Fe atom exchange between aqueous Fe2+ and magnetite

Christopher Aaron Gorski, Robert M. Handler, Brian L. Beard, Timothy Pasakarnis, Clark M. Johnson, Michelle M. Scherer

Research output: Contribution to journalArticle

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Abstract

The reaction between magnetite and aqueous Fe2+ has been extensively studied due to its role in contaminant reduction, trace-metal sequestration, and microbial respiration. Previous work has demonstrated that the reaction of Fe2+ with magnetite (Fe3O4) results in the structural incorporation of Fe2+ and an increase in the bulk Fe2+ content of magnetite. It is unclear, however, whether significant Fe atom exchange occurs between magnetite and aqueous Fe 2+, as has been observed for other Fe oxides. Here, we measured the extent of Fe atom exchange between aqueous Fe2+ and magnetite by reacting isotopically "normal" magnetite with 57Fe-enriched aqueous Fe2+. The extent of Fe atom exchange between magnetite and aqueous Fe2+ was significant (54-71%), and went well beyond the amount of Fe atoms found at the near surface. Mössbauer spectroscopy of magnetite reacted with 56Fe2+ indicate that no preferential exchange of octahedral or tetrahedral sites occurred. Exchange experiments conducted with Co-ferrite (Co2+Fe2 3+O4) showed little impact of Co substitution on the rate or extent of atom exchange. Bulk electron conduction, as previously invoked to explain Fe atom exchange in goethite, is a possible mechanism, but if it is occurring, conduction does not appear to be the rate-limiting step. The lack of significant impact of Co substitution on the kinetics of Fe atom exchange, and the relatively high diffusion coefficients reported for magnetite suggest that for magnetite, unlike goethite, Fe atom diffusion is a plausible mechanism to explain the rapid rates of Fe atom exchange in magnetite.

Original languageEnglish (US)
Pages (from-to)12399-12407
Number of pages9
JournalEnvironmental Science and Technology
Volume46
Issue number22
DOIs
StatePublished - Nov 20 2012

Fingerprint

Ferrosoferric Oxide
magnetite
Ion exchange
Atoms
goethite
substitution
Substitution reactions
ferrite
Oxides
trace metal
Ferrite
respiration

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Gorski, C. A., Handler, R. M., Beard, B. L., Pasakarnis, T., Johnson, C. M., & Scherer, M. M. (2012). Fe atom exchange between aqueous Fe2+ and magnetite. Environmental Science and Technology, 46(22), 12399-12407. https://doi.org/10.1021/es204649a
Gorski, Christopher Aaron ; Handler, Robert M. ; Beard, Brian L. ; Pasakarnis, Timothy ; Johnson, Clark M. ; Scherer, Michelle M. / Fe atom exchange between aqueous Fe2+ and magnetite. In: Environmental Science and Technology. 2012 ; Vol. 46, No. 22. pp. 12399-12407.
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Gorski, CA, Handler, RM, Beard, BL, Pasakarnis, T, Johnson, CM & Scherer, MM 2012, 'Fe atom exchange between aqueous Fe2+ and magnetite', Environmental Science and Technology, vol. 46, no. 22, pp. 12399-12407. https://doi.org/10.1021/es204649a

Fe atom exchange between aqueous Fe2+ and magnetite. / Gorski, Christopher Aaron; Handler, Robert M.; Beard, Brian L.; Pasakarnis, Timothy; Johnson, Clark M.; Scherer, Michelle M.

In: Environmental Science and Technology, Vol. 46, No. 22, 20.11.2012, p. 12399-12407.

Research output: Contribution to journalArticle

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Gorski CA, Handler RM, Beard BL, Pasakarnis T, Johnson CM, Scherer MM. Fe atom exchange between aqueous Fe2+ and magnetite. Environmental Science and Technology. 2012 Nov 20;46(22):12399-12407. https://doi.org/10.1021/es204649a