Demineralized water is water which removes or reduces a strong electrolyte which is easily removed to a certain extent. The remaining salt content in the desalted water should be between 1 and 5 mg/l.

 

Method for preparing desalinated water:

1 Distillation method, the salt-containing water is heated and evaporated, and the steam is condensed to obtain desalted water. The distillation method is mostly used in the laboratory for washing containers or preparing solutions, and is suitable for places where the amount of purity is not high. 

 

2 ion exchange method, the salt-containing water is passed through an exchange column containing zeolite or ion exchanger (see ion exchange), calcium and magnesium ions are left on the exchange column, and the filtered water is desalted water;

 

3 Electrodialysis method, by the ion exchange membrane selective ion permeability, under the action of an external electric field, the cations and anions in the water between the two ion exchange membranes are concentrated to the cathode and the anode through the exchange membrane.

 

Thus, the intermembrane zone becomes a fresh water zone, and the outer membrane is a concentrated water zone. The water drawn from the freshwater area is desalinated.

 

The ion exchange method and the electrodialysis method are mostly used in chemical industries such as boiler water to reduce scale and corrosion, and are suitable for places where the amount of purity is not very high.