Influence of arsenic on iron sulfide transformations

Wolthers, M., Butler, I. B. and Rickard, D. ORCID: https://orcid.org/0000-0002-4632-5711 2007. Influence of arsenic on iron sulfide transformations. Chemical Geology 236 (3-4) , pp. 217-227. 10.1016/j.chemgeo.2006.09.010

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Abstract

The association of arsenate, As(V), and arsenite, As(III), with disordered mackinawite, FeS, was studied in sulfide-limited (Fe:S = 1:1) and excess-sulfide (Fe:S = 1:2) batch experiments. In the absence of arsenic, the sulfide-limited experiments produce disordered mackinawite while the excess-sulfide experiments yield pyrite with trace amounts of mackinawite. With increasing initially added As(V) concentrations the transformation of FeS to mackinawite and pyrite is retarded. At S:As = 1:1 and 2:1, elemental sulfur and green rust are the end products. As(V) oxidizes S(-II) in FeS and (or) in solution to S(0), and Fe(II) in the solid phase to Fe(III). Increasing initially added As(III) concentrations inhibit the transformation of FeS to mackinawite and pyrite and no oxidation products of FeS or sulfide, other than pyrite, were observed. At low arsenic concentrations, sorption onto the FeS surface may be the reaction controlling the uptake of arsenic into the solid phase. Inhibition of iron(II) sulfide transformations due to arsenic sorption suggests that the sorption sites are crucial not only as sorption sites, but also in iron(II) sulfide transformation mechanisms.

Item Type:	Article
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	Elsevier
ISSN:	0009-2541
Last Modified:	25 Oct 2022 13:28
URI:	https://orca.cardiff.ac.uk/id/eprint/119936

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