Abstract: The phases and compositions of sodium zeolite A, X and Y before and after exchange with lanthanum ions were determined by X-ray, atomic absorbtion spectrometry, differential thermal gravimentric analysis and chemical analysis. The ionic conductivity was measured by alternating impedance spectrograph. The dominant mobile charge carrier in these system is hydrated Na⁺. The activation energies of sidium zeolite A, X and Y obtained from the relationship between conductivity and temperature are 54.9 kJ/mol, 38.8 kJ/mol and 49.6 kJ/mol respectively. Appropriately exchanged with lanthanum ions, the conductivity apparent activation energies of zeolite LaNaA, LaNaX and LaNaY can be decreased to 34.6 kJ/mol, 27.9 kJ/mol and 41.3 kJ/mol respectively. The effect of exchanged lanthanum contents on the migration of sodium ion of the zeolites has been discussed.

Key words: NaA, NaX, NaY, zeolite, lanthanum ion exchange, AC conductivity, apparent activation energy