Structure of uranium sorption complexes at montmorillonite edge sites

Hennig, Christoph; Reich, Tobias; Dähn, Rainer; Scheidegger, André M.

doi:10.1524/ract.2002.90.9-11_2002.653

Cited by 127 publications

(141 citation statements)

References 21 publications

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“…U-Fe distances of ∼3.45 Å, which are also commonly observed in U(VI)-reacted iron oxyhydroxides (e.g., refs 15 and 23) were observed. In initial fitting, we included U-Al (∼3.3 Å) and U-Fe distances (∼3.42 Å) (5,15,24) to account for possible adsorbed U(VI) species on iron oxyhydroxide, aluminosilicate, and Fe-containing phyllosilicates that are known to exist in these sediments. However, a reasonable fit could not be obtained with any of these adsorbed species.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic Evidence for Uranium Bearing Precipitates in Vadose Zone Sediments at the Hanford 300-Area Site

Arai

Marcus

Tamura

et al. 2007

Environ. Sci. Technol.

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Uranium (U) solid-state speciation in vadose zone sediments collected beneath the former North Process Pond (NPP) in the 300 Area of the Hanford site (Washington) was investigated using multi-scale techniques. In 30 day batch experiments, only a small fraction of total U (∼7.4%) was released to artificial groundwater solutions equilibrated with 1% pCO 2 . Synchrotron-based micro-X-ray fluorescence spectroscopy analyses showed that U was distributed among at least two types of species: (i) U discrete grains associated with Cu and (ii) O) at some U discrete grains, and muscovite at U intermediate concentration areas, were identified in synchrotron-based micro-X-ray diffraction. Scanning electron microscopy/energy dispersive X-ray analyses revealed 8-10 µm size metatorbernite particles that were embedded in C-, Al-, and Si-rich coatings on quartz and albite grains. In µ-and bulk-X-ray absorption structure (µ-XAS and XAS) spectroscopy analyses, the structure of metatorbernite with additional U-C and U-U coordination environments was consistently observed at U discrete grains with high U concentrations. The consistency of the µ-and bulk-XAS analyses suggests that metatorbernite may comprise a significant fraction of the total U in the sample. The entrapped, micrometer-sized metatorbernite particles in C-, Al-, and Si-rich coatings, along with the more soluble precipitated uranyl carbonates and uranophane, likely control the long-term release of U to water associated with the vadose zone sediments.

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Section: Resultsmentioning

confidence: 99%

Spectroscopic Evidence for Uranium Bearing Precipitates in Vadose Zone Sediments at the Hanford 300-Area Site

Arai

Marcus

Tamura

et al. 2007

Environ. Sci. Technol.

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“…12). These R values are not consistent with binding of U(VI) to mineral surfaces such as goethite or clays precluding the presence of such species in significant concentrations (Redden et al, 2001;Hennig et al, 2002).…”

Section: U Binding To Dischma Soilsmentioning

confidence: 87%

Speciation of naturally-accumulated uranium in an organic-rich soil of an alpine region (Switzerland)

Regenspurg

Margot-Roquier

Harfouche

et al. 2010

Geochimica et Cosmochimica Acta

106

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Very high concentrations of uranium (up to 4000 ppm) were found in a natural soil in the Dischma valley, an alpine region in the Grisons canton in Switzerland. The goal of this study was to examine the redox state and the nature of uranium binding in the soil matrix in order to understand the accumulation mechanism. Pore water profiles collected from Dischma soil revealed the establishment of anoxic conditions with increasing soil depth.

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“…Differences in U(VI) adsorption extent to quartz and ferrihydrite as compared to the results of Fox et al (2006) were noted that result from solid-liquid ratio effects. Direct comparisons are not easily made with other previous studies of U(VI) adsorption to smectites Morris et al, 1994;McKinley et al, 1995;Turner et al, 1996;Sylwester et al, 2000;Chisholm-Brause et al, 2001;Hennig et al, 2002;Chisholm-Brause et al, 2004;Kowal-Fouchard et al, 2004;Catalano and Brown, 2005) and quartz or amorphous silica (Glinka et al, 1997;Arnold et al, 1998;Gabriel et al, 2001;Froideval et al, 2003) because of differences in solution pH, U(VI) concentration, solid-to-liquid ratio, and carbonate concentration as well as the procedure of mineral preparation. U(VI) affinity varied by more than two orders of magnitude for the phyllosilicates with the highest K d values observed for chlorites, particularly the ones rich in Mg but poor in Fe (Table 3).…”

Section: U(vi) Adsorption Affinity On Reference Mineralsmentioning

confidence: 90%

Determining individual mineral contributions to U(VI) adsorption in a contaminated aquifer sediment: A fluorescence spectroscopy study

Wang

Zachara

Boily

et al. 2011

Geochimica et Cosmochimica Acta

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The adsorption and speciation of U(VI) was investigated on contaminated, fine grained sediment materials from the Hanford 300 area (SPP1 GWF) in simulated groundwater using cryogenic laser-induced U(VI) fluorescence spectroscopy combined with chemometric analysis. A series of reference minerals (montmorillonite, illite, Michigan chlorite, North Carolina chlorite, California clinochlore, quartz and synthetic 6-line ferrihydrite) was used for comparison that represents the mineralogical constituents of SPP1 GWF. Surface area-normalized K d values were measured at U(VI) concentrations of 5 Â 10 À7 and 5 Â 10 À6 mol L À1 that displayed the following affinity series: 6-line-ferrihydrite > North Carolina chlorite % California clinochlore > quartz % Michigan chlorite > illite > montmorillonite. Both time-resolved spectra and asynchronous twodimensional (2D) correlation analysis of SPP1 GWF at different delay times indicated that two major adsorbed U(VI) species were present in the sediment that resembled U(VI) adsorbed on quartz and phyllosilicates. Simulations of the normalized fluorescence spectra confirmed that the speciation of SPP1 GWF was best represented by a linear combination of U(VI) adsorbed on quartz (90%) and phyllosilicates (10%). However, the fluorescence quantum yield for U(VI) adsorbed on phyllosilicates was lower than quartz and, consequently, its fractional contribution to speciation may be underestimated. Spectral comparison with literature data suggested that U(VI) exist primarily as inner-sphere complexes with surface silanol groups on quartz and as surface U(VI) tricarbonate complexes on phyllosilicates. Published by Elsevier Ltd.

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Structure of uranium sorption complexes at montmorillonite edge sites

Cited by 127 publications

References 21 publications

Spectroscopic Evidence for Uranium Bearing Precipitates in Vadose Zone Sediments at the Hanford 300-Area Site

Spectroscopic Evidence for Uranium Bearing Precipitates in Vadose Zone Sediments at the Hanford 300-Area Site

Speciation of naturally-accumulated uranium in an organic-rich soil of an alpine region (Switzerland)

Determining individual mineral contributions to U(VI) adsorption in a contaminated aquifer sediment: A fluorescence spectroscopy study

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