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[Purafil, Inc.] A registered trademark for purple air-cleaning pellets. First developed in 1960 by Borg-Warner Corporation, Purafil® is composed of activated alumina (45-55 %) impregnated with potassium permanganate (4-8 %), sodium bicarbonate (10-20 %) and water (15-25 %). It is used to improve indoor air quality by absorbing airborne pollutants, odors and particulates. Purafil® is normally sold in filter units that are incorporated in HVAC systems for dry-scrubbing air filtration. It will absorb sulfur dioxide, nitrogen oxide, formaldehyde, ozone and hydrogen sulfide. Since potassium permanganate is a strong oxidizing agent, it reacts with many atmospheric pollutants to permanently remove the contaminant. Thus, the potassium permanganate infiltrated alumina product will not offgas pollutants when the filter becomes saturated. However, it will release chlorine gas as a reaction product from absorbed hydrogen chloride.


  • Nonflammable.
  • Resistant to biological growth.
  • Purafil: MSDS

Physical and Chemical Properties

Will partially dissolve in water. Soluble in concentrated acids and alkalis.

Resources and Citations

  • Pam Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002
  • Purafil, 'Environmental Control for Museums, Libraries and Archival Storage Areas, Purafil, Georgia., 1800-222-6367.