Abstract: Effects of pH value on the sorption and diffusion of Eu(Ⅲ) in compacted benton ite were studied with the capillary method. The results suggest that diffusion of Eu(Ⅲ) in compacted bentonite decreases with increasing pH value. The sorption of Eu(Ⅲ) increases with increasing pH value. The intensity of the compacted bentonite, i.e., the interlaminary space of compacted bentonite, significantly contributes to the diffusion and sorption of radionuclides in compacted bentonite. The results fit the Ficks second law very well.

Key words: capillary method, bentonite, Eu(Ⅲ), diffusion, sorption