SODIUM METABISULFITE

PRODUCT IDENTIFICATION

CAS NO.

********4

EINECS NO.

********0

FORMULA

Na2S2O5

MOL WT.

**0.*0

SYNONYMS

Dinatriumdisulfit; Disulfito de disodio; Disulfite de disodium;

Disodium disulfite; Disodium Salt Pyrosulfurous Acid; Disulfurous acid, disodium salt; Pyrosulfurous acid, disodium salt; Sodium Metabisulfite; Sodium disulfite; Sodium Pyrosulfite;

PHYSICAL AND CHEMICAL PROPERTIES

PHYSICAL STATE

white crystalline powder with odor of sulfur dioxide

MELTING POINT

**0 C (Decomposes)

SPECIFIC GRAVITY

1.*8

SOLUBILITY IN WATER

Freely soluble (**0g/l)

pH

3.5 - 5

NFPA RATINGS

Health: 1; Flammability: 0; Reactivity: 0

STABILITY

Stable under ordinary conditions. Hygroscopic.

GENERAL DESCRIPTION & APPLICATIONS

Sodium Metabisulfite is a white to slightly yellowish crystalline powder with sulfur dioxide odor; readily soluble in water. Sodium metabisulfite containing more than *5.0% SO2 w/w releases sulfur dioxide gas when mixed with water.

It forms a bisulfite adduct with aldehyde and with ketones to a sulfonic acid. It is used to purify or isolate aldehydes and ketones. Sodium metabisulfite's reductive and sulfonating properties provide versatile applications. It is used as an oxygen scavenger to eliminate the dissolved oxygen in waste water and in pipes.

Bisulfite is a reductive bleaching agent. It reduces carbonyl and alcohol groups, which function as colorants of the substances. It is used in bleaching mechanical paper pulp, cotton, wool and kaolin clay. Additional applications include as a preservative (antioxidant), a hair waving agent, and Ensiling agent. Bisulfites are used in industries concerned with leather processing, food and beverage processing, gas purification, water treatment  to remove excess chlorine, textiles and pulp processing, and many others.

It is used as a reducing agent in chemical manufacturing. It is an alternative to sulfur dioxide which is used in sterlization of equipment.

Examples of other metallic bisulfite

• Calcium Bisulfite [*********5, Ca(HSO3)2] A white powder, used as an antiseptic and in pulping process.
• Potassium Bisulfite [********8, KHSO3] Also called potassium acid sulfite, white, water-soluble powder with sulfur dioxide odor; insoluble in alcohol; decomposes when heated; used as an antiseptic and reducing chemical, tanning, and bleaching.
• Magnesium Bisulfite [*********9, Mg(HSO3)2]

SALES SPECIFICATION

TECH GRADE

APPEARANCE

White to slightly yellowish crystalline powder

CONTENT

*8.0% min

SO2

*5.0% min

Na2S2O4

2.0% max

INSOLUBLES IN WATER

0.*5% max

PARTICLE SIZE

*5% (mesh **0)

pH

4 *4.6

Fe

5ppm max

FOOD GRADE

APPEARANCE

White to slightly yellowish crystalline powder

CONTENT

*8.0% min

SO2

*5.0% min

Na2S2O4

2.0% max

INSOLUBLES IN WATER

0.*5% max

PARTICLE SIZE

*5% (mesh **0)

HEAVY METALS

*0ppm max

As

1ppm max

Fe

5ppm max

pH

4.5 - 5.5

PACKING

*5kgs in bag