A generalized model for the measurement of effective diffusion coefficients of heterovalent ions in ion exchangers by the zero-length column method

Abstract

A generalized theoretical model for the measurement of effective diffusion coefficients of heterovalent ions in ion exchange resins by the zero-length column method was developed. The model included the resistance to mass transfer both in the particle and in the film and described ion fluxes with Nernst–Planck equations. Equilibria were described using a model based on the mass action law. The values of intraparticle diffusivity of Cu 2+, Cd 2+, Zn 2+, and H + on commercial Amberlite IR-120 were obtained by non-linear regression, these values agree fairly well with data reported previously in literature. The following trend was observed: D Cu> D Zn> D Cd.