Ion-exchange resin

An ion-exchange resin or ion-exchange polymer is an insoluble matrix (or support structure) normally in the form of small (0.5-1 mm diameter) beads, usually white or yellowish, fabricated from an organic polymer substrate. The beads are typically porous, providing a high surface area. The trapping of ions occurs with the accompanying releasing of other ions; thus the process is called ion-exchange. There are multiple types of ion-exchange resin. Most commercial resins are made of polystyrene sulfonate.