Structure of uranium sorption complexes on alumino-silicate minerals studied by x-ray absorption spectroscopy
- Lawrence Livermore National Lab., CA (United States); and others
The local geometry of uranium bound to mineral surfaces was investigated by uranium L{sub 3}-edge EXAFS. Uranium(6+) in solution was exposed to vermiculite and clinoptilolite, under conditions which favor sorption by either cation exchange or surface complexation. The aqueous speciation of uranium in each solution was predicted using the thermodynamic modeling code EQ3/6, and is dominated by complexes of the uranyl ion (UO{sub 2}{sup 2+}). EXAFS of the resulting mineral samples indicates that in all cases the sorbed species is a monomeric uranyl complex. A larger distortion of the uranyl equatorial shell is observed for cation exchange, possibly due to steric effects at internal cation exchange sites. The uranyl U-O axial bond distance is greater for surface complexation than for ion exchange.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 370494
- Report Number(s):
- CONF-960376-; TRN: 96:003805-0546
- Resource Relation:
- Conference: Spring national meeting of the American Chemical Society (ACS), New Orleans, LA (United States), 24-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 211th ACS national meeting; PB: 2284 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Experimental study of uranium(6+) sorption of the zeolite mineral clinoptilolite
X-ray absorption studies of uranium sorption on mineral substrates