PMID: 18186346Jan 12, 2008Paper

Modeling cation diffusion in compacted water-saturated sodium bentonite at low ionic strength

Environmental Science & Technology
Ian C BourgAlain C M Bourg

Abstract

Sodium bentonites are used as barrier materials for the isolation of landfills and are under consideration for a similar use in the subsurface storage of high-level radioactive waste. The performance of these barriers is determined in large part by molecular diffusion in the bentonite pore space. We tested two current models of cation diffusion in bentonite against experimental data on the relative apparent diffusion coefficients of two representative cations, sodium and strontium. On the "macropore/nanopore" model, solute molecules are divided into two categories, with unequal pore-scale diffusion coefficients, based on location: in macropores or in interlayer nanopores. On the "surface diffusion" model, solute molecules are divided into categories based on chemical speciation: dissolved or adsorbed. The macropore/nanopore model agrees with all experimental data at partial montmorillonite dry densities ranging from 0.2 (a dilute bentonite gel) to 1.7 kg dm(-3) (a highly compacted bentonite with most of its pore space located in interlayer nanopores), whereas the surface diffusion model fails at partial montmorillonite dry densities greater than about 1.3 kg dm(-3).

References

Jan 31, 2002·Journal of Contaminant Hydrology·T B Boving, P Grathwohl
Feb 25, 2003·Journal of Contaminant Hydrology·Michael H Bradbury, Bart Baeyens
Sep 25, 2004·Applied Radiation and Isotopes : Including Data, Instrumentation and Methods for Use in Agriculture, Industry and Medicine·Xiangke Wang, Xiaoping Liu
Sep 13, 2005·Journal of Colloid and Interface Science·P LeroyD Coelho
Dec 27, 2005·Journal of Contaminant Hydrology·Mingliang XieHua Shao

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Citations

Sep 26, 2013·Environmental Science & Technology·Martin A GlausLuc R Van Loon
Feb 12, 2010·Environmental Science & Technology·Ian C Bourg, Garrison Sposito
Jan 26, 2011·Environmental Science & Technology·T Gimmi, G Kosakowski
Jan 18, 2019·Environmental Science & Technology·Yuankai Yang, Moran Wang
Jan 24, 2018·Environmental Science & Technology·Emmanuel TertreEric Ferrage

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