Overview of Pure Water Production in Ion Exchange Resin Systems

　　The ion exchange system is a traditional water treatment process that replaces various anions and cations in water through anion and cation exchange resins. By combining anion and cation exchange resins in different proportions, ion exchange cation bed systems, ion exchange anion bed systems and ion exchange mixed bed systems can be formed. The mixed bed system is usually used as the terminal process for producing ultrapure water and high-purity water after water treatment processes such as reverse osmosis. It is currently one of the irreplaceable means for preparing ultrapure water and high-purity water. The conductivity of its effluent can be lower than1uS/cmBelow, the resistivity of the effluent water reaches1MΩ.cmAs mentioned above, depending on different water qualities and usage requirements, the resistivity of the effluent can be controlled within1~18MΩ.cmBetween. It is widely applied in the preparation of industrial ultrapure water and high-purity water such as ultrapure water for electronics and power, chemical industry, electroplating, boiler feed water and pharmaceutical use.

　　The working principle of using ion exchange resin to produce pure water

　　By using the ion exchange method, the cations and anions in water in ionic form can be removed, such as sodium chloride(NaCl)Representing inorganic salts in water, the basic reactions of water desalination can be expressed by the following equation:

　　1Cation exchange resinR-H+Na+ R-Na+H+

　　2Anion exchange resinR-OH+Cl- R-Cl+OH-

　　The overall reaction equation for cation and anion exchange resins can be written as:

　　RH+ROH+NaCl-RNa+RCL+H2O

　　From this, it can be seen that in the waterNaClIt has been respectively applied to the resinH+andOH-It is replaced, and the reaction products are onlyH2OTherefore, the effect of removing salt from water has been achieved

　　The pure water used for ultrasonic cleaning adopts a two-stage reverse osmosis method

　　The process is as follows:

　　Tap water→Electric valve→Multi-media filter→Activated carbon filter→Water softener→Middle water tank→Low-pressure pump→Precision filter→First-stage reverse osmosis→PHRegulation→Mixer→Secondary reverse osmosis(The surface of reverse osmosis membranes carries a positive charge)→Pure water tank→Pure water pump→Microporous filter→Water usage point.

　　The ultrapure water used for ultrasonic cleaning is added by reverse osmosisEDI"Method"

　　The process is as follows:

　　Tap water→Electric valve→Multi-media filter→Activated carbon filter→Water softener→Middle water tank→Low-pressure pump→PHValue adjustment system→Mixer→Precision filter→Reverse osmosis→Middle water tank→EDIWater pump→EDISystem→Microporous filter→Water usage point.

　　The characteristics and application fields of the ultrapure water preparation process

　　Ion exchange equipment is a traditional deionized water device. The water quality it produces is stable and the cost is relatively low. In the past, the feed water for power plant boilers was all provided by cation beds+"Yin bed"+Mixed bed treatment process.

　　In recent years, with the development of reverse osmosis,EDIWith the development of technology, the disadvantages of ion exchange equipment, such as complex operation, difficulty in achieving automation, waste of acid and alkali, and high operating costs, have become more prominent. Currently, it is more widely used in the advanced treatment of reverse osmosis.

　　Small-scale ion exchange equipment often uses acrylic exchange columns, which is conducive to observing the operation of the resin. Such as whether the regeneration stratification of the mixed ion exchanger is sufficient, whether the cations are "poisoned", etc., and the condition of resin loss, etc.

　　Large-scale ion exchange equipment is made of carbon steel lined with epoxy resin or rubber, with a visual device reserved in the middle to facilitate online observation of the water level of the regenerant during ion regeneration.

　　1The industrial ultrapure water treatment process is one of the most widely used processes in the preparation of industrial ultrapure water at present.

　　2Industrial ion exchange resins can be used in industrial equipment such as sugar refining, monosodium glutamate production, wine refining, and biological product manufacturing.

　　3Ion exchange resins in the pharmaceutical industry play a significant role in the development of new generations of resins and the quality improvement of original resins. The successful development of streptomycin is a prominent example.