Uranyl sorption onto gibbsite studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

Baumann, Nils; Brendler, Vinzenz; Arnold, Timothy; Geipel, Gerhard; Bernhard, Gert

doi:10.1016/j.jcis.2004.10.076

Cited by 78 publications

(91 citation statements)

References 32 publications

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“…Similarly, the lifetime s 3 may relate either to surface U atoms or to U atoms of dinuclear surface complexes/polynuclear surface oligomers not directly anchored to aluminol sites. Baumann et al (2005) have argued, since H 2 O in the coordination environment of uranyl quenches fluorescence lifetime, that clusters of polynuclear surface species have lifetimes larger than that of mononuclear, bidentate inner-sphere complex on aluminol groups of gibbsite. By contrast, Chisholm-Brause et al (2001) have suggested that loss of coordinated water of inner-sphere U(VI) sorption complexes (relative to aqueous uranyl species) results in long fluorescence lifetimes, whereas polymeric surface species on montmorillonite exhibit shorter lifetimes as poorly crystalline phases.…”

Section: Discussion: Single Sorption Species Versus Multiple Sorptionmentioning

confidence: 99%

“…Regarding Al-(hydr)oxides, two pH-dependent uranyl surface species have been observed by XPS and/or TRLFS at low U surface coverage (C 6 0.07 lmol U/m 2 ) of c-alumina (Kowal-Fouchard et al, 2004) and at moderate to high surface coverage (0.05 6 C 6 0.5 lmol U/m 2 ) of gibbsite (Baumann et al, 2005), for solids equilibrated with solutions at ½U I AQ values of 100 and 10 lM, respectively. Baumann et al (2005) have interpreted their results by the formation of polynuclear uranyl complexes at nearneutral pH in addition to the mononuclear inner-sphere complexation occurring at lower pH, based on the EXAFS study of Sylwester et al (2000).…”

Section: Introductionmentioning

confidence: 99%

“…Baumann et al (2005) have interpreted their results by the formation of polynuclear uranyl complexes at nearneutral pH in addition to the mononuclear inner-sphere complexation occurring at lower pH, based on the EXAFS study of Sylwester et al (2000). Kowal-Fouchard et al (2004) have suggested that the U surface species arise from the U aqueous speciation i.e.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussion: Single Sorption Species Versus Multiple Sorptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…Experiments have evaluated the U sorption to a vast array of soil mineral and organic surfaces, as well as other sorbents, such as quartz (Prikryl et al 2001;Greathouse et al 2002;Froideval et al 2003;Fox et al 2006), mackinawite Livens et al 2004), granite (Baik et al 2004a), hematite surfaces colonized by sulfate-reducing bacteria (Neal et al 2004), gibbsite (Baumann et al 2005), negatively charged cell walls of Bacillus subtilis (Gorman- Lewis et al 2005), synthetic imogolite (Arai et al 2006), amorphous silica (Sylwester et al 2000), silica gel (Reich et al 1998), gamma alumina (Sylwester et al 2000, nanocrystalline titanium dioxide (Wazne et al 2006), zero valent iron (Noubactep et al 2005), biogenic manganese oxide (Webb et al 2006), bone charcoal and bone meal apatite (Fuller et al 2003), hydroxyapatite (Fuller et al 2002), clinoptilolite (Prikryl et al 2001), natural sediments (Kohler et al 1996;Rosentreter et al 1998;Waite et al 2000;Davis 2001;Bostick et al 2002;Davis and Curtis 2003;Curtis et al 2004Curtis et al , 2006Davis et al 2004Davis et al , 2006Kohler et al 2004;Qafoku et al 2005Qafoku et al , 2008aQafoku et al , 2008bPayne and Airey 2006;Um et al 2007a), and nanoporous zirconium-phosphate (Um et al 2007b). There has been some recent resea...…”

Section: U(vi) Sorption To Soil Mineralsmentioning

confidence: 99%

Interactions of aqueous U(VI) with soil minerals in slightly alkaline natural systems

Qafoku

Icenhower

2008

Rev Environ Sci Biotechnol

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Uranium (U) is a common contaminant at numerous surface and subsurface sites in proximity to areas involved with weapons manufacturing and atomic energy related activities. This paper covers some important aspects of the aqueous hexavalent uranium [U(VI)] interactions with soil minerals that are present in contaminated soils and sediments. The retention of U via interactions with soil minerals has significant consequences for the prediction of its short-and long-term behavior in soils and geological systems. Studies of the nature and type of these interactions have provided the necessary evidence for assessing the geochemical behavior of U in natural systems under different physical, biogeochemical, hydrological, and reducing or oxidizing conditions. Over the last 20 years, aqueous U(VI): soil mineral interactions have been studied by geochemists, soil chemists, clay and soil mineralogists, and the progress in some areas is remarkable. Although a mechanistic description and understanding of the complex interactions involving U and soil minerals in natural systems is currently difficult, results from carefully designed and executed field and laboratory experiments with these materials have improved our understanding of the heterogeneous system's behavior and U contaminant mobility and transport. There are, however, areas that warrant further exploration and study. Numerous research publications were reviewed in this paper to present recent important findings to reveal the current level of the understanding of the U(VI) interactions with soil minerals, and to provide ideas for future needs and research directions.

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“…In addition to the formation of mononuclear/binuclear inner-sphere sorption complex(es) when sorbed onto mineral surfaces, uranyl is also known to form polymeric species at neutral to basic pH ranges or at high concentrations (e.g., Sylwester et al, 2000;Kowal-Fouchard et al, 2004;Baumann et al, 2005;Froideval et al, 2006). Therefore, parallel experiments were carried out with different U concentrations and corresponding alumina loading and As concentrations.…”

Section: Batch Sorption Experimentsmentioning

confidence: 99%