Cesium sorption by clay minerals and shales at elevated temperatures

Cesium sorption from 0.02 N CaCl₂ and NaCl solutions by montmorillonites, illites, micas, kaolinites, chlorites and shales decreased significantly with increasing temperature. For example, Cs sorption by AZ montmorillonite in 0.02 N CaCl₂ decreased from 1.05 meq/100 g at 25°C to 0.69 meq/100 g at 80°C. At all the temperatures used for Cs sorption, a greater amount of Cs was sorbed by all the minerals from 0.02 N NaCl than from 0.02 N CaClin2. The results of this study clearly suggest that the effect of geothermal gradient on Cs sorption by clay minerals and shales is considerable and therefore may be considered before determining the suitability of a shale for a radioactive waste repository.