TY - JOUR
T1 - Interactions of uranium with bacteria and kaolinite clay
AU - Ohnuki, Toshihiko
AU - Yoshida, Takahiro
AU - Ozaki, Takuo
AU - Samadfam, Mohamad
AU - Kozai, Naofumi
AU - Yubuta, Kunio
AU - Mitsugashira, Toshiaki
AU - Kasama, Takeshi
AU - Francis, Arokiasamy J.
N1 - Funding Information:
Part of this study was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan to T. Ohnuki and in part by the U.S. Department of Energy's Office of Science Biological and Environmental Research, Natural Accelerated Bioremediation Research (NABIR) program, under Contract DE-AC02-98CH10886. [DR]
PY - 2005/8/5
Y1 - 2005/8/5
N2 - We assessed the accumulation of uranium (VI) by a bacterium, Bacillus subtilis, suspended in a slurry of kaolinite clay, to elucidate the role of microbes on the mobility of U(VI). Various mixtures of bacteria and the koalinite were exposed to solutions of 8 × 10-6 M- and 4 × 10-4 M-U(VI) in 0.01 M NaCl at pH 4.7. After 48 h, the mixtures were separated from the solutions by centrifugation, and treated with a 1 M CH3COOK for 24 h to determine the associations of U within the mixture. The mixture exposed to 4 × 10-4 M U was analyzed by transmission electron microscope (TEM) equipped with EDS. The accumulation of U by the mixture increased with an increase in the amount of B. subtilis cells present at both U concentrations. Treatment of kaolinite with CH3COOK, removed approximately 80% of the associated uranium. However, in the presence of B. subtilis the amount of U removed was much less. TEM-EDS analysis confirmed that most of the U removed from solution was associated with B. subtilis. XANES analysis of the oxidation state of uranium associated with B. subtilis, kaolinite, and with the mixture containing both revealed that it was present as U(VI). These results suggest that the bacteria have a higher affinity for U than the kaolinite clay mineral under the experimental conditions tested, and that they can immobilize significant amount of uranium.
AB - We assessed the accumulation of uranium (VI) by a bacterium, Bacillus subtilis, suspended in a slurry of kaolinite clay, to elucidate the role of microbes on the mobility of U(VI). Various mixtures of bacteria and the koalinite were exposed to solutions of 8 × 10-6 M- and 4 × 10-4 M-U(VI) in 0.01 M NaCl at pH 4.7. After 48 h, the mixtures were separated from the solutions by centrifugation, and treated with a 1 M CH3COOK for 24 h to determine the associations of U within the mixture. The mixture exposed to 4 × 10-4 M U was analyzed by transmission electron microscope (TEM) equipped with EDS. The accumulation of U by the mixture increased with an increase in the amount of B. subtilis cells present at both U concentrations. Treatment of kaolinite with CH3COOK, removed approximately 80% of the associated uranium. However, in the presence of B. subtilis the amount of U removed was much less. TEM-EDS analysis confirmed that most of the U removed from solution was associated with B. subtilis. XANES analysis of the oxidation state of uranium associated with B. subtilis, kaolinite, and with the mixture containing both revealed that it was present as U(VI). These results suggest that the bacteria have a higher affinity for U than the kaolinite clay mineral under the experimental conditions tested, and that they can immobilize significant amount of uranium.
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U2 - 10.1016/j.chemgeo.2005.03.008
DO - 10.1016/j.chemgeo.2005.03.008
M3 - Article
AN - SCOPUS:21844457138
SN - 0009-2541
VL - 220
SP - 237
EP - 243
JO - Chemical Geology
JF - Chemical Geology
IS - 3-4
ER -