Sorption of U(VI) at the TiO2–water interface: An in situ vibrational spectroscopic study

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dc.contributor.authorMuller, Ken_AU
dc.contributor.authorFoerstendorf, Hen_AU
dc.contributor.authorMeusel, Ten_AU
dc.contributor.authorBrendler, Ven_AU
dc.contributor.authorLefevre, Gen_AU
dc.contributor.authorComarmond, MJen_AU
dc.contributor.authorPayne, TEen_AU
dc.date.accessioned2014-05-09T04:46:14Zen_AU
dc.date.available2014-05-09T04:46:14Zen_AU
dc.date.issued2012-01-01en_AU
dc.date.statistics2014-05-09en_AU
dc.description.abstractMolecular-scale knowledge of sorption reactions at the water-mineral interface is important for predicting U(VI) transport processes in the environment. In this work, in situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy was used in a comprehensive investigation of the sorption processes of U(VI) onto TiO2. The high sensitivity of the in situ ATR FT-IR technique allows the study of U(VI) concentrations down to the low micromolar range, which is relevant to most environmental scenarios. A set of highly purified and well characterized TiO2 phases differing in their origin, the ratio of the most stable polymorphs (anatase and rutile), in specific surface area, isoelectric points and in particle size distribution was investigated. Irrespective of the composition of the mineral phase, it was shown that U(VI) forms similar surface complexes, which was derived from the antisymmetric stretching mode nu(3)(UO2) showing a characteristic shift to lower wavenumbers compared to the respective aqueous species. The availability of a fast scanning IR device makes it feasible to perform time-resolved experiments of the sorption processes with a time resolution in the sub-minute range. It is shown that during the early stages of the U(VI) uptake, a surface species on the mineral phase is formed, characterized by a significantly red-shifted absorption maximum which is interpreted as a bidendate inner-sphere complex. After prolonged sorption, the IR spectra indicate the formation of a second surface species showing a smaller shift compared to the aqueous species. These findings were verified by a series of spectroscopic experiments performed on a U(VI)-saturated surface, at different U(VI) concentrations, pH values and in the absence of atmospheric-derived carbonate. This work provides new molecular insights into the sorption processes of U(VI) on TiO2. Basic thermodynamic ideas of surface complexation are substantiated by in situ infrared spectroscopy. © 2012, Elsevier Ltd.en_AU
dc.identifier.citationMuller, K., Foerstendorf, H., Meusel, T., Brendler, V., Lefevre, G., Comarmond, M. J., & Payne, T. E. (2012). Sorption of U(VI) at the TiO2–water interface: an in situ vibrational spectroscopic study. Geochimica et Cosmochimica Acta, 76, 191-205. doi:10.1016/j.gca.2011.10.004en_AU
dc.identifier.govdoc4484en_AU
dc.identifier.issn0016-7037en_AU
dc.identifier.journaltitleGeochimica et Cosmochimica Actaen_AU
dc.identifier.pagination191-205en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.gca.2011.10.004en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/5561en_AU
dc.identifier.volume76en_AU
dc.language.isoenen_AU
dc.publisherPergamon-Elsevier Science Ltden_AU
dc.subjectSorptionen_AU
dc.subjectAdsorptionen_AU
dc.subjectTitaniumen_AU
dc.subjectWateren_AU
dc.subjectInterfacesen_AU
dc.subjectIron oxidesen_AU
dc.titleSorption of U(VI) at the TiO2–water interface: An in situ vibrational spectroscopic studyen_AU
dc.typeJournal Articleen_AU
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