Adsorbed U(VI) surface species on muscovite identified by laser fluorescence spectroscopy and transmission electron microscopy

Thuro Arnold, Satoshi Utsunomiya, Gerhard Geipel, Rodney C. Ewing, Nils Baumann, Vinzenz Brendler

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)4646-4652
Number of pages7
JournalEnvironmental Science and Technology
Volume40
Issue number15
DOIs
Publication statusPublished - Aug 1 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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