CAS：7757-83-7
Sodium sulfite
Sodium sulfite, commonly known as sulfur oxide powder, exists in two forms: anhydrous sodium sulfite and sodium sulfite heptahydrate. It is a sodium sulfite salt. Cooking plant fibers with sodium sulfite liquor under specific temperature and pressure is one of the important pulping methods in the paper industry, which is also the largest consumer of sodium sulfite. Due to its low price, readily available sources, and rapid reaction with oxygen, sodium sulfite is widely used to remove dissolved oxygen from water. In leather treatment, sodium sulfite makes leather soft, full, and tough, and provides waterproofing, fold resistance, and abrasion resistance. Sodium sulfite is a widely used food additive permitted by the state, and can be used as a bleaching agent, preservative, leavening agent, antioxidant, color protectant, and freshness preserver in food processing.
Anhydrous sodium sulfite appearance: White crystals or powder;
Sodium sulfite heptahydrate appearance: Colorless or slightly yellow crystals;
Odor: No obvious odor, may have a slight sulfur smell after being exposed to moisture;
Solubility: Easily soluble in water, aqueous solution is weakly alkaline;
Stability: Easily effloresces in air and is oxidized to sodium sulfate, belonging to a strong reducing agent.
Product Details
Core Chemical Properties
Strong reducing properties: Quickly reduces strong oxidizing agents such as sodium hypochlorite, potassium permanganate, and hydrogen peroxide; a commonly used dechlorinating and deoxidizing agent.
Reaction to strong acids: Reacts with hydrochloric acid, sulfuric acid, etc., to produce sulfur dioxide gas.
Easily oxidized: Gradually deteriorates with prolonged open storage.
Main Uses
1. Water treatment: Removes residual chlorine from tap water, deoxygenates boiler water, and reduces wastewater.
2. Printing and dyeing textiles: Dechlorinates fabrics, reduces bleaching, and prevents brittleness.
3. Chemical/Laboratory: Reducing agent, developer component, and organic synthesis auxiliary agent.
4. Food/Pharmaceutical: Food-grade can be used as an antioxidant and preservative (strictly limited).
Packaging: Outer polypropylene woven bag, inner polyethylene plastic bag, paper-plastic composite bag, kraft paper bag, etc.
Product Parameters
| Item | Superior Grade | First Grade | Qualified Grade |
| Sodium Sulfite (Na₂SO₃) Content, % ≥ | 97 | 96 | 93 |
| Iron (Fe) Content, % ≤ | 0.003 | 0.005 | 0.02 |
| Water Insoluble Matter Content, % ≤ | 0.02 | 0.03 | 0.05 |
| Free Alkali (as Na₂CO₃) Content, % ≤ | 0.1 | 0.4 | 0.8 |
| Sulfate (as Na₂SO₄) Content, % ≤ | 2.5 | — | — |
| Chloride (as NaCl) Content, % ≤ | 0.1 | — | — |
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