The semi-permeable membrane electrodialysis using is actually an ion exchange membrane which can be divided into cation exchange membrane (cationic membrane) and anion exchange membrane (negative membrane) according to the charge properties of ions. In aqueous electrolyte solutions, cation passes through the cationic membrane while the anion is blocked because of the selective permeability of the ion exchange membrane, and vice versa for anionic membrane. During electrodialysis process, the ion exchange membrane will not exchange resin and aqueous solution of some kind of ion exchange, but only select different electrical ions in the ion exchange membrane which doesn’t need to be regenerated. The electrode and membrane composed of the polar chamber, where the electrochemical reaction occurs.
 
Electrodialysis is a relatively mature technology in the process of membrane separation, and has been widely used in brackish water desalination to produce freshwater in some areas of the world. The newly developed charge film has higher selectivity, lower membrane resistance, better thermal stability phase chemical stability and higher mechanical strength, it is not only applied in desalination, food, medicine and chemical industry, but also many other industrial applications, such as industrial wastewater treatment ( recover acid and metal from waste waters of acid washing solutions, recover heavy metal ions from electroplating waste, recover sulphate from synthetic fiber wastewater, recover sulfite from pulp waste). Furthermore, it is also used in milk desalination, separation of ionic and non-ionic substances, even used as can be used as artificial kidney in clinical treatment.
 
Automatic control of frequent inverted electrodialysis (EDR) is easy and convenient to be operated. Raw water utilization rate is up to 80% while the general recovery rate ranges from 45 to 70%. Electrodialysis is mainly used for the primary desalination of water with a desalination rate between 45 and 90%. It is widely used in seawater and brackish water desalination, pure water preparation and water desalination softening of boiler and power equipment.
 
Actually, electrodialysis is a desalination technology, because a variety of different water (including natural water, tap water, industrial wastewater) has a certain amount of salt whose anions and cations will move to the opposite direction in the role of direct current. Ion exchange membrane has a selective permeability and only allows relative ions or cation to pass freely. So, in the space of two membranes, the concentration of the salt will decrease due to the directional migration of the ions and finally reach the aim of desalination in the middle desalination chamber.
 
In practical applications, an electrodialysis instrument is not only composed of one pair of anion and cation exchange membranes (because of the low efficiency), but a hundred pairs, or even hundreds of pairs of exchange membranes to enhance efficiency.

Applications:

RO concentrated water recovery desalination

Primary softening desalination of boiler feed water

Recovery of acid and metal from waste liquid of Acid cleaning metal surface;

Recovery of heavy metal ions from Electroplating wastewater;

Recovery of sulphate from Synthetic fiber wastewater to;

Recovery of sulfite from pulp waste

Milk desalination for infant formula;

Separation of ionic and nonionic substances;

Concentration of salt from seawater

Refined dairy products

Salt removal and primary material purification

Amino acid desalination

Soybean oligosaccharides desalination

Electroplating wastewater recycling

Preparation of organic acids

Alkali preparation