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Surface chemistry of disordered mackinawite (FeS)

Wolthers, M; Charlet, L; van Der Linde, PR; Rickard, D; van Der Weijden, CH; (2005) Surface chemistry of disordered mackinawite (FeS). Geochimica et Cosmochimica Acta , 69 (14) 3469 - 3481. 10.1016/j.gca.2005.01.027. Green open access

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Abstract

Disordered mackinawite, FeS, is the first formed iron sulfide in ambient sulfidic environments and has a highly reactive surface. In this study, the solubility and surface chemistry of FeS is described. Its solubility in the neutral pH range can be described by Ksapp = {Fe2+} · {H2S(aq)} · {H+}−2 = 10+4.87±0.27. Acid-base titrations show that the point of zero charge (PZC) of disordered mackinawite lies at pH ∼7.5. The hydrated disordered mackinawite surface can be best described by strongly acidic mono-coordinated and weakly acidic tricoordinated sulfurs. The mono-coordinated sulfur site determines the acid-base properties at pH < PZC and has a concentration of 1.2 × 10−3 mol/g FeS. At higher pH, the tricoordinated sulfur, which has a concentration of 1.2 × 10−3 mol/g FeS, determines surface charge changes. Total site density is 4 sites nm−2. The acid-base titration data are used to develop a surface complexation model for the surface chemistry of FeS.

Type: Article
Title: Surface chemistry of disordered mackinawite (FeS)
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.gca.2005.01.027
Publisher version: http://dx.doi.org/10.1016/j.gca.2005.01.027
Language: English
Additional information: © 2005 Elsevier. This is an author's manuscript version of the article. The final publishers version of this article is available at http://dx.doi.org/10.1016/j.gca.2005.01.027
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1397002
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