Time-Revolved Laser Spectroscopy of Europium Adsorbed on Gibbsite and Silica
EMSL Project ID
15392
Abstract
This proposal is to continue and expand exploration of adsorbate-substrate interactions in environmentally-relevant systems using state-of-the-art spectroscopic methods. The previous phase of this study has been focused on the exploration of uranyl adsorbed on gibbsite using data of time-resolved laser-induced fluorescence spectroscopy (TRLIFS). Work that has been carried out by the University of Washington team (Prof. Gregory Korshin, Hyun-Shik Chang) in close cooperation with Drs. John Zachara and Zheming Wang has shown that it is possible to deconvolute TRLIFS spectra of adsorbed uranyl to determine contributions of three or four principal components. In this study, we propose to apply a similar approach to determine the speciation of europium (a proxy for americium and an important radionuclide per se) adsorbed on the surfaces of gibbsite and silica at varying pHs and other relevant parameters. All samples to be explored by TRLIFS will be prepared at the University of Washington and shipped to PNNL. We propose to obtain TRLIFS spectra (in cryogenic conditions) of adsorbed europium and determine effects of substrate and adsorption parameters on the number of spectroscopically distinct adsorbed species. This will be done by the UW team using numerical deconvolution. We also propose to measure the lifetime of emission of adsorbed europium to determine the number of water molecules in the inner shell of adsorbed Eu species. In addition, we propose to carry out EXAFS examination of gibbsite and silica samples containing adsorbed europium to determine the composition of the inner complexation shell of this cation retained on the relevant surface and to generate independent data that are expected to be extremely useful for the interpretation of Eu TRLIFS and adsorption data. EXAFS experiments with Eu samples will be carried at Brookhaven National Laboratory jointly with Prof. Anatoly Frenkel. As a result of this work, we expect to obtain fundamentally novel and uniquely detailed information concerning the mechanisms of interaction of Eu with silica and gibbsite.
Project Details
Project type
Exploratory Research
Start Date
2005-07-01
End Date
2006-11-01
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Chang, H.S., G.V.Korshin, Zheming Wang, J.M.Zachara (2006). Adsorption of uranyl on gibbsite: a time-resolved laser-induced fluorescence spectroscopy (TRLIFS) study. Environmental Science and Technology, 40 (4), 1244-1249.