Castner–Kellner process

[2][3] It is a type of chloralkali process, but in this role it is gradually being replaced by membrane electrolysis which has lower energy cost and fewer environmental concerns.

His process was not an economically feasible method for producing sodium hydroxide though because it could not prevent the chlorine that formed in the brine solution from reacting with its other constituents.

American chemist and engineer, Hamilton Castner, solved the mixing problem with the invention of the mercury cell and was granted a U.S. patent in 1894.

In order to avoid a legal battle they became partners in 1895, founding the Castner-Kellner Alkali Company, which built plants employing the process throughout Europe.

The other type of cell, shown in the center of the diagram, uses an electrolyte of sodium hydroxide solution, a mercury anode (M), and an iron cathode (D).