Enabling Collection of Rare Earth Elements by Bacteria - Discovery of Enrichment of Rare Earth Elements by Bacteria (Press Release)
- Release Date
- 17 Nov, 2010
- BL01B1 (XAFS)
Hiroshima University
High Energy Accelerator Research Organization
Japan Synchrotron Radiation Research Institute
Key research findings
○ First observation of higher concentration of rare earth elements (REEs) on bacterial cell surfaces than the surrounding area without bacteria, in aqueous solution
○ Enabling enrichment of REEs by a factor of 10-100 compared with the cation exchange resin conventionally used to collect metallic ions
○ Discovery of anomalous enrichment where particularly rare and precious REEs are enriched
○ Clarification of the enrichment mechanism by extended X-ray absorption fine structure (EXAFS) method using synchrotron radiation
○ Demonstration of the effectiveness of bacteria use for the development and recycling of rare earth resources
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A research group led by Professor Yoshio Takahashi at the Department of Earth and Planetary System Science, Graduate School of Science, Hiroshima University, found the phenomenon of REE enrichment on bacterial cell surfaces, compared with the surrounding area without bacteria, in an aqueous solution. They also found that particularly rare and precious REEs are selectively enriched. They clarified the enrichment mechanism by the EXAFS method*2 using synchrotron radiation.*1 REEs are metal resources indispensable in the high-technology industry, and ensuring a stable supply of REEs has become a serious problem in Japan. REEs are a collective term for a total of 17 elements; the 15 lanthanoid elements from lanthanum to lutetium, plus scandium and yttrium; REEs are collected from minerals containing these elements. The establishment of the technologies for the collection and separation of REEs is especially important because specific REEs need to be separated and refined from minerals in the high-technology industry. The research group found the enrichment of REEs on bacterial cell surfaces. Analyzing the enrichment mechanism by the EXAFS method, they clarified that the enrichment is caused by bonding between REEs and the phosphate sites in the bacterial cell walls. The enrichment of REEs on bacterial cell surfaces demonstrates that the methods using bacteria are effective for the development of rare earth resources, and for the collection and separation of REEs during the recycling process. These research achievements were published in the October issue (2010) of Geochimica et Cosmochimica Acta, Journal of The Geochemical Society and the Meteoritical Society. （Publication） |
《Glossary》
*1 Sychrotron radiation
When the orbit of an electron, the speed of which is close to the speed of light, is bent by applying a magnetic field, a light is emitted in the tangential direction to the orbit. This light is called synchrotron radiation. It is used in various scientific and technological fields as the best light source with a wide range of wavelengths from microwaves to X-rays.
*2 Extended X-ray absorption fine structure (EXAFS) method
In the EXAFS method, the absorption of X-rays by a target material is measured while changing the energy (wavelength) of the X-rays irradiated on the material. Information on the valence of the atoms that absorb X-rays and the placement of the surrounding atoms can be obtained. By measuring the intensity of the X-rays emitted from the atoms that absorb X-rays (i.e., fluorescent X-rays), information on the sparse atoms can be obtained. Synchrotron radiation is optimum for EXAFS experiments because of the high selectivity of X-ray energy.
《Figure》
(Enrichment ratio: the ratio of concentration of a REE in bacteria to that in diluted aqueous solution. The prices of the REEs are cited from Mineral Yearbook 2004.)
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