Uranium (VI) sorption on colloidal magnetite under anoxic environment: experimental study and surface complexation modelling

Missana, Tiziana; Garcı́a-Gutiérrez, Miguel; Fernńdez, Victor

doi:10.1016/s0016-7037(02)01350-9

Cited by 111 publications

(70 citation statements)

References 17 publications

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“…This was not unexpected, given the minimal changes in bulk structure and surface chemistry imbued by vacuum annealing and a concurrent decrease in surface area (by 22.1%). [19][20][21]. A second minor peak centred at 11.8 ∘ 2 was also recorded for both nanomaterials, which is ascribed to akaganéite ( -FeOOH), with a lattice reflection of (110) [22].…”

Section: Changes In Aqueous Fe Concentrationmentioning

confidence: 91%

The Effect of Vacuum Annealing of Magnetite and Zero-Valent Iron Nanoparticles on the Removal of Aqueous Uranium

Crane

Scott

2013

Journal of Nanotechnology

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As-formed and vacuum annealed zero-valent iron nanoparticles (nano-Fe 0 ) and magnetite nanoparticles (nano-Fe 3 O 4 ) were tested for the removal of uranium from carbonate-rich mine water. Nanoparticles were introduced to batch systems containing the mine water under oxygen conditions representative of near-surface waters, with a uranyl solution studied as a simple comparator system. Despite the vacuum annealed nano-Fe 0 having a 64.6% lower surface area than the standard nano-Fe 0 , similar U removal (>98%) was recorded during the initial stages of reaction with the mine water. In contrast, ≤15% U removal was recorded for the mine water treated with both as-formed and vacuum annealed nano-Fe 3 O 4 . Over extended reaction periods (>1 week), appreciable U rerelease was recorded for the mine water solutions treated using nano-Fe 0 , whilst the vacuum annealed material maintained U at <50 g L −1 until 4 weeks reaction. XPS analysis of reacted nanoparticulate solids confirmed the partial chemical reduction of U VI to U IV in both nano-Fe 0 water treatment systems, but with a greater amount of U IV detected on the vacuum annealed particles. Results suggest that vacuum annealing can enhance the aqueous reactivity of nano-Fe 0 and, for waters of complex chemistry, can improve the longevity of aqueous U removal.

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Section: Changes In Aqueous Fe Concentrationmentioning

confidence: 91%

The Effect of Vacuum Annealing of Magnetite and Zero-Valent Iron Nanoparticles on the Removal of Aqueous Uranium

Crane

Scott

2013

Journal of Nanotechnology

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“…Magnetite formation has also been reported during biooxidation of Fe(II) coupled to denitrification (Chaudhuri et al, 2001). A number of studies have investigated the role of magnetite in uranium reduction and the findings varied greatly ranging from no observable reduction (Dodge et al, 2002) to clear evidence of reduction (Scott et al, 2005;Aamrani et al, 2007;O'Loughlin et al, 2010) to the formation of a mixed-valence U(IV)-U(VI) phase (Missana et al, 2003;Aamrani et al, 2007;Regenspurg et al, 2009) or the formation of U(V) (Ilton et al, 2010). The variation in findings is presumably linked to variability in morphology, specific surface area and phase stoichiometry Scherer, 2009, Gorski et al, 2010) of the magnetite used as well as differences in experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

Products of abiotic U(VI) reduction by biogenic magnetite and vivianite

Veeramani

Alessi

Suvorova

et al. 2011

Geochimica et Cosmochimica Acta

138

123

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Reductive immobilization of uranium by the stimulation of dissimilatory metal-reducing bacteria (DMRB) has been investigated as a remediation strategy for subsurface U(VI) contamination. In those environments, DMRB may utilize a variety of electron acceptors, such as ferric iron which can lead to the formation of reactive biogenic Fe(II) phases. These biogenic phases could potentially mediate abiotic U(VI) reduction. In this work, the DMRB Shewanella putrefaciens strain CN32 was used to synthesize two biogenic Fe(II)-bearing minerals: magnetite (a mixed Fe(II)-Fe(III) oxide) and vivianite (an Fe(II)-phosphate). Analysis of abiotic redox interactions between these biogenic minerals and U(VI) showed that both biogenic minerals reduced U(VI) completely. XAS analysis indicates significant differences in speciation of the reduced uranium after reaction with the two biogenic Fe(II)-bearing minerals. While biogenic magnetite favored the formation of structurally ordered, crystalline UO 2 , biogenic vivianite led to the formation of a monomeric U(IV) species lacking U-U associations in the corresponding EXAFS spectrum. To investigate the role of phosphate in the formation of monomeric U(IV) such as sorbed U(IV) species complexed by mineral surfaces, versus a U(IV) mineral, uranium was reduced by biogenic magnetite that was pre-sorbed with phosphate. XAS analysis of this sample also revealed the formation of monomeric U(IV) species suggesting that the presence of phosphate hinders formation of UO 2 . This work shows that U(VI) reduction products formed during in situ biostimulation can be influenced by the mineralogical and geochemical composition of the surrounding environment, as well as by the interfacial solute-solid chemistry of the solid-phase reductant.

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“…In addition, formation of FeSe x and Fe(S,Se) x phases was found [173,189]. The potential reduction of U(VI) in presence of magnetite is discussed controversially in the literature [190][191][192]. Partly no reduction is found, partly the existence of intermediately forming U(V) species is reported.…”

Section: Radionuclide Retention By Coprecipitation and Sorptionmentioning

confidence: 99%

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

et al. 2012

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UO 2 fuel corrosion / Radionuclide release / Instant release fraction / Hydrogen effect / Coprecipitation / SorptionSummary. Even though chemical processes related to the corrosion of spent nuclear fuel in a deep geological repository are of complex nature, knowledge on underlying mechanisms has very much improved over the last years. As a major result of numerous studies it turns out that alteration of irradiated fuel is significantly inhibited under the strongly reducing conditions induced by container corrosion and consecutive H 2 production. In contrast to earlier results, radiolysis driven fuel corrosion and oxidative dissolution appears to be less relevant for most repository concepts. The protective hydrogen effect on corrosion of irradiated fuel has been evidenced in many experiments. Still, open questions remain related to the exact mechanism and the impact of potentially interfering naturally occurring groundwater trace components. Container corrosion products are known to offer considerable reactive surface area in addition to engineered buffer and backfill material. In combination, waste form, container corrosion products and backfill material represent strong barriers for radionuclide retention and retardation and thus attenuate radionuclide release from the repository near-field.

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Uranium (VI) sorption on colloidal magnetite under anoxic environment: experimental study and surface complexation modelling

Cited by 111 publications

References 17 publications

The Effect of Vacuum Annealing of Magnetite and Zero-Valent Iron Nanoparticles on the Removal of Aqueous Uranium

The Effect of Vacuum Annealing of Magnetite and Zero-Valent Iron Nanoparticles on the Removal of Aqueous Uranium

Products of abiotic U(VI) reduction by biogenic magnetite and vivianite

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

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