THORIUM EQUILIBRIA WITH THE SODIUM FORM OF CLINOPTILOLITE AND MORDENITE

A study has been performed in order to examine the ion exchange behavi or of tetravalent thorium ions using natural sodium clinoptilolite and mordenite. The free energy values, DELTAG0, were calculated and found to be 3.33 kJ/g eq for the Th/Na-CLI system, and for Th/Na-MOR 3.94 k J/g eq. Despite the fact that the overall preference of the zeolites i s for the sodium ions,thorium uptake was quite significant for mordeni te. covering 30% of its theoretical exchange capacity at the equilibri um point, while for clinoptilolite only 10% was occupied.