A novel solid-state NMR method for the investigation of trivalent lanthanide sorption on amorphous silica at low surface loadings.
The modelling of radionuclide transport in the subsurface depends on a comprehensive understanding of their interactions with mineral surfaces. Spectroscopic techniques provide important insight into these processes directly, but at high concentrations are sometimes hindered by safety concerns and limited solubilities of many radionuclides, especially the actinides. Here we use Eu(iii) as a surrogate for trivalent actinide species, and study Eu(iii) sorption on the silica surface at pH 5 where sorption is fairly limited. We have applied a novel, surface selective solid-state nuclear magnetic resonance (NMR) technique to provide information about Eu binding at the silica surface at estimated surface loadings ranging from 0.1 to 3 nmol m(-2) (<0.1% surface loading). The NMR results show that inner sphere Eu(iii) complexes are evenly distributed across the silica surface at all concentrations, but that at the highest surface loadings there are indications that precipitates may form. These results illustrate that this NMR technique may be applied in solubility-limited systems to differentiate between adsorption and precipitation to better understand the interactions of radionuclides at solid surfaces.
Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA. mason42@lnll.gov.
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Mason
Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA. mason42@lnll.gov.
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Begg
Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA. mason42@lnll.gov.
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Maxwell
Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA. mason42@lnll.gov.
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Kersting
Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA. mason42@lnll.gov.
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Zavarin
D000327:Adsorption; D028581:Lanthanoid Series Elements / Q000032:analysis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011868:Radioisotopes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000032:analysis* / Q000737:chemistry*; D012995:Solubility
D028581:Lanthanoid Series Elements; D011868:Radioisotopes; D012822:Silicon Dioxide