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Issue 16, 2012
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Uranyl adsorption on solvated edge surfaces of pyrophyllite: a DFT model study

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Abstract

In a computational study we addressed the adsorption of uranyl UO22+ on solvated (110) and (010) edge surfaces of pyrophyllite, applying a density functional approach to periodic slab models. We explored bidentate adsorption complexes on various partially deprotonated adsorption sites: octahedral Al(O,OH), tetrahedral Si(O,OH), and mixed AlO–SiO. Aluminol sites were determined to be most favorable on the (110) surface of pyrophyllite, while on the (010) surface mixed AlO–SiO sites are preferred. The structural parameters of all low-energy complexes on both surfaces agree rather well with EXAFS results for the structurally similar mineral montmorillonite. We calculate the average U–O distance to surface and aqua ligand oxygen atoms to increase with the increasing coordination number of uranyl whereas EXAFS results indicate the opposite trend. According to our results, several adsorption species, with different coordination numbers on different edge faces, may coexist on clay minerals. This computational finding rationalizes why earlier spectroscopic studies indicated the existence of more than one adsorption species, whereas a single type of adsorption complex was suggested from most EXAFS results.

Graphical abstract: Uranyl adsorption on solvated edge surfaces of pyrophyllite: a DFT model study

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Publication details

The article was received on 05 Dec 2011, accepted on 09 Feb 2012 and first published on 08 Mar 2012


Article type: Paper
DOI: 10.1039/C2CP23886A
Citation: Phys. Chem. Chem. Phys., 2012,14, 5815-5823
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    Uranyl adsorption on solvated edge surfaces of pyrophyllite: a DFT model study

    A. Kremleva, B. Martorell, S. Krüger and N. Rösch, Phys. Chem. Chem. Phys., 2012, 14, 5815
    DOI: 10.1039/C2CP23886A

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