Size distribution analysis of colloid generated from compacted bentonite in low ionic strength aqueous solutions

摘要: Abstract An experimental methodology is presented, with the objective of investigating erosion and colloid generation from compacted bentonite, to evaluate its possible effects on radionuclide migration in a deep geological repository (DGR) crystalline rock. Bentonite studies were performed using natural bentonite considering two scenarios existing DGR rock: first one, where water hydrating stagnant ( static scenario ) second one can flow at surface, simulating existence conducting fracture dynamic ). In particular, size generated colloids was analysed, as it very important parameter for transport retention/filtration processes rock and, ultimately, colloid-driven transport. The analysis distribution colloids, detected experiments, carried out by sensitive single particle counting (SPC) technique. As are particularly stable mobile low ionic strength (I) solutions, these chemical conditions considered particular interest. Results showed that quantity depends chemistry water, presence calcium electrolyte inhibits maximum colloidal particles. concentration solution corresponds particles around 50–100 nm. similar all analysed cases, but smaller (50–100 nm) always higher absence calcium, indicating clear effect this element their aggregation. also evidenced importance water/clay interactions: be extreme evaluation stability long term.