Résumé
While bulk PuO
is known to be strongly resistant to dissolution, even under ultrasonic irradiation, this study demonstrates that nanometric PuO
samples can exhibit enhanced reactivity when sonicated under an Ar/(20 %)O
atmosphere. Sonication of powdered PuO
nanoparticles (∼5 nm) in pure water was found to be ineffective. In contrast, colloidal PuO
nanoparticles (∼3 nm) prepared via hydrolysis exhibited markedly different behavior, leading to the accumulation of Pu(VI), with sonochemically-generated H
O
playing a crucial role in the process. Further investigations identified an intermediate species implicated in the dissolution process, agreeing with a recently described Pu(IV) peroxide compound. Despite the chemical similarity of the PuO
nanoparticles, this study highlights their dual reactivity under conditions favoring H
O
formation highlighting an important role of the material's preparation method. Beyond underscoring the critical role of H
O
in the reactivity of PuO
nanoparticles, this study also evidences a potential pathway for their transformation under environmental conditions where radiolysis can generate similar chemical environments.