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

With the aim to determine influence of dominant interlayer cation on sorption and diffusion properties bentonite, experiments with Sr compacted homoionous Ca- Na-forms Czech natural Mg/Ca bentonite using planar source method were performed. The was 1400 kg·m−3, lasted 1, 3 or 5 days. Two methods apparent coefficient Da determination based analytical solution equation for ideal boundary conditions in a linear form compared applied. determined value Ca-bentonite 1.36 times higher than that Na-bentonite sample. Values Kd independent batch extrapolated bentonite. In spite this treatment, use values by loose material effective De from proved be inconsistent standard Fickian description taking into account only pore Discrepancies between measured experiments, those resulted evaluation could well explained phenomenon surface diffusion. obtained coefficients Ds similar both studied systems, predicted total De(tot) describing transport four Ca-bentonite.