Sodium hydroxide is one of the primary chemicals used in virtually all industries. It is used both as feedstock (sodium carrier) in various types of synthesis for the production of ionic surfactants, in the pharmaceutical industry (e.g. to manufacture aspirin, salicylic acid, sulfanilamides), to produce aluminium from the processing of bauxites, to manufacture water glass from silica, for the production of fats and soaps, and in many other types of organic and inorganic synthesis.
It is also widely used as an auxiliary material in the cellulose and paper industry for bleaching cellulose pulp, for bleaching, dyeing and preserving dyes in the textile and viscose industries, in the processing of crude oil, in the refining of oils, in petrochemical processes, in the manufacture of synthetic dyes, processing of liquid coking products, treatment of water for industrial applications, wastewater treatment, and in the food industry (dairies, breweries, meat processing plants, sugar refineries) as a cleaning and disinfecting agent. Sodium hydroxide in solid form can also be used as a catalyst (or activator) in rapeseed oil transesterification to produce biodiesel.