Rates of Anion Exchange of Tungstates with Ion Exchange Resin.

Using the batch method, the exchange rate of tungstate on weak base anion exchange resin, amberlite IR-45, has been measured, and also the applicability of rate equations which were previously proposed in literature was discussed. Experiments were carried out with dilute tungstate solutions of pH 9.80 and 5.05 which contained chloride ions, in a thermostatted bath at 15，20, 25 and 30±0.1℃. For these conditions, the rates of exchange of chloride-tungstate anions (tungstate is in-going ion) in alkaline solution were higher than in acidic one. At the first step of exchange reaction, the rate was controlled by particle diffusion process, and it was found that the equation of particle diffusion derived by Boydet al, was applicable. The effectve diffusion coefficient in resin phase, D, and the activation energy, E, for the exchange reaction were calculated from the data obtained above. In order to elucidate the rate-controlling mechanism many experimental studies on the rates of ion exchange reaction had been made by Kunin and Myers. Boyd, Adamson and Myers and Reichenberg. Particularly, a great clarification of the field was made by Boyd, Adamson and Myers. Although a chemical process, film diffusion and particle diffusion had previously all been separately postulated as possible rate-controlling mechanisums, they gave for the the first time a clear analysis of the kinetics corresponding to each hypothesis. The present authers have reported on the rate of ion exchange of vanadate anions which produces several different anionic species of different size and ionic charge, showing that the pH value of the solution had an influence on the rate and that the particle diffusion was the rate-controlling prosess.