On the Structures of the Predominant Hydrolysis Products of Uranyl(VI) in Solution.

Åberg, Märtha; Lindqvist, Oliver; Wikander, Göran; Karrer, P.; Shimizu, Akira

doi:10.3891/acta.chem.scand.24-2901

Cited by 53 publications

(38 citation statements)

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“…electronic annex EA-2) by including a U-U shell resulting in an average of one U neighbour (±20%) at 3.92 Å . Similar U-U distances are reported in the literature for aqueous polynuclear uranyl species (Aberg, 1970;Navaza et al, 1984;Dent et al, 1992;Moll et al, 2000) and for uranyl oxide hydrates . On the one hand, the EXAFS parameters give an average model structure consistent with a dinuclear, bidentate inner-sphere uranyl surface complex in edge-sharing connection with [AlO 6 ] octahedra.…”

Section: The Acidic-ph Sorption Samplessupporting

confidence: 87%

“…For this shell, the coordination number and the Debye-Waller factor, taken as free parameters during the fits, are strongly correlated and the standard deviation on N UÀOeq values is estimated to be ±20%. The U-O eq distances of 2.41-2.46 Å are close to those of U atoms coordinated by 5-6 equatorial oxygen atoms of aqueous species (Aberg, 1970;Dent et al, 1992;Chisholm-Brause et al, 1994;Allen et al, 1997;Thompson et al, 1997;Wahlgren et al, 1999) or of outer-sphere surface complexes onto clays (ChisholmBrause et al, 1994;Hudson et al, 1999;Sylwester et al, 2000). They are also close to an average of the bond lengths reported for 5-6 oxygen atoms split in two equatorial subshells of sorbed U as a bidentate inner-sphere uranyl surface complex onto c-alumina (Sylwester et al, 2000).…”

Section: The Acidic-ph Sorption Samplesmentioning

confidence: 65%

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Uranyl sorption species at low coverage on Al-hydroxide: TRLFS and XAFS studies

Froideval

Nero

Gaillard

et al. 2006

Geochimica et Cosmochimica Acta

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International audienceDetailed understanding of the respective roles of solution and surface parameters on the reactions at uranyl solution/Al-(hydr)oxide interfaces is crucial to model accurately the behaviour of U in nature. We report studies on the effects of the initial aqueous uranyl speciation in moderately acidic solutions, e.g. of mononuclear, polynuclear uranyl species and/or (potential) U(VI) colloids, on the sorption of U by large surface areas of amorphous Al-hydroxide. Investigations by Extended X-ray Absorption Fine Structure (EXAFS) and Time-Resolved Laser-induced Fluorescence Spectroscopy (TRLFS) reveal similar U coordination environments on Al-hydroxide for low to moderate U loadings of sorption samples obtained at pH 4–5, independently of the presence of mononuclear or polynuclear aqueous species, or of the potential instability of initial solutions favoring true U-colloids formation. EXAFS data can be interpreted in terms of a dimeric, bidentate, inner-sphere uranyl surface complex as an average of the U surface structures. TRLFS data, however, provide valuable insights into the complex U surface speciation. They indicate multiple uranyl surface species under moderately acidic conditions, as predominant mononuclear and/or dinuclear, inner-sphere surface complexes and as additional minor species having U atoms in a uranyl (hydr)oxide-like coordination environment. The additional species probably occur as surface polymers and/or as adsorbed true U colloids, depending on the aqueous U concentration level (1–100 μM). These results are of importance because they suggest that Al-hydroxide surface characteristics strongly control uranyl surface species in moderately acidic systems

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Section: The Acidic-ph Sorption Samplessupporting

confidence: 87%

Section: The Acidic-ph Sorption Samplesmentioning

confidence: 65%

Uranyl sorption species at low coverage on Al-hydroxide: TRLFS and XAFS studies

Froideval

Nero

Gaillard

et al. 2006

Geochimica et Cosmochimica Acta

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show abstract

“…However, if these species do undergo cation exchange, then they do not stay hydrolyzed, as the EXAFS data have an aqueous UO 2 2ϩ component. Hydrolysis and polymerization of uranyl would produce different EXAFS spectra, as U-O eq interatomic distances decrease upon deprotonation of H 2 O ligands (e.g., Åberg, 1970;Moll et al, 2000;Tsushima and Reich, 2001).…”

Section: Uranyl Binding Site Distributionmentioning

confidence: 99%

Uranyl adsorption onto montmorillonite: Evaluation of binding sites and carbonate complexation

Catalano

Brown

2005

Geochimica et Cosmochimica Acta

258

195

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“…These values are characteristic of the system with hydrogen bonds. The parameters a and c were taken from structural data [6] (a = 0.2Å and c = 6.064Å). These distances are specific for hydrogenbonded crystal compounds of uranile with different sorts of atom inclusion (λ T=298K = −0.078).…”

Section: Statistical Model Of Double-bounded Polymer Chainmentioning

confidence: 99%

Model Description of the H-Bonded Transuranium Complexes

Stasyuk¹,

Ivankiv²,

Velychko³

et al. 1999

Condens. Matter Phys.

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In the framework of configurational model it is established that regions of existence of various forms of actinide hydroxocomplexes at variation of solution pH depend on differences of configuration energies and temperature. Saturation effect is found out, which leads to a sharp change of ligand concentration. Model of the polymerization of ionic groups UO 2 [(OH) 2 UO 2 ] 2+ n into chain structure via hydrogen bonds is proposed. The thermodynamic stability of such a formation is investigated depending on the number of links at different temperatures and at various boundary conditions.

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On the Structures of the Predominant Hydrolysis Products of Uranyl(VI) in Solution.

Cited by 53 publications

References 0 publications

Uranyl sorption species at low coverage on Al-hydroxide: TRLFS and XAFS studies

Uranyl sorption species at low coverage on Al-hydroxide: TRLFS and XAFS studies

Uranyl adsorption onto montmorillonite: Evaluation of binding sites and carbonate complexation

Model Description of the H-Bonded Transuranium Complexes

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