Sodium hydroxide

Sodium hydroxide (CAS 1310-73-2), also sold as caustic soda or lye, is a strong inorganic base used to control pH and neutralize acids in industrial and food-grade processing.

Where is Sodium hydroxide used?

• Water treatment: raises pH, precipitates heavy metals, conditions water for safe distribution
• Pulp and paper: breaks down lignin during the kraft process, enabling cellulose separation at scale
• Textile and leather: drives mercerization of cotton and assists in dehairing hides
• Food processing: curing olives, pretzel glazing, pH adjustment in cocoa processing
• As E524, it is approved for direct food contact applications.
• Refining of vegetable oils.
• Aluminum production: dissolving and purifying bauxite ore.
• Metal surface treatment: pH adjustment, alkalization, degreasing, and pickling.
• Production of soaps and detergents.

Good to know: Standard grades include food-grade (FCC), pharmaceutical (USP/BP/Ph. Eur.), and technical grade. Membrane cell grades with low chloride content are available for applications requiring high purity.

Formulation notes

• Corrosive to most metals.

Typical specification

• Supplied in solid (flake or pearl) and liquid (30–50% concentration) forms depending on the application.
• 32% solution has a mass fraction of 31–33%.
• Microprill grades are solid, molten caustic soda beads with a consistent diameter of less than 1 mm, ensuring fast and easy dissolution in common solvents like water, ethanol, and methanol.
• NaOH titre is between 97.0% and 100.5%.

Regulatory status

• Harmonized classification and labeling are mandatory according to Annex VI of the CLP regulation (EC No 1272/2008).

Storage, packaging and handling

• Dissolution in water or neutralization with acid liberates substantial heat that may ignite combustible materials.
• Strongly corrosive; corrosion-resistant tanks and pipes must be used, solid product must be protected from moisture, and dilution must be controlled.

Frequently asked questions about Sodium hydroxide

What are the typical uses of sodium hydroxide in metal surface treatment?

It is used for surface cleaning, oxide removal, and pre-coating preparation.

How does sodium hydroxide function in soap and detergent production?

It saponifies triglycerides to form sodium salts of fatty acids and glycerol.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.