Explosion with sodium chlorite

Kenneth J. TerBeek
Manager, Environmental, Safety, Health & Regulatory Affairs, Aldrich Chemical Co., Milwaukee

Chemical & Engineering News (22 Mar 1993) Vol. 71, No. 12, pp. 4.

Aldrich shares Simoyi's concern for chemical safety and agrees that chemicals be handled properly to prevent incidents. The material safety data sheet describes sodium chlorite as a strong oxidizer. Therefore, care must be taken to ensure that friction or contamination with incompatible materials does not occur. Typically, sodium chlorite is sold as technical grade with an assay of 79-81%. The balance of the material is usually sodium chloride, sodium sulfate, water, and sodium chlorate with small amounts of sodium hydroxide and sodium carbonate. Sodium chlorite from Aldrich does not contain organic solvents, so recrystallizing from water to remove such contaminants may be unnecessary. It is generally considered that sodium chloride acts as a stabilizer in the mixture. Recrystallization and drying may create a less stable mixture. In addition, the use of iron, nickel, or copper utensils cannot be allowed during the recrystallization. Finally, we believe that because sodium chlorite is a Class-III oxidizer and probably generates its own supply of oxygen, in case of fire, a water extinguisher is preferred to act primarily as a coolant to surrounding containers. NFPA 43A specifically prohibits the use of multipurpose dry chemical extinguisher (Class A:B:C) in areas where oxidizers that can release chlorine are stored.

In closing, we appeal to all of our customers and chemists alike to make sure that they know of the hazards associated with a chemical before they use it. Once the hazards are known, the next step is to use the appropriate protective equipment to minimize the risk, in the event of an incident.

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