Abstract
Sodium-form taeniolite, NaT, has very high selectivity in ion-exchange reaction for some alkaline metal ions. NaT was granulated for removing potassium ion or caesium ions from brine with ion-exchange columns in which granular NaT was packed. A mixing-agitation granulator successfully granulated NaT from powder NaT and colloidal silica of 10wt% to NaT as binder. Granulation caused few changes in its ion-exchange property. In batch reactions, the exchange reaction of granular NaT became slightly slower than those of powdered form. The reaction rates were determined by the film diffusion in the beginning of the batch reactions, and then the intraparticle diffusion determined the rates in the middle and final stages of the reactions. This translation of the rate-determining step may be because of a decrease of the intraparticle diffusion coefficient with an increase the exchange rate. Columns packed with granular NaT removed potassium and caesium ions as well as in the batch reactions. The removal properties of the columns depended on the particle size of the grain packed. Granular NaT-packed columns removed potassium and caesium ions as selectively as powder NaT did from model seawaters. The smallest grain of NaT studied was found most suitable for columns. It is indicated that granular NaT-packed columns are useful for separation of potassium and caesium ions from brine.
