Intraparticle mass tranfer in weak acid ion‐exchanger

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Abstract
Resin phase mass transfer in a weak acid ion‐exchanger was analyzed based on a shrinking core model. It was assumed that H‐form core and metallic ion‐form shell appear in sorption of metallic ion, while metallic ion‐form core and H‐form shell appear in regeneration of metallic ion‐type resin. At the moving boundary, instantaneous irreversible reaction occurs, namely, neutralization reaction in the sorption and the protonation reaction in the regeneration. The Nernst‐Planck equation was applied to the fluxes of ions diffusing through the shell and the analytical solutions of sorption and regeneration rates were derived by assuming a pseudo‐steady state diffusion. Those solutions agreed fairly well with the experimental results in R‐H‐NaOH system (sorption) and in R‐Na‐HCl, R‐Cu‐HCl and R‐Cu‐H2SO4 systems (regeneration).