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Peracetic acid (peroxyacetic acid, or PAA), is a chemical in the organic peroxide family. It is a bright, colorless liquid with a characteristic acrid acetic acid type odor. It has a strong oxidizing potential, is highly corrosive, and can explode at temperatures exceeding 110ºC.
Peracetic acid is produced by continuously feeding acetic acid and hydrogen peroxide into an aqueous reaction medium containing a sulfuric acid catalyst. The reaction is allowed to continue for up to ten days in order to achieve high yields of product according to the following equation. 
Peracetic acid is always sold in solution with acetic acid and hydrogen peroxide to maintain the stability of the chemical. The concentration of the acid as the active ingredient can vary, and usually depends on its application. Additional methods of preparation involve the oxidation of acetaldehyde or alternatively as an end product of the reaction of acetic anhydride, hydrogen peroxide, and sulfuric acid. Another method involves the reaction of tetraacetylethylenediamine (TAED) in the presence of an alkaline hydrogen peroxide solution. PAA is also formed naturally in the environment through a series of photochemical reactions involving formaldehyde and photo-oxidant radicals.
Peracetic acid is an ideal antimicrobial agent due to its high oxidising potential. It is broadly effective against microorganisms and is not deactivated by catalase and peroxidase, the enzymes which break down hydrogen peroxide. It also breaks down to food safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications. It can be used over a wide temperature range (0-40°C), wide pH range (3.0-7.5), in clean-in-place (CIP) processes, in hard water conditions, and is not affected by protein residues.
Mechanism of action
Peracetic acid kills microorganisms by oxidation and subsequent disruption of their cell membrane, via the hydroxyl radical (OH·). As diffusion is slower than the half-life of the radical, it will react with any oxidizable compound in its vicinity. It can damage virtually all types of macromolecules associated with a microorganism: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyr and o-Tyr). This ultimately leads to cell lysis and true microbial death.
US EPA first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces. Use sites include agricultural premises, food establishments, medical facilities, and home bathrooms. Peracetic acid is also registered for use in dairy/cheese processing plants, on food processing equipment and in pasteurizers in breweries, wineries, and beverage plants. It is also applied for the disinfection of medical supplies, to prevent bio film formation in pulp industries, and as a water purifier and disinfectant. Peracetic acid can be used as a cooling tower water disinfect where it prevents bio film formation and effectively controls Legionella bacteria.
Peracetic acid can be used as a synthesis chemical, where it's oxidizing properties are used to add an oxygen atom to double bonds, e.g. in ethene and propene, to form epoxides and alcohols. It can also be used in producing synthetic glycerol from propene, and is used in nylon manufacturing. 
Peracetic acid can be used as a bleaching agent. Since it emits oxygen more readily and at lower temperatures than other bleaching agents, it is gentle on the material to be bleached. Bleaching of wood pulp with peracetic acid gives paper which is totally chlorine free (TCF).
- United States Department of Agriculture. Agriculture Marketing Service Peracetic acid. (PDF document). URL accessed on 11 November 2006.
- U.S. National Library of Medicine. Hazardous Substances Data Bank. URL accessed on 11 November 2006.
- U.S. Environmental Protection Agency. Hydrogen Peroxide and Peroxyacetic Acid. URL accessed on 11 November 2006.
- KEMI - Information on Substances. Peracetic Acid. URL accessed on 11 November 2006.