CAS：7681-57-4
Sodium metabisulfite
Appearance: White or slightly yellow crystalline powder
Odor: Slightly pungent odor of sulfur dioxide (SO₂)
Solubility: Easily soluble in water; aqueous solution is acidic
Stability: Moisture-sensitive, cannot be stored for long periods, easily decomposes upon heating, releasing SO₂; has strong reducing properties.
Product Details
Key Chemical Properties
Strong reducing power: Can reduce oxidizing agents (such as sodium hypochlorite, potassium permanganate, etc.), often used as a deoxidizer, bleaching agent, and antioxidant.
Reaction to acids: Reacts with strong acids, releasing toxic sulfur dioxide gas.
Cannot be mixed with sodium hypochlorite (NaClO): A redox reaction will occur, rendering both ineffective.
Main Uses
Food Industry: Food-grade bleaching agent, antioxidant, leavening agent, preservative, and color-protecting agent (for dried fruit, candied fruit, and fresh fruit and vegetable preservation, etc., use is strictly limited).
Water Treatment: Removes residual chlorine from water, acts as a deoxidizer, and reduces heavy metals.
Printing & Dyeing/Chemical Industry: Fabric bleaching, reducing agent, developing aid, and wastewater treatment.
Mineral Processing/Leather: Mineral processing reagent, leather tanning and reducing agent.
Product Parameters
Quality Standard: HG/T2826-2008
| Item | National Standard (HG/T2826-2008) | Enterprise Typical Value | |
| Superior Grade | First Grade | ||
| Main Content (as Na₂S₂O₅), % | ≥96.5 | ≥95.0 | ≥97.0 |
| Iron Content (as Fe), % | ≤0.005 | ≤0.010 | ≤0.002 |
| Water Insoluble Matter, % | ≤0.05 | ≤0.05 | ≤0.02 |
| Arsenic Content (as As), % | ≤0.0001 | — | ≤0.0001 |
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