Journal article
Fe(II)-catalyzed recrystallization of goethite revisited
Environmental science & technology, Vol.48(19), pp.11302-11311
10/07/2014
DOI: 10.1021/es503084u
PMID: 25248028
Abstract
Results from enriched (57)Fe isotope tracer experiments have shown that atom exchange can occur between structural Fe in Fe(III) oxides and aqueous Fe(II) with no formation of secondary minerals or change in particle size or shape. Here we derive a mass balance model to quantify the extent of Fe atom exchange between goethite and aqueous Fe(II) that accounts for different Fe pool sizes. We use this model to reinterpret our previous work and to quantify the influence of particle size and pH on extent of goethite exchange with aqueous Fe(II). Consistent with our previous interpretation, substantial exchange of goethite occurred at pH 7.5 (≈ 90%) and we observed little effect of particle size between nanogoethite (average size of 81 × 11 nm; ≈ 110 m(2)/g) and microgoethite (average size of 590 × 42 nm; ≈ 40 m(2)/g). Despite ≈ 90% of the bulk goethite exchanging at pH 7.5, we found no change in mineral phase, average particle size, crystallinity, or reactivity after reaction with aqueous Fe(II). At a lower pH of 5.0, no net sorption of Fe(II) was observed and significantly less exchange occurred accounting for less than the estimated proportion of surface Fe atoms in the particles. Particle size appears to influence the amount of exchange at pH 5.0 and we suggest that aggregation and surface area may play a role. Results from sequential chemical extractions indicate that (57)Fe accumulates in extracted Fe(III) goethite components. Isotopic compositions of the extracts indicate that a gradient of (57)Fe develops within the goethite with more accumulation of (57)Fe occurring in the more easily extracted Fe(III) that may be nearer to the surface.
Details
- Title: Subtitle
- Fe(II)-catalyzed recrystallization of goethite revisited
- Creators
- Robert M Handler - Sustainable Futures Institute, Michigan Technological University 1400 Townsend Drive, Houghton, Michigan 49931, United StatesAndrew J FrierdichClark M JohnsonKevin M RossoBrian L BeardChongmin WangDrew E LattaAnke NeumannTimothy PasakarnisW A P J PremaratneMichelle M Scherer
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.48(19), pp.11302-11311
- Publisher
- United States
- DOI
- 10.1021/es503084u
- PMID
- 25248028
- ISSN
- 0013-936X
- eISSN
- 1520-5851
- Grant note
- DOI: 10.13039/100000001, name: National Science Foundation, award: EAR-1123978, EAR-1347848; DOI: 10.13039/100000015, name: Department of Energy, award: PNNL FWP 56674 / DE-SC0009364
- Language
- English
- Date published
- 10/07/2014
- Academic Unit
- Civil and Environmental Engineering; IIHR--Hydroscience and Engineering
- Record Identifier
- 9983991936402771
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