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Stabilization of Plutonium Nano-Colloids by Epitaxial Distortion on Mineral Surfaces.

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Bibliographic Details
Title: Stabilization of Plutonium Nano-Colloids by Epitaxial Distortion on Mineral Surfaces.
Authors: Powell, Brian A.1 bpowell@clemson.edu, Zurong Dai2, Zavarin, Mavrik2, Pihong Zhao2, Kersting, Annie B.2
Source: Environmental Science & Technology. 4/1/2011, Vol. 45 Issue 7, p2698-2703. 6p.
Subject Terms: *Environmental chemistry, *Plutonium, *Radioactive waste disposal & the environment, Nanofluids, Transmission electron microscopy, Radioactive waste characterization, Diffusion in hydrology
Abstract: The subsurface migration of Pu may be enhanced by the presence of colloidal ferns of Pu. Therefore, complete evaluation of the risk posed by subsurface Pu contamination needs to include a detailed physical/chemical understanding of Pu colloid formation and interactions of Pu colloids with environmentally relevant solid phases. Transmission electron microscopy (TEM) was used to characterize Pu nanucolloids and interactions of Pu nanocolloids with goethite and quartz. We report that intrinsic Pu nanocolloids generated in the absence of goethite or quartz were 2-5 nm in diameter, and both electron diffraction analysis and HRTEM confirm the expected Fm3m space group with the fcc, PuO2 structure. Plutonium nanocolloids formed on goethite have undergone a lattice distortion relative to the ideal fluorite-type structure, fcc, PoO2, resulting in the formation of a bcc, Pu4O7 structure. This structural distortion results from an epitaxial growth of the plutonium colloid on goethite, leading to stronger binding of plutonium to goethite compared with other minerals such as quartz: where the distortion was not observed. This finding provides new insight for understanding how molecular-scale behavior at the mineral-water interface may facilitate transport of plutonium at the field scale. [ABSTRACT FROM AUTHOR]
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Abstract:The subsurface migration of Pu may be enhanced by the presence of colloidal ferns of Pu. Therefore, complete evaluation of the risk posed by subsurface Pu contamination needs to include a detailed physical/chemical understanding of Pu colloid formation and interactions of Pu colloids with environmentally relevant solid phases. Transmission electron microscopy (TEM) was used to characterize Pu nanucolloids and interactions of Pu nanocolloids with goethite and quartz. We report that intrinsic Pu nanocolloids generated in the absence of goethite or quartz were 2-5 nm in diameter, and both electron diffraction analysis and HRTEM confirm the expected Fm3m space group with the fcc, PuO2 structure. Plutonium nanocolloids formed on goethite have undergone a lattice distortion relative to the ideal fluorite-type structure, fcc, PoO2, resulting in the formation of a bcc, Pu4O7 structure. This structural distortion results from an epitaxial growth of the plutonium colloid on goethite, leading to stronger binding of plutonium to goethite compared with other minerals such as quartz: where the distortion was not observed. This finding provides new insight for understanding how molecular-scale behavior at the mineral-water interface may facilitate transport of plutonium at the field scale. [ABSTRACT FROM AUTHOR]
ISSN:0013936X
DOI:10.1021/es1033487