PHYSICAL STATE

white crystalline powder with odor of sulfur dioxide

MELTING POINT

150 C (Decomposes)

BOILING POINT

SPECIFIC GRAVITY

1.48

SOLUBILITY IN WATER

Freely soluble (470g/l)

pH

3.5 - 5

VAPOR DENSITY

AUTOIGNITION

NFPA RATINGS

Health: 1; Flammability: 0; Reactivity: 0

REFRACTIVE INDEX

FLASH POINT

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 65.0% 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.

SALES SPECIFICATION

TECH GRADE

APPEARANCE

White to slightly yellowish crystalline powder

CONTENT

98.0% min

SO2

65.0% min

Na2S2O4

2.0% max

INSOLUBLES IN WATER

0.05% max

PARTICLE SIZE

85% (mesh 200)

pH

4 -4.6

Fe

5ppm max

FOOD GRADE

APPEARANCE

White to slightly yellowish crystalline powder

CONTENT

98.0% min

SO2

65.0% min

Na2S2O4

2.0% max

INSOLUBLES IN WATER

0.05% max

PARTICLE SIZE

85% (mesh 200)

HEAVY METALS

10ppm max

As

1ppm max

Fe

5ppm max

pH

4.5 - 5.5