| Autor: |
Yusov, A., Shilov, V., Fedoseev, A., Astafurova, L., Delegard, C. |
| Předmět: |
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| Zdroj: |
Radiochemistry; Jul2005, Vol. 47 Issue 4, p352-357, 6p |
| Abstrakt: |
The interaction of NpO ions with orthosilicic acid Si(OH)4 and polymeric silicic acids (PSAs) in aqueous solutions was studied spectrophotometrically. The interaction at pH ≤ 4.5 is described by the equation NpO + Si(OH)4 = NpO2OSi(OH) + H+ with the equilibrium constant log K = − 2.88±0.12 at the ionic strength I = 0.1–0.2 (log K0 = −2.61±0.12 recalculated to I = 0); the stability constant of the complex NpO2OSi(OH) ( I = 0) is log β0 = 7.20± 0.12. At pH > 5, a second complex of NpO with PSAs of the presumed composition NpO2(≡ SiO)2(≡SiOH) m − 2, where (≡SiOH)m denotes a PSA molecule with surface Si-OH groups, is formed. The absorption spectra of the complexes NpO2OSi(OH) and NpO2(≡ SiO)2(≡SiOH) m − 2 were obtained. In contrast to the hydroxo complexes, they have pronounced maxima at 560 – 600 nm with the molar extinction coefficients of about 25–30 l mol−1 cm−1, which is several times higher compared to the Np(VI) aqua ion. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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