| AVS 63rd International Symposium & Exhibition | |
| Actinides and Rare Earths Focus Topic | Thursday Sessions |
| Session AC+AS+SA-ThM |
| Session: | Chemistry and Physics of the Actinides and Rare Earths |
| Presenter: | Thomas Dumas, CEA, France |
| Authors: | T. Dumas, CEA, France E. Dalodière, ICSM Marcoule M. Virot, ICSM Marcoule V. Morosini, CEA Marcoule T. Chave, ICSM Marcoule C. Hennig, Helmholtz Zentrum Dresden-Rossendorf T. Wiss, European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements D.K. Shuh, Lawrence Berkeley National Laboratory T. Tyliszcaak, Lawrence Berkeley National Laboratory P. Moisy, CEA Marcoule I. Nikitenko, ICSM Marcoule |
| Correspondent: | Click to Email |
Colloidal species of Pu(IV) were shown to play a central role in the speciation of plutonium in various aqueous wastes and in biosphere [1-3]. However, a comprehensive understanding of the behavior and structure of Pu colloids remains elusive and hinders progress on the development of reliable processes of their management. Preparation of plutonium colloidal species with controlled composition and properties is still a challenge. Herein, we report the preparation of stable Pu(IV) colloids by the action of ultrasonic waves on PuO2 in salt-free water conditions. Sonochemical colloid was compared with hydrolytic colloid using HRTEM, Pu LIII-edge EXFAS and STXM/NEXAFS techniques.
HRTEM revealed nanostructured morphology for both colloids composed of particles of PuO2 (fcc, space group) measuring about 7 nm and 3 nm, respectively. The EXAFS spectra of colloidal PuO2 nanoparticles were fitted on the basis of PuO2 cristal structure. Combined HRTEM and EXAFS results revealed the correlation between the coordination numbers (i.e. Pu-O and Pu-Pu) and atomic surface-to-volume ratio of studied PuO2 nanoparticles.
The STXM/NEXAFS technics implemented at ALS BL 11-0-2 was used for the first time to study plutonium colloids. It offers a new topographic angle to describe colloids combined to spectroscopic measurements at oxygen K edge. It first revealed that the oxygen state of hydrolytic Pu colloid is influenced by hydrolyzed Pu(IV) species in much more extend than the sonochemical colloids. Moreover the topographic analysis highlight discrepancies in plutonium and oxygen distribution for hydrolytic Pu colloid on the contrary to sonolitic one.
Complementarily to previous studies, this work confirmed that plutonium colloids (hydrolytic and sonochemical) can be described as core-shell nanoparticles composed of quasi stoichiometric PuO2 core and hydrolyzed Pu(IV) moieties at the surface shell. Nevertheless, the application of soft X-ray technics highlight the strong influence of the synthetic route on colloid chemical composition and hence its expectable reactivity.
1. A. B. KERSTING, Plutonium Transport in the Environment, Inorg. Chem.,52, 3533 (2013).
2. A. I. ABDEL-FATTAH, D. ZHOU, H. BOUKHALFA, S. TERIMALA, S. D. WARE, A. A. KELLER, Dispersion Stability and Electrokinetic Properties of Intrinsic Plutonium Colloids: Implications for Subsurface Transport, Env. Sci. Technol., 47, 5626 (2013).
3. C. WALTER, M. A. DENECKE, Actinide Colloids and Particles of Environmental Concern, Chem. Rev., 113, 995 (2013).