Can you make hypochlorous acid from bleach?

Can you make hypochlorous acid from bleach?

We often get asked why diluting bleach down to a neutral pH isn't the same as making hypochlorous acid in a generator. This is certainly a valid question. Hypochlorous acid is the same chemical element (chlorine) as bleach (sodium hypochlorite) and is the active disinfecting agent in bleach. The main difference is that hypochlorous exists at a neutral pH while bleach is alkaline, so it would seem logical that adding water or vinegar to bleach to bring the pH down would be a quick DIY way of making hypochlorous. Indeed, there are plenty of internet accounts of people doing this with seemingly harmless results.

So why do you need a machine? And why make hypochlorous acid instead of just using bleach? First of all, adding vinegar to bleach results in a chemical reaction that produces toxic chlorine gas. Even at levels of 5 ppm, chlorine gas causes irritation to the mucus membranes in your respiratory system. At levels above 400 ppm, chlorine gas can be deadly within minutes. Aside from the safety hazards this creates, this reaction also means that your chlorine (the main disinfecting agent) is leaving the bleach solution. This leaves you with a very weak disinfectant, even if the pH is at 7. Not only is this method ineffective--it's also highly dangerous, and falls under the category of 'DO NOT TRY THIS AT HOME'!

While adding water to bleach will not result in the same chemical reaction, some chlorine will still be lost in the form of chlorine gas. Diluting bleach with water is not a new concept and can be a lifesaver in situations where drinking water needs to be rapidly disinfected. One tablespoon of bleach added to 1 gallon of water creates a solution of 50-200ppm free available chlorine (FAC). However, this solution is not stable and the chlorine will begin to disappear from the solution in the form of chlorine gas within 24 hours.

Bleach is much less effective as a biocide, so it needs to have a very high FAC in order to achieve the same results as hypochlorous acid. A high FAC means more salt, more chlorine generation, and thus more corrosivity. Not only will bleach break down your equipment, it’s also the least effective chlorine-based disinfectant and it comes with significant health and environmental risks. When you use bleach, you’re essentially getting the worst of both worlds—low efficacy and high risk.

Hypochlorous acid, on the other hand, is highly effective as a biocide and routinely outperforms bleach in kill claims for pathogens. It comes with no toxic side effects and actually has powerful healing properties as well. Because it can sanitize more efficiently at a lower FAC, the salt and chlorine content is reduced, which in turn means lower corrosivity. Making hypochlorous acid onsite with a machine reduces supply chain dependence and the ingredients are affordable and accessible.

Of course, there may be times when you want to use bleach instead of hypochlorous acid--for example, when you are trying to whiten fabric or remove stains. Because our Hypo 7.5 machine is an electrolysis cell, hypothetically it could also be used to produce bleach. However, this is not a process we have tested or designed the machine for, so we can't offer any information on how to produce bleach. 

Photo by Towfiqu barbhuiya on Unsplash


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