Abstract
A mass transfer model for deionization by mixed cation and anion exchange resins is presented in this paper. This model is based on ion exchange and neutralization reactions and is composed by considering ionic valence, diffusion resistances in both resin and liquid phases and mixed volume fraction of the resins. A simplified form of the above model is also shown for deionization by the mixed resin as adsorption of a salt.
The calculated results for a batch system were studied and it was found that: 1) pH value of the solution showed complicated behavior in the course of deionization, even though equal-normality mixed resins were used. Its behavior was greatly affected by the mixed-resin volume fraction and the initial concentration of a salt; 2) both strict and simplified models were compared, and it was found that the neutralization reaction has a large effect on the deionization rate.
