N.B. Ferapontov *, V.I. Gorshkov, L.R. Parbuzina,

N.L. Strusovskaya, A.N. Gagarin

M.V. Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory, GSP-2, 119992 Moscow, Russian Federation

Received 18 March 2005; received in revised form 28 June 2006; accepted 19 August 2006

Available online 2 October 2006

Abstract

This work deals with thermodynamic description of equilibrium between an ion exchange resin and the solution of low molecular weight electrolyte. The suggested approach allows calculating thermodynamic constant of ion exchange equilibrium.

In order to calculate the activity of ion exchange groups in the resin having monoionic form we used published reference data assuming that the activity of resin exchange sites and that of corresponding monomer are equal in the solutions with equal concentrations. For ion exchange resin in mixed form in equilibrium with the mixed solution of corresponding low molecular weight electrolytes the method of calculating each of ionic forms was also suggested. These activities were used to determine the constant of ion exchange equilibrium.

 2006 Elsevier B.V. All rights reserved.

Keywords: Ion-exchange resin; Equilibrium; Theory

1. Introduction

A bead of ion exchange resin represents a threedimensional

polymeric matrix (network) with positively

or negatively charged functional groups. The

study of water and electrolyte sorption by ion

exchange resins was proceeding vigorously as far

back as 50–60th of the last century. These studies

were reviewed in many books; see for instance [1–

5]. The notions of these phenomena currently present

in physical chemistry of ion exchange resins are

based on the concept of quasi-homogeneity of swollen

resin. Moreover, the notions employed the

model of electrolyte Donnan distribution in which

the bead surface is likened to semi-permeable membrane

[6,7].

In practice, the distribution law followed from

the Donnan equation is not always fulfilled. To

explain the discrepancies Glueckauf and Watts [8]

supposed that both the functional sites and cross

linking bridges are distributed non-uniformly

throughout the entire volume of resin beads. Certain

shortcomings of this approach were reported

in [3, p. 31–32].

Davies and Yeoman [9] were the first to suggest

the idea of heterogeneous structure of ion exchange

1381-5148/$ – see front matter  2006 Elsevier B.V. All rights reserved.

doi:10.1016/j.reactfunctpolym.2006.08.005

* Corresponding author. Tel.: +7 95 939 4019; fax: +7 95 939

0283.

E-mail address: nferapontov@mtu-net.ru (N.B. Ferapontov).

Reactive & Functional Polymers 66 (2006) 1749–1756

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