Revisiting Selenium Interactions with Pyrite: From Adsorption to Coprecipitation
Journal Article
·
· ACS Earth and Space Chemistry
- Institut des Sciences de la Terre (ISTerre), Grenoble (France); Univ. of Grenoble Alpes, Grenoble (France); Univ. Savoie Mont Blanc, Grenoble (France); Centre National de la Recherche Scientifique (CNRS), Grenoble (France); Institut de Recherche pour le Développement (IRD), Grenoble (France); Univ. Gustave Eiffel, Grenoble (France); Central Michigan Univ., Mount Pleasant, MI (United States); Univ. Nacional de Colombia, Bogotá (Colombia)
- Institut des Sciences de la Terre (ISTerre), Grenoble (France); Univ. of Grenoble Alpes, Grenoble (France); Univ. Savoie Mont Blanc, Grenoble (France); Centre National de la Recherche Scientifique (CNRS), Grenoble (France); Institut de Recherche pour le Développement (IRD), Grenoble (France); Univ. Gustave Eiffel, Grenoble (France)
- Central Michigan Univ., Mount Pleasant, MI (United States)
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Institut des Sciences de la Terre (ISTerre), Grenoble (France); Univ. of Grenoble Alpes, Grenoble (France); Univ. Savoie Mont Blanc, Grenoble (France); Centre National de la Recherche Scientifique (CNRS), Grenoble (France); Institut de Recherche pour le Développement (IRD), Grenoble (France); Univ. Gustave Eiffel, Grenoble (France); Univ. of Science and Technology of China, Hefei (China)
- European Synchrotron Radiation Facility (ESRF), Grenoble (France); Helmholtz-Zentrum Dresden-Rossendorf - Helmholtz (HZDR) (Germany)
Interactions of selenium (Se), a trace element bio-essential at low concentrations but highly toxic at high concentrations, with the most abundant sulfide mineral in the Earth's crust, namely pyrite, was investigated over a wide range of time scales. At the nanosecond scale, selenate Se(VI)O42– adsorption onto the net pyrite surface is shown by ab-initio computations to proceed via the formation of a chemical bond between an oxyanion oxygen atom and a surface Fe atom, weakening the other Se-O bonds and reducing Se atom oxidation state. At the hour-to-day scale, adsorption and coprecipitation of selenate Se(VI)O42– and selenite, Se(IV)O32–, were investigated through wet chemical batch experiments at various pH values at different sulfide concentrations. Selenium removal from solution is slower and weaker for selenate than for selenite. After 24h, only 10% of selenate, against 60% of selenite (up to 100% in the presence of sulfide), is removed by the pyrite surface. Independently of its original oxidation state, adsorbed Se is completely reduced to elemental trigonal selenium via adsorption, precipitation or coprecipitation, as shown by XANES spectroscopy. Here, our EXAFS results, compared to published data on Se-rich pyrite, show a Se to S substitution within the pyrite structure. The reductive coprecipitation mechanism of selenium with pyrite represents valuable new insights for improving our understanding of modern and ancient biogeochemical cycles involving Se. In addition, several industries can benefit from direct applications of our findings, such as water treatment, green technologies and sustainable mining.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB)
- Grant/Contract Number:
- AC05-76RL01830
- Other Award/Contract Number:
- 2051199
- OSTI ID:
- 3020392
- Report Number(s):
- PNNL-SA--188814
- Journal Information:
- ACS Earth and Space Chemistry, Journal Name: ACS Earth and Space Chemistry Journal Issue: 1 Vol. 8; ISSN 2472-3452
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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