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SONOCHEMICAL SYNTHESIS AND REACTIVITY OF INTRINSIC Pu(IV) COLLOIDS

Abstract : Pu(IV) is highly prone to hydrolysis phenomenon and can lead to the formation of stable colloidal suspensions referred to as intrinsic Pu colloids.[1,2] Such species can be generated in industrial hydrometallurgical processes and have been designated, in addition to pseudo-colloids (adsorption of actinides onto mineral colloids), as being potentially responsible for actinide migration in the environment.[3-5] Despite the growing interest given to Pu(IV) colloids, structural and reactional properties of these species have been poorly described in the literature. We recently demonstrated that the ultrasound irradiation of PuO2 suspensions in pure water under Ar/(10 percent)CO atmosphere leads, after centrifugation to remove bigger particles that did not react, to the preparation of stable intrinsic Pu(IV) colloid suspensions.[6] The preparation of these suspensions, without addition of counter ions of stabilizing agents, can be attributed to both physical and chemical effects driven by the acoustic cavitation phenomenon which is the nucleation, growth and rapid implosive collapse of gas and vapour filled microbubbles generated in solutions submitted to ultrasonic waves.[7] Indeed, this phenomenon produces drastic temporary conditions leading to the formation of excited and radical species in addition to physical effects able to activate low-reactive surfaces. The as-prepared colloidal suspensions were compared to classical hydrolytic colloids and which were found to be composed of spherical, crystalline and monodispersed PuO2 nanoparticles of 7.0 nm and 2.9 nm, respectively, thus offering standardized methods for the preparation of stable colloidal suspensions composed by a controlled particle size and dispersion medium.[6] This presentation focuses on the last results obtained by the group on the sonochemical preparation and characterization of Pu(IV) colloidal suspensions. Particularly, it was found that the nature of PuO2 powder used to prepare sonochemical colloids plays an important role on formation kinetics and rates. The characterization of Pu colloids with HR-TEM, EXAFS and SAXS will be discussed. Finally, the chemical and sonochemical behaviour towards dissolution and stability, for both hydrolytic and sonolytic Pu(IV) colloids, will be described.
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https://hal-cea.archives-ouvertes.fr/cea-02316749
Contributor : Bibliothèque Cadarache <>
Submitted on : Tuesday, October 15, 2019 - 3:16:49 PM
Last modification on : Tuesday, April 28, 2020 - 11:28:13 AM

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  • HAL Id : cea-02316749, version 1

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M. Virot, C. Micheau, T. Dumas, S. Dourdain, O. Dieste Blanco, et al.. SONOCHEMICAL SYNTHESIS AND REACTIVITY OF INTRINSIC Pu(IV) COLLOIDS. MIGRATION 2019, 2019, inconnu, Unknown Region. ⟨cea-02316749⟩

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