Isotopic effect on the formation kinetics of Pu(IV) intrinsic colloids - CEA - Commissariat à l’énergie atomique et aux énergies alternatives
Communication Dans Un Congrès Année : 2022

Isotopic effect on the formation kinetics of Pu(IV) intrinsic colloids

Résumé

Fundamental knowledge of the intrinsic colloids of plutonium is a major issue in predicting their behavior in the environment.[1,2] It has been demonstrated that these species are spherical nanoparticles measuring ca. 2 nm with a local structure similar to the one of bulk PuO2.[3,4] Recent studies have questioned the contribution of small Pu clusters in the formation mechanism of Pu(IV) intrinsic colloids.[5] The current work draws attention to this issue by investigating an unprecedented kinetic isotopic effect (KIE) observed during the preparation of Pu(IV) colloids in light (H2O) or heavy (D2O) water. Plutonium colloids have been synthetized by the dilution of acidic Pu(IV) solutions in H2O and D2O.Time dependent measurements carried out with UV-Vis absorption spectroscopy demonstrated a much lower formation rate of the Pu(IV) colloids in D2O compared to H2O (Figure 1a). The observed KIE was attributed to the difference in zero-point energies of OH and O-D bonds. This finding has confirmed that the formation of Pu(IV) colloids is limited by the rupture of O-H bonds during hydrolysis and polymerization of Pu(IV) species. In addition, formation of some unstable intermediate Pu(IV) species was observed during colloid formation. A thorough investigation of this intermediate using synchrotron SAXS and XAS techniques revealed the presence of an hexanuclear Pu(IV) cluster of quasi-spherical shape measuring ca. 0.8 nm and agreeing with the literature (Figure 1b).[6,7]

Domaines

Matériaux
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Dates et versions

cea-03779851 , version 1 (06-11-2024)

Identifiants

  • HAL Id : cea-03779851 , version 1

Citer

Manon Cot Auriol, Matthieu Virot, Thomas Dumas, Olivier Diat, Denis Menut, et al.. Isotopic effect on the formation kinetics of Pu(IV) intrinsic colloids. Plutonium Futures 2022, Sep 2022, Avignon, France. ⟨cea-03779851⟩
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