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SUMMARY:Influence of ionic strength\, pH and silicate on colloidal UO2 for
 mation
DTSTART:20081121T100000
DTSTAMP:20260929T005922Z
UID:c8c0e2efce0a4587b8a55ac4e9a2bca0ac1ce9de7cb1f4f0d8362763
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Christoph Hennig - Forschungszentrum Dresden-Rossendorf\, I
 nstitute of Radiochemistry\nThe solubility of uranium in aqueous solutions
  under anaerobic conditions is low and the probability of solid UO2 format
 ion increases with the U(IV) concentration. Only in solutions with low pH 
 and high ionic strength the U(IV) hydrate itself is stable even at higher 
 U(IV) concentrations. With increasing pH several U(IV) hydroxides becomes 
 dominant. Below their solubility limits two solid phases can be observed\,
  i.e. the microcrystalline UO2 and the amorphous UO2•xH2O/U(OH)4 which b
 oth can occur as colloids in solution. Also the presence of silicate influ
 ence the formation and structure of U(IV) nanoparticles. However\, even in
  solutions with equimolar ratio of UO2 and SiO2 the precipitation do not r
 esult in the formation of a USiO4-like phase\, which can be observed easil
 y under hydrothermal conditions. Some structural aspects of the resulting 
 solid phases have been investigated with x-ray diffraction\, EXAFS and wid
 e angle x-ray scattering techniques and will be briefly discussed. 
LOCATION:CH C3 30
STATUS:CONFIRMED
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