Product Overview
Sodium Metabisulfite Technical Grade is a white crystalline powder that functions as a strong reducing agent across water treatment, dechlorination, and industrial chemical processes. Also known as Sodium Pyrosulfite or Disodium Metabisulfite (CAS 7681-57-4), it dissolves readily in water and releases sulfur dioxide — the active species behind most of its industrial utility.
This Technical Grade product is offered in pack sizes from 2 lbs to 50 lbs bags, serving bench-scale trials through ongoing production use. Alliance Chemical provides SDS, COA, and TDS documentation for every lot ordered.
Why This Grade
Technical Grade sodium metabisulfite is the standard procurement choice for water treatment operators, industrial process engineers, and maintenance teams whose applications do not require a tighter analytical specification. It delivers the reducing power needed for dechlorination, chemical reduction, and process antioxidant use at a lower cost point than laboratory or analytical grades.
Buyers running municipal or industrial dechlorination systems, textile dye-reduction baths, or photographic processing lines typically specify Technical Grade because the work demands consistent reducing activity — not a narrow assay window tied to a published analytical standard. If your process does require documentation against a specific purity monograph, ask our team about alternative grades.
Chemical Profile
Sodium metabisulfite (Na2O5S2, molecular weight 190.11 g/mol, CAS 7681-57-4) appears as a white crystalline or powder solid with a slight sulfur odor. In the presence of even trace moisture it develops the unmistakable sharp odor of sulfur dioxide — a useful field indicator that the container seal has been compromised. The solid is denser than water at a density of 1.4 and dissolves readily, with a water solubility of 54%. It is noncombustible under normal conditions but may decompose at elevated temperatures to release toxic sulfur oxide and sodium oxide fumes.
Industrial Applications
Sodium metabisulfite's value in industry traces to one core property: it is a fast-acting reducing agent that liberates sulfur dioxide on contact with water. That chemistry drives its use across several sectors.
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Water Treatment & Dechlorination — Municipal and industrial water systems use sodium metabisulfite to neutralize residual chlorine before discharge or reuse. In dechlorination applications it reacts rapidly with free and combined chlorine, converting them to chloride ions. This is standard practice ahead of membrane systems, boiler feed lines, and permitted outfalls.
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Chemical Reduction — As a general-purpose industrial reducing agent, sodium metabisulfite participates in processes where controlled reduction of oxidized species is required — from hexavalent chromium reduction in wastewater streams to oxygen scavenging in closed-loop systems.
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Photography — Darkroom and large-format photographic processing rely on sodium metabisulfite as a preservative and mild acidifier in stop baths and fixing solutions, where it controls oxidation of developing agents.
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Textile Processing — In dyeing operations, sodium metabisulfite serves as a reducing agent in vat dye application and discharge printing, where it strips color in controlled patterns or prepares fibers for dye uptake.
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Chemical Synthesis — Process-scale chemical operations use sodium metabisulfite as a reducing agent and sulfonation source in the production of intermediates and specialty compounds.
Handling & Storage
Sodium metabisulfite carries a Danger signal word under its GHS classification (per the product's GHS classification). The two primary hazard statements are H302 — harmful if swallowed — and H318 — causes serious eye damage (per the product's GHS classification). Operators should wear chemical splash goggles, impervious gloves, and a dust respirator when handling the dry powder. In enclosed spaces, ensure adequate ventilation — the sulfur dioxide released on contact with moisture or acids is a respiratory irritant.
Store in a cool, dry area in tightly sealed containers. Sodium metabisulfite is hygroscopic and will degrade on moisture exposure, losing reducing activity and generating SO2 off-gas. Keep it isolated from strong acids, strong oxidizers, and bases. Containers that have been opened should be resealed promptly and consumed within a reasonable timeframe to preserve quality.
Hazmat & Shipping
Sodium Metabisulfite Technical Grade is not classified as a DOT hazardous material for transport — it carries no UN number, hazard class, or packing group assignment (per 49 CFR 172.101). Shipments do not require a DOT hazmat placard. Carriers may still apply their own handling or routing requirements based on the product's GHS hazard classification, and receivers should verify local storage and permitting obligations independently. All shipping and transport guidance for this product has been reviewed by Andre Taki, DOT Hazmat Specialist.
Documentation
Every order of Sodium Metabisulfite Technical Grade ships with a Safety Data Sheet (SDS) in English. A lot-specific Certificate of Analysis (COA) is available on request, documenting analytical results for the production lot you receive. A Technical Data Sheet (TDS) is also provided for specification reference. Contact our team if you need documentation in advance of placing an order.
Why Buy from Alliance Chemical
This product ships with full lot documentation — SDS, COA, and TDS — because industrial buyers selecting a reducing agent need verifiable data, not marketing language. Alliance Chemical has served over 50,000 customers since 1998, operating from our warehouse at 204 S Edmond St, Taylor, Texas 76574. Shipping and handling protocols for this product are reviewed by Andre Taki, DOT Hazmat Specialist, so your order arrives with the correct classification, packaging, and paperwork.
