The chelating disk has an affi nity for multivalent (primarily +2
and +3) transition elements. The functional group exhibits
differing ionic charges depending on the pH of the solution.
At pH 2, the carboxylate groups are neutral and the nitrogen
has a net positive charge. This allows the sorbent to function
as a weak anion exchanger. Increasing the pH ionizes the
carboxylate groups and at pH =5, both are negatively charged.
As the pH approaches neutral, the sorbent functions as a cation
exchanger or a chelating resin.