Caustic soda is a white, deliquescent solid in various forms with no odour. It is very soluble in ethyl alcohol and water. It is a strong base, reacts violently with acid and is corrosive in moist air to metals like zinc, aluminium, tin and lead forming a combustible/explosive gas (hydrogen). It rapidly absorbs carbon dioxide and water from air while contact with moisture or water may generate heat.
Its main uses are in the manufacture of pulp and paper, alumina, soap and detergents, petroleum products and chemical production. Other applications include water treatment, food, textiles, metal processing, mining, glass making and others.
The production of alumina from bauxite is a major end-use application for caustic soda.
Caustic soda is a basic feedstock in the manufacture of a wide range of chemicals. It is used as an intermediate and a reactant in processes that produce solvents, plastics, synthetic fibres, bleach, adhesives, coatings, herbicides, dyes, inks and pharmaceuticals.
Other uses include the saponification or conversion of fat, tallow and vegetable oils in soap manufacture, and in the manufacture of surfactants for detergents. It is used in the petroleum and natural gas industries to remove acidic materials from hydrocarbons and off-gases. In the textile sector, it is used in the chemical processing of cotton and the dyeing of synthetic fibres.