Stability constants important to the understanding of plutonium in environmental waters, hydroxy and carbonate complexation of PuO(sub 2)(sup +).

摘要

The formation constants for the reactions PuO(sub 2)(sup +) + H(sub 2)O = PuO(sub 2)(OH) + H(sup +) and PuO(sub 2)(sup +) + CO(sub 3)(sup 2) = PuO(sub 2)(CO(sub 3))(sup (minus)) were determined in aqueous sodium perchlorate solutions by laser-induced photoacoustic spectroscopy. The molar absorptivity of the PuO(sub 2)(sup +) band at 569 nm decreased with increasing hydroxide concentration. Similarly, spectral changes occurred between 540 and 580 nm as the carbonate concentration was increased. The absorption data were analyzed by the non-linear least-squares program SQUAD to yield complexation constants. Using the specific ion interaction theory, both complexation constants were extrapolated to zero ionic strength. These thermodynamic complexation constants were combined with the oxidation-reduction potentials of Pu to obtain Eh versus pH diagrams. 120 refs., 35 figs., 12 tabs.