Home Physical Sciences Properties of U(VI)/U(IV) and Fe(III)/Fe(II) pairs and equilibrium U(VI) + 2Fe(II) ⇄ U(IV) + 2Fe(III) in solutions of unsaturated heteropolytungstates K10P2W17O61 and K8SiW11O39
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Properties of U(VI)/U(IV) and Fe(III)/Fe(II) pairs and equilibrium U(VI) + 2Fe(II) ⇄ U(IV) + 2Fe(III) in solutions of unsaturated heteropolytungstates K10P2W17O61 and K8SiW11O39

  • A. B. Yusov , V. P. Shilov , A. M. Fedosseev and Ph. Moisy
Published/Copyright: September 25, 2009

The unsaturated phosphotungstate K10P2W17O61 and silicotungstate K8SiW11O39 are strong and selective complexants of An(IV) in aqueous solution. In presence of these complexants, the redox properties of actinides are changed drastically due to stabilization of the tetravalent actinides.

Redox potentials of Fe(III)/Fe(II) and U(VI)/U(IV) pairs were measured in K10P2W17O61 and K8SiW11O39, solutions with various HClO4 concentration and absolute complexes stability constants of Fe(III) ions with phosphotungstate and silicotungstate ions were determined: logβabsFe(III)=17.4 ± 0.8 and 20.1 ± 0.8 respectively. The equilibrium constant of reaction between U(VI) and Fe(II) in 1 M HClO4 was determined. The equilibrium constant, Keq, depends on excess of heteropolyanion, and is close to 104 in 1 M HClO4 at [P2W17O61]free ∼ 5 × 10-4 M.

Received: 2006-6-16
Accepted: 2006-11-10
Published Online: 2009-9-25
Published in Print: 2007-4-1

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