The concentration and pH dependent diffusion of 137Cs in compacted bentonite by using capillary method

Wang, Xiangke; Tan, Xiaoli; Chen, Lei

doi:10.1016/j.jnucmat.2005.05.015

Cited by 33 publications

(3 citation statements)

References 14 publications

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“…As pH increasing, the number of protons on the soil surface decreasing and more electrostatically attractive surface to the cations occur, allowing more Cs + to be sorbed. Wang et al [23] found that at high pH, Cs sorption on bentonite may be dominated by surface complexation and thus the distribution coefficient of Cs is higher at high pH values than those at low pH. According to Oscarson et al [24] less Cs is sorbed at pH 5 than at pH 8.5.…”

Section: Resultsmentioning

confidence: 99%

Sorption behavior of cesium on various soils under different pH levels

Giannakopoulou

Haidouti

Chronopoulou

et al. 2007

Journal of Hazardous Materials

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Section: Resultsmentioning

confidence: 99%

Sorption behavior of cesium on various soils under different pH levels

Giannakopoulou

Haidouti

Chronopoulou

et al. 2007

Journal of Hazardous Materials

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“…Because of their high surface area (about 800 m 2 g –1 ), large negative structural charge (0.7–1.7 mmol c g –1 ), and high swelling capacity, these minerals strongly influence the permeability, mechanics, and geochemistry of argillaceous porous media such as soils, rocks, and geologic faults. − The same properties make them valuable as catalysts or sorbents in many industrial processes and as barrier materials in the isolation of contaminated sites and proposed high-level radioactive waste (HLRW) repositories. , The design of HLRW repositories, in particular, requires a fundamental understanding of the self-diffusion coefficients ( D ) of water and solutes in compacted water-saturated smectite clay barriers. These D values have been extensively characterized at the macroscopic scale, but most of the experimental data were obtained at ambient temperatures. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Water and Sodium Diffusion in Smectite Interlayer Nanopores as a Function of Pore Size and Temperature

2013

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The diffusion coefficients (D) of water and solutes in nanoporous Na-smectite clay barriers have been widely studied because of their importance in high-level radioactive waste (HLRW) management and in the isolation of contaminated sites. However, few measurements have been carried out at the high temperatures that are expected to occur in HLRW repositories. We address this knowledge gap by using molecular dynamics (MD) simulations to predict the temperature dependence of diffusion in clay interlayer nanopores, expressed as a pore scale activation energy of diffusion (E a ). Our sensitivity analysis shows that accurate prediction of pore scale D and E a values requires careful consideration of the influence of pore size, simulation cell size, and clay structure flexibility on MD simulation results. We find that predicted D values in clay interlayer nanopores are insensitive to the size of the simulation cell (contrary to the behavior observed in simulation of bulk liquid water) but sensitive to the vibrational motions of clay atoms (particularly in the smallest pores investigated here, the one-, two-, and three-layer hydrates). Our predicted D and E a values are consistent with experimental data. They reveal, for both water and Na + , that E a increases by ∼6 kJ mol −1 with increasing confinement, when going from bulk liquid water to the one-layer hydrate of Na-montmorillonite.

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“…The diffusion of water and ions in water-saturated compacted clay barriers has, therefore, been extensively characterized, though mostly at ambient temperatures (Molera and Eriksen, 2002;Molera et al, 2003;Nakashima, 2003;Wang et al, 2005;Melkior et al, 2009;Tachi et al, 2010;Glaus et al, 2011;Tanaka et al, 2011;Holmboe et al, 2011).…”

Section: Temperature Dependence Of Water and Solute Diffusion In The Ebsmentioning

confidence: 99%