Interactions of uranium with bacteria and kaolinite clay

Toshihiko Ohnuki, Takahiro Yoshida, Takuo Ozaki, Mohamad Samadfam, Naofumi Kozai, Kunio Yubuta, Toshiaki Mitsugashira, Takeshi Kasama, Arokiasamy J. Francis

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47 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)237-243
Number of pages7
JournalChemical Geology
Volume220
Issue number3-4
DOIs
Publication statusPublished - 2005 Aug 5

Keywords

  • Accumulation
  • Bacillus subtilis
  • Bacteria-mineral mixture
  • Kaolinite
  • Migration
  • Uranium

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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  • Cite this

    Ohnuki, T., Yoshida, T., Ozaki, T., Samadfam, M., Kozai, N., Yubuta, K., Mitsugashira, T., Kasama, T., & Francis, A. J. (2005). Interactions of uranium with bacteria and kaolinite clay. Chemical Geology, 220(3-4), 237-243. https://doi.org/10.1016/j.chemgeo.2005.03.008