Surface structures and stability of arsenic(III) on goethite: Spectroscopic evidence for inner-sphere complexes

Journal Article · Sat Aug 15 04:00:00 EDT 1998 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es9802201· OSTI ID:653155

Manning, B A; Goldberg, S ^[1]; Fendorf, S E ^[2]

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1. Agricultural Research Service, Riverside, CA (United States). Salinity Lab.
2. Univ. of Idaho, Moscow, ID (United States). Soil Science Div.

The adsorption and stability of arsenite [As(III)] on goethite ({alpha}-FeOOH) was investigated using a combination of standard batch techniques and X-ray absorption spectroscopy (XAS). The reactivity of As(III) with {alpha}-FeOOH at varying pH and As(III) concentration provided macroscopic evidence for strong complexation on the {alpha}-FeOOH surface. Extended X-ray absorption fine structure (EXAFS) spectroscopy gave an average As(III)-Fe interatomic distance of 3.378 {+-} 0.014 {angstrom}, which is indicative of bidentate binuclear bridging As(III) complexes on the {alpha}-FeOOH surface and which is similar to other oxyanions which adsorb on {alpha}-FeOOH by an inner-sphere mechanism. X-ray absorption near-edge structure (XANES) analysis indicated that the As(III)-{alpha}-FeOOH surface complex is stable toward heterogeneous oxidation to As(V), as determined by the energy position of the X-ray absorption edge. The structural information from EXAFS was included in the description of As(III) adsorption on the {alpha}-FeOOH surface using a surface complexation model (the constant capacitance model). These results suggest that As(III) surface complex formation on iron(III) oxides may plan an important role in the environmental behavior of arsenic.

• OSTI ID: 653155
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 16 Vol. 32; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
ARSENIC
CHEMICAL REACTION KINETICS
ENVIRONMENTAL TRANSPORT
GOETHITE
GROUND WATER
SOILS
X-RAY SPECTROSCOPY