UO22+ and NpO2+ Complexation with Citrate in Brine Solutions

  • M. Bronikowski
  • O. S. Pokrovsky
  • M. Borkowski
  • G. R. Choppin


Complexation of uranyl (UO2 2+) and neptunyl (NpO2 +) with citrate at high ionic strengths I(m) has been investigated by solvent extraction with HDEHP. β1 app values were obtained for I(m) between 0.3 m and 5.0 m NaCl. For NpO2 +, at pHm = 4.7–6.4 only the 1:0:1 complex was formed while for UO2 2+ at pHm 3.0 the 1:1:1 and 1:0:1 complexes were detected with the latter species more dominant. Values obtained for β1 app ranged from 2.62 ± 0.05 to 2.56 ± 0.03 for neptunyl and from 7.30 ± 0.04 to 7.03 ± 0.08 for uranyl as 1 increased from 0.3m to 5.0m NaCl. The β1 app values were used to estimate the concentration of citrate required in a neutral brine to provide a 10% competition with hydrolysis.


Ionic Strength Stability Constant High Ionic Strength Carbonate Complexation Spectrophotometric Study 
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Copyright information

© Kluwer Academic / Plenum Publishers, New York 1999

Authors and Affiliations

  • M. Bronikowski
    • 1
  • O. S. Pokrovsky
    • 1
  • M. Borkowski
    • 2
  • G. R. Choppin
    • 1
  1. 1.Department of ChemistryThe Florida State UniversityTallahasseeUSA
  2. 2.Department of RadiochemistryInstitute of Nuclear Chemistry and TechnologyWarsawPoland

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