Ion exchange resin structure is mainly made of polymer skeleton and active group two parts. (1) polymer scaffold structure matrix also says, it has the mesh structure, it is insoluble in acid or alkali polymer material. According to its polymerization monomer polymer scaffold can be divided into styrene are, the phenolic system and acrylic department, etc. (2) activity groups it firmly in polymer scaffold with, by not free mobile functional group ion and can move freely interchange ion two parts. Among them: (1) the ion functional group decision of ion exchange resin "acid", "base" sex and exchange ability strong and the weak. Ion is of strong acid functional groups (low SO3-is called strong acidic ion exchange resins; Is the alkali (≡ N +), is called a strong alkali ion exchange resin. Also, according to the nature of the ion functional groups, but also can have a weak (ionized as-coo-its (NH2 +) and other types of ion exchange resin. (2) can exchange ions. Modern exchange theory, the ion exchange resin as a colloid type material: polymer scaffold is "glue nuclear", active groups as polymer scaffold surface "electric double layer", functional groups and part can be composed of exchange ions adsorption, ion exchange of another part of diffusion layer. Owing to exchange ions adsorption of layer, the other part of the ion exchange of diffusion layer. Owing to exchange ions can be free to move, and with the water of the symbols can occur with ion exchange reaction. If ion exchange resin on the ion exchange for cationic, such as H +, call the H cation exchange resin; If can exchange ions for anion, for example-OH, it is called OH type anion exchange resin. The rest can in turn on.