Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

Waychunas, Glenn A.; Rea, Brigid A.; Fuller, Christopher C.; Davis, James A.

doi:10.1016/0016-7037(93)90567-g

Cited by 1,034 publications

(916 citation statements)

References 45 publications

Supporting

131

Mentioning

765

Contrasting

Unclassified

Order By: Relevance

“…As-O and As-Fe distances in Table 1 matched very well with those previously reported for As bound to Fe (hydr)oxides (47). They were also very similar to the distance expected from an As-Cr backscattering pair present in As bound in CCA-treated wood (4).…”

supporting

confidence: 87%

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

Hopp

Nico

Marcus

et al. 2008

Environ. Sci. Technol.

View full text Add to dashboard Cite

This research combined the use of selective extractions and x-ray spectroscopy to examine the fate of As and Cr in a podzolic soil contaminated by chromated copper arsenate (CCA). Iron was enriched in the upper 30 cm due to a previous one-time treatment of the soil with Fe(II). High oxalate-soluble Al concentrations in the Bs horizon of the soil and micro-XRD data indicated the presence of short-range ordered aluminosilicates (i.e. proto-imogolite allophane, PIA). In the surface layers, Cr, as Cr(III), was partitioned between a mixed Fe(III)/Cr(III) solid phase that formed upon the Fe(II) application (25-50%) and a recalcitrant phase (50-75%) likely consisting of organic material such as residual CCA-treated wood. Deeper in the profile Cr appeared to be largely in the form of extractable (hydr)oxides. Throughout the soil, As was present as As(V). In the surface layers a considerable fraction of As was also associated with a recalcitrant phase, probably CCA-treated woody debris, and the remainder was associated with (hydr)oxide-like solid phases. In the Bs horizon, however, XAS and XRF findings strongly pointed to the presence of PIA acting as an effective adsorbent for As. This research shows for the first time the relevance of PIA for the adsorption of As in natural soils.

show abstract

supporting

confidence: 87%

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

Hopp

Nico

Marcus

et al. 2008

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…As noted above, this reflects the much higher concentration of Fe and Al in these two soils and probably also their much lower pH values. The formation of a variety of inner-sphere surface complexes of arsenate with Fe oxides has been observed in spectroscopic studies (Waychunas et al, 1993;Fendorf et al, 1997).…”

Section: Comparison Of As Fractionation In Unpolluted and As-amendedmentioning

confidence: 99%

The ageing effect on the bioaccessibility and fractionation of arsenic in soils from China

et al. 2007

View full text Add to dashboard Cite

Ingestion of contaminated soil has been recognized as an important exposure pathway of arsenic for humans, especially for children through outdoor hand-to-mouth activities. An improved sequential extraction procedure was employed in an attempt to reveal the relationship between bioaccessibility and fractionation of As in five soils from China. Arsenic bioaccessibility in acidic (%pH 4.5) soils reached approximately stable levels after a sharp decline within one week of ageing. In contrast, As bioaccessibility in higher pH (>6.0) soils was found to be significantly higher and took two weeks of ageing to reach stable levels. The artificially added As was more labile than indigenous As. The main proportions of added As were found in the specifically sorbed and amorphous and poorly-crystalline hydrous Fe/Al oxide-bound fractions. Correlation analysis shows that the non-specifically and specifically sorbed As are likely to constitute the main proportion of bioaccessible soil As. The soil content of amorphous and crystalline Fe/Al oxides and soil pH appear to be the key factors controlling, not only the time needed to reach a steady state, but also the magnitude of the bioaccessibility of As added to the soils.

show abstract

“…Extended X-ray absorption fine structure (EXAFS) is sensitive to crystal structure and the local environment of the absorbing atoms, and thus, can be employed to identify and quantify the local structure of arsenate binding with iron (Waychunas et al, 1986. Several recent EXAFS investigations have shown that at least two complexes exist in As(V)eiron oxide adsorption system: binuclear bidentate complex and monodentate mononuclear complex Waychunas et al, 1993;Fendorf et al, 1997;Wang et al, 2010). However, detailed knowledge has been lacking on the nature of arsenic complexation at the surfaces of starch-stabilized magnetite nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

Zhang

Pan

Zhao

et al. 2011

Environmental Pollution

View full text Add to dashboard Cite

a b s t r a c tIt has been shown that starch can effectively stabilize nanoscale magnetite particles, and starch-stabilized magnetite nanoparticles (SMNP) are promising for in situ remediation of arsenic-contaminated soils. However, a molecular level understanding has been lacking. Here, we carried out XAFS studies to bridge this knowledge gap. Fe K-edge XAFS spectra indicated that the FeeO and FeeFe coordination numbers of SMNP were lower than those for bare magnetite particles, and these coordination numbers decreased with increasing starch concentration. The decrease in the average coordination number at elevated stabilizer concentration was attributed to the increase in the surface-to-volume ratio. Arsenic K-edge XAFS spectra indicated that adsorbed arsenate on SMNP consisted primarily of binuclear bidentate (BB) complexes and monodentate mononuclear (MM) complexes. More BB complexes (energetically more favorable) were observed at higher starch concentrations, indicating that SMNP not only offered greater adsorption surface area, but also stronger adsorption affinity toward arsenate.

show abstract

Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

Cited by 1,034 publications

References 45 publications

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

The ageing effect on the bioaccessibility and fractionation of arsenic in soils from China

XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

Contact Info

Product

Resources

About