title: Uranyl interaction with the hydrated (001) basal face of gibbsite: a combined theoretical and spectroscopic study.
abstract: The sorption of uranyl cations and water molecules on the basal (001) face of gibbsite was studied by combining vibrational and fluorescence spectroscopies together with density functional theory (DFT) computations. Both the calculated and experimental values of O-H bond lengths for the gibbsite bulk are in good agreement. In the second part, water sorption with this surface was studied to take into account the influence of hydration with respect to the uranyl adsorption. The computed water configurations agreed with previously published molecular dynamics studies. The uranyl adsorption in acidic media was followed by time-resolved laser-induced fluorescence spectroscopy and Raman spectrometry measurements. The existence of only one kind of adsorption site for the uranyl cation was then indicated in good agreement with the DFT calculations. The computation of the uranyl adsorption has been performed by means of a bidentate interaction with two surface oxygen atoms. The optimized structures displayed strong hydrogen bonds between the surface and the -yl oxygen of uranyl. The uranium-surface bond strength depends on the protonation state of the surface oxygen atoms. The calculated U-O(surface) bond lengths range between 2.1-2.2 and 2.6-2.7 A for the nonprotonated and protonated surface O atoms, respectively.
authors.affiliation: Institut de Physique Nucleaire d'Orsay, Universite Paris-Sud 11, CNRS UMR 8608, 15 Rue Georges Clemenceau, Bâtiment 100, 91406 Orsay Cedex, France.
authors.forename: Edouard
authors.initials: E
authors.lastname: Veilly
authors.forename: Jérôme
authors.initials: J
authors.lastname: Roques
authors.forename: Marie-Camille
authors.initials: MC
authors.lastname: Jodin-Caumon
authors.forename: Bernard
authors.initials: B
authors.lastname: Humbert
authors.forename: Romuald
authors.initials: R
authors.lastname: Drot
authors.forename: Eric
authors.initials: E
authors.lastname: Simoni
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011312:Pressure; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D017974:Uranium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D017974:Uranium Compounds; D014867:Water; D000536:Aluminum Hydroxide; C031356:hydroxide ion; C012597:uranium dioxide