Abstract
The objective of this study was to investigate the influence of 1） cation exchange capacity （CEC） of clays and 2） the percentage of seawater in leaching solutions on the immobilization efficiency of F－ with the addition of MgO. It was found that the immobilization efficiency of F－ was higher for kaolinite（ relatively lower CEC） than for montmorillonite （higher CEC） when distilled deionized water was used as a leaching solution. On the other hand, when diluted seawater was used, the difference was unremarkable. These results showed that the CEC of soils influences the formation of Mg（OH）2 and consequently F－ immobilization efficiency with MgO when the concentration of Mg2＋ in leaching solution is low.
