Sodium metabisulfite (SMB), CAS 7681-57-4 (Na2S2O5), is a solid, high-SO2 reducing agent used for dechlorination, cyanide destruction, chromium(VI) reduction and food preservation. PolyBlueChem supplies it in industrial and food grades with competitive pricing on bulk volumes, per-batch COA and SDS.
Grades
| Grade | Use |
|---|---|
| Industrial grade | Dechlorination, cyanide destruction, Cr(VI) reduction, oxygen scavenging, textile and leather processing |
| Food grade (E223) | Food and beverage preservation (tighter arsenic and heavy-metal limits) |
A full specification sheet and a certificate of analysis (COA) for each batch are available on request – tell us the grade and the parameters you need.
Basic Information
| CAS number | 7681-57-4 |
| Synonyms | Sodium metabisulfite; sodium pyrosulfite; SMB |
| Molecular formula | Na2S2O5 |
| Molecular weight | 190.11 g/mol |
| Appearance | White to pale-yellow crystalline powder or granules |
| SO2 equivalent | About 65% (theoretical 67.4%) |
| Solution character | Dissolves to give an acidic sodium bisulfite solution |
| Food additive number | E223 |
Applications
- Water treatment – dechlorination of drinking water, wastewater and RO feed; boiler-water oxygen scavenging.
- Mining – cyanide destruction in gold tailings (SO2/air process); flotation depression and pulp conditioning.
- Metal treatment – reduction of hexavalent chromium (Cr(VI)) to Cr(III) in wastewater.
- Food and beverage – preservative and antioxidant (E223).
- Leather, textile and pulp/paper – reducing and bleaching agent.
Packaging and documentation
- 25 kg PP/PE bags and 1000 kg jumbo bags; palletised for container shipment.
- Per-batch certificate of analysis (COA) and safety data sheet (SDS).
- Store sealed and dry, away from acids and oxidising agents (acid contact releases sulphur dioxide).
PolyBlueChem supplies sodium metabisulfite (CAS 7681-57-4) in industrial and food grades, with competitive pricing on bulk volumes, per-batch COA and SDS, and FOB/CIF delivery to African ports and worldwide. Contact us with your tonnage and delivery port for a quotation.
