Kinetics of Uranium(VI) Desorption from Contaminated Sediments: Effect of Geochemical Conditions and Model Evaluation

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Environmental Science & Technology, 43(17):6560-6566

DOI:https://doi.org/10.1021/es900666m· OSTI ID:965557

Liu, Chongxuan; Shi, Zhenqing; Zachara, John M

Stirred-flow cell experiments were performed to investigate the kinetics of uranyl [U(VI)] desorption from a contaminated sediment collected from the Hanford 300 Area at the US Department of Energy (DOE) Hanford Site, Washington. Three influent solutions of variable pH, Ca and carbonate concentrations that affected U(VI) aqueous and surface speciation were used under dynamic flow conditions to evaluate the effect of geochemical conditions on the rate of U(VI) desorption. The measured rate of U(VI) desorption varied with solution chemical composition that evolved as a result of thermodynamic and kinetic interactions between the influent solutions and sediment. The solution chemical composition that led to a lower equilibrium U(VI) sorption to the solid phase yielded a faster desorption rate. The experimental results were used to evaluate a multi-rate, surface complexation model (SCM) that has been proposed to describe U(VI) desorption kinetics in the Hanford sediment that contained complex sorbed U(VI) species in mass transfer limited domains. The model was modified and supplemented by including multi-rate, ion exchange reactions to describe the geochemical interactions between the solutions and sediment. With the same set of model parameters, the modified model reasonably well described the evolution of major ions and the rates of U(VI) desorption under variable geochemical and flow conditions, implying that the multi-rate SCM is an effective way to describe U(VI) desorption kinetics in subsurface sediments.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 965557
• Report Number(s): PNNL-SA-65042; 32898; 31295; KP1504010
• Journal Information: Environmental Science & Technology, 43(17):6560-6566, Journal Name: Environmental Science & Technology, 43(17):6560-6566 Journal Issue: 17 Vol. 43
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
54 ENVIRONMENTAL SCIENCES
CALCIUM
CARBONATES
CONCENTRATION RATIO
DESORPTION
Environmental Molecular Sciences Laboratory
GEOCHEMISTRY
HANFORD RESERVATION
ION EXCHANGE
KINETICS
MATHEMATICAL MODELS
PH VALUE
SEDIMENTS
SORPTIVE PROPERTIES
URANIUM
multi-rate
mass transfer
diffusion
uranium
transport