Sinoright Blog
Sodium Sulfite | Anhydrous & Food/Industrial Grade | CAS
Sodium Sulfite (Na₂SO₃, CAS No.7757-83-7, EINECS:231-821-4, EU food additive code E221) is a mainstream water-soluble inorganic sulfite compound, supplied by our factory with three mainstream specifications: anhydrous industrial grade, refined food grade and reagent grade heptahydrate sodium sulfite. After decades of optimized production line upgrading, our finished goods reach stable purity from 97.0%~99.2%, widely exported to Southeast Asia, Middle East, Europe, North America and Latin America, serving downstream manufacturers across water treatment, pulp & paper, textile printing & dyeing, food processing, fine chemical synthesis and electroplating wastewater treatment industries.
1. Core Physical & Chemical Properties
Our self-produced anhydrous sodium sulfite appears as white crystalline powder or small granule, odor-free with slight sulfur salty taste; easily soluble in purified water, moderately soluble in glycerol, barely soluble in ethanol and insoluble in organic alkane solvents. Aqueous solution shows weak alkalinity with pH value 8.5~10.2 under 1% aqueous concentration; featured with outstanding reducing activity, slowly oxidized into sodium sulfate when exposed to open air, fully decomposed into sulfide and sulfur oxide under high-temperature calcination above 600℃. Compared with conventional small-factory products, our finished material strictly controls heavy metal, insoluble impurity and sulfate residue, greatly lowering oxidation rate during long-term sealed storage.
2. Graded Product Technical Index
| Item | Industrial Grade (Min.) | Food Grade E221 (Min.) | Lab Reagent Grade |
|---|---|---|---|
| Na₂SO₃ Main Content | 97.0% | 98.5% | ≥99.0% |
| Sodium Sulfate Impurity | ≤1.8% | ≤0.8% | ≤0.3% |
| Water Insoluble Matter | ≤0.05% | ≤0.01% | ≤0.005% |
| Heavy Metal(Pb) | ≤10ppm | ≤2ppm | ≤1ppm |
Packaging options: 25kg woven bag with inner PE liner, 500kg/1000kg bulk jumbo bag, customized small barrel packing for laboratory clients; HS Code:2832100000 for global customs clearance.
3. Multi-industry Practical Application
① Water Treatment Industry (Top searched keyword: Sodium Sulfite Oxygen Scavenger)
Act as high-efficiency oxygen scavenger for boiler feed water and oilfield injection water, eliminating dissolved oxygen to restrain pipeline electrochemical corrosion; in electroplating & chemical wastewater disposal, reduce toxic hexavalent chromium into harmless trivalent chromium, also work as dechlorinating agent to remove residual free chlorine after water disinfection. Many domestic and overseas environmental protection factories choose our stable-content sodium sulfite to reduce dosing frequency and cut overall water treatment cost.
② Pulp & Paper Manufacturing
Core raw material for sulfite pulping process, decompose lignin inside wood fiber to separate pure cellulose; also used as deinking auxiliary for waste paper recycling, improve pulp whiteness without extra strong oxidant bleacher. Our low-impurity grade avoids abnormal yellowing of finished paper during long-time storage, favored by medium & large paper mills globally.
③ Textile Printing & Dyeing
Commonly used as fabric bleaching, desulfurization and post-dye dechlorinating agent for cotton, wool and viscose fiber; remove residual chlorine after chlorine bleaching to prevent cloth fiber brittleness and color fading, also serve as reducing auxiliary for sulfur dye and vat dye production. Eco-friendly low-sulfur formula meets EU textile environmental access standard.
④ Food & Beverage Field (E221 Food Preservative Grade)
Certified compliant with FDA & EU E221 food additive standard, applied as antioxidant and color fixative for dried fruits, preserved vegetables, fruit wine and baked food, inhibit enzymatic browning and microbial reproduction to extend shelf life, strictly controlled heavy metal index to satisfy global food safety inspection.
⑤ Fine Chemical & Other Downstream Fields
Key raw material for sodium thiosulfate, sulfonation intermediate and photographic developer production; in mineral flotation & non-ferrous metal smelting, reduce precious metal oxide to improve silver, copper ore recovery rate; partial high-purity grade used for analytical chemical reagent and pharmaceutical raw material antioxidant.
4. Our Factory Advantages
- Full-process independent production from raw sulfur dioxide & soda ash, no middleman markup, flexible MOQ for bulk order and trial small order;
- Complete food grade certification including HALAL, KOSHER, factory inspection report and MSDS document for each batch, support third-party SGS testing as clients’ requirement;
- Professional export logistics team, coordinate sea/air freight, provide customized customs declaration document for different countries’ import regulation;
- Stable monthly output over 3000MT, ensure uninterrupted spot supply even during global raw material price fluctuation.
5. Storage & Safety Notice
Keep sealed storage under cool dry warehouse, avoid direct sunlight and damp air; separate storage from strong acid and oxidant chemicals; wear protective gloves and goggles during manual feeding operation, rinse skin with plenty of clean water once accidental contact occurs.