Unusual selectivity:

Many of these inorganic ion exchangers show high selectivity for particular ions and therefore, the separation of these ions can be more conveniently carried out than on typical organic resins. Such examples are numerous in literature. Zirconium antimonate exchanger has been used for the separation of Rb⁺ and Cs⁺. Cerric antimonate is more or less specific for Hg²⁺ and is used for the separation of Hg²⁺ from Cd²⁺/ Pb²⁺. Zirconium phosphate like ferrocyanides and heteropoly acid salts shows unusual selectivity for Cs⁺ and is used for the removal of Cs⁺ from the nuclear reprocessing solution. Because of high capacity of zirconium phosphate for NH₄⁺, it is used in artificial kidney machine. The selectivity features are not only confined to column separations but they have been extended to paper chromatography in which the papers are impregnated with the inorganic ion exchangers.

The unusual selectivity and stability of synthetic inorganic ion exchangers make them suitable for use in ion selective electrodes. They have been investigated for use as materials for membranes.

Apart from the uses mentioned above, the studies on inorganic ion exchangers throw light on problems such as sorption of ions by precipitates, electrophoretic behaviour of suspensions, isotopic exchange in heterogenous systems and many other areas of solid state chemistry.

Towards the concluding stage of discussion on synthetic ion exchangers, it is important to point out that very few inorganic exchangers have been used on commercial scale. The main reason seems to be that among the useful ones, the majority are based on metals which are costly. The other deterent seems to be that their regeneration power is not as good as that of their organic counterparts.