Influence of Surface Compositions on the Reactivity of Pyrite toward Aqueous U(VI)
Author(s):
Ma, Bin; Fernández Martínez, Alejandro; Kang, Mingliang; Wang, Kaifeng; Lewis, Aled R; Maffeis, Thierry G. G.; Findling, Nathaniel; Salas Colera, Eduardo; Tisserand, Delphine; Bureau, Sarah; Charlet, Laurent
Publisher:
American Chemical Society (ACS).
Issued date:
2020-07-07
Citation:
Ma, B., Fernandez-Martinez, A., Kang, M., Wang, K., Lewis, A. R., Maffeis, T. G. G., Findling, N., Salas-Colera, E., Tisserand, D., Bureau, S., & Charlet, L. (2020). Influence of Surface Compositions on the Reactivity of Pyrite toward Aqueous U(VI). In Environmental Science & Technology, 54(13), 8104–8114
ISSN:
0013-936X
xmlui.dri2xhtml.METS-1.0.item-contributor-funder:
European Commission
Sponsor:
The authors are grateful to Eugene S. Ilton (PNNL, USA) for the XPS data interpretation and Robin Pauer (Empa, Switzerland) for the EDX spectrum treatment. This work was financially supported by the National Natural Science Foundation of China (NSFC, nos. 41773095 and 41403075), the Fundamental Research Funds for the Central Universities of Sun Yat-sen University (no. 201545000-31610011), ANDRA, and Labex OSUG@2020 (Investissements d’avenir—ANR10 LABX56). B.M. also appreciates the financial support from the China Scholarship Council (CSC) and European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 754364. The synchrotron facilities ESRF (BM25A-25-01-976) are acknowledged for the allocation of beam time.
Project:
info:eu-repo/grantAgreement/EC/H2020/754364
Keywords:
Transfer reactions
,
Redox reactions
,
Uranium
,
Pyrite
,
X-Ray photoelectron spectroscopy
Rights:
© 2020 American Chemical Society
Abstract:
Pyrite plays a significant role in governing the mobility of toxic uranium in an anaerobic environment via an oxidation–reduction process occurring at the mineral–water interface, but the factors influencing the reaction kinetics remain poorly understood. In t
Pyrite plays a significant role in governing the mobility of toxic uranium in an anaerobic environment via an oxidation–reduction process occurring at the mineral–water interface, but the factors influencing the reaction kinetics remain poorly understood. In this study, natural pyrites with different impurities (Pb, As, and Si) and different surface pretreatments were used to react with aqueous U(VI) from pH ∼3.0 to ∼9.5. Both aqueous and solid results indicated that freshly crushed pyrites, which do have more surface Fe2+/Fe3+ and S2– sites that were generated from breakage of Fe(S)–S bonds during ball milling, exhibited a much stronger reactivity than those treated with acid washing. Besides, U(VI) reduction which involves the possible intermediate U(V) and the formation of hyperstoichiometric UO2+x(s) was found to preferentially occur at Pb- and As-rich spots on the pyrite surface, suggesting that the incorporated impurities could act as reactive sites because of the generation of lattice defects and galena- and arsenopyrite-like local configurations. These reactive surface sites can be removed by acid washing, leaving a pyrite surface nearly inert toward aqueous U(VI). Thus, reactivity of pyrite toward U(VI) is largely governed by its surface compositions, which provides an insight into the chemical behavior of both pyrite and uranium in various environments.
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