Preparation and properties of americium(VI) in aqueous carbonate solutions

Article abstract of DOI:10.1021/ic50005a017

Hexavalent americium is conveniently prepared as a soluble, red-brown complex in aqueous Na₂CO₃ or NaHCO₃ by O₃ or S₂O₈^-2 oxidation of americium in lower valence states. The solutions in 0.1 to 0.5 M NaHCO₃ are stable at 90° to reduction by H₂O, Cl^-, and Br^-, but are readily reduced by I^-, N₂H₄, H₂O₂, NO₂^-, and NH₂OH. Reduction by water occurs at 90° in 2 M Na₂CO₃. The spectra of Am(VI) in the 500-1300 mμ region are markedly different in carbonate solutions than in acid. The infrared spectra of solid sodium americyl(VI) carbonates establish the presence of the O-Am-O group in the carbonate complex. Based on the properties of Am(VI) in carbonate solution, a new procedure for the preparation of Am(V) free from traces of Am(III) and a useful process for the separation of americium and curium are reported.