Production of Caustic Soda

Caustic Soda – a common name of sodium hydroxide. The electrolysis of a concentrated sodium chloride solution (brine) produces three products: hydrogen, caustic soda and chlorine.

The Membrane Cell method – the membrane is permeable to cations so only the sodium ions can flow through and the hydroxide ions cannot flow back to the anode. The membrade is a porous, thin, flexible sheet.

• At the cathode, Hydroxide ions are formed (produced together with the hydrogen)
• As the sodium ions move towards the cathode, a solution of sodium hydroxide is thereby formed
• The water molecules are reduced at the cathode
• The sodium ions are not reduced and apart from moving through membrane do not change
• Chlorine is used in PVC and in water
• Sodium Hydroxide is used in pulp and paper, and