Cs Leaching Behavior During Alteration Process of Calcium Silicate Hydrate and Potassium Alumino Silicate Hydrate

Zeolite, used to remove Cs from a contaminated water, would be solidified for the safety disposal. Recently, geopolymer is considered as a new binder for disposal. Geopolymer has an advantage that primary phases such as potassium almino silicate hydrate (K-A-S-H) may sorb radioactive nuclides. In this study, Cs adsorption, co-precipitation and desorption experiment were conducted, and C-S-H, which is primary phases of cement, were also employed for experiments for comparison. From these experiments, it is obtained that K-A-S-H has higher adsorption capacity of Cs than C-S-H. Cs adsorption ratio and co-precipitation ratio by C-S-H were almost same. Cs is likely sorbed by C-S-H thoroughly via ion exchanging. The desorption experiment demonstrated that most Cs was desorbed from C-S-H while 90% of Cs remained in K-A-S-H. Therefore, K-A-S-H has a higher retention capacity than that of C-S-H. Consequently, geopolymer is considered to be a better material in terms of Cs storage.