Plutonium is highly susceptible to hydrolysis, with a tendency to form intrinsic nanocolloids in a wide variety of aqueous media. This tendency has been considered a nuisance in laboratory-scale Pu chemistry, and has significant implications on the mobility of Pu in the environment. Pu colloids were first described as large, amorphous polymers but modern studies have revealed aggregates of nanocrystalline Pu-oxide particles typically under 10 nm in diameter. Different structures have been observed, with some studies indicating mixed oxyhydroxide clusters, while others have determined crystalline Pu oxide structures with no evidence of Pu-OH bonds. Limited data are available concerning the influence of the solution matrix on the structure, size, and aggregation behavior of Pu nanoparticles. The present work aims to determine how different counter-ions and co-ions impact the properties of Pu colloids formed by hydrolysis of Pu(IV) in mildly acidic and circum-neutral pH solutions. Pu colloid solutions were prepared by adding Pu(IV) in HCl to 1 M salt solutions (NaClO4, NaNO3, NaCl, LiCl, CsCl, MgCl2, SrCl2, BaCl2) yielding total Pu concentration of 1*10-4 M. Each sample was characterized by transmission electron microscopy (TEM) and Pu LIII-edge X-ray absorption spectroscopy (XAS). Results of these experiments will be discussed.

Effect of solution composition on Pu oxide nanoparticle morphology

253rd National Meeting (2017)

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