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What is HOCl?

HOCl, or hypochlorous acid, is widely used as a disinfectant, because of its oxidizing properties. It is very effective against bacteria,viruses, fungi, and yeasts. 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). The process itself and the active substance are both sustainable while being safe for humans, animals, and 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 conventional disinfecting agents. The main advantages are the reduction in the use of harmful chemicals and its by-products. Hypochlorous acid is produced by electrochemical activation, which means that only water, salt and electricity are necessary. During the ECA process, the salt solution is electrolysed and creates a powerful and effective disinfectant. Our Watter System utilizes this process and therefore produces a disinfection solution on-site and on-demand. 

Where can HOCl be applied?

Hypochlorous acid can be applied in many sectors where disinfection and hygiene are essential. For instance, it is used in the industry to disinfect process water, in livestock farming to disinfect the drinking water of animals, or for Legionella and biofilm control in drinking water systems. HOCl can also be used to disinfect surfaces and spaces.

Hypochlorous acid - the natural disinfectant

Hypochlorous acid is also naturally found in the humans’ and other mammals’ bodies. This substance is an important part of the immune defense system. It is produced by the white blood cells to fight infections by acting against a wide range of microorganisms (bacteria, viruses, fungi, and yeasts). Thanks to its 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), known as household bleach, is formed from chlorine (Cl) and sodium hydroxide (NaOH). The scientific names and formulas sound very similar, hypochlorous acid (HOCl) and sodium hypochlorite (NaOCl), however, these are two significantly 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 compared to 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
  • Fungi
  • 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 chart above shows how the composition of chlorine changes in relation to the pH value in three phases of Cl2, HOCl, and OCl-. A lot of HOCl can be produced when the water pH is between 4.0 and 7.0.

HOCl has a stronger oxidizing effect than OCl- and Cl², which means that even at a low concentration, HOCl can achieve sufficient disinfection. At a pH of 9, as shown in the diagram, a solution of sodium hypochlorite (NaOCl) contains only 5% hypochlorous acid (HOCl), while 95% is OCl-. Although OCl- also has a disinfecting effect, a higher concentration will be needed to achieve the same disinfecting effect as with a solution with a higher level of HOCl.

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