Surface catalysis of uranium(VI) reduction by iron(II)

Liger, Emmanuelle; Charlet, Laurent; Cappellen, Philippe Van

doi:10.1016/s0016-7037(99)00265-3

Cited by 590 publications

(602 citation statements)

References 73 publications

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“…One of the processes of Fe oxidation is due to reduction of U 6+ . The significant role of these surface-bound Fe 2+ →Fe 3+ /U 6+ →U 4+ redox systems for the fixing of uranium onto rock surfaces was investigated in details by Liger et al (1999), their findings were in full correspondence with the previous work of Stumm and Sulzberger (1992). As an indirect proof of Fe 2+ oxidation induced by U 6+ reduction, the uptake experiments were repeated on fresh D-11 thin sections with structures similar to the original ones.…”

Section: Resultsmentioning

confidence: 69%

Characteristics of uranium uptake of Boda Claystone Formation as the candidate host rock of high level radioactive waste repository in Hungary

et al. 2014

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In Hungary two geological sites of the Boda Claystone Formation (BCF) located in the W-Mecsek Mountains (South Hungary) have been selected for the study of potential host rocks for high level radioactive waste (HLW), Gorica (G) Block and W-Mecsek Anticline (WMA) Block. The aim of the study was to obtain information on the uranium uptake characteristics of both sites. Our results revealed that in the sample, taken from WMA Block, where dolomites have ankerite rims and U-bearing rings, newly formed FeOOH precipitations were observed, which partly replaced the ankerite at near neutral pH (6.8). UO 2 2+ ions were adsorbed easily due to the enhanced specific surface area and high adsorption capacity of FeOOH formed from the dissolution of ankerite. The oxidation of Fe 2+ leads to the formation of FeOOH parallel to partial reduction of U 6+ to U 4+ . 75% of uranium was taken up by clay minerals and 25% by FeOOH although the ankerite concentration is as low as 6% in WMA Block of BCF. In G Block, the argillaceous matrix was found to be mainly responsible for the UO 2 2+ uptake. The study demonstrated that the U retention capacity of different BCF locations was significantly influenced by the mineralogy of these sites.

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Section: Resultsmentioning

confidence: 69%

Characteristics of uranium uptake of Boda Claystone Formation as the candidate host rock of high level radioactive waste repository in Hungary

et al. 2014

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“…Research thus far has demonstrated U(VI) reduction by Fe(II) sorbed onto a variety of iron oxides/oxyhydroxides (Charlet et al, 1998;Liger et al, 1999;Fredrickson et al, 2000;Jeon et al, 2004), Fe(II)-containing natural sediments (Behrends and Van Cappellen, 2005;Jeon et al, 2005), Fe(II)-containing carboxyl-functionalized microspheres (Boyanov et al, 2007), Fe(II) sorbed on corundum (Regenspurg et al, 2009) and Fe(II) sorbed on montmorillonite (Chakraborty et al, 2010). These studies primarily consider surface catalyzed processes that involved either concomitant or sequential adsorption of aqueous Fe(II) and U(VI) species onto a solid phase adsorbent or mineral to mediate abiotic U(VI) reduction.…”

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

135

122

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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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“…Therefore an elevated concentration of OH -counter-ions will form near the surface, locally shifting the Fe(II) speciation equilibrium in favour of the faster oxidising FeOH + and Fe(OH) 2 0 species. 2) Reactive surface species mechanism (Tamura et al, 1976;Wherli, 1990;Liger et al, 1999): Chemisorbtion of Fe(II) at the Fe(III)oxyhydroxide surface enhances its reactivity in electron transfer reactions in the same way that hydrolysis promotes electron transfer in dissolved Fe(II). 3) Semiconductor mechanism (Park and Dempsey, 2005 and references therein): Fe(III)oxyhydroxide can act as a semiconductor in the presence of adsorbed Fe(II) due to electron transfer with the underlying Fe(III).…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Fe(II) oxidation and zeta potential

Barnes¹,

Sapsford

Dey³

et al. 2009

Journal of Geochemical Exploration

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Zeta potential was used as a tool alongside kinetic experiments to delineate between three plausible mechanisms for the heterogeneous oxidation of Fe(II) by dissolved oxygen. One of these mechanisms is dependant on the positive surface charge that exists on Fe(III)oxyhydroxide surfaces at pH values below the Iso-Electric Point (IEP). However, this mechanism can be disputed as, in the presence of bicarbonate alkalinity typical of many UK mine waters, catalysis is still observed at pH 6.5 despite an IEP shift from pH 8 to 4. As well as an IEP shift an overall reduction of the zeta potential is observed that may have beneficial effects to particle coagulation, settling and permeability characteristics in passive mine water treatment systems.

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Surface catalysis of uranium(VI) reduction by iron(II)

Cited by 590 publications

References 73 publications

Characteristics of uranium uptake of Boda Claystone Formation as the candidate host rock of high level radioactive waste repository in Hungary

Characteristics of uranium uptake of Boda Claystone Formation as the candidate host rock of high level radioactive waste repository in Hungary

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

Heterogeneous Fe(II) oxidation and zeta potential

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