Sodium metabisulfite
CAS 7681-57-4
EC 231-673-0
Formula H2O5S2.2Na
MW 294.17 g/mol
Salts & Minerals Water TreatmentFood & NutritionPharmaceuticals & HealthcareTextile, Leather & PaperPulp & Paper Preservation & BiocideAntioxidant & StabilizerCatalysisBleaching & Whitening
Description
Sodium metabisulfite (CAS 7681-57-4), also known as sodium disulfite or sodium dissulfite, is an inorganic sulfur salt commercially available under trade names including Fertisilo. It carries no E-number designation and is registered under EC 231-673-0 with the molecular formula H2O5S2.2Na.
In water treatment, sodium metabisulfite acts as a reducing agent that neutralizes residual chlorine by converting it to chloride ions, protecting downstream membranes and ion exchange resins. In food processing, it inhibits microbial growth and enzymatic browning by releasing sulfur dioxide, which disrupts oxidative pathways in target substrates.
Sodium metabisulfite is supplied in food-grade (FCC), pharmaceutical-grade (Ph.Eur.), and technical-grade forms as a white crystalline powder. It is fully REACH-registered and available in standard packaging formats including 25 kg bags and bulk quantities. Buyers should confirm grade specification against their application requirements prior to procurement.
In water treatment, sodium metabisulfite acts as a reducing agent that neutralizes residual chlorine by converting it to chloride ions, protecting downstream membranes and ion exchange resins. In food processing, it inhibits microbial growth and enzymatic browning by releasing sulfur dioxide, which disrupts oxidative pathways in target substrates.
Sodium metabisulfite is supplied in food-grade (FCC), pharmaceutical-grade (Ph.Eur.), and technical-grade forms as a white crystalline powder. It is fully REACH-registered and available in standard packaging formats including 25 kg bags and bulk quantities. Buyers should confirm grade specification against their application requirements prior to procurement.
Physical Properties
| Melting Point | 150 °C (decomp) |
| Density | 1.4 g/cm³ |
| Appearance | Sodium metabisulfite is a white crystalline powder. Sulfur dioxide odor. It may be considered the anhydride of 2 molecules of sodium disulfite. |
| Color | White to slightly yellow |
| Odor | Sulphorous |
| Form | Powder/Solid |
| Water Solubility | 540 g/L (20 ºC) |
| Refractive Index | 1.474 |
| pH | 3.5-5 (50g/l, H2O, 20℃) |
Safety & Handling (Learn More)
Danger GHS05 GHS07 GHS08
H
H302H317H318H320H334H335H372H402H412
P
P233P260P261P264P270P271P272P273P280P284P317P319P321P330P403P405P501P264+P265P301+P317P302+P352P304+P340P333+P317P337+P317P342+P316P362+P364P403+P233P305+P351+P338P305+P354+P338
Trade & Regulatory
| HS Code | 28323010 |
| Storage Class | 13 - Non Combustible Solids |
| WGK (Germany) | 1 |
Other Names
sodium pyrosulfitedisodium pyrosulfitesodium metabisulphiteSMBSfertisiloSODIUM BISULFITESodium disulphite
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Raw Materials
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