Interaction of U(VI) with pyrite, galena and their mixtures: a theoretical and multitechnique approach

Aubriet, Hugues; Humbert, Bernard; Perdicakis, Michel

doi:10.1524/ract.2006.94.9-11.657

Cited by 19 publications

(20 citation statements)

References 7 publications

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“…These limitations may account for the incomplete reduction products that were observed in this study and in most previous experiments regarding U(VI) reduction by Fe(II)-bearing minerals. 10,[20][21][22][23][24][25]48 A similar mechanism was proposed for Se(IV) reduction by Fe(II)-bearing minerals. 49 The findings in this study are directly linked to key geochemical processes that govern the mobility of toxic U in the environment.…”

Section: Sem and Tem Analyses For U(vi)-reacted Pyritementioning

confidence: 59%

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Inhibition of U(VI) Reduction by Synthetic and Natural Pyrite

Yang

Kang

et al. 2014

Environ. Sci. Technol.

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Reductive precipitation is an effective method of attenuating the mobility of uranium (U) in subsurface environments. The reduction of U(VI) by synthetic and naturally occurring pyrite was investigated at pH 3.0-9.5. In contrast to thermodynamic calculations that were used to predict UO2(s) precipitation, a mixed U(IV) and U(VI) product (e.g., U3O8/U4O9/U3O7) was only observed at pH 6.21-8.63 and 4.52-4.83 for synthetic and natural pyrite, respectively. Under acidic conditions, the reduction of UO2(2+) by surface-associated Fe(2+) may not be favored because the mineral surface is nearly neutral or not negative enough. At high pH, the sorption of negatively charged U(VI) species is not favored on the negatively charged mineral surface. Thus, the redox reaction is not favored. Trace elements generally contained within the natural pyrite structure can affect the reactivity of pyrite and lead to a different result between the natural and synthetic pyrite. Because UO2(s) is extremely redox-sensitive toward U(VI), the observed UO2+x(s) phase reduction product indicates a surface reaction that is largely controlled by reaction kinetics and pyrite surface chemistry. These factors may explain why most laboratory experiments have observed incomplete U(VI) reduction on Fe(II)-bearing minerals.

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Section: Sem and Tem Analyses For U(vi)-reacted Pyritementioning

confidence: 59%

“…The occurrence of U(VI) reduction on natural pyrite has been reported under acidic conditions (pH 3.6−6.1) over a short reaction time (e.g., 4 or 48 h). 20,21,23 Natural pyrite generally holds minor elements (e.g., As, Co, Ni, etc.) that enhance its reactivity, particularly for As-and Co-doped pyrite.…”

Section: Sem and Tem Analyses For U(vi)-reacted Pyritementioning

confidence: 99%

Inhibition of U(VI) Reduction by Synthetic and Natural Pyrite

Yang

Kang

et al. 2014

Environ. Sci. Technol.

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“…Formation of hyperstoichiometric UO 2+x such as U 4 O 9 (s), U 3 O 7 (s) and to a less extent UO 2 (s) seems to be favoured even if U 3 O 8 (s) was proposed as the U reduced phase (Wersin et al, 1994;Aubriet et al, 2006).…”

Section: Uranium Reductionmentioning

confidence: 99%

“…Studies of U (VI) interaction with Fe (II) -bearing phases such as magnetite indicate that U (VI) can simply adsorb, but also can be subsequently reduced to U (IV) and precipitate as hyperstoichiometric UO 2+x (Grambow et al, 1996;Scott et al, 2005;El Aamrani et al, 2007). Uranium reactivity with pyrite has scarcely been studied, and most studies were performed in the pH range of roughly 4.8-6, and high U concentration, somewhat above the solubility of schoepite (Wersin et al, 1994;Aubriet et al, 2006;Eglizaud et al, 2006;Scott et al, 2007). Therefore, even if sorption occurred, it is rather difficult to extend their results to lower concentration.…”

Section: Introductionmentioning

confidence: 99%

Uptake of uranium and trace elements in pyrite (FeS2) suspensions

Descostes

Schlegel

Eglizaud

et al. 2010

Geochimica et Cosmochimica Acta

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“…The Raman spectrum displayed a weak inelastic signal with adsorption that was characteristic of the symmetric stretching mode of uranyl cations. 49,50 The difference spectrum obtained by a normalized subtraction of the initial sample Raman spectrum by the sorbed sample Raman spectrum is displayed in Fig. 8.…”

Section: Uranyl Adsorptionmentioning

confidence: 99%

Uranyl interaction with the hydrated (001) basal face of gibbsite: A combined theoretical and spectroscopic study

Veilly

Roques

Caumon

et al. 2008

The Journal of Chemical Physics

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The sorption of uranyl cations and water molecules on the basal (001) face of gibbsite was studied by combining vibrational and fluorescence spectroscopies together with density functional theory (DFT) computations. Both the calculated and experimental values of O-H bond lengths for the gibbsite bulk are in good agreement. In the second part, water sorption with this surface was studied to take into account the influence of hydration with respect to the uranyl adsorption. The computed water configurations agreed with previously published molecular dynamics studies. The uranyl adsorption in acidic media was followed by time-resolved laser-induced fluorescence spectroscopy and Raman spectrometry measurements. The existence of only one kind of adsorption site for the uranyl cation was then indicated in good agreement with the DFT calculations. The computation of the uranyl adsorption has been performed by means of a bidentate interaction with two surface oxygen atoms. The optimized structures displayed strong hydrogen bonds between the surface and the -yl oxygen of uranyl. The uranium-surface bond strength depends on the protonation state of the surface oxygen atoms. The calculated U-O(surface) bond lengths range between 2.1-2.2 and 2.6-2.7 A for the nonprotonated and protonated surface O atoms, respectively.

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Interaction of U(VI) with pyrite, galena and their mixtures: a theoretical and multitechnique approach

Abstract: Pyrite and/or galena particles previously conditioned with U(VI) at pH 6 have been characterized by micro-Raman spectrometry, voltammetry, scanning electron microscopy and high resolution X-ray photoelectron spectroscopy. U

Cited by 19 publications

References 7 publications

Inhibition of U(VI) Reduction by Synthetic and Natural Pyrite

Inhibition of U(VI) Reduction by Synthetic and Natural Pyrite

Uptake of uranium and trace elements in pyrite (FeS2) suspensions

Uranyl interaction with the hydrated (001) basal face of gibbsite: A combined theoretical and spectroscopic study

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