The University of Southampton
University of Southampton Institutional Repository

Vanadium(V) adsorption onto goethite (?-FeOOH) at pH 1.5 to 12: a surface complexation model based on ab initio molecular geometries and EXAFS spectroscopy

Record type: Article

We measured the adsorption of V(V) onto goethite (?-FeOOH) under oxic (PO2 = 0.2 bar) atmospheric conditions. EXAFS spectra show that V(V) adsorbs by forming inner-sphere complexes as VO2(OH)2 and VO3(OH). We predicted the relative energies and geometries of VO2(O, OH)2-FeOOH surface complexes using ab initio calculations of the geometries and energetics of analogue Fe2(OH)2(H2O)6O2VO2(O, OH)2 clusters. The bidentate corner-sharing complex is predicted to be substantially (57 kJ/mol) favoured energetically over the hypothetical edge-sharing bidentate complex. Fitting the EXAFS spectra using multiple scattering shows that only the bidentate corner-sharing complex is present with Fe-V and V-O distances in good agreement with those predicted. We find it important to include multiple scattering in the fits of our EXAFS data otherwise spurious V-Fe distances near 2.8 Å result which may be incorrectly attributed to edge-sharing complexes. We find no evidence for monodentate complexes; this agrees with predicted high energies of such complexes. Having identified the Fe2O2V(OH)2+ and Fe2O2VO(OH)0 surface complexes, we are able to fit the experimental vanadium(V) adsorption data to the reactions
2FeOH2++VO2+=Fe2O2V(OH)2++2H+
and 2FeOH+HVO42?=Fe2O2VO(OH)0+2OH?
We also determined the first acid dissociation constant of the Fe2O2VO2H2+ surface complex. Fits of sorption edges to surface complexation models are ambiguous. This is one of the first studies to provide a surface complexation model of sorption edges that is consistent with both spectroscopic and quantum mechanical constraints.

Full text not available from this repository.

Citation

Peacock, Caroline L. and Sherman, David M. (2004) Vanadium(V) adsorption onto goethite (?-FeOOH) at pH 1.5 to 12: a surface complexation model based on ab initio molecular geometries and EXAFS spectroscopy Geochimica et Cosmochimica Acta, 68, (8), pp. 1723-1733. (doi:10.1016/j.gca.2003.10.018).

More information

Published date: 15 April 2004

Identifiers

Local EPrints ID: 41811
URI: http://eprints.soton.ac.uk/id/eprint/41811
ISSN: 0016-7037
PURE UUID: 98b497d2-643a-46dc-b628-e4ce1046774a

Catalogue record

Date deposited: 05 Oct 2006
Last modified: 17 Jul 2017 15:27

Export record

Altmetrics

Contributors

Author: Caroline L. Peacock
Author: David M. Sherman

University divisions


Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×