Sodium hydroxide

Raw materials

1. Aqueous solution of sodium chloride

Process

Sodium hydroxide is produced (along with chlorine and hydrogen) via the chloralkali process. This involves the electrolysis of an aqueous solution of sodium chloride. The sodium hydroxide builds up at the cathode, where water is reduced to hydrogen gas and hydroxide ion:

2 Na⁺ + 2 H₂O + 2 e^– → H₂ + 2 NaOH

More accurately:

2 Na⁺Cl^– + 2 H₂O + 2 e^– → H₂ + 2 Cl^– + 2 NaOH

The Cl^– ions are oxidized to chlorine gas at the anode.

Product

Sodium hydroxide

Used for

Manufacture of sodium salts and detergents, pH regulation, organic synthesis, Bayer process of aluminium production, additive in drilling mud to increase alkalinity in bentonite mud systems increases the mud viscosity, neutralizing acid gas (such as hydrogen sulfide and carbon dioxide) which may be encountered in the geological formation as drilling progresses, treating poor quality crude oil to remove sulfurous impurities in a process known as caustic washing

Production facility

Toowoomba, QLD

Export

San Jose, Costa Rica