Abstract
Atom exchange between aqueous Fe(II) and Fe oxides: fate of As(V)
Mineralogical magazine, Vol.76(6), p.1871
Goldschmidt 2012
2012
Abstract
Human exposure to arsenic in groundwater is a global concern, and arsenic mobility in groundwater is often controlled by iron minerals. Recently, it has been shown that electron transfer and atom exchange between aqueous Fe(II) and iron oxides can enable structural incorporation of trace elements into iron oxides. The structural incorporation of As(V) into magnetite has been observed during magnetite precipitation, and during the reductive transformation of lepidocrocite and 2-line ferrihydrite to magnetite. As(V) does not appear, however, to be incorporated into goethite and hematite in the presence of aqueous Fe(II). To better understand the controls on As(V) incorporation into iron oxides, we investigate whether the presence of As(V) inhibits atom exchange between aqueous Fe(II) and goethite or magnetite, and whether As(V) is incorporated into goethite, magnetite, and ferrihydrite in the presence of Fe(II). Enriched Fe isotope experiments were used to investigate the extent of Fe atom exchange between aqueous Fe(II) and goethite in the presence of varying concentrations of As(V). Near-complete atom exchange between aqueous Fe(II) and goethite was observed at 1 mg/L As(V), whereas exchange was severely inhibited at the exceedingly high concentration of 20 mg/L As(V). Surface-adsorbed As was determined by phosphate extraction, and the remaining As was recovered by complete dissolution of the solid. As(V) remained adsorbed to the surface of the goethite rather than being incorporated, with 96% of the As(V) recoverable by a phosphate extraction on the time frame of near-complete atom exchange. Additional experiments are underway to explore the fate of As(V) during Fe atom exchange between aqueous Fe(II) and magnetite and ferrihydrite. We hypothesize that atom exchange between aqueous Fe(II) and magnetite will occur in the presence of As(V) and that that As(V) may be incorporated into the magnetite structure, since As incorporation into magnetite has been observed in other systems.
Details
- Title: Subtitle
- Atom exchange between aqueous Fe(II) and Fe oxides: fate of As(V)
- Creators
- Brittany L Huhmann - University of IowaMichelle M SchererAnke Neumann
- Resource Type
- Abstract
- Publication Details
- Mineralogical magazine, Vol.76(6), p.1871
- Conference
- Goldschmidt 2012
- Publisher
- Mineralogical Society
- ISSN
- 0026-461X
- eISSN
- 1471-8022
- Alternative title
- Goldschmidt 2012 abstract volume
- Language
- English
- Date published
- 2012
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984202245602771
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