| Project/Area Number |
14580539
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
SEKINE Tsutomu Tohoku University, Department of Chemistry, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (20154651)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | TECHNETIUM / RADIATION EFFECT / NANOPARTICLES / TECHNETIUM DIOXIDE / PERTECHNETATE / SOLUBLE TC(IV) SPECIES / コロイド |
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| Research Abstract |
Radiolytic formation of the nanoparticles of technetium dioxide hydrate was found by irradiation of aqueous pertechnetate solutions with bremsstrahlung generated from a linear accelerator. Transmission electron microscopy revealed the size distribution of the colloids between 50 and 130 nm, and the particle was found as an aggregate of nanoparticles. The composition of the colloids was confirmed by dispersive x-ray spectrometry. An amorphous structure of the colloids was found by electron diffraction analysis. The yield of the colloids was strongly inhibited in the presence of radical scavengers such as oxygen and nitrous oxide gases. However, 90% of Tc was found as the colloids for the Ar-saturated solutions. In the formation of Tc(IV) species as a precursor of technetium dioxide colloids, it was found that hydrated electrons played an important role on the reduction processes of pertechnetate ions followed by successive disproportionation reactions of Tc( VI) and Tc(V).
The nanoparticles were radiolytically produced only at solution's pH higher than 3, while a soluble Tc(IV) species were newly formed at pH lower than 3. The soluble Tc(IV) species showed absorption peaks at 320 nm (strong) and 500 nm (weak). The absorption spectra of the species were not changed before and after ultrafiltration. We found that the nanoparticles of technetium dioxide hydrate were formed by addition of NaGH solution to the solution of Tc(IV) soluble species. This fact strongly suggests that the Tc(IV) soluble species act as a precursor of the nanoparticles.
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