The Principle of Ion Exchange Resin

　　The principle of ion exchange resin is that the ion exchange tree separates the salt from the solution: in the aqueous solution in which the ion exchange resin acts, the metal cations (Na+, Ca2+, K+, Mg2+, Fe3+, etc.) and the acid groups such as sulfonic acid group (-SO3H), carboxyl group (-COOH) or phenol group (-C6H4OH) contained in the cation exchange resin are easy to form H + ions in the water.+ Ion exchange is carried out so that cations in the solution are transferred to the resin, and H + on the resin is exchanged into water (i.e. the principle of cation exchange resin); anions in the aqueous solution (Cl-, HCO 3-etc.) are exchanged with basic groups such as anion exchange resin (containing quaternary amines [-N (CH3) 3OH], amino groups (-NH2) or imino groups (-NH2), which are easy to form OH-ions in water. The anion is transferred to the resin, and the OH - on the resin is exchanged to the water (that is, the principle of anion exchange resin). The combination of H + and OH - forms water to achieve the purpose of desalination.

　　Sodium chloride (NaCl) is used to represent inorganic salts in water. The principle of ion exchange resin (i.e. the basic reaction of water desalination can be expressed by the following equation):

　　Cation Exchange Resin: R-H+Na+R-Na+H+

　　Anion Exchange Resin: R-OH+Cl-R-Cl+OH-

　　The general reaction formulas of cation and anion exchange resins can be written as follows:

　　RH+ROH+NaCl-RNa+RCL+H2O

　　It can be seen from this that NaCl in water has been replaced by H + and OH - on the resin respectively, and the reaction product is only hydrogen peroxide, so it can remove salt from water.

　　Above, also known as anion and cation exchange resin principle, ion exchange resin principle.