Showing papers by "Takeshi Kataoka published in 1981"

Intraparticle mass tranfer in weak acid ion‐exchanger

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). Le transfert de masse dans la phase resine d'un echangeur d'ious faiblement acide, a ete analyse en utilisant un modele du type noyau retrecissant (UCM). On a suppose que dans la periode de sorption d'un ion metallique, le noyau etait constitue de la forme-ion metallique. Au contraire pendant la regeneration le noyau comporte la forme-ion metallique alors que I'enveloppe qui apparait comporte la forme-H. La reaction irreversible instantanee c'est-a-dire la neutralisation en periode de sorption et la protonation pendant la regeneration, se produit a I'interface mobile. L'equation de Nernst-Planck a ete appliquee aux flux d'ous diffusant au travers de I'enveloppe et les solutions analytiques ont ete obtenues en supposant un regime pseudostationnaire de diffusion. Ces solutions sont en bon accord avec les resultats experimentaux obtenus pour le systeme R-H-NaOH (sorption) et les systemes R-Na-HCI, R-CU-HCI et R-Cu-H2SO4 (regeneration).