Disproportionation also occurs in this reaction. The oxidation number changes from zero in Cl2 to -1 in Cl2 to +5 in ClO-3(oxidation).
The early diaphragms made of asbestos posed environmental problems. A solution is to use thin plastic membranes made of polymers, supported on a Teflon mesh. One such polymer used is naflon, a copolymer of tetrafluoroethylene and perfluorosulfonylethoxy ether.
In a diaphragm cell, less than half of the aqueous sodium chloride is converted to aqueous sodium hydroxide. Although the sodium hydroxide obtained is free of chlorate ions, it is still contaminated with sodium chloride.