Sodium chlorite is a white powder that dissolves in water to create an alkaline solution. When mixed with acid, the solution generates chlorine dioxide, a powerful biocide and bleaching agent. In 1967, the Environmental Protection Agency approved liquid chlorine dioxide for treating drinking and wastewater, disinfecting food and food processing equipment and bleaching paper and textile products. Gaseous chlorine dioxide sterilizes manufacturing and laboratory equipment and cleans rooms. If you use sodium chlorite for these applications, consult a material data safety sheet, because chlorine dioxide can be toxic and corrosive.
Drinking Water Treatment
Water sterilization by chlorine gas leaves behind trihalomethane byproducts, which are carcinogenic. Acidified sodium chlorite is preferred to chlorine because it oxidizes cellular components. The resulting disruption in microbial metabolism produces nontoxic residues that can be removed by filtration or other processes. Chlorine dioxide from acidified sodium chlorite removes odors and tastes from drinking water by oxidizing sulfur-containing compounds. Oxidation of iron and manganese in drinking water results in improved color and fewer stains on your sinks and toilets.
Wastewater Treatment
Sodium chlorite is more effective, less toxic and less corrosive than chlorine, according to the Centers for Disease Control and Prevention. An advantage to generating chlorine dioxide by acidified sodium chlorite is that the gas can be produced on site, eliminating the need for transportation. Wastewater can contain toxic phenolic agents as well as pathogenic microbes--contaminants that are neutralized by chlorine dioxide.
Food Decontamination
Bacterial contamination of processed food poses a public health threat. In 2005, the Food and Drug Administration approved acidified sodium chlorite as an antibacterial spray or dip for red meat, poultry, seafood, vegetables and fruits. The Code of Federal Regulations allows the use of sodium chlorite solutions for sanitizing food-processing equipment and utensils.
Paper and Textile Bleaching
Chlorine dioxide bleaches lignin in pulp products without harming the cellulose. It is preferred over chlorine gas because chlorinated byproducts are absent. In the textile industry, chlorine dioxide bleaches and can even change the properties of some of the fibers. For example, "shrinkproof" wool emerges after chlorine dioxide reacts with the disulfide bonds in the fibers.
Decontamination of Surfaces
Chlorine dioxide can remove bacterial slime colonies from industrial and residential plumbing surfaces. Oxidation of algal growth by chlorine dioxide in industrial cooling towers eliminates the need for costly shutdowns. Laboratory equipment and clean rooms are sterilized by gaseous chlorine dioxide. In 2001 and 2002, the Hart Senate Office Building and the U.S. Postal Service Brentwood Processing and Distribution Center in Washington, D.C., were treated with gaseous chlorine dioxide to kill anthrax spores that had passed through these facilities in the mail. The anthrax spores were completely destroyed by the gas, which was generated by activating sodium chlorite.
Other Uses
Used in mouthwash, sodium chlorite can freshen your breath and provide protection against dental plaque. Chlorine dioxide oxidizes sulfides in oil well systems, eliminating free sulfur that can further contaminate the environment.
Anecdotal testimonials described sodium chlorite's healing powers when ingested or applied to the skin. But a placebo-controlled study of 60 adult, healthy males in 1982, published in "Environmental Health Perspective," concluded that drinking a sodium chlorite solution for 12 weeks did not affect the study subjects.
Caution
Use caution when working with sodium chlorite; doses as low as 1.65 percent have produced toxic effects in rodents and fish. Consult your health care professional before drinking or applying sodium chlorite solution.
Solid sodium chlorite powder can become unstable and explode or burn.
References
- U.S. Environmental Protection Agency: Anthrax Spore Decontamination with Chlorine Dioxide
- "Archives of Biochemistry and Biophysics"; Interaction of Sodium Chlorite with Phospholipids
- International Agency for Research on Cancer: Sodium Chlorite
- Centers for Disease Control and Prevention: Chlorine Dioxide and Chlorite
- Code of Federal Regulations 21 CFR 173.325: Acidified Sodium Chlorite
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