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Catalysts & Catalyst Precursors

Sodium sulfite

CAS: 7757-83-7

Overview

Sodium sulfite (CAS 7757-83-7 ), also known as sodium sulphite and approved as food additive E221 , is an inorganic reducing agent and antioxidant used across food processing and water treatment.

Its oxygen-scavenging capability makes it a practical choice for preserving product quality and controlling oxidative degradation in both aqueous systems and dry formulations for industrial manufacturing.

In food and beverage production, E221 functions as a preservative and antioxidant in dried fruits, wines, and starch products, inhibiting browning and microbial growth during the storage process.

Water treatment operations use it to dechlorinate process water and boiler feedwater, neutralizing residual chlorine before discharge or reuse to protect sensitive equipment and the environment.

Pulp and paper manufacturers apply it in kraft and sulfite pulping processes to delignify wood fiber and control brightness. In textile and leather processing, it acts as a reducing agent.

It is also used as a stripping agent to correct uneven dyeing in dyebath preparation. Sodium sulfite is supplied as a white crystalline powder or granules in the anhydrous form for easy handling.

Standard grades include food-grade ( FCC , E221), pharmaceutical-grade ( USP , BP ), and technical-grade for industrial applications. Packaging typically ranges from 25 kg bags to bulk quantities.

Depending on grade and application requirements, this chemical ensures stability and performance. It remains a critical component for manufacturers seeking reliable antioxidant and dechlorination solutions.

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Physical Properties

Melting Point500 °C
Density2.63 g/cm³
AppearanceSodium sulfite is a white crystalline solid
ColorWhite to slightly yellow
OdorOdorless
FormSolid
Water Solubility23 g/100 mL (20 ºC)
Refractive Index1,484
pH9.0-10.5 (25℃, 1M in H2O)

Safety & Handling

Danger GHS05 GHS07 Hazard Statements H302 Harmful if swallowed H314 Causes severe skin burns and eye damage H315 Causes skin irritation H318 Causes serious eye damage H319 Causes serious eye irritation Precautionary Statements P260 Do not breathe dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P280 Wear protective gloves/protective clothing/eye protection/face protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P321 Specific treatment (see … on this label). P330 Rinse mouth. P363 Wash contaminated clothing before reuse. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P332+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P362+P364 Take off contaminated clothing and wash it before reuse. P301+P330+P331 Rinse mouth. Do NOT induce vomiting. P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. P305+P354+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code28321000
Storage Class13 - Non Combustible Solids
WGK (Germany)1

Other Names

sulfurous aciddisodium salt | sodium sulphite | sodium sulfite anhydrous | Na2SO3 | dried sodium sulfite | anhydrous sodium sulfite | Disodium sulfite | Natrium sulfurosum | E221

Related Products

Chemical Properties

CAS Number
7757-83-7
EC Number
231-821-4
Mol. Weight
126.05
HS Code
28321000

Industries

Documentation