Astatine Standard Redox Potentials and Speciation in Acidic Medium

Abstract : A combined experimental and theoretical approach is used to define astatine (At) speciation in acidic aqueous solution and answer the two main questions raised from literature data: does At(0) exist in aqueous solution and what is the chemical form of At(III), if it exists. The experimental approach considers that a given species is characterized by its distribution coefficient (D) experimentally determined in a biphasic system. The change in speciation arising from a change in experimental conditions is observed by a change in D value. The theoretical approach involves quasi-relativistic quantum chemistry calculations. The results show that At at the oxidation state 0 cannot exist in aqueous solution. The three oxidation states present in the range of water stability are At(-I), At(I) and At(III) and exist as At-, At+ and AtO+, respectively, in the 1 to 2 pH range. The standard redox potentials of the At+/At- and AtO+/At+ couples have been determined, the respective values being 0.36 ± 0.01 and 0.74 ± 0.01 V vs. NHE.
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Submitted on : Wednesday, January 27, 2010 - 10:25:46 AM
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Julie Champion, C. Alliot, E. Renault, M. Mokili, M. Chérel, et al.. Astatine Standard Redox Potentials and Speciation in Acidic Medium. Journal of Physical Chemistry A, American Chemical Society, 2010, 114, pp.576-582. ⟨10.1021/jp9077008⟩. ⟨in2p3-00450771⟩



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