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Sodium Metabisulphite

Sodium metabisulfite, also known as sodium pyrosulfite, is a widely used inorganic compound.

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1、 Product Information

Chemical Formula: Na₂S₂O₅
Molecular Weight: 190.12
CAS No.: 7681-57-4
Common Specifications: Industrial Grade, Food Grade

Industrial Grade Food Grade

PROJECT			STANDARD
Main content (Na₂S₂O₅),%≥			96.5
Fe content		≤	0.005
Water insoluble content	%	≤	0.05
As content	%	≤	0.0001

PROJECT		STANDARD
Main content (Na₂S₂O₅)%≥		96.5
Fe content	≤	0.003
Clarity		through experiments
As content	≤	0.0001
Heavy metal (pb)，% ≤		0.0005

Storage Conditions

Store in a cool, dry, and well-ventilated place with temperature ≤30℃ and relative humidity ≤75%, away from heat sources and ignition sources.
Adopt double-layer packaging (e.g., inner liner bag + outer woven plastic bag). Storage with open mouths is strictly prohibited to prevent oxidation and deterioration caused by contact with air. Store separately, keep away from strong acids and oxidizing agents (such as potassium permanganate, chlorates) to avoid chemical reactions. Do not mix with food or pharmaceutical raw materials.

2、Physical Properties

Appearance: White or slightly yellow crystalline powder, with a strong sulfur dioxide odor (the odor becomes more obvious when trace water is present).
Density: 1.4g/cm³
Decomposition Temperature: 150℃; heating to this temperature will cause decomposition, producing substances such as sulfur dioxide.
Solubility: Good solubility—easily soluble in water and glycerol. At 25℃, its solubility in water reaches 54g/100mL, and solubility increases with rising temperature. Slightly soluble in ethanol; its aqueous solution is acidic.
Stability: Poor stability—easily oxidizes and deteriorates when exposed to air, continuously releasing sulfur dioxide and eventually converting to sodium sulfate. Therefore, long-term storage is not recommended.

3、Main Applications

● Food Industry Grade

Used as a bleaching agent for candies, pastries, etc.

Used as a leavening agent for bread, biscuits, etc.

Used as a preservative and fresh-keeping agent for fruit juices, canned foods, seafood, fruits, and vegetables. It inhibits oxidation and microbial growth, extending the shelf life of food.

● Industrial Field Grade

Printing and Dyeing Industry: Used as a dechlorinating agent for fabrics after bleaching and a reducing decolorizing agent for dyes.
Papermaking Industry: Used as a fiber bleaching agent.
Rubber Industry: Used as a rubber coagulant.
Wastewater Treatment: Applied to treat chromium-containing wastewater; also used to process gold and silver leaching residues via oxidation.
Mineral Processing: Used as an activator to promote the recovery of valuable metals.

● Pharmaceutical Field Grade

Used in the production of pharmaceutical intermediates such as vitamin K and vitamin A.
Applied in the production of drugs like sulfadimidine and metamizole sodium.
In some scenarios, it can be used as an alternative raw material related to electrolytes.

● Other Fields Grade

Photography Industry: Used as a reducing agent for developers and a protective agent for fixing solutions.
Fragrance Industry: Used in the production of alkyl aromatic aldehydes such as vanillin.

4、Packaging Specifications

25kg outer woven bag (with inner lining bag)
25kg kraft paper bag (with inner lining bag)
1000kg ton bag (with inner lining bag)
1250kg large bag (with inner lining bag)

Note: According to customer needs, we also provide other packaging methods, such as ton bags, full plastic bags, kraft paper bags, and drums. Different packaging options correspond to different costs.

5、Core Advantages

● Versatile and High Adaptability

It integrates multiple functions, including bleaching, preservation, reduction, and dechlorination. It meets the safety requirements of industries such as food and pharmaceuticals, and also adapts to industrial scenarios like industrial wastewater treatment and printing and dyeing—with an extremely wide application range.

● Cost-Effective

The main raw materials for production (e.g., soda ash) are widely available and low-cost. Meanwhile, mature production processes (such as the wet process) enable large-scale production, resulting in affordable product prices. Compared with some special additives, it has significant cost advantages.

● Efficient Treatment Effect

In wastewater treatment: Using it to treat chromium-containing wastewater produces less sludge and improves detection accuracy.
In food preservation: It quickly inhibits oxidation and browning reactions, achieving fresh-keeping and color-protection effects in a short time.

● Good Process Compatibility

As a reducing agent, sulfonating agent, etc., in chemical synthesis, it has mild and controllable reactions and good compatibility with various chemical substances. For example, in printing and dyeing, it can be used in combination with sodium borohydride to achieve rapid stripping, demonstrating strong process compatibility.

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