Anode Effect in Aqueous Electrolysis

A phenomenon which closely resembles "anode effect" in molten electrolysis can be developed in the electrolysis of aqueous solutions at high current density. Normal operation of the electrode ceases and a so‐called "transition period" begins when the electrode temperature reaches the boiling point of the electrolyte. When the applied voltage is increased beyond a critical value the transition behavior suddenly changes to the "aqueous anode‐effect." During this effect the surface temperature of the anode rises far above the boiling point of the electrolyte. Evidence is provided which indicates that the gaseous envelope surrounding the anode during the aqueous anode‐effect is maintained by the vaporization of the electrolyte against the hot anode surface. An aqueous cathode‐effect was also obtained. The relation between aqueous anode‐effect and anode effect in molten media is discussed.