Peroxyacetic Acid (Peracetic Acid / PAA)
Other Names
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Peracetic acid
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PAA
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Ethaneperoxoic acid
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Peroxyacetic acid
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Acetyl hydroperoxide
CAS Number: 79-21-0
📘 1. Definition
Peroxyacetic Acid (PAA) is a powerful oxidizing agent and disinfectant, formed from a reaction between acetic acid and hydrogen peroxide. It is commonly used in sterilization, sanitation, and industrial disinfection applications because of its very strong antimicrobial activity.
It is effective against:
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Bacteria
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Viruses
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Fungi
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Spores
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Biofilm
PAA is considered a “cold sterilant” because it works at low temperatures without requiring heat.
🧪 2. Chemical & Physical Properties
| Property | Value |
|---|---|
| Chemical Formula | C₂H₄O₃ |
| Molecular Weight | 76.05 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | Strong, vinegar-like |
| pH | Acidic (2.5–3.5 depending on concentration) |
| Boiling Point | Decomposes before boiling |
| Flash Point | Non-flammable but strong oxidizer |
| Solubility | Fully miscible with water |
| Stability | Decomposes into oxygen, water, and acetic acid |
Important note:
Because PAA decomposes into safe byproducts (H₂O, O₂, CH₃COOH), it leaves no harmful residue, which makes it ideal for food, pharma, and medical applications.
🧰 3. Applications / Uses
A) Food & Beverage Industry
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CIP (Clean-In-Place) sanitation
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Equipment sterilization
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Surface and tank disinfection
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Bottle and packaging sterilization
B) Medical & Healthcare
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Cold sterilization of medical devices
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Surgical instruments
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Endoscope disinfection
C) Water Treatment
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Wastewater disinfection
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Cooling tower biocide
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Biofilm removal
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Alternative to chlorine (no harmful byproducts)
D) Agriculture
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Disinfection in dairy, poultry, and meat plants
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Fruit & vegetable washing
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Greenhouse sanitation
E) Industries
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Pulp & paper bleaching
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Textile bleaching
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Oil & gas microbial control
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Industrial disinfectant formulations
⚠️ 4. Safety & Handling
Peracetic acid is a strong oxidizer and corrosive.
Safety considerations include:
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Can cause severe eye and skin burns
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Strong respiratory irritant
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Should be used with adequate ventilation
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Use PPE: gloves, goggles, face shield
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Store in cool, ventilated areas away from organic materials or metals
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Avoid strong reducing agents, combustibles, and alkalis
📦 5. Commercial Concentrations
Commonly sold in:
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5% PAA (food & beverage)
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15% PAA (industrial disinfection)
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35–40% PAA (technical-grade, strong oxidizer)
Most commercial products also contain:
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Acetic acid
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Hydrogen peroxide
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Stabilizers
📌 Summary
Peroxyacetic Acid (Peracetic Acid, PAA) is a highly effective disinfectant and oxidizer, widely used in food processing, healthcare, water treatment, agriculture, and industrial sanitation. It works rapidly, leaves no harmful residues, and kills a wide spectrum of microorganisms.
