Controls on Soluble Pu Concentrations in PuO_2/Magnetite Suspensions

摘要

Time-dependent reduction of PuO_2(am) was studied over a range of pH values in the presence of aqueous Fe(II) and magnetite (Fe_3O_4) nanopartides. At early time frames (up to 56 days) very little aqueous Pu was mobilized from PuO_2(am), even though measured pH and redox potentials, coupled to equilibrium thermodynamic modeling, indicated the potential for significant reduction of PuO_2(am) to relatively soluble Pu(III). Introduction of Eu(III) or Nd(III) to the suspensions as competitive cations to displace possible sorbed Pu(III) resulted in the release of significant concentrations of aqueous Pu. However, the similarity of aqueous Pu concentrations that resulted from the introduction of Eu(III)/Nd(m) to suspensions with and without magnetite indicated that the Pu was solubilized from PuO_2(am), not from magnetite.