Investigation on sorption equilibria of Mn(II), Cu(II) and Cd(II) on a carboxylic resin by the Gibbs-Donnan model

Citation
R. Biesuz et al., Investigation on sorption equilibria of Mn(II), Cu(II) and Cd(II) on a carboxylic resin by the Gibbs-Donnan model, TALANTA, 55(3), 2001, pp. 541-550
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
TALANTA
ISSN journal
0039-9140 → ACNP
Volume
55
Issue
3
Year of publication
2001
Pages
541 - 550
Database
ISI
SICI code
0039-9140(20010913)55:3<541:IOSEOM>2.0.ZU;2-W
Abstract
Sorption mechanism of bivalent metal ions on a weak cationic resin containi ng the carboxylic group is studied. The Gibbs-Donnan model is used to descr ibe and then to predict the sorption through the determination of the intri nsic complexation constants. These quantities characterize the sorption bei ng independent of experimental conditions. They are determined according to a well established procedure and using a recently proposed iterative metho d for calculation of counter ion concentration in the resin phase. Sorption mechanisms are also studied adding appropriate soluble ligands whose compl exing properties are exactly known to the solution containing the resin and the metal ion. Competing with the resin for the complexation of the metal, they shift the sorption curve to higher pH and often this allows detecting other complexes between the metal and the resin. In this way for Mn(II), b esides the 1:1 complex formed in the more acidic solution, with log beta (1 10) = -4.55, the complex ML2, characterized by log beta (120) = -9.80, is f ound; for Cd(II), besides the ML complex, with log beta (110) = -3.01, at p H higher than 7, the specie MLOH with log beta (11-1) = -8.28. For Cu(II) t he complex ML2 is detected, confirming previous findings, with log beta (12 0) = -7.24. In the presence of two different ligands, sulphosalicylic and m alonic acid, a different complex, ML2OH, is identified, with the same intri nsic complexation constant for the two ligands, log beta (12-1) = 13.35. As expected from the model, the intrinsic complexation constants, especially for the 1:1 complex, are in a good agreement with the complexation constant s of acetic acid. (C) 2001 Elsevier Science BN. All rights reserved.