A DONNAN MODEL FOR THE ANALYSIS OF METAL COMPLEXATION OF WEAK-ACIDIC POLYELECTROLYTES - AN APPROACH TO THE QUANTITATIVE ANALYTICAL TREATMENT OF THE METAL COMPLEXATION EQUILIBRIA OF HUMIC SUBSTANCES

被引:0
作者
MIYAJIMA, T
KANEGAE, Y
YOSHIDA, K
KATSUKI, M
NAITOH, Y
机构
关键词
HUMIC SUBSTANCES; COMPLEXATION; POLYELECTROLYTE; CARBOXYMETHYL-DEXTRAN; GEL;
D O I
暂无
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
A Donnan model, a novel analytical treatment of the proton and metal binding equilibria of humic substances proposed by Marinsky (J. Environ. Sci. Technol., 20 (1986) 349-354), is examined by use of metal binding equilibria of monovalent (Ag+) and divalent (Ca2+) ions to carboxymethyl-dextran, CmDx, and the cross-linked CmDx, CM-Sephadex (Pharmacia, Sweden), in sodium salt media at 25-degrees-C. A separate phase (a Donnan phase) is assumed in the vicinity of the polymer skeleton from the bulk solution phase. Both a Donnan potential term and a Donnan phase volume term were determined by use of their acid-dissociation properties. In spite of substantial variation in the macroscopic binding constants determined under various pH and ionic strengths, constancy was obtained in the microscopic stability constants of the monodentate ligand complexes in both cases, which validates the model.
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页码:129 / 137
页数:9
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