Electrodialysis Working Mode

Electrodialysis uses thin-film ion exchangers. When operating under an electric field, the cation exchanger allows only cations to pass through while repelling anions, and the anion exchanger allows only anions to pass through while repelling cations. These two types of membranes are arranged alternately in compartments, with anodes and cathodes at both ends, and a direct current is applied to form an electrodialysis unit. During operation, raw water is introduced into the electrodialysis unit. Under the influence of the electric field, various cations in the water tend towards the cathode, and various anions tend towards the anode. However, cations can only pass through the cation exchanger and are blocked by the adjacent anion exchanger, while anions do the opposite. Thus, cations and anions concentrate in some compartments, forming concentrated water with high salinity, while in other compartments, the migration of cations and anions reduces the salinity, forming fresh water. This method can achieve a single-stage desalination efficiency of 85%–90%, and a two-stage efficiency of 99%. For seawater with high salinity, this method is more economical than ion exchange.