Speaker
Description
The bentonite materials are frequently designed as buffer/backfill material for engineered barrier in final disposal for spent nuclear fuels (SNFs) or high-level radioactive waste (HLW) repository. The clay minerals showed a favourable environment for sorption of Cs and Sr, bentonite having high sorption toward Cs and Sr were encapsulated in the biopolymer matrices (sodium alginate, NaALG) in this study. The characterization of bentonite-alginate microcapsules (MCs) enclosing different bentonite (Taiwan, China, U.S) was examined and analysed by SEM, and the sorption of Cs and Sr in different bentonite-alginate MCs was investigated by batch methods. Spherical and elastic granules were obtained, and the particle size of microcapsules was about 500 -700 μm. A relatively higher distribution coefficient (Kd) of Cs for bentonite-alginate MCs than Sr. The sorption isotherm of Cs and Sr followed a Langmuir-type equation and it indicated that the sorption capacity of different bentonite-alginate MCs in Cs were ( 233.96 - 266.57mg/g) higher than Sr ( 19.40 - 63.01mg/g). In fact, the ZH bentonite-alginate MCs has a lowest sorption capacity for Sr due to the ZH bentonite is Ca-type bentonite and the higher Ca2+ component and pyrite (FeS) mineral would may have a soption competetion with Sr2+ in the solution.
