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Environ Sci Technol. 2012 May 1;46(9):4869-76. doi: 10.1021/es204181q. Epub 2012 Apr 9.

Nanocomposite pyrite-greigite reactivity toward Se(IV)/Se(VI).

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1
Environmental Geochemistry Group, ISTerre, University of Grenoble I, 38041 Grenoble, France. charlet38@gmail.com

Abstract

A nanopyrite/greigite composite was synthesized by reacting FeCl(3) and NaHS in a ratio of 1:2 (Wei et al. 1996). Following this procedure, the obtained solid phases consisted of 30-50 nm sized particles containing 28% of greigite (Fe(2+)Fe(3+)(2)S(4)) and 72% pyrite (FeS(2)). Batch reactor experiments were performed with selenite or selenate by equilibrating suspensions containing the nanosized pyrite-greigite solid phase at different pH-values and with or without the addition of extra Fe(2+). XANES-EXAFS spectroscopic techniques revealed, for the first time, the formation of ferroselite (FeSe(2)) as the predominant reaction product, along with elemental Se. In the present experimental conditions, at pH 6 and in equilibrium with Se(0), the solution is oversaturated with respect to ferrosilite. Furthermore, thermodynamic computations show that reaction kinetics likely played a significant role in our experimental system.

PMID:
22424403
DOI:
10.1021/es204181q
[Indexed for MEDLINE]
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