Solubility of PuO2(am,hyd) and the Formation of Pu(IV) Carbonate Complexes in Carbonate Solutions Containing 0.1–5.0 mol·dm−3 NaNO3

The solubility of plutonium hydrous oxide (PuO2(am, hyd)) was investigated in the presence carbonate neutral to alkaline, dilute concentrated sodium nitrate (NaNO3) solutions. observed dependence Pu(IV) low medium concentration NaNO3 agreed with previously reported data and well reproduced by thermodynamic model curves, containing species \({\text{Pu(CO}}_{3} )_{4}^{4 - }\), )_{5}^{6 \({\text{Pu(OH)}}_{{2}} {\text{(CO}}_{3} )_{2}^{2 }\). Significant deviations between experimental modeled were, however, for 2 mol·dm−3 A more comprehensive chemical including complex )_{3}^{4 }\) established, that reproduces results reasonably well. conditional formation constants were extrapolated I = 0 using specific ion interaction theory (SIT) Pitzer approaches, corresponding parameters evaluated.