Characterization of ion exchange resins

The use of ion exchange resins and natural or synthetic inorganic exchange materials in the nuclear industry is well documented ( ). In the waste solidification application, the titanates or niobates offer no unique sorption properties. They do, however, provide a relatively high overall sorption capacity for a variety of nuclides in materials which can be converted into a stable ceramic host for the sorbed ions. After the sorption process, the column bed must be consolidated to reduce surface area. The project emphasis was directed toward a stable waste form and a considerable effort was devoted to producing and characterizing a highly dense form with favorable physical, chemical and thermal properties (l ). 

The most direct method for determining charge content of a gel is by titration of the sample. These methods are extensively used to determine the capacity of ion exchange resins and are discussed in detail in that literature [24]. The method of the titration briefly described here is for anionic gels characterization of cationic gels would require the analogous titration be performed using acid solution as a titrant. 

Suspension Polymers. Methacrylate suspension polymers are characterized by thek composition and particle-size distribution. Screen analysis is the most common method for determining particle size. Melt-flow characteristics under various conditions of heat and pressure are important for polymers intended for extmsion or injection molding appHcations. Suspension polymers prepared as ion-exchange resins are characterized by thek ion-exchange capacity, density (apparent and wet), solvent sweUing, moisture holding capacity, porosity, and salt-spHtting characteristics (105). 

Chromatographic methods (essentially using ion-exchange resins) are especially useful for separating heparin from other glycosaminoglycans, for further analytical and structural characterization. However, it should be realized that recovery of heparin from resins is seldom quantitative,42 probably because of irreversible absorption of heparin fractions in the... 

Alexandratos, S. D., Trochimiczuk, A. W., Horwitz, E. P., Catrone, R. C., synthesis and characterization of a bifunctional ion exchange resin with polystyrene-immobilized diphosphonic acid ligands, J. Appl. Polymn. Sci. 61,1996,273-278. 

By means of both conventional and MAS high resolution NMR, a characterization of macroporous ion-exchange resins were characterized (PS-DVB with 2, 4, 8, 15 and 25 nominal % of DVB) was also made 173,174). 

Different resins have been used to clean up or prefractionate anthocyanins prior to isolation or characterization, including ion-ex-change resins, polyamide powders, and gel materials. Chromatography on Dowex or Amber-lite ion-exchange resins, as well as polyamide powders such as polyvinylpyrrolidone (PVP), have been used to isolate polar nonphenolic compounds from crude anthocyanin extracts. Column chromatography on Sephadex LH-20 can be used for fractionation of crude extracts and is also particularly useful for purification... 

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