ABSTRACT
This chapter introduces the most important factors affecting the use and performance of ion-exchange resins in biotechnology. It describes the theory and operation of ion-exchange systems in sufficient detail to allow one to select and use ion-exchange resins for one’s own applications. The ideal ion exchanger should be made from a tough material that has few extractables and is chemically inert under process conditions. It should be available in several types of functional groups and a variety of matrix porosities. Nonfunctionalized copolymer beads similar to those used to make macroporous ion-exchange resins are useful as nonpolar adsorbents. The highly ionic functional groups of styrenic ion-exchange resins transform the hydrophobic starting copolymers into hydrophilic resins that imbibe water and swell as much as the cross-linked matrix will allow. The lower cross-linked regions, being subject to greater volume changes, are more susceptible to degradation due to osmotic shock than are the more highly cross-linked ones.
