Surface speciation and interactions between adsorbed chloride and water on cerium dioxide

Sophie Sutherland-Harper, Robin Taylor, Jeff Hobbs, Simon Pimblott, Richard Pattrick, Mark Sarsfield, Melissa Anne Denecke, Francis Livens, Nikolas Kaltsoyannis, Bruce Arey, Libor Kovarik, Mark Engelhard, John Waters, Carolyn Pearce

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Abstract

Ceria particles with different specific surface areas (SSA) were contaminated with chloride and water, then heat treated at 500 and 900 °C to investigate sorption behaviour of these species on metal oxides. Results from x-ray photoelectron spectroscopy and infrared spectroscopy showed chloride and water adsorption onto particles increased with surface area and that these species were mostly removed on heat treatment (from 6.3 to 0.8 at% Cl- on high SSA and from 1.4 to 0.4 at% on low SSA particles). X-ray diffraction revealed that chloride was not incorporated into the bulk ceria structure, but crystal size increased upon contamination. Ce LIII-edge x-ray absorption spectroscopy confirmed that chloride was not present in the first co-ordination sphere around Ce(IV) ions, so was not bonded to Ce as chloride in the bulk structure. Sintering of contaminated high SSA particles occurred with heat treatment at 900 °C, and they resembled low SSA particles synthesised at this temperature. Physical chloride-particle interactions were investigated using electron microscopy and energy dispersive x-ray analysis, showing that chloride was homogeneously distributed on ceria and that reduction of porosity did not trap surface-sorbed chloride inside the particles as surface area was reduced during sintering. This has implications for stabilisation of chloride-contaminated PuO2 for long term storage.
Original languageEnglish
Pages (from-to)16-25
JournalJournal of Solid State Chemistry
Volume262
Early online date26 Feb 2018
DOIs
Publication statusPublished - Jun 2018

Keywords

  • 4f/5f metal oxides
  • Chloride and water adsorption
  • Physical and chemical entrapment mechanisms
  • Heat treatment
  • Desorption processes
  • Particle morphology, porosity and surface area

Research Beacons, Institutes and Platforms

  • Dalton Nuclear Institute

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