Leaching behavior of adsorbed Sr from granular potassium dititanate and its inhibition effect by heat treatment

Abstract

Simulated spent adsorbent with Sr adsorbed on granular potassium dititanate was prepared and its leaching behavior was evaluated. Since Sr was adsorbed on the granular potassium dititanate by ion-exchange, Sr was leached into acidic solutions or solutions with high cation concentration. The influence of the cationic species in the solution on Sr leachability was larger for Ca than for Na. It can be seen the ion selectivity of potassium dititanate is higher for alkaline earth metals such as Ca and Sr than for alkali metals such as Na and K. Heat treatment was effective in reducing Sr leaching from the simulated spent adsorbent. The heat treatment at 500°C was not effective enough to reduce the Sr leaching, but the heat treatment above 900°C showed a significant reduction in the Sr leaching ratio. This might be related to the stabilization of Sr as Sr₂Ti₆O₁₃ crystal and the reduction of specific surface area of the simulated spent adsorbent. At the heat treatment temperature of 1100°C, there was no significant difference in the crystal phase formed from that at 900°C. However, the specific surface area of the simulated spent adsorbent was reduced, therefore the effect of reducing Sr leaching was even larger.