title: Insights into the sonochemical synthesis and properties of salt-free intrinsic plutonium colloids.
abstract: Fundamental knowledge on intrinsic plutonium colloids is important for the prediction of plutonium behaviour in the geosphere and in engineered systems. The first synthetic route to obtain salt-free intrinsic plutonium colloids by ultrasonic treatment of PuO2suspensions in pure water is reported. Kinetics showed that both chemical and mechanical effects of ultrasound contribute to the mechanism of Pu colloid formation. In the first stage, fragmentation of initial PuO2particles provides larger surface contact between cavitation bubbles and solids. Furthermore, hydrogen formed during sonochemical water splitting enables reduction of Pu(IV) to more soluble Pu(III), which then re-oxidizes yielding Pu(IV) colloid. A comparative study of nanostructured PuO2and Pu colloids produced by sonochemical and hydrolytic methods, has been conducted using HRTEM, Pu LIII-edge XAS, and O K-edge NEXAFS/STXM. Characterization of Pu colloids revealed a correlation between the number of Pu-O and Pu-Pu contacts and the atomic surface-to-volume ratio of the PuO2nanoparticles. NEXAFS indicated that oxygen state in hydrolytic Pu colloid is influenced by hydrolysed Pu(IV) species to a greater extent than in sonochemical PuO2nanoparticles. In general, hydrolytic and sonochemical Pu colloids can be described as core-shell nanoparticles composed of quasi-stoichiometric PuO2cores and hydrolyzed Pu(IV) moieties at the surface shell.
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM- UMR5257, CNRS/CEA/UM/ENCSM, Site de Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Dalodière
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM- UMR5257, CNRS/CEA/UM/ENCSM, Site de Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Virot
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM- UMR5257, CNRS/CEA/UM/ENCSM, Site de Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Morosini
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM- UMR5257, CNRS/CEA/UM/ENCSM, Site de Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Tony
authors.initials: T
authors.lastname: Chave
authors.affiliation: CEA/DEN/MAR/DRCP, Nuclear Energy Division, Radiochemistry and Process Department, BP17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dumas
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hennig
authors.affiliation: European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe, Germany.
authors.forename: Thierry
authors.initials: T
authors.lastname: Wiss
authors.affiliation: European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Postfach 2340, 76125 Karlsruhe, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Dieste Blanco
authors.affiliation: Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Shuh
authors.affiliation: Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA.
authors.forename: Tolek
authors.initials: T
authors.lastname: Tyliszcak
authors.affiliation: CEA/DEN/MAR/DRCP, Nuclear Energy Division, Radiochemistry and Process Department, BP17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Venault
authors.affiliation: CEA/DEN/MAR/DRCP, Nuclear Energy Division, Radiochemistry and Process Department, BP17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Moisy
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM- UMR5257, CNRS/CEA/UM/ENCSM, Site de Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Nikitenko