In general, ion exchangers consist of a cross-linked polymer matrix with a uniform distribution of fixed ionic groups sited throughout the resin structure. These must be balanced by a similar number of ions of the opposite charge, the counter ions, to maintain electrical neutrality. Cation exchangers therefore exchange and enrich only cations, anion exchangers only anions. In contrast adsorber resins have a non ionic, but depending on the structure a somewhat polar character and don't adsorb stoichiometrically both: anions, cations, as well as uncharged compounds.
Possible applications are:
Trace enrichment by using chelating ion exchangers
Determination of total salt content of solutions and water by H+ exchange
Removals of interfering cations or anions
Digestion of insoluble compounds
Application as a catalyst