Membrane electrolysis

Membrane electrolysis is a process whereby both electrode reactions, i.e. the cathodic reduction as well as the anodic oxidation, are linked to the transport and transfer of charged ions. In membrane electrolysis, the electrode reaction is essential to the actual separation process. The purpose of the membrane is to separate the anode loop (anolyte) from the cathode loop (catholyte) by a fluid, in order to avoid unwanted secondary reactions, so as to combine the electrode reaction with a separation step or to isolate separately the products formed on the electrode. In water electrolysis, such products may be in a gaseous form such as oxygen and hydrogen as well as the acids (H+) and bases (OH-) formed on the electrode or the combination of gaseous chlorine and caustic soda solution and hydrogen as in sodium chloride electrolysis.

Electrochemical reactions, that are frequently observed, include metal deposition as well as the formation of hydrogen on the cathode and the anodic oxidation of organic compounds but also of ions such as chloride, cyanide, nitrite and others.

Depending on the purpose of the separation process, both oxidative and reductive conversion are of interest to industry. The electrolysis of sodium chloride for the production of chlorine and caustic soda solution is the most important electro-membrane process worldwide. Nowadays, roughly 48 million tons of chlorine are produced each year, with more than 30% of this sum being converted by membrane electrolysis. Furthermore, membrane electrolysis is applied for the production of sodium hypochlorite for drinking water disinfection. Recently, electrolysis processes for the production of ozone, chlorine dioxide or hypochlorous acid have been increasingly applied in drinking water disinfection.

FUMATECH BWT GmbH supplies not only the required membranes for membrane electrolysis but also professional multi-chamber membrane modules (electrolyzer) ranging from laboratory to industrial scale.

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