Overview of Sodium Chlorite

History

The development of sodium chlorite as an industrial chemical began in 1921 when E. Schmidt found that cellulosic fibers could be purified with chlorine dioxide without being appreciably damaged. Unfortunately, chlorine dioxide gas is extremely explosive at high concentrations. These discoveries prompted researchers to look for safe and economical ways to deliver chlorine dioxide for bleaching purposes. The first company to introduce sodium chlorite for this purpose was the Mathieson Chemical Corporation.

In 1960, sodium chlorite became the standard material for continuous bleaching operations in the United States, replacing hydrogen. In subsequent years, other uses for sodium chlorite were discovered.

background

Sodium chlorite is a chemical formula used for water treatment as disinfection and purification. It is produced in massive quantities as flakes or a liquid from chlorine dioxide and sodium hydroxide. In 1920s, scientist discovered sodium cholide formula for textile belaching. Today, sodium chlorite is an important ingredient chemical with gross sales over $18 million annually.

Sodium chlorite (NaClO2) is a white or light yellow-green solid as a dried state. The greenish tint comes from trace amounts of CdO2 or iron, which are production residuals. Sodium chlorite has a molecular mass of 90.44 and decomposes at around 392oF (200oC). It is generally soluble in water, but its solubility increases as high as water temprature. Sodium chlorite is a powerful oxidizer that will not combusse on percussion. The anhydrous salt does not absorb water and is stable enough for up to 10 years.

Sodium chlorite is used for varies degree of applications. It is used as a disinfectant and purification chemical for water treatment. It is also used as a textile-bleaching and water anti-fouling agent. Additionally, it is used in the pulp paper and electronics manufacturing industries as a bleaching media.

Raw Materials

The primary raw materials used in the production of sodium chlorite are chlorine dioxide, sodium hydroxide, and hydrogen peroxide. Chlorine dioxide is a gas at room temperature. Its color is intensely greenish-yellow. Chlorine dioxide provides the source of chlorine that is converted to sodium chlorite. In production, it is stored as a liquid solution in glass-lined steel containers.

Other materials are typically added to sodium chlorite powders or solutions before they are sold. Commercial sodium chlorite bleaching solutions contain special ingredients including anticorrosive agents, buffering agents, chlorine dioxide fume controllers, and surfactants. Anticorrosive agents are used to prevent the corrosion of stainless steel bleaching equipment.

Application

PRODUCT IDENTIFICATION
CAS NO. 7758-19-2
EINECS NO. 231-836-6
FORMULA NaClO2
MOL WT. 90.44
H.S. CODE  2828.90
TOXICITY Oral rat LD50: 165 mg/kg
SYNONYMS Chlorous Acid, Sodium Salt; Chlorite (sodium salt);
PHYSICAL AND CHEMICAL PROPERTIES
PHYSICAL STATE white crystalline powder
MELTING POINT 175 C (Decomposes)
SOLUBILITY IN WATER Soluble
NFPA RATINGS  Health: 1 Flammability: 0 Reactivity: 1 
FLASH POINT Not considered to be a fire hazard
STABILITY Stable under ordinary conditions. Mildy hygroscopic.
sales specification
80% (SOLID)
APPEARANCE white crystalline powder
NaClO2 80.0% min
NaClO3

5.0% max

NaCl 15.0% max
WATER 1.0% max
25% (SOLUTION)
APPEARANCE clear to pale yellow solution
NaClO2 25.0 ± 0.5%
NaClO3 1.5% max
NaCl 5.0% max
SPECIFIC GRAVITY 1.208 ± 0.02 (at 20C)
transportation
PACKING 50kgs in drum , 200kgs in drum
HAZARD CLASS 5.1 (Packing group: II)
UN NO. 1496