Ion exchange is a special solid adsorption process that takes place in an electrolyte solution with an ion exchanger. The common ion exchanger is a solid granular substance that is insoluble in water, namely ion exchange resin. It can absorb a certain cation or anion from an electrolyte solution and exchange out an equal amount of another ion with the same charge symbol it contains and release it into the solution. This is what is called ion exchange. According to the types of ions exchanged, ion exchangers can be classified into two major categories: cation exchangers and anion exchangers.

Ion exchange

aFirst, electrolyte ions(Ions such as calcium, magnesium, iron and sodium)Pass through the liquid film and enter the resin surface;

bIons enter the interior of the resin;

cIon exchange;

d,HIon orOHRoot ions diffuse to the outside of the resin;

e,HIon orOHRoot ions enter water to formH2O. The double-bed, also known as the compound bed, is a series connection of two different types of ion exchangers, namely cation and anion, such as the series connection of strong acid cation exchange resin and strong base anion exchange resin. The equipment composed of a cation bed and an anion bed connected in series is called a compound bed. Water first passes through the cation bed to remove positively charged ions(Such asCa2+,Mg2+,K+,Na+)And replace itH+Ions into water;Then remove the negative ions from the water(Such asSO2-4,Cl-,HCO- 3)And replace itOH-Ions into water. Meanwhile,H+Ion andOH-Ions combine to form waterH2OThereby achieving the effect of deionization.

Mixed bed

In the same exchanger, anion and cation exchange resins are filled in a certain volume ratio. Under a uniform mixed state, anion and cation exchanges are carried out to remove salts from water, which is called mixed bed desalination treatment. During the exchange process of the anion and cation exchange resins in the mixed bed, as they are in a uniformly mixed state, crisscrossed and in contact with each other, it can be regarded as a multi-stage complex bed composed of numerous anion and cation exchange resins, which can be equivalent to1000～2000Grade. Because it is a uniform mixture, the exchange reactions of anions and cations almost occur simultaneously, and the resulting productH+andOH-Immediately synthesizedH2OThe exchange reaction is carried out very thoroughly, and the effluent quality is high.

System structure process

Pretreatment equipment(Multi-media filtration equipment, activated carbon filtration equipment)+Ion exchange equipment=Pure water

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