Intraparticle Ion-Exchange Kinetics in Selective Systems

Institute of Physical Chemistry, Russian Academy of Science, 

With few exceptions discussed elsewhere [14,44] and also mentioned by Helfferich [5], the reaction rate is much more rapid than the diffusion process so that the effect of the reaction on the kinetic process becomes apparent through the reaction parameters measured in the approach to equilibrium [7-12,25-28,44-47]. 

The purpose of this review is to discuss IE kinetics in selected systems using the kinetic model developed in this author s research [26-27,45-50]. It is an attempt to demonstrate, in particular, that phenomenological regularities and criteria describing intraparticle diffusion kinetics for conventional ion exchange are not applicable for the selective ion-exchange systems. 

The dissociation constants of the complexes Ri (i = B or A) are assumed to be independent of the degree of conversion F. In the case of weakly dissociated components (when K /Cg 1) the selectivity factor RA RB responsible for the shape of the exchange isotherm a, = fi(CQ,c (where i = B or A) in the resin phase. The exchange isotherm is favorable (or convex ) for invading ion B if the resin is selective for this ion and unfavorable (or concave ) for it if the resin is selective for the counterion A being displaced. The relationship I /Kng 1, holds in the first case and the relationship Kp /Kkb 1, is applicable in the second case. 

In our experiments the commercial type of ion exchangers CB-4 (carboxylic), VPC (vinylpyridine carboxylic), ANKB (ampholyte), and AN-13 (ampholyte) were used. 

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INVESTIGATION OF INTRAPARTICLE ION-EXCHANGE KINETICS IN SELECTIVE SYSTEMS A. 1. Kalinitchev... 

Investigation of Intraparticle Ion-Exchange Kinetics in Selective Systems... 

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