Stability, composition and core-shell particle structure of uranium(IV)-silicate colloids

Thomas Samuel Neill, Katherine Morris, Carolyn I. Pearce, Nicholas K. Sherriff, M. Grace Burke, Philip Chater, Arne Janssen, Louise S. Natrajan, Samuel Shaw

    Research output: Contribution to journalArticlepeer-review


    Uranium is typically the most abundant radionuclide by mass in radioactive wastes and is a significant component of effluent streams at nuclear facilities. Actinide(IV) (An(IV)) colloids formed via various pathways, including corrosion of spent nuclear fuel, have the potential to greatly enhance the mobility of poorly soluble An(IV) forms, including uranium. This is particularly important in conditions relevant to decommissioning of nuclear facilities and the geological disposal of radioactive waste. Previous studies have suggested that silicate could stabilize U(IV) colloids. Here the formation, composition, and structure of U(IV)-silicate colloids under the alkaline conditions relevant to spent nuclear fuel storage and disposal were investigated using a range of state of the art techniques. The colloids are formed across a range of pH conditions (9-10.5) and silicate concentrations (2-4 mM) and have a primary particle size 1-10 nm, also forming suspended aggregates <220 nm. X-ray absorption spectroscopy, ultrafiltration, and scanning transmission electron microscopy confirm the particles are U(IV)-silicates. Additional evidence from X-ray diffraction and pair distribution function data suggests the primary particles are composed of a UO 2-rich core and a U-silicate shell. U(IV)-silicate colloids formation correlates with the formation of U(OH) 3(H 3SiO 4) 3 2- complexes in solution indicating they are likely particle precursors. Finally, these colloids form under a range of conditions relevant to nuclear fuel storage and geological disposal of radioactive waste and represent a potential pathway for U mobility in these systems.

    Original languageEnglish
    Pages (from-to)9118-9127
    Number of pages10
    JournalEnvironmental Science & Technology
    Issue number16
    Early online date12 Jul 2018
    Publication statusPublished - 21 Aug 2018


    • Colloids
    • Uranium(IV)
    • Core-shell
    • uranium silicate
    • nuclear fuel storage
    • EXAFS
    • SAXS


    Dive into the research topics of 'Stability, composition and core-shell particle structure of uranium(IV)-silicate colloids'. Together they form a unique fingerprint.

    Cite this