Uranium(VI) sorption on iron oxides in Hanford Site sediment: Application of a surface complexation model

Um, Wooyong; Serne, R. Jeffrey; Brown, Christopher F.; Rod, Kenton A.

doi:10.1016/j.apgeochem.2008.05.013

Cited by 38 publications

(22 citation statements)

References 13 publications

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“…For example, Stubbs et al [2] identified metatorbernite, Cu(H 2 O)[(UO 2 ) 2 (PO 4 ) 2 ], and five other hosts for U 6+ in contaminated sediments at the Hanford site. The above results suggest that interactions of these hosts with the local pore water (pH 7.2, Um et al [60]) result in the formation of nanometer-thick coatings of uranyl minerals on the surface of each host. The above experiments further indicated that the type of uranyl mineral in the coating varies primarily with the pH and composition of the ambient solution, suggesting that the type of host material has little effect on the type of uranyl-mineral present in the surface coating.…”

Section: Neutral and Basic Conditionsmentioning

confidence: 82%

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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Summary.Understanding the mechanism(s) of uraniummineral dissolution is crucial for predictive modeling of U mobility in the subsurface. In order to understand how pH and type of cation in solution may affect dissolution, experiments were performed on mainly single crystals of curite, PbSolutions included: deionized water; aqueous HCl solutions at pH 3.5 and 2; 0.5 mol L −1 Pb(II)-, Ba-, Sr-, Ca-, Mg-, HCl solutions at pH 2; 1.0 mol L −1 Na-and K-HCl solutions at pH 2; and a 0.1 mol L −1 Na 2 CO 3 solution at pH 10.5. Uranyl mineral basal surface microtopography, micromorphology, and composition were examined prior to, and after dissolution experiments on micrometer scale specimens using atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Evolution of etch pit depth at different pH values and experimental durations can be explained using a stepwave dissolution model. Effects of the cation in solution on etch pit symmetry and morphology can be explained using an adsorption model involving specific surface sites. Surface precipitation of the following phases was observed: (a) a highly-hydrated uranyl-hydroxy-hydrate in ultrapure water (on all minerals), (b) a Na-uranyl-hydroxy-hydrate in Na 2 CO 3 solution of pH 10.5 (on uranyl-hydroxy-hydrate minerals), (c) a Na-uranyl-carbonate on zippeite, (d) Ba-and Pb-uranylhydroxy-hydrates in Ba-HCl and Pb-HCl solutions of pH 2 (on uranophane), (e) a (SiO x (OH) 4−2x ) phase in solutions of pH 2 (uranophane), and (f) sulfate-bearing phases in solutions of pH 2 and 3.5 (on zippeite).

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Section: Neutral and Basic Conditionsmentioning

confidence: 82%

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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“…FHOs play very important roles in transport and immobilization of radionuclides, as well as in the transport and bioavailability of non-radioactive contaminants (e.g., Cu, Pb, Zn, As, Ni, Cd) [14]. For example, the SRS sediments, like a host of other Atlantic Coastal Plain sediments, are coated with goethite (␣-FeOOH) and hematite (␣-Fe 2 O 3 ) [15][16][17], and the Hanford fine sediments are coated with varying Fe oxides (especially ferrihydrite (Fe 2 O 3 ·0.5H 2 O) and goethite) [18,19]. The FHO coatings on sediments greatly increase metal and radionuclide removal capability by surface and subsurface sediments [18].…”

Section: Introductionmentioning

confidence: 99%

“…For example, the SRS sediments, like a host of other Atlantic Coastal Plain sediments, are coated with goethite (␣-FeOOH) and hematite (␣-Fe 2 O 3 ) [15][16][17], and the Hanford fine sediments are coated with varying Fe oxides (especially ferrihydrite (Fe 2 O 3 ·0.5H 2 O) and goethite) [18,19]. The FHO coatings on sediments greatly increase metal and radionuclide removal capability by surface and subsurface sediments [18]. Zero-valent Fe has been used in permeable reactive barriers (PRB) or other engineered facilities for organic and inorganic contaminant removal [20].…”

Section: Introductionmentioning

confidence: 99%

Sorption coefficients and molecular mechanisms of Pu, U, Np, Am and Tc to Fe (hydr)oxides: A review

Kaplan

2012

Journal of Hazardous Materials

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“…6L-Fh was included because a small amount of poorly crystalline Fe(III) oxide exists in the sediment Um et al, 2008Um et al, , 2010. Ferrihydrite displays high affinity for U(VI) over broad pH range (Hsi and Langmuir, 1985;Waite et al, 1994) and has been implicated as a U adsorbent in Hanford sediments (Barnett et al, 2002).…”

Section: Reference Phasesmentioning

confidence: 99%

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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Uranium(VI) sorption on iron oxides in Hanford Site sediment: Application of a surface complexation model

Cited by 38 publications

References 13 publications

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Sorption coefficients and molecular mechanisms of Pu, U, Np, Am and Tc to Fe (hydr)oxides: A review

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

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