Recognition, separation and concentration of metal ions with chelating resins or chelating reagent impregnated resins (Review)

The history of studies on the recognition, separation and concentration of metal ions with chelating resins or chelating reagent impregnated resins (RIR) has been briefly surveyed with 195 references. Both types of chelating resins have been extensively studied in order to develop highly effective separation and detection methods for various metal ions. In this review, the preparation and adsorption mechanisms are mainly summarized. Especially, a method called Molecular Imprinting has recently been developed to make new types of chelating resins having high selectivity for specific metal ions. It is shown that chelating resins synthesized based on this idea have high selectivity for imprinted metal ions. The adsorption of metal ions with RIR has attracted considerable attention since it was introduced, because of its advantage of easy preparation. Adsorption mechanisms have recently been studied for various types of RIR. It has been suggested that different preparation methods for RIR give different adsorption mechanisms. Thus, information on the physical state of the reagent impregnated in the resin particles should also be very important to prepare efficient RIR. The separation and concentration of metal ions with these solid materials are expected to be highlighted in the 21st century, since they can provide simple and clean separation technologies that cause few environmental problems.