Effect of pH and concentration on column dynamics of weak electrolyte ion exchange

Abstract

The column dynamics of simple ion-exchange processes involving acetic acid and

pH dependence of ion‐exchange equilibrium of proteins

“…Jansen et al (1996) showed that this is at variance with experiment. The second and the third approach do allow penetration of coions into the ion exchanger and are about equally good in describing the experimental results of Jansen et al (1996). In this article we use the second approach.…”

“…(For convenience we will assume that there are pores in the interior of ion exchange particles, although many ion exchangers consist of a polymer network that contains no real pores.) Jansen et al (1996) compared three approaches to describe the adsorption of small ions to ion exchangers: the SMA model with the pore liquid as part of the adsorbing phase; the SMA model with the pore liquid as part of the liquid phase; and the Donnan equilibrium with the pore liquid as part of the adsorbing phase.…”

Buffer salt effect on pH in the interior of an anion exchange resin

“…The complete exclusion of co-ions is rarely achieved in reality, and this assumption leads to inaccuracies in the estimation of species concentrations in the resin phase [4]. There have been efforts to relax this assumption and develop more broadly applicable models [8][9][10][11][12][13], however, these models still rely on adjustable parameters that must be fit to experimental data. Jansen et al [8] visualize the resin as a homogeneous phase in which the active sites are randomly distributed and uses a Donnan approach to estimate pH of the resin phase.…”

“…The stoichiometric relationship may [1][2][3]6] or may not [7][8][9][10][11] be incorporated into the model to account for interactions between mobile species and resin fixed-charge sites. When the stoichiometric relationship is not included, the phase equilibrium is usually seen to be described by means of an equilibrium constant [7] or selectivity factor [9][10][11]. Many of these models assume that coions are essentially excluded from the resin phase due to Donnan equilibrium forces [4][5][6][7].…”

“…The resin can be visualized as a homogeneous phase with the charges distributed evenly throughout [1][2][3][4][5][6][7][8][9][10][11]. The stoichiometric relationship may [1][2][3]6] or may not [7][8][9][10][11] be incorporated into the model to account for interactions between mobile species and resin fixed-charge sites.…”