Peracetic acid can be safely neutralized by adding a reducing agent such as sodium bisulfite or sodium thiosulfate, or by using an alkaline base like sodium hydroxide. The chosen neutralizer converts the oxidizer into harmless by‑products such as acetic acid, water, and sulfate salts.
Why neutralization is necessary
Peracetic acid is a strong oxidizer that can damage skin, eyes, and materials. Neutralizing it removes the oxidizing power and reduces the risk of fire or corrosion.
Common neutralizing agents
- Sodium bisulfite (NaHSO₃) – reacts with peracetic acid to form acetic acid and sodium bisulfate. The reaction is mild, produces little heat, and is widely used in industry.
- Sodium thiosulfate (Na₂S₂O₃) – a reducing agent that converts peracetic acid to sulfate, water, and thiosulfate. It is effective but may require a higher dose than bisulfite.
- Alkaline bases (NaOH, KOH, Ca(OH)₂) – neutralize the acid by proton transfer. The reaction is rapid but releases heat and oxygen, so it must be controlled.
Procedure for safe neutralization
- Wear chemical‑resistant gloves, goggles, and an apron.
- Work in a well‑ventilated area or under a fume hood.
- Prepare the neutralizing solution (5–10 % sodium bisulfite is common).
- Add the neutralizer slowly to the peracetic acid while stirring.
- Monitor the temperature; if it rises above 30 °C, pause and allow cooling.
- Check the pH or use a PAA test strip to confirm neutralization.
- Dispose the neutralized solution according to local regulations.
When to use enzymatic breakdown
In wastewater treatment, catalase enzymes can accelerate the decomposition of the peroxide component of peracetic acid. This biological method is slower than chemical neutralization but can be integrated into existing treatment streams.
Environmental considerations
The main by‑products—acetic acid, sulfate salts, and water—are biodegradable and pose minimal environmental risk. Adjust the final pH to 5–9 before discharge, and verify compliance with local discharge limits.