In Situ Structural Study of Sb(V) Adsorption on Hematite (11̅02) Using X‑ray Surface Scattering

The binding mechanism of Sb­(V) on a single-crystal hematite (11̅02) surface was studied using crystal truncation rod X-ray diffraction (CTR) under in situ conditions. The best-fit CTR model indicates Sb­(V) adsorbs at the surface as an inner-sphere complex forming a tridentate binding geometry with...

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Bibliographic Details
Published in:Environmental science & technology 2018-10, Vol.52 (19), p.11161-11168
Main Authors: Qiu, Canrong, Majs, Frantisek, Douglas, Thomas A, Schmidt, Moritz, Trainor, Thomas P
Format: Article
Language:English
Subjects:
Adsorption
Binding
Chemical reactions
Crystals
Diffraction
Hematite
Iron
Organic chemistry
Protonation
Scattering
Single crystals
Stoichiometry
X-ray diffraction
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Summary:The binding mechanism of Sb­(V) on a single-crystal hematite (11̅02) surface was studied using crystal truncation rod X-ray diffraction (CTR) under in situ conditions. The best-fit CTR model indicates Sb­(V) adsorbs at the surface as an inner-sphere complex forming a tridentate binding geometry with the nearest Sb–Fe distance of 3.09(4) Å and an average Sb–O bond length of 2.08(5) Å. In this binding geometry, Sb is bound at both edge-sharing and corner-sharing sites of the surface Fe–O octahedral units. The chemical plausibility of the proposed structure was further verified by bond valence analysis, which also deduced a protonation scheme for surface O groups. The stoichiometry of the surface reaction predicts the release of one OH– group at pH 5.5.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.8b03903