Working Principle of Ion Exchange Resin

　　Working Principle of Ion Exchange Resin

　　The materials that combine ionic functional groups with resins (organic polymers) are called "ion exchange resins". The resin with sulfonic acid on its surface is called cation exchange resin, while the resin with ammonia ion is anion exchange resin. Ion exchange resins can remove anions and cations from water effectively, so they are often used in the manufacturing process of pure water and ultra-pure water. (See figure below)

　　Although functional groups on ion exchange resins can remove ions from raw water (Feed water), after a period of time, due to the saturation of functional groups, the deionization efficiency decreases, which leads to the shortcomings of water quality deterioration. In addition, ion exchange resins are also organic substances, which can be dissolved by oxidation, mechanical rupture and efflux of supports. In addition, charged organic substances are also adsorbed by ion exchange resins, which make ion exchange resins vulnerable to organic contamination (Fouling). Some microorganisms are also adsorbed by cation exchange resin because of the negative electricity on the surface of bacteria. The surface of resin becomes the breeding ground of microorganisms and pollutes the pure water. At the same time, the metabolites produced by microorganisms will also become the source of organic pollution. These are the areas that cause deterioration of water quality when ion exchange resin is used.

　　Ion exchange resins, which usually lose the ability of ion removal (saturation), can be regenerated by acid and alkali reagents to achieve the purpose of reuse, but if the efficiency of adsorption (pollution) of organic substances is not good, the removal performance of resins will be reduced. In addition, according to the quality of regenerative chemicals, there is also a risk of contamination of ion exchange resins themselves. Therefore, the ion exchange resin used in ultra-pure water system can hardly be regenerated.