Auxiliary electrolyte solution – fresh water or aqueous electrolyte solution, which is not mechanically mixed with initial solution in the process of its electrochemical transformations, but plays the role of second class conductor closing the electric circuit of electrochemical reactor in the process of initial solution unipolar electrochemical treatment, and, as required, is donor or acceptor of ions (cations or anions) in relation to the initial solutions.
Vitold Bakhir Electrochemical Systems and Technologies