Adsorbed U(VI) Surface Species on Muscovite Identified by Laser Fluorescence Spectroscopy and Transmission Electron Microscopy
Journal
Environmental Science & Technology
Journal Volume
40
Journal Issue
15
Start Page
4646
End Page
4652
ISSN
0013-936X
1520-5851
Date Issued
2006-06-30
Author(s)
Abstract
Time-resolved laser-induced fluorescence spectroscopy (TRLFS) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) were applied to investigate the species of uranyl(VI) adsorbed onto muscovite platelets and muscovite suspensions (grain size: 63-200 μm). TRLFS provided evidence for the presence of two adsorbed uranium(VI) surface species on edge-surfaces of muscovite. The two species showed different positions of the fluorescence emission bands and different fluorescence lifetimes indicating a different coordination environment for the two species. HAADF-STEM revealed that nanoclusters of an amorphous uranium phase were attached to the edge-surfaces of muscovite powder during batch sorption experiments. These U-nanoclusters were not observed on {00/} cleavage planes of the muscovite. The surface species with the shorter fluorescence lifetimes are interpreted as truly adsorbed bidentate surface complexes, in which the U(VI) binds to aluminol groups of edge-surfaces. The surface species with the longer fluorescence lifetimes are interpreted to be an amorphous U(VI) condensate or nanosized clusters of polynuclear uranyl(VI) surface species with a particle diameter of 1 to 2 nm. Depending on the size of these clusters the fluorescence lifetimes vary; i.e., the larger the nanosized clusters, the longer is the fluorescence lifetime.
Subjects
Adsorption
Aluminum Silicates
Electroplating
Lasers
Metal Nanoparticles
Microscopy
Electron
Transmission
Minerals
Nanotechnology
Radioactive Pollutants
Spectrometry
Fluorescence
Uranium
Uranium Compounds
Biodiversity
Complexation
Environmental engineering
Scanning electron microscopy
Transmission electron microscopy
hydroxyl group
iron
muscovite
silicate
unclassified drug
uranium
Fluorescence lifetimes
High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM)
Muscovite
Time-resolved laser-induced fluorescence spectroscopy (TRLFS)
adsorption
cleavage
experimental study
fluorescence spectroscopy
transmission electron microscopy
aqueous solution
article
complex formation
fluorescence microscopy
granite
half life time
oxidation reduction reaction
particle size
precipitation
room temperature
surface property
time resolved laser induced fluorescence spectroscopy
X ray photoelectron spectroscopy
Publisher
American Chemical Society (ACS)
Type
journal article