Previous studies of NH4+ removal by mean of clinoptilolite led to this examination of the exchange mechanisms between NH4+ and Na+ cations on clinoptilolite grains. It was found that the diffusivities were equal to 5.7 x 10-8, 6.3 x 10-8 and 9.0 x 10-8cm2/s for grain-sizes of 0.25 to 0.315, 0.315 to 0.4 and 0.5 to 0.63mm, respectively.

Intracrystalline Self-Diffusion of Ions in Clinoptilolite Ammonia and Sodium Cations Studies. A.Neveu, M.Gaspard, G.Blanchard, G.Martin: Water Research, 1985, 19[5], 611-8