Impact of uranyl-calcium-carbonato complexes on uranium(VI) adsorption to synthetic and natural sediments
Journal Article
·
· Environmental Science & Technology
- Stanford University
- ORNL
Adsorption on soil and sediment solids may decrease aqueous uranium concentrations and limit its propensity for migration in natural and contaminated settings. Uranium adsorption will be controlled in large part by its aqueous speciation, with a particular dependence on the presence of dissolved calcium and carbonate. Here we quantify the impact of uranyl speciation on adsorption to both goethite and sediments from the Hanford Clastic Dike and Oak Ridge Melton Branch Ridgetop formations. Hanford sediments were preconditioned with sodium acetate and acetic acid to remove carbonate grains, and Ca and carbonate were reintroduced at defined levels to provide a range of aqueous uranyl species. U(VI) adsorption is directly linked to UO{sub 2}{sup 2+} speciation, with the extent of retention decreasing with formation of ternary uranyl-calcium-carbonato species. Adsorption isotherms under the conditions studied are linear, and K{sub d} values decrease from 48 to 17 L kg{sup -1} for goethite, from 64 to 29 L kg{sup -1} for Hanford sediments, and from 95 to 51 L kg{sup -1} for Melton Branch sediments as the Ca concentration increases from 0 to 1 mM at pH 7. Our observations reveal that, in carbonate-bearing waters, neutral to slightly acidic pH values ({approx}5) and limited dissolved calcium are optimal for uranium adsorption.
- Research Organization:
- Oak Ridge National Laboratory (ORNL)
- Sponsoring Organization:
- ORNL work for others
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 986427
- Journal Information:
- Environmental Science & Technology, Journal Name: Environmental Science & Technology Journal Issue: 3 Vol. 44; ISSN 1520-5851; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Influence of uranyl speciation and iron oxides on uranium biogeochemical redox reactions
Spectroscopic confirmation of uranium(VI)-carbonato adsorption complexes on hematite
Spectroscopic Confirmation of Uranium (VI)-Carbonato Adsorption Complexes on Hematite
Journal Article
·
Mon Mar 15 00:00:00 EDT 2010
· Geomicrobiology Journal
·
OSTI ID:993851
Spectroscopic confirmation of uranium(VI)-carbonato adsorption complexes on hematite
Journal Article
·
Thu Jul 15 00:00:00 EDT 1999
· Environmental Science and Technology
·
OSTI ID:6192004
Spectroscopic Confirmation of Uranium (VI)-Carbonato Adsorption Complexes on Hematite
Technical Report
·
Mon May 03 20:00:00 EDT 1999
·
OSTI ID:10076