Gel Type Ion Exchange Resin For Water Softener and Water treatment Industry Ion exchange resin is a resin or polymer that acts as a medium for ion exchange. It is an insoluble matrix (or support structure) normally in the form of small (0.25-1.43 mm radius) microbeads,.The beads are porous, providing a large surface area on and inside them where the trapping of ions occurs along with the accompanying release of other ions, and thus the process is called ion exchange. Application: Cation exchange resin is used to replace magnesium and calcium ions in hard water with sodium ions. At the same time, ion exchange resins can also be used for beverage processing in the food industry, extraction of antibiotics in biopharmaceuticals, and metal separation in wet metallurgy.