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Article

Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition

1
Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic
2
Department of Nuclear Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičová 6, Mlynská dolina, 842 15 Bratislava, Slovakia
*
Author to whom correspondence should be addressed.
Academic Editor: Tushar Kanti Sen
Water 2021, 13(11), 1520; https://doi.org/10.3390/w13111520
Received: 25 April 2021 / Revised: 22 May 2021 / Accepted: 24 May 2021 / Published: 28 May 2021
(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)
With the aim to determine the influence of dominant interlayer cation on the sorption and diffusion properties of bentonite, diffusion experiments with Sr on the compacted homoionous Ca- and Na-forms of Czech natural Mg/Ca bentonite using the planar source method were performed. The bentonite was compacted to 1400 kg·m−3, and diffusion experiments lasted 1, 3 or 5 days. Two methods of apparent diffusion coefficient Da determination based on the analytical solution of diffusion equation for ideal boundary conditions in a linear form were compared and applied. The determined Da value for Ca-bentonite was 1.36 times higher than that for Na-bentonite sample. Values of Kd were determined in independent batch sorption experiments and were extrapolated for the conditions of compacted bentonite. In spite of this treatment, the use of Kd values determined by batch sorption experiments on a loose material for the determination of effective diffusion coefficient De values from planar source diffusion experiments proved to be inconsistent with the standard Fickian description of diffusion taking into account only the pore diffusion in compacted bentonite. Discrepancies between Kd and De values were measured in independent experiments, and those that resulted from the evaluation of planar source diffusion experiments could be well explained by the phenomenon of surface diffusion. The obtained values of surface diffusion coefficients Ds were similar for both studied systems, and the predicted value of total effective diffusion coefficient De(tot) describing Sr transport in the Na-bentonite was four times higher than in the Ca-bentonite. View Full-Text
Keywords: bentonite; planar source method; diffusive transport; sorption bentonite; planar source method; diffusive transport; sorption
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MDPI and ACS Style

Baborová, L.; Viglašová, E.; Vopálka, D. Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition. Water 2021, 13, 1520. https://doi.org/10.3390/w13111520

AMA Style

Baborová L, Viglašová E, Vopálka D. Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition. Water. 2021; 13(11):1520. https://doi.org/10.3390/w13111520

Chicago/Turabian Style

Baborová, Lucie, Eva Viglašová, and Dušan Vopálka. 2021. "Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition" Water 13, no. 11: 1520. https://doi.org/10.3390/w13111520

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