Two topics about electrode are described as a peculiar problem of the chlor-alkali membrane process and one about electrochemical corrosion as a general problem of common electrolysis process. A life of the anode converted from the mercury process was noticed to be short because OH~- back-migrating from catholyte through a membrane attacked the conventional RuO_2 coated as catalyst on the anode surface of titanium substrate. This problem was solved by IrO_2 addition. The authors tried to separate the gas bubble quantitatively into from the electrode and from the membrane surface and obtained the most effective geometry shape of electrode to release the gas. Industrial cells are connected by series and a shunt current may cause often electrochemical corrosion. The authors assembled an electrolysis circuit simulator where laboratory rectifiers and auxiliary electrodes are installed. This simulator was helpful to reduce shunt current and/or prevent a nozzle from electrochemical corrosion.
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