Hypochlorous acid (HOCl) is a weak acid that occurs naturally in our bodies as part of our immune response. When our white blood cells encounter pathogens, they produce HOCl to neutralize these threats. This same compound is the key active ingredient in electrolyzed water. It acts as an effective disinfectant where it can be up to 80-100 times more efficacious than OCl- a comparable cleaning agent found in bleach.

In electrolyzed water, HOCl is formed when chloride ions from salt (NaCl) are oxidized during the electrolysis process. The efficiency of Hypochlorous acid is due to its neutral charge, which allows it to penetrate cell walls more easily. Hypochlorous acid works by oxidizing key cellular components of microorganisms, disrupting cell membranes, and denaturing proteins. It acts quickly, often achieving a 3-log reduction (99.9% kill) of bacteria within seconds of contact. Despite its potency against microorganisms, HOCl is non-toxic to humans and animals in the concentrations found in electrolyzed water, making it an ideal disinfectant.

It’s important to distinguish this from hydrochloric acid (HCl), as they have very different properties and roles in solution. HCl is a strong, highly corrosive acid that’s widely used in various industries. In nature, it’s found in small amounts in gastric acid, helping our stomachs digest food. Industrially, HCl is primarily produced through the chloralkali process, which involves the electrolysis of sodium chloride (table salt) solution. When added to the electrolysis chamber for SAEW production, HCl provides the chloride ions necessary for creating the disinfecting hypochlorous acid, while also helping to maintain the slightly acidic pH that optimizes the solution’s antimicrobial efficacy. Unlike hypochlorous acid, HCl fully dissociates in water, forming hydronium (H3O+) and chloride (Cl-) ions. This dissociation contributes to the acidity of the solution without directly participating in the disinfection process. By carefully controlling the amount of HCl used, manufacturers can fine-tune the properties of the electrolyzed water, balancing its pH and chlorine content to create a powerful yet safe disinfectant.

Academic Sources:

• de Vargas Brião, G., da Costa, T. B., Antonelli, R., & Martins Costa, J. (2024). Electrochemical processes for the treatment of contaminant-rich wastewater: A comprehensive review. Chemosphere. https://doi.org/10.1016/j.chemosphere.2024.141884
• Ding, T., Oh, D.-H., & Liu, D. (Eds.). (2019). Electrolyzed water in food: Fundamentals and applications. Springer. https://doi.org/10.1007/978-981-13-3807-6