Caustic soda

Caustic soda (sodium hydroxide, NaOH; CAS 1310-73-2) is a strong inorganic base produced primarily by the chlor-alkali electrolysis of brine. Also known as lye or soda lye, it carries no E-number designation and is traded under references including BETZ 0234 and Ascarite. Its HS code is 2815 11 00.

In water treatment, caustic soda raises pH to precipitate heavy metals and neutralise acidic effluents. In pulp and paper production, it breaks down lignin during the kraft process, separating cellulose fibres from wood. In food-grade applications, it drives saponification and acts as a pH buffer in processing operations such as olive curing and pretzel glazing.

Caustic soda is available in technical, food-grade (FCC), and pharmaceutical (Ph.Eur.) grades as pellets, flakes, or aqueous solution (typically 32% or 50% w/w). It is registered under REACH and subject to CLP classification. Packaging ranges from 25 kg bags to bulk liquid tankers.