Feature:

Ion exchangers owe their features to a particular feature of their structure. They are built of a framework that is held together through chemical bonds or lattice energy. The framework carries a positive or negative surplus charge that is compensated by ions of opposite charge, known as counter ions. The counter ions are free to move inside the framework and be replaced through other ions of same sign. The framework of cation exchanger might be regarded as a macromolecule or a crystalline polyanion, that of an anion exchanger as a polycation.

From the above discussion, it emerges out in which a useful ion exchanger must have the following requisites:

i) It should have negligible solubility in the medium to be used.

ii) It must hold enough number of accessible ion exchange groups and it must be chemically stable.

iii) It should be sufficiently hydrophilic to allow diffusion of ions through the structure at a finite and usable rate.

iv) The swollen exchanger has to be denser than water.