Dynamic neutron radiography studies of water migration in beds of natural zeolite

The results of the experiments on water migration in unsaturated beds of natural zeolite (clinoptilolite) performed with a dynamic neutron radiography technique are presented. It was found that the migration of water in zeolites is much slower than in quartz sand composed of the same size grains. The effect is attributed to the enormous grain surface roughness of the zeolite. The influence of gravity was found to be significant only for beds formed by the coarsest grains. It was found that the water imbibition rate increases with time in finest grain zeolite beds. The results show the difficulties of the classical theory of adhesion driven motion of the liquid in the single capillary as a model of water imbibition by zeolite beds.