磷酸盐
X射线吸收精细结构
酵母
铈
透射电子显微镜
砷酸盐
感应耦合等离子体
化学
酿酒酵母
核化学
矿化(土壤科学)
化学工程
材料科学
纳米技术
光谱学
无机化学
砷
生物化学
有机化学
工程类
物理
氮气
等离子体
量子力学
作者
Mingyu Jiang,Toshihiko Ohnuki,Naofumi Kozai,Kohei Tanaka,Yoshinori Suzuki,Fuminori Sakamoto,Eigo Kamiishi,Satoshi Utsunomiya
标识
DOI:10.1016/j.chemgeo.2010.07.010
摘要
In order to understand the nanoscale mineralization process of REE phosphate on microorganism surfaces, we have investigated the mechanism underlying Ce sequestration by yeast Saccharomyces cerevisiae after exposure to Ce(III) solution for 4–120 h at pH 3, 4, or 5. A variety of analytical techniques have been employed, including field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectrometry (ICP-AES), and synchrotron-based X-ray absorption fine structure (XAFS). Cerium concentration in solutions decreases as a function of exposure time and more rapidly at pH 5 than at pH 3 or 4. Analyses of the yeast cells by FESEM, TEM, and XAFS show that needle-shaped Ce(III) phosphate nanocrystallites with a monazite structure formed on the yeast cells by exposure to Ce(III) for 42 h, even though the initial solutions did not contain any P species. The Ce(III) phosphate nanocrystals grew from about 50 nm to hundreds of nanometers when pH increased from 3 to 5. Lower pH resulted in higher P concentration in the solution after the yeast cells were inoculated, indicating the release of P from the yeast cells. These results suggest that the sorbed Ce on the cell surfaces reacted with P released from inside the yeast cell, resulting in the formation of Ce(III) phosphate nanocrystallites. This post-sorption nanocrystallization on the microbial cell surface should play a key role in constraining the long-term migration of REEs and trivalent actinides in geological repositories.
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