 3. Extraction is dependent on pH and ionic strength. Single-pulse 31P NMR on U(VI) contacted samples revealed that U(VI)only interacts with a fraction of the ligands present on the surface. At pH 4 the U(VI) extraction capacity of the material is limited to 27ā€“37% of the theoretical capacity, based on ligand loading. We combined single pulse 31P NMR on U(VI)-contacted samples with batch studies to measure a ligand-to-metal ratio of approximately 2 : 1 at pH 3 and 4. Batch studies and cross-polarization NMR measurements reveal that U(VI) binds to deprotonated phosphonate and/or silanol sites. We use 31Pā€“31P DQ-DRENAR NMR studies to compare the average dipolar coupling between phosphorus spins for both U(VI)-complexed and non-complexed ligand environments. Furthermore, these measurements reveal that U(VI) extraction is not limited by inadequate surface distribution of ligands, but rather by low stability of the surface phosphonate complex.},
doi = {10.1039/C6DT01200K},
journal = {Dalton Transactions},
number = 25,
volume = 45,
place = {United States},
year = {2016},
month = {5}
}