A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
Request SDS →Sodium metabisulfite (SMBS, CAS 7681-57-4, Na2S2O5) is a versatile reducing agent used to dechlorinate water, scavenge oxygen, preserve reverse-osmosis membranes, and as a food preservative and antioxidant. Dissolved in water it forms bisulfite, which rapidly reduces free and combined chlorine.
Sodium Metabisulfite: Applications & Grades
In water treatment, SMBS is the standard reducing agent for dechlorination ahead of RO membranes and discharge, for oxygen scavenging in boiler and process water, and for short-term RO membrane preservation. Food-grade SMBS (E223) is an antioxidant and preservative in beverages, dried fruit, and processing. It is also used in mining, textiles, and photography.
Grades Compared
Comparing reducing agents? Sodium bisulfite is the solution form of the same chemistry. Send your application and volume on an RFQ.
Frequently Asked Questions
What is sodium metabisulfite used for?
Sodium metabisulfite is a reducing agent used to dechlorinate water (protecting RO membranes and meeting discharge limits), scavenge dissolved oxygen, preserve RO membranes, and — as food grade E223 — preserve and antioxidize foods and beverages. RawSource supplies technical and food grades in bulk.
Sodium metabisulfite vs sodium bisulfite — what’s the difference?
They are the same sulfite chemistry in different forms: sodium metabisulfite is a dry powder (Na2S2O5) that forms bisulfite when dissolved; sodium bisulfite is typically supplied as a ready-to-feed solution. Dry SMBS ships and stores more economically; the solution avoids on-site mixing. RawSource quotes both.
Is food-grade (E223) sodium metabisulfite available?
Yes. RawSource supplies FCC food-grade sodium metabisulfite (E223) for use as a preservative and antioxidant, alongside technical grade for water treatment. Specify your grade and spec on the RFQ and we confirm against the CoA.
How is sodium metabisulfite supplied in bulk?
RawSource supplies sodium metabisulfite as powder/granular in bags and supersacks under CAS 7681-57-4 / HS 2832.10, in technical or food (E223) grade. Grade, purity, packaging, and MOQ confirmed at quotation against the CoA. Submit a bulk RFQ.