Pesavento Maria, Biesuz Raffaela, Alberti Giancarla, Sturini Michela
Dipartimento di Chimica Generale dell'Università degli Studi di Pavia, Via Taramelli 12, 27100 Pavia, Italy.
Anal Bioanal Chem. 2003 Aug;376(7):1023-9. doi: 10.1007/s00216-003-1951-9. Epub 2003 Jun 13.
The sorption of uranium(VI) on two cationic resins containing different complexing groups, the iminodiacetic resin Chelex 100 and the weak carboxylic resin Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and to predict the sorption through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize the sorption as being independent of experimental conditions. The sorption mechanism of the metal on the complexing resins was also studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH values. The ligand competes with the resin for the complexation with the metal ion. Uranium is also strongly sorbed on Chelex 100 at very acid pH, through formation of two complexes in the resin phase: ML with log beta(110i)=-1.16, in more acidic solution, and ML(2 )with log beta(120i)=-5.72. Only the presence of the competitive ligand in solution makes the determination of the second complex possible. Also on Amberlite CG-50 the sorption is strong and involves the formation of the complex ML(2), in more acidic solution, with log beta(120i)=-3.16. In the presence of the ligand EDTA, the complex ML(2)(OH)(2 )was characterized with log beta(12-2i)=-5.15. In all the experiments the hydrolysis reaction in the aqueous phase was quantitatively considered.
研究了铀（VI）在两种含有不同络合基团的阳离子树脂（亚氨基二乙酸树脂Chelex 100和弱羧酸树脂Amberlite CG - 50）上的吸附情况。通过测定本征络合常数，利用吉布斯 - 唐南模型来描述和预测吸附过程。这些量虽然不是热力学量，但能表征吸附过程与实验条件无关。还通过添加一种竞争性可溶性配体来研究金属在络合树脂上的吸附机理，该配体使吸附曲线向更高pH值移动。该配体与树脂竞争与金属离子的络合。在非常酸性的pH条件下，铀也能强烈吸附在Chelex 100上，通过在树脂相中形成两种络合物：在酸性更强的溶液中，ML的logβ(110i)= - 1.16；以及ML₂的logβ(120i)= - 5.72。只有溶液中存在竞争性配体时，才能确定第二种络合物。在Amberlite CG - 50上，吸附也很强，在酸性更强的溶液中会形成络合物ML₂，其logβ(120i)= - 3.16。在配体EDTA存在的情况下，络合物ML₂(OH)₂的logβ(12 - 2i)= - 5.15。在所有实验中，都对水相中的水解反应进行了定量考虑。
