Exploring the processes that control uranyl reduction by magnetite and the growth of nanoparticulate surface precipitates by X-ray scattering and X-ray absorption spectroscopy
EMSL Project ID
42192
Abstract
Uranium (U) has been released into the environment through mining operations, nuclear testing, and accidental spills, and is a contaminant in soils, sediments and groundwater at 70% of the Department of Energy (DOE) facilities. Developing accurate predictive models of subsurface U transport in contaminated environments is a major goal of the DOE Environmental Remediation Sciences Program (ERSP). Understanding the fundamental processes by which U can be sequestered into an immobile phase (including adsorption, precipitation, and reduction) is critically important in attaining this goal. In particular, it is unclear what the role calcium (Ca) has in U(VI) adsorption and reduction at mineral surfaces, such as magnetite. This project aims to determine the size, structure, composition, and morphology of U(VI)-surface complexes and U(VI)-bearing nanoprecipitates. This study will use a suite of complimentary techniques including transmission electron and scanning probe microscopy and counterpart synchrotron-based X-ray scattering and X-ray absorption spectroscopy using magnetite thin films and single crystals. These techniques will provide information to accurately describe sorption complexes and surface precipitates from the initial exposure of magnetite to aqueous U solution species, and the transformations that occur during nucleation and particle growth. Understanding the geochemical controls on these processes from the molecular scale and up is critical to better predict the long-term potential for U retention or migration.
Project Details
Project type
Exploratory Research
Start Date
2010-11-05
End Date
2011-11-06
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Singer, D. M.; Chatman, S. M.; Ilton, E. S.; Rosso, K. M.; Banfield, J. F.; Waychunas, G. A., Identification of Simultaneous U(VI) Sorption Complexes and U(IV) Nanoprecipitates on the Magnetite (111) Surface. Environmental Science & Technology 2012, 46, (7), 3811-3820.
Singer, D. M.; Chatman, S. M.; Ilton, E. S.; Rosso, K. M.; Banfield, J. F.; Waychunas, G. A., U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface. Environmental Science & Technology 2012, 46, (7), 3821-3830.