Journal ArticleDOI
Arsenate and Chromate Retention Mechanisms on Goethite. 1. Surface Structure
TLDR
In this paper, the authors used Extended X-ray absorption fine structure (EXAFS) spectroscopy to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH).Abstract:
The molecular structure of ions retained on mineral surfaces is needed to accurately model their sorption process and to determine their stability. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used in this study to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH). Based on the oxyanion−Fe distances, it was concluded that three different surface complexes exist on goethite for both oxyanions: a monodentate complex, a bidentate-binuclear complex, and a bidentate-mononuclear complex. At low surface coverages, the monodentate complex was favored while at higher coverages the bidentate complexes were more prevalentthe bidentate-binuclear complex appears to be in the greatest proportion at these highest surface coverages. Therefore, modeling efforts for chromate or arsenate retention on goethite need to consider a monodentate complex at very low coverages, both the monodentate and bidentate complexes at in...read more
Citations
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Journal ArticleDOI
A predictive model (ETLM) for arsenate adsorption and surface speciation on oxides consistent with spectroscopic and theoretical molecular evidence
TL;DR: In this paper, an extended triple layer model of surface complexation was used to predict the evolution of arsenate surface species in a wide range of oxides, including iron oxides and goethites.
Journal ArticleDOI
Surface complexation of carbonate on goethite: IR spectroscopy, structure and charge distribution
TL;DR: The evaluation shows that for goethite the magnitude of band splitting Deltanu3 falls within the range of values that is representative for bidentate complex formation, despite contrarily assignments made in literature.
Journal ArticleDOI
Fate of As(V)-treated nano zero-valent iron: Determination of arsenic desorption potential under varying environmental conditions by phosphate extraction
TL;DR: The results of the sequential extraction experiments demonstrated that a larger fraction of As was sorbed in the crystalline phases after aging, making it less susceptible to phosphate displacement, and at pH 9, a slightly higher proportion of phosphate-extractable As was observed in the 60- day sample than in the 30-day sample.
Journal ArticleDOI
Distinctive arsenic(V) trapping modes by magnetite nanoparticles induced by different sorption processes.
Yuheng Wang,Guillaume Morin,Georges Ona-Nguema,Farid Juillot,Georges Calas,Gordon E. Brown,Gordon E. Brown +6 more
TL;DR: XAFS results suggest that As(V) could form complexes at the surfaces of the small nanoparticles and could be progressively incorporated in their structure with increasing As loading, and TEM observations indicate the formation of amorphous coatings and small (~3 nm) nanoparticles associated with larger magnetite nanoparticles, which are absent in the adsorption samples.
Journal ArticleDOI
Impacts of Shewanella putrefaciens strain CN-32 cells and extracellular polymeric substances on the sorption of As(V) and As(III) on Fe(III)-(hydr)oxides.
TL;DR: The results from this study have implications for the solubility of As(V) in the soil rhizosphere and in geochemical systems undergoing microbially mediated reduction and indicate that the presence of sorbed oxyanions may affect Fe-reduction and biofilm development at mineral surfaces.
References
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Book
Environmental Chemistry of Soils
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Iron Oxides in the Laboratory: Preparation and Characterization
Udo Schwertmann,R. M. Cornell +1 more
TL;DR: In this paper, the main aim of the second edition is to present reliable, well-tested, up-to-date methods of synthesizing pure iron oxides, including monodispersed particles, presently of great interest to industry.
Journal ArticleDOI
Theoretical X-ray Absorption Fine Structure Standards
John J. Rehr,John J. Rehr,J. Mustre de Leon,S. I. Zabinsky,S. I. Zabinsky,R. C. Albers,R. C. Albers +6 more
Journal ArticleDOI
Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate
TL;DR: In this article, the As and Fe K-edges were collected from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages.