Effect of mechanical activation on the properties of natural zeolites

We have examined the effect of mechanical activation on the Sr(2+) and Cu(2+) ion exchange selectivity of Russian natural zeolites: clinoptilolite-containing tuffs and chabazite concentrates. We have studied their structural changes and thermal properties and determined the specific surface area and porosity of the mechanically activated zeolites. At specific milling energies below 0.5-0.7 kJ/g, the dominant process is disintegration of zeolite particles and changes in their bulk porosity. At higher milling energies, amorphization prevails. Our results demonstrate that, in the initial stage of activation, one can markedly raise the Sr(2+) selectivity of some zeolites (e.g., by 16 times for Shivyrtuiskoe clinoptilolites and by 300 times for chabazite) and increase the Cu(2+) selectivity (by 40 to 100 times), which will persist at high specific milling energies.