Hypochlorous Acid

HOCl

An oxidant the human body produces to protect and heal, learn why it's now considered nature's germ killer. 

About Hypochlorous Acid - HOCl 

What is HOCl? 

Quick Facts 

  • HOCl is the scientific formula for hypochlorous acid, a weak acid similar to that of a mild citrus juice. 
  • HOCl is made naturally by white blood cells in all mammals for healing and protection. 
  • HOCl is a powerful oxidant that is effective against invading bacteria, fungi, and viruses. 
  • Generating HOCl by running electricity through a solution of saltwater was discovered in 1970s. 
  • HOCl is now used in healthcare, food safety, water treatment, and general sanitation. 
  • How is HOCl made? 

    History of Electrolysis 

  • Michael Faraday founded the laws of electrolysis and it became commercially available in the 1870s. 
  • Generating HOCl from the electro-chemical activation (ECA) of salt water was developed in the 1970s. 
  • Early ECA technology used membranes to force saltwater into two solutions of HOCl and NaOH. 
  • In the 1980s, single stream systems were developed that produced one solution of HOCl without byproduct. 
  • In recent, single stream systems have been innovated to last longer and generate more stable solutions. 
  • Why is HOCl more efficient at killing pathogens? 

    Hypochlorous Acid (HOCl) vs. Sodium Hypochlorite (Chlorine Bleach) 

    Hypochlorite ion carries a negative electrical charge, while hypochlorous acid carries no electrical charge. The hypochlorous acid moves quickly, able to oxidize the bacteria in a matter of seconds, while the hypochlorite ion might take up to a half hour to do the same. Germ surfaces carry a negative electrical charge which results in a repulsion of the negatively charged hypochlorite ion to the area of the germ surfaces, making hypochlorite ion less effective at killing germs. The ratio of the two compounds is determined by the relative acidity (pH) of the water. Water treatment specialists can adjust the pH level to make hypochlorous acid more dominate, as it is more efficient at killing bacteria. The hypochlorous acid's lack of electrical charge allows it to more efficiently penetrate the protective barriers surrounding germs. 

    Home use of HOCl 

      Home Electrolysis Systems 
    There are several home electrolysis systems that have been developed that can generate stable hypochlorous acid using table salt and water. Distilled vinegar is sometimes added to lower the pH allowing for a solution of free chlorine more dominated by the hypochlorous acid molecule. When choosing a home system, an important factor to consider is the quality of the electrolysis cell. Higher quality systems may cost more but will last much longer due to the durability of the alloys in the metals used to make the cells. 

      What are the benefits? 
    Hypochlorous acid, unlike chlorine bleach, is 100% safe and non-irritant. If it gets on your skin or in your eyes, it will not burn. Even if it were accidentally ingested, it is completely harmless. Yet, it is 70-80 times more efficient at killing microbial pathogens than chlorine bleach. 

      Where can it be used? 
    In the home, hypochlorous acid is useful anywhere you need a sanitizer but don't feel comfortable using a toxic chemical. A perfect example is in the kitchen. Instead of rinsing leafy greens with water, use hypochlorous acid. Or for pesonal items such as toothbrushes or razors, hypochlorous acid is safe. Want to sanitize laundry without damaging or discoloring clothing, hypochlorous acid is the answer. 

    Although hypochlorous acid usually does not cause bleaching or discoloration, some lower quality dyes may bleed when exposed to hypochlorous acid.

    Commercial use of HOCl 

      Membrane Cell Electrolysis 
    The technology behind generating hypochlorous acid has evolved tremendously over the past 20 years. The market used to be dominated by membrane cell electrolysis that used high pressures to force saltwater into two separate streams, an acidic stream and an alkaline stream. The acidic stream would contain hypochlorous acid (HOCl), the anolyte or oxidizing agent, and the alkaline stream would contain sodium hydorixde (NaOH), the catholyte or reducing agent. The benefit of these systems were that two useful solutions were generated, a sanitizer and a degreaser. The downside of these systems were that they were expensive, required high maintenance, and would generate unstable solutions that lost their oxidation-reduction potential (ORP) within a short period of time. 

      Single Cell Electrolysis 
    With the development of single cell electrolysis, many of these obstacles were overcome. Single cell electrolysis does not use high pressures across a membrane therefore little to no maintenance is required. And because single cell electrolysis does not force the saltwater into two streams of opposite oxidation-reduction potential and opposite pH, a more stable solution is generated, a solution that is not seeking to regain an equilibrium. Single cell systems generate only one solution, an anolyte in the pH range of 5 to 7. This pH range is optimal for hypochlorous acid in regards to stability and effectiveness as a sanitizer. 

    Stainless steel can corrode as well if submersed in high concentrations of hypochlorous acid (>200 ppm) for extended periods of time.

    Food Safety 

    The majority of the research that has been done regarding the practical applications of hypochlorous acid has been in the field of food safety. Since the Food Safety Modernization Act (FSMA) was signed into law in 2011, the focus of food safety has shifted from responding to contamination to preventing it. There is probably no food sanitizer more researched and more understood than hypochlorous acid. The research clearly demonstrates that hypochlorous acid is safe and efficient for ensuring microbial counts are maintained below infectious levels on food and contact surfaces. 

      Surface Sanitation 

      Hypochlorous Acid vs. Quaternary Ammonium (Quats) 
    Hypochlorous acid has advantages over chemicals such as Quats when sanitizing food contact surfaces because Quats are not safe on food. Before cleaning with Quats, all food must be removed from the area before sanitation can take place. This is not required when using hypochlorous acid. Hypochlorous acid can be used continuously throughout the work day regardless of whether food is exposed. 

      Direct Food Sanitation 

      Hypochlorous Acid vs. Ozone 
    Hypochlorous acid has advantages over ozone. Ozone is a gas and is not stable in solution therefore it cannot be used to sanitize contact surfaces. Ozone is however used for food sanitation however it must continuously be regenerated as it is continuously leaving solution into the air. Being that ozone is an irritant to the lungs and respiratory tracts, ozone is limited in the concentrations that can be used, therefore limiting the oxidation potential that can be obtained for killing microbial pathogens. Hypochlorous acid is non-irritant and is also stable in solution. Hypochlorous acid can be used at high concentrations (60 ppm) for food sanitation without requring a post-rinse. 

    The FDA Food Contact Notification 1811 allows for hypochlorous acid to be used on raw or processed fruits & vegetables, fish & seafood, meat, poultry and shell eggs at up to 60 ppm. Sanitizing Leafy Greens
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