Sodium hydroxide
Description
Sodium hydroxide (CAS 1310-73-2), also sold as caustic soda or lye, is a strong inorganic base used across industrial and food-grade processing to control pH and neutralize acids. As E524, it is approved for direct food contact applications.
Demand for this versatile chemical spans water treatment, pulp and paper, textiles, and chemical manufacturing. In pulp and paper production, it breaks down lignin during the kraft process, enabling cellulose separation at scale.
Water treatment plants use it to raise pH, precipitate heavy metals, and condition water for safe distribution. Food processors apply it for curing olives, pretzel glazing, and pH adjustment in cocoa processing.
In textile and leather operations, it drives mercerization of cotton and assists in dehairing hides. These processes improve fiber uptake and surface finish, ensuring high-quality results in industrial manufacturing environments.
Sodium hydroxide is supplied as white flakes, micropearls, and solid pellets, as well as aqueous solution. The most common liquid format is the 50% concentration, which is widely used for bulk industrial applications.
Standard grades include food-grade (FCC), pharmaceutical (USP/BP/Ph. Eur.), and technical grade for industrial use. These certifications ensure the material meets the rigorous safety requirements of each specific industry.
Membrane cell grades with low chloride content are available for applications requiring high purity. This ensures that sensitive chemical reactions and high-end manufacturing processes maintain consistent quality and performance.
Physical Properties
| Melting Point | 323 °C |
| Boiling Point | 1388 °C |
| Density | 2.13 g/cm³ @ Temp: 25 °C |
| Flash Point | 176-178°C |
| Appearance | NaOH is a white, odorless, deliquescent material sold as pellets, flakes, lumps, or sticks. Aqueous solutions are known as soda lye |
| Color | White |
| Odor | Odorless |
| Form | beads |
| Water Solubility | SOLUBLE |
| Vapor Pressure | 1 mm Hg ( 745 °C) |
| Refractive Index | 1,473-1,475 |
| pH | >14 (100g/l, H2O, 20℃) |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 2815 11 00 |
| UN Number | 1824 |
| ADR Class | 8 |
| Packing Group | II |
| Storage Class | 8B - Non-combustible corrosive hazardous materials |
| WGK (Germany) | 1 |
Documentation
Other Names
white caustic|sodium hydrate|soda lye|caustic soda|lye|Soda, caustic|Rohrputz|Sodium hydroxide (Na(OH))|NaOH|E524
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