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Gilles Montavon, A. Mansel, A. Seibert, H. Keller, Jens Volker Kratz, N. Trautmann
Complexation studies of UO22+ with humic acid at low metal ion concentrations by indirect speciation methods
The complexation of uranium(VI) with humic acid was studied at pH 4 and 5 in 0.1 mol/l and 4.10-3 mol/l NaClO4 by indirect speciation methods, i.e., electrophoretic ion focusing (EIF) and anion exchange (AE). The concentration range investigated was from 10-8 mol/l to 5 · 10-6 mol/l for the uranyl ion and from 1 to 2.5 mg/l for the humic acid. The experimental data obtained by AE are well described by the complexation reaction involving the charge neutralization of the uranyl ion with two exchanging sites of humic acid. The complexation constant calculated by taking the loading capacity values into account is found to be log β = 6.08 &plusm; 0.15. Concerning EIF, an interfering interaction between the humic acid and U(VI), occurring under the effect of the electric field, is evident and makes this separation technique not well suitable for the investigation of the U(VI):humic acid system.
Radiochimica Acta, Oldenbourg Wissenschaftsverlag
Print ISSN: 0033-8230
Volume: 88, 01/2000
Pages: 017