Astatine Standard Redox Potentials and Speciation in Acidic Medium

Julie Champion (1) , C. Alliot , E. Renault , M. Mokili (1) , M. Chérel , N. Galland , Gilles F Montavon (1)

1 SUBATECH - Laboratoire SUBATECH Nantes

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.

Domaines: Radiochimie

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, 2010, 114, pp.576-582. ⟨10.1021/jp9077008⟩. ⟨in2p3-00450771⟩