Ion exchange resins are high molecular material with an ion exchange function. in the solution, the ion of itself will have an exchange with the ion which has the same symbol in the solution. According to the nature of different exchange groups, the ion exchange resins can be classified into two categories cation exchange resin and anion exchange resin, most of the cation exchange resin have a sulfonic acid group (-SO3H), carboxyl (-COOH) or phenol (-C6H4OH), etc. and other acidic group, wherein the hydrogen ions can have a exchange with a metal ion in solution or other cation ion, anion exchange resin containing quaternary amine [-N (CH3) 3OH], amino (-NH2 ) or imino (-NH2 ) and other alkali basic group. They can generate OH- ions in water, which can have the exchange interaction with various anions, and the ion exchange resin is in very widely use, it is mainly used for the isolation and purification.
the mechanism are as follows: Ion exchange resins are high molecular material with an ion exchange function. in the solution, the ion of itself will have an exchange with the ion which has the same symbol in the solution. According to the different nature of the exchange groups, the ion exchange resin can be divided into cation exchange resin and an anion exchange resin. Most of the cation exchange resin has a sulfonic acid group (-SO3H), carboxyl (-COOH) and phenol (-C6H4OH) and other acidic group, wherein the hydrogen ions in solution can have an exchange with a metal or other cation. For example, the polymers of styrene and divinylbenzene by sulfonation is giving strong acid cation exchange resin and the structure can be simply expressed as R-SO3H, wherein R represents a resin matrix, the exchange mechanism is 2R-SO3H + Ca2 + (R-SO3 ) 2Ca + 2H this is the mechanism of water softening. Anion exchange resin comprises quaternary amine [-N (CH3) 3OH], amino (-NH2 ) or imidogen (-NH2 ) and other alkaline group. They can generate OH- ions in the water, and have exchange interaction with a variety of anions, the exchange mechanism is R-N (CH3) 3OH + Cl- R-N (CH3) 3Cl + OH- due to the ion exchange is reversible, so the used ion exchange resin is suitable to wash with acid or base resin with a suitable ion exchange concentration, to restore the original state and repeated use, so the process is called regeneration. cation exchange resin can be washed with dilute hydrochloric acid, dilute sulfuric acid solution; the anion exchange resin can be treated with sodium hydroxide solution, etc., and then reproduced. ion exchange resins are widely used, and it is mainly for the isolation and refinement. For example, softening water system and producing deionized water, recycling metal in industrial wastewater, separating rare metals and precious metals separation and purification of antibiotics.
