Determination of stability constants of U(VI)-Fe(III)-citrate complexes

KANTAR Ç. , Gillow J., Harper-Arabie R., Honeyman B., Francis A.

ENVIRONMENTAL SCIENCE & TECHNOLOGY, cilt.39, sa.7, ss.2161-2168, 2005 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 39 Konu: 7
  • Basım Tarihi: 2005
  • Doi Numarası: 10.1021/es048852c
  • Sayfa Sayıları: ss.2161-2168


Ion-exchange experiments were performed to evaluate the formation of the uranium-citrate and uranium-iron-citrate complexes over a wide concentration range; i.e., environmentally relevant concentrations (e.g., 10(-6) M in metal and ligand) and concentrations useful for spectroscopic investigations (e.g., 10(-4) M in metal and ligand). The stability of the well-known uranium-citrate complex was determined to validate the computational and experimental methods applied to the more complex system. Values of the conditional stability constants for these species were obtained using a chemical equilibrium model in FITEQL. At a pH of 4.0, the stability constant for uranium-citrate complex (log beta(1,1)) was determined to be 8.71 +/- 0.6 at I = 0. Analysis of the results of ion-exchange experiments for the U-Fe-citric acid system indicates the formation of the 1:11:11 and 1:11:2 ternary species with stability constants (log beta) of 17.10 +/- 0.41 and 20.47 +/- 0.31, respectively, at I = 0.