Influence of wax coatings on release rate of anions from ion-exchange resin beads.

Ion-exchange resin beads were coated with various waxes to improve and control their release. The in vitro release rates of benzoate ions from the coated-resin beads were then investigated using a rotating sieve basket technique. The dramatic differences in release rates observed with the different waxes can be discussed in terms of the wax to resin ration and the solubility characteristics of the waxes. The initial release rates can be expressed in terms of a mathematical expression previously reported for the diffusion of ions in ion-exchange resins, thereby aiding in the elucidation of the effect of the waxes on release.