Electrodialysis in the alternating arrangement of many positive and negative membrane, separated into small water chamber.When raw water enters these Chambers, under the action of the direct current field, ions in the solution migrate in a directional manner.The cationic membrane allows only cationic ions to pass through and trap anions.The membrane allows only anions to pass through and trap cations.As a result, some of these cells become fresh water Chambers with few ions, and the water is called fresh water.The chamber adjacent to the fresh water chamber becomes a concentrated water chamber with a large number of ions, and the water outlet is called concentrated water.Thus the ions are separated and concentrated, and the water is purified.
Compared with ion exchange, electrodialysis has the following similarities and differences:
(1) although the working medium for ion separation is all ion exchange resin, the former is a lamellar film, while the latter is a round and spherical particle;
(2) from the perspective of action mechanism, ion exchange belongs to ion transfer and replacement, and ion exchange reaction occurs in the process of ion exchange resin.Electrodialysis is a kind of ion interception replacement, and ion exchange membrane plays the role of ion selective transmission and interception in the process.To be more precise, ion-exchange membranes should be called ion-selective permeable membranes;
(3) the working medium of electrodialysis does not need regeneration, but consumes electric energy;The working medium of the ion exchange must be regenerated without consuming electricity.