Influence of Differences in Resin-Matrix Structure on Ion-Exchange Adsorption of Trace Amounts of Ag(I), Co(II) and Cr(III)

The influence of differences in resin-matrix structure on the ion-exchange adsorption of trace amounts of Ag(I), Co(H) and Cr(H) was studied by using both macroreticular and gel-type resins. The results indicate that the rate-determining step of the exchange mechanism of these ions is film diffusion under conditions of finite volume and at an ionic strength of 1×10−4. The diffusion coefficient decreases with increasing size of the hydrated ions—in the order DAg>DCo>Dcr. It may be said that the faster rate of exchange in the macroreticular resin is due to the larger surface area and pore size of this resin. Also, in a column system—as opposed to batch operation, it is assumed that the rate-determining step of the exchange reaction is film diffusion. With both resins, the kinetic coefficient β decreases in the order: βAg>βCo>βcr. For the same linear velocity, a higher/3-value is obtained with the macroreticular than with the gel-type resin. Consequently, a higher separating efficiency may be expected from t...