Biological nano-mineralization of Yb phosphate by

Onuki, Toshihiko; Jiang, M.; Kamiishi, Eigo*; Utsunomiya, Satoshi*; Tanaka, Kazuya  ; Kozai, Naofumi   ; Suzuki, Yoshinori*

We have investigated the association of heavy REE of Yb with yeast after exposure at pH of 3, 4 or 5. A variety of analytical techniques including FESEM-EDS, TEM, ICP-AES, XAFS have been employed to investigate the sequestration mechanism of Yb by yeast as a function of exposure time. Ytterbium concentrations in solutions decrease as the exposure time increases. FESEM, TEM, and XAFS analyses revealed that nano-sized blocky Yb phosphate with amorphous phase formed on the yeast cells surface after 24 h. These results suggest that the sorbed Yb on the cell surfaces reacted with P released from inside of the yeast cell, resulting in the formation of amorphous Yb phosphate.