Surface chemistry of disordered mackinawite (FeS). - Archive ouverte HAL
Article Dans Une Revue Geochimica et Cosmochimica Acta Année : 2005

Surface chemistry of disordered mackinawite (FeS).

Résumé

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 not, vert, similar7.5. 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.

Domaines

Géochimie

Dates et versions

hal-00109254 , version 1 (24-10-2006)

Identifiants

Citer

M.R. Wolthers, Laurent Charlet, P.R. van Der Linde, D. Rickard, C.H. van Der Weijden. Surface chemistry of disordered mackinawite (FeS).. Geochimica et Cosmochimica Acta, 2005, 69 (14), pp.3469-3481. ⟨10.1016/j.gca.2005.01.027⟩. ⟨hal-00109254⟩

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