Structure and stability of arsenate adsorbed on α-Al2O3 single-crystal surfaces investigated using grazing-incidence EXAFS measurement and DFT calculation

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Zhang, M., He, G. and Pan, G. ORCID: 0000-0003-0920-3018, 2014. Structure and stability of arsenate adsorbed on α-Al2O3 single-crystal surfaces investigated using grazing-incidence EXAFS measurement and DFT calculation. Chemical Geology, 389, pp. 104-109. ISSN 0009-2541

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Official URL: http://doi.org/10.1016/j.chemgeo.2014.10.002

Abstract

Direct characterization of contaminants on single-crystal planes is required because the specific adsorption characteristics on different exposed crystal planes constitute their actual behavior at water–mineral interfaces in aquifers. Here, the structure and stability of arsenate on α-Al2O3 (0001) and (View the MathML source112¯0) surfaces were characterized by using a combination of grazing-incidence extended X-ray absorption fine structure (GI-EXAFS) spectra and periodic density functional theory (DFT) calculation. The combined results indicated that arsenate was mainly adsorbed as inner-sphere monodentate and bidentate complexes on both surfaces, but the orientational polar angles on the (0001) surface were commonly 10–20° greater than that on the (View the MathML source112¯0) surface. The DFT calculation showed that the large polar angle was more favorable for arsenate stabilized on the alumina surfaces. Based on the spectroscopic and computational data, the dominant bonding modes of arsenate on the two crystal planes of α-Al2O3 were identified as bidentate binuclear structures, and the (0001) surface displayed a stronger affinity toward arsenate.

Item Type:

Journal article

Publication Title:

Chemical Geology

Creators:

Zhang, M., He, G. and Pan, G.

Publisher:

Elsevier

Date:

2014

Volume:

389