Introduction to the working principle and pretreatment of ion exchange resin system

The working principle of ion exchange resin

The ion exchange method is used to remove the cations and anions in the ionic state in the water. Sodium chloride (NaCl) is used to represent the inorganic salts in the water. The basic reaction of water quality desalination can be expressed by the following equation:
1. Cation exchange resin: R—H+Na+ R—Na+H+
2. Anion exchange resin: R—OH+Cl- R—Cl+OH-
The total reaction formula of cation and anion exchange resin can be written as:
RH+ROH+NaCl——RNa+RCL+H2O
It can be seen that the NaCl in the water has been replaced by H+ and OH- on the resin, and the reaction product is only H2O, so it has achieved the effect of removing salt in the water.

Pretreatment of ion exchange resin

Pretreatment of cation exchange resin

First rinse the resin with clean water, then alternately soak the exchange column with 4~5% HCl and NaOH for 2~4 hours, rinse with a lot of water between acid and alkali until the effluent is close to neutral, repeat 2~ 3 times, the amount of acid and alkali each time is 2 times the volume of the resin. The last treatment should be carried out with 4~5% HCl solution, drain the acid solution, rinse with clean water until it is neutral, and then set it aside.

Pretreatment of anion exchange resin

First rinse the resin with clean water, then alternately soak the exchange column with 4 ~5% NaOH and HCl for 2 ~ 4 hours, rinse with a large amount of water between alkali and acid until the effluent is close to neutral, repeat 2~ 3 times, the amount of acid and alkali each time is 2 times the volume of the resin. The last treatment should be carried out with 4~5% NaOH solution, use up the lye, rinse with water until it is neutral, and then set it aside.

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