UraniumVI sorption behavior on silicate mineral mixtures

Prikryl, James D.; Jain, Anima; Turner, David R.; Pabalan, Roberto T.

doi:10.1016/s0169-7722(00)00153-4

Cited by 139 publications

(92 citation statements)

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“…However, significant progress has been made over the past 10 years in the application of more complex adsorption models (e.g., the surface-complexation model) to soils and sediments (Turner et al 1996;Davis et al 1998;Zachara and Westall 1998;Prikryl et al 2001;Arnold et al 2001;Curtis et al 2004;Davis et al 2004a;Barnett et al 2002), leading to the use of these codes and associated application approaches for radionuclide-performance assessment (Turner and Pabalan 1999;Davis et al 2005). Moreover, such codes have been applied to describe U(VI) groundwater-contaminant-plume dynamics associated with uranium-mill tailings (Curtis et al 2006), and are, therefore, applicable to field-scale migration processes.…”

Section: Variable K D Versus Constant Value K Dmentioning

confidence: 99%

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Zachara¹,

Brown²,

Christensen³

et al. 2007

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Executive SummaryUranium (U) is an important risk-driving contaminant at the Hanford Site. Over 200,000 kg have been released to the vadose zone over the course of site operations, and a number of vadose zone and groundwater plumes containing the uranyl cation [UO 2 2+ , U(VI)] have been identified. U is recognized to be of moderate-to-high mobility, conditions dependent. The site is currently making decisions on several of these plumes with long-lasting implications, and others are soon to come.Uranium is one of nature's most intriguing and chemically complex elements. The fate and transport of U(VI) has been studied over the long lifetime of the Hanford Site by various contractors, along with the Pacific Northwest National Laboratory (PNNL) and its collaborators. Significant research has more recently been contributed by the national scientific community with support from the U.S. Department of Energy's (DOE) Office of Science through its Environmental Remediation Sciences Division (ERSD). This report represents a first attempt to integrate these findings into a cohesive view of the subsurface geochemistry of U at the Hanford Site. The objective is to inform all interested Hanford parties about the in-ground inventory of U and its geochemical behavior. This report also comments on the prospects for the development of a robust generic model to more accurately forecast future U(VI) migration at different Hanford waste sites, along with further research necessary to reach this goal.To accomplish the report objectives, the environmental geochemistry of U at the Hanford Site is discussed in terms of both the vadose and saturated zone, to the extent that it is known. Hexavalent uranium [U(VI)] is the dominant valence form of U under the predominantly oxidizing subsurface conditions at the Hanford Site, and the researchers' analyses consequently emphasize this species. The nature and concentration of background U in Hanford subsurface sediments is identified to place contaminant U(VI) concentrations and behavior in perspective to the natural system. In-ground U-waste inventories are quantified and characterized with regard to source term, to the extent possible, and the most important sites from an inventory perspective are identified. The U-isotopic content of various waste streams are discussed from the perspective of waste-source tracking. The geochemical attenuation processes responsible for slowing the rate of subsurface U migration, relative to the transporting water front, are illustrated through careful consideration of both field characterization studies of existing U vadose-zone and groundwater plumes, and laboratory studies of derived contaminated and uncontaminated sediments. Both empirical and more mechanistic models of these attenuation processes are considered as well as the parameters that define attenuation magnitude. Attention is given to the behavior of contaminant U(VI) that has been in contact with Hanford sediments for extended periods (circa 10-50 years), as long contact imparts unique characte...

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Section: Variable K D Versus Constant Value K Dmentioning

confidence: 99%

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Zachara¹,

Brown²,

Christensen³

et al. 2007

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“…24 Sorption studies with U(VI) typically demonstrate that it has low affinity for zeolites (such as zeolite X and clinoptilolite) at high pH (9-11)-particularly in the presence of elevated inorganic carbon. 1,25 This is because the higher levels of inorganic carbon favor the formation of negatively-charged, highly soluble U(VI)-carbonate complexes, which have low affinities for similarly-charged surfaces. Studies with zeolite X indicate that uptake of U decreases with increasing temperature at high solution U concentrations.…”

Section: -mentioning

confidence: 99%

“…Studies with zeolite X indicate that uptake of U decreases with increasing temperature at high solution U concentrations. 1 Some of the sorption studies with U do not reveal the ionic strength of the solutions used 1 whereas other studies report doing their studies at 0.1 M. 25,26 Sorption studies with HEU-type (heulandite and clinoptilolite) zeolites and excessively high initial U solution concentrations (i.e., 20 g U L -1 ) report that multiple uptake mechanisms were operative: including ion exchange (outer sphere sorption), specific adsorption and precipitation (of U). 27 These studies also concluded that the mechanism of uptake was pH-dependent.…”

Section: -mentioning

confidence: 99%

Uranium Sorption on Sodium Aluminosilicates and Gibbsite

Duff¹

2003

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“…Sorption studies with U(VI) typically demonstrate that it has low affinity for zeolites at high pH (9-11)-particularly in the presence of elevated inorganic carbon. 23,24,25,26 This is because the higher levels of dissolved inorganic carbon favor the formation of negatively-charged, highly soluble U(VI)-carbonate complexes, which have low affinities for similarly-charged surfaces. Few sorption studies have been done with U and zeolites above pH 12.…”

Section: +mentioning

confidence: 99%

Characterization of Uranium in Archived 2H Evaporator Scale

Duff¹

2004

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UraniumVI sorption behavior on silicate mineral mixtures

Cited by 139 publications

References 10 publications

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

A Site Wide Perspective on Uranium Geochemistry at the Hanford Site

Uranium Sorption on Sodium Aluminosilicates and Gibbsite

Characterization of Uranium in Archived 2H Evaporator Scale

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