In a membrane cell, brine (sodium chloride solution) is fed into the anode compartment where chloride ions are oxidized to form chlorine gas. Simultaneously, in the cathode compartment, water is reduced to form hydroxide ions and hydrogen gas. The ion-selective membrane, typically made of a perfluorinated polymer, allows sodium ions to pass from the anode to the cathode compartment while preventing the backflow of chlorine gas and hydroxide ions.
