Differences between pre-formed and in situ peracetic acid, and chlorine dioxide

Pre-Formed Peracetic Acid

There are two main processes to manufacture and produced that peracetic acid can be produced.

The traditional way to manufacture peracetic acid is through reaction of very concentrated solutions of acetic acid and hydrogen peroxide in the presence of a strong acid, this results in pre-formed solutions of peracetic acid with pH values in the range of 1 – 3. These pre-formed solutions of peracetic acid have varying concentrations in the range of 5 – 30 %, and require dilution on site using specialist equipment so that it can be used for disinfectant purposes. Both the undiluted and diluted solution will have a strong inorganic acid like; sulfuric or phosphoric acid, present in order to maintain a low pH and stabilise the peracetic acid in solution. Once diluted for disinfectant use, the pH will still maintain acidic and in the range of 2 – 4. The hazards labels on these types of products are typically; oxidising, flammable and corrosive, which makes them difficult to transport, store and handle.

In Situ Peracetic Acid

In situ peracetic acid differs from pre-formed peracetic acid, because it generates a pre-determined concentration on site in warm tap water from a powder or tablet formulation when disinfection is required. This means that the starting powder or tablet formulation effectively has a zero concentration of peracetic acid, until dissolved in warm tap water. This makes it much safer to transport and storage, unlike liquid based oxidising disinfectants. Once dissolved the pH of the disinfectant solution is near neutral. In the case of Peracide the pH is 8.4 and has the inclusion of corrosion inhibitors to further limit the risk of corrosion to metal surfaces, it is also mild on polymer-based surfaces and does not damage or discolour. One 3-gram Peracide tablet dissolved in 500 mL of warm tap water will produce 1000 ppm of peracetic acid and has a two-colour system to indicate when the disinfectant solution is ready to be use and ready to be discarded.

A few additional benefits of using an in situ peracetic acid formulation, like Peracide, is that Peracide has been formulated with a surfactant; which classes Peracide as a 2-in-1 cleaner and disinfectant, which is not possible for pre-formed peracetic acid solutions. The inclusion of a fragrance in the formulation and the chosen pH of the Peracide product, allows for a reduction in the odour, that is usually associated with peracetic acid solutions making it more pleasant for both the user and patients that may be present during cleaning procedures.

Chlorine Dioxide

Solutions react together to form chlorine dioxide, which is a gas dissolved in solution, with a pH value of 2.5 – 5.5. The low pH of the chlorine dioxide solution and the innate oxidising ability of chlorine dioxide, is similar to that of pre-formed peracetic acid, and therefore the risk of corrosion and damage to surfaces will very much be present.