Chlorine Dioxide & Corrosion

Rust is a form of corrosion.

Chlorine dioxide is a compound with the molecular formula ClO2. It is a potent oxidizing agent used primarily to bleach wood pulp and disinfect drinking water. While chlorine dioxide is considered corrosive, its effects are fairly minimal, especially compared to other common alternatives.

Function

Chlorine dioxide is a member of a class of compounds called free radicals, meaning that it has a single unpaired electron. Consequently, it is an unstable compound that reacts readily with a variety of organic compounds. As a disinfectant, chlorine dioxide is thought to be more effective than chlorine, but less so than ozone.

Features

Chlorine dioxide is moderately corrosive and becomes more so at higher concentrations or in solutions with an acidic pH. It is most corrosive when applied to soft metals like brass, copper or aluminum. Plastics like PVC are unaffected by chlorine dioxide.

Considerations

The potential for corrosion from chlorine dioxide is limited, especially when compared to other chlorine chemicals. A 2003 article in the journal Infection Control and Hospital Epidemiology found that a chlorine dioxide disinfection system, "did not appear to cause increased corrosion of copper pipes," even after 17 months of use. In general, while chlorine dioxide can corrode metal in water with an acidic pH, it only accelerates corrosion slightly at low concentrations and under normal conditions.

References

• "Infection Control and Hospital Epidemiology"; A 17-month evaluation of a chlorine dioxide water treatment system; Srinivasan, Bova et al; 2003.
• "Journal of Dairy Science"; Corrosivity of Chlorine Dioxide Used as Sanitizer; Bohner and Bradley; 1991.
• Lenntech: Chlorine Dioxide
• University of Idaho: The Use of Chlorine Dioxide in Potato Storage