Diffusion of Re(VII), Se(IV) and Cr(VI) in compacted GMZ bentonite

The diffusion of Re(VII), Se(IV) and Cr(VI) in compacted Gaomiaozi bentonite was conducted by an integrated diffusion setup. The effective diffusion coefficient and the rock capacity factor of Re(VII), Se(IV) and Cr(VI) were measured. Re(VII) and Cr(VI) were excluded from the surface of bentonite particles with an accessible porosity of 0.40 and 0.23. The geometric factor decreased in a sequence of Cr(VI) < Se(IV) < Re(VII), indicating that Cr(IV) had a lower tortuosity, a larger diffusion pore diameter, and a stronger anionic exclusion effect from the surface of bentonite platelets. (author)