Effect of compaction on dissolution rate of smectite under hyperalkaline condition

Sato, Tsutomu*; Takayama, Hideki*; Chino, Daisuke*; Nakabayashi, Ryo*; Oda, Chie  ; Yoneda, Tetsuro*

The dissolution experiments for the compacted smectite with different dry densities were performed to understand the effect of compaction on dissolution rate of smectite. From the experimental results, it is clearly showed that the more compacted smectite has the less dissolution rate. According to the results of caesium adsorption test, variable charge density was decreased with increasing of dry density. This decreasing indicates that active edge surface area was decreased. According to the previous studies such as Yokoyama, et al. (2005), smectite particles are predominantly dissolved from the edge of the particle. However, the difference in dissolution rate between lower and higher compacted smectites can not be fully explained by considering of the decreasing in the reactive surface area. According to the results of reactive transport modeling, delta-Gr effect obtained by Sato, et al. (2007) should be took into account for filling the gap in dissolution rate.