Modeling of the interaction of Pu(VI) with the mixture of microorganism and clay

Onuki, Toshihiko; Yoshida, Takahiro*; Ozaki, Takuo; Kozai, Naofumi   ; Sakamoto, Fuminori  ; Nankawa, Takuya ; Suzuki, Yoshinori; Francis, A. J.*

Model analysis of the transformation of Pu(VI) in a mixture of a common soil bacterium, Bacillus subtilis, and kaolinite clay was carried out. When we assumed in the model analysis that reduction rate of Pu(V) to Pu(IV) was higher on B. subtilis than on kaolinite, the estimated fractions of Pu in the solution and in the mixture, oxidation states of Pu in the solution and in the mixture were in good agreement with the measured ones. On the contrary, assumption that reduction rate of Pu(V) to Pu(IV) was the same on kaolinite as on gave wrong prediction of Pu association with the mixture. These results strongly suggested the electron transfer from the bacteria to Pu(V) on the bacterial cell to be reduced to Pu(IV) during the accumulation of Pu(VI) to the mixture.