Electrodialysis is a process that combines the use of ion exchange membranes with an electric potential gradient, in order to remove ionic species from aqueous solutions. It is able to remove ions with positive or negative electrical charges.
A typical application is the Tartaric Stabilization of Wine and Grape Juice by the removal of tartrate and potassium and calcium ions to prevent the precipitation of potassium tartrate.
The K + and Ca ++ cations are attracted to the Cothode and the Tart- and H.Tart anions. - are attracted to the Anode. The Anionic and Cationic membranes allow the passage of Anions and Cations respectively, repelling the Cations and Anions, respectively.
The cationic and anionic membranes are stacked alternately with spacers between them, this allows the solutions to flow. The schematic drawing below illustrates what occurs in Electrodialysis.