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What is HOCl?

HOCl, or hypochlorous acid, is widely used as a disinfectant, because of it's oxidizing properties. It is very effective against bacteria, fungi, and viruses. It also has an acidic component, but it's a very weak acid, comparable to citrus fruits.

HOCl is produced with the use of a technology called electrochemical activation (ECA) by the electrolysis of water containing dissolved sodium chloride (salt). This process and the active substance are sustainable and is suitable for humans, animals or the ecosystem. We believe it's the future of disinfection.

What is electrochemically activated water (ECA water)?

Electrochemically activated water is an environmentally friendly alternative to current disinfecting agents. The main advantage is that ECA water reduces the use of chemicals. As described above, HOCl can be produced using the ECA technique. This means that HOCl is produced by electrolysing a salt solution via electrochemical activation. Electrochemically activated water can be produced with an ECA machine on site, with the Watter-System.

Where can HOCl be applied?

Hypochlorous acid has a wide range of applications, where disinfection and hygiene are of high importance. It is used, for instance, in the treatment of process water (e.g. in the food industry), disinfection of the drinking water supply for farm animals or for legionella and biofilm control in medical facilities.

Hypochlorous acid - the natural disinfectant

Hypochlorous acid is also produced in the human body by white blood cells to fight infection by acting against a wide range of microorganisms. It is an important part of the innate immune system. This acid has a bactericidal effect and immediately destroys bacteria. Thanks to it's high biocidal activity, it is not cytotoxic to human and animal cells, when applied correctly.

What is the difference between hypochlorous acid (HOCl) and sodium hypochlorite (NaOCl)?

Sodium hypochlorite (NaOCl), which is household bleach, is formed from chlorine (Cl) and sodium hydroxide (NaOH). The names and scientific formulas of hypochlorous acid and sodium hypochlorite sound very similar, however, these are two different substances. The biggest difference can be seen in the effectiveness: you need a lot more bleach (sodium hypochlorite) to achieve the same anti-microbial power as with the use of hypochlorous acid.

A more detailed comparison can be seen in the table below:

  Hypochlorous Acid Sodium hypochlorite
Common name Electrolyzed water Bleach
Scientific formula HOCl NaOCl
Production Through the electrolysis of water containing dissolved sodium chloride (salt) Through a chemical reaction between chlorine and sodium hydroxide
Colour Colourless Pale greenish-yellow
Efficacy Highly effective against:
  • Bacteria
  • Viruses
  • Funghi/yeasts
Lower effectiveness than HOCl in the same concentrations
Toxicity Non-toxic and non-irritating Irritating to skin, eyes and not safe when inhaled

Equilibrium chart on chlorine in solution

hypochlorous acid graph

The above graph presents how chlorine composition changes according to pH value in three phases of Cl2, HOCl and OCl-. A lot of HOCl can be formed if the pH of water is between 4.0 and 7.0.

Since HOCl (hypochlorous acid) has been proven to be the main disinfectant, it can be, therefore, used for effective disinfection, although the chlorine concentration is only 10-30 ppm. On the other hand, a sodium hypochlorite solution contains only about 5% of hypochlorous acid, which means that a very high chlorine concentration of around 100 to 200 ppm should be used. The remaining 95% is OCl-, which has a very low bactericidal effect, remains unused and will be discarded in wastewater.

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