1, the basic types of ion exchange resin (1) strong acid cation exchange resin such resins contain large amounts of strongly acidic groups, such as sulfonic acid group-SO3H, easily dissociate in solution H +, it is strongly acidic. Resin after dissociation, the body contained in the negative groups, such as SO3-, can be adsorbed with other cations in the solution. Both the reaction of the resin in the H + and the cation exchange solution. Dissociation of strong acid resins are strong in acidic or alkaline solution, and can produce dissociation ion exchange. Resin in use for some time, to be regenerated, that the ion exchange reaction with chemicals in the opposite direction, the functional group of the resin return to the original state, in order for re-use. As described above with a strong acid cationic resin is regenerated, then release the adsorbed cation resin, and then with H + binding to restore the original composition. (2) weak acid cation exchange resin such resins containing acidic groups such as a carboxyl group-COOH, can dissociate in water and acidic H +. Resin remaining after dissociation negative groups, such as R-COO-(R is hydrocarbon group), with the adsorption solution with other cations, thereby generating cation exchange. This resin is weak acid that dissociates at low pH and is difficult to dissociate the ion exchange, only in alkaline, neutral or slightly acidic solution (eg pH5 ~ 14) work. Such resins are regenerated with acid (easier than the strongly acidic resin regeneration). (3) strong base anion exchange resin such resins containing strongly basic groups such as quaternary amine (also known as four amino)-NR3OH (R is hydrocarbon group), can dissociate in water and showed OH- strongly alkaline. Positively charged groups of this resin with a solution with anion adsorption, thereby generating an anion exchange effect. Dissociation of this resin is very strong, at different pH can work properly. It is with a strong base (eg NaOH) for regeneration.