Diffusion mechanisms of strontium, cesium and cobalt in compacted sodium bentonite

Conference · Wed Jan 01 04:00:00 EST 1986 · Mater. Res. Soc. Symp. Proc.; (United States)

OSTI ID:5414648

Muurinen, A; Rantanen, J; Penttilae-Hiltunen, P

For a porous water-saturated material where diffusion in the porewater, sorption on the solid material and diffusion of the sorbed ions (surface diffusion) occur, a diffusion equation can be derived where the apparent diffusivity includes two terms. One represents diffusion in the pore-water, the other surface diffusion. In this research diffusion mechanisms were studied. The apparent diffusivities of strontium, cesium and cobalt in compacted sodium bentonite were measured by a non-steady state method. The sorption factors were adjusted using different sodium chloride solutions, groundwater and addition of EDTA for saturation of the bentonite samples. The corresponding sorption factors were measured by a batch method. The results suggest that cations diffuse also while being sorbed. A combined pore diffusion-surface diffusion model has been used to explain the transport and the corresponding diffusivities have been evaluated. The surface diffusivities (D/sub s/) of Sr and Cs were 8-9 x 10/sup -12/ m/sup 2//s and 4-7 x 10/sup -13/ m/sup 2//s respectively. The pore diffusivity epsilon D/sub p/ of Cs was 3.5 x 10/sup -11/ m/sup 2//s which has been used also for Sr. The sorption mechanisms of Co seems to be different from that of Sr or Cs and the results allow no specific conclusions of the diffusion mechanisms of Co. The apparent diffusivity of Co ranged from 2 x 10/sup -14/ to 7 x 10/sup -14/ m/sup 2//s. The anionic Co-EDTA seems to follow some other diffusion mechanism than the cations.

• Research Organization: Technical Research Centre of Finland, Espoo
• OSTI ID: 5414648
• Report Number(s): CONF-850995-
• Conference Information: Journal Name: Mater. Res. Soc. Symp. Proc.; (United States) Journal Volume: 50
• Country of Publication: United States
• Language: English

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ALKALI METALS
ALKALINE EARTH METALS
BENTONITE
CESIUM
CLAYS
COBALT
DIFFUSION
ELEMENTS
GROUND WATER
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
MANAGEMENT
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OXYGEN COMPOUNDS
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE KINETICS
SORPTION
STRONTIUM
TRANSITION ELEMENTS
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WATER