Chelating resin is a special ion exchange resin that can form a cross-linking functional polymer with a multi-coordination complex with metal ions. Among the functional groups, there are atoms such as O, N, S, P, and As which have unbonded lone pairs of electrons.
The structure of the chelating resin is generally more complicated than that of the ion exchange resin
, but the synthesis method is substantially similar to that of the ion exchange resin, that is, the resin precursor is first synthesized, and then the ligand group is introduced by a functional group reaction. It is also possible to prepare a monomer having a ligand first and then polymerize to obtain a chelating resin, but the foregoing method is more widely used.
Taking the aminocarboxylic acid resin in the N, O ligand chelating resin as an example, the polystyrene precursor can be firstly subjected to a chloromethylation route or a direct amination method to obtain a primary amine ball, and then a primary amine ball and a chloroacetic acid. The reaction gives an aminocarboxylic acid resin. The cleavable portion of some chelating resin
functional groups can also form ionic bonds with metal ions like ordinary ion exchange resins.