Emergency chlorine generator for water and surface sterilisation

I've featured similar devices to this in the past, notably a spray bottle that generates chlorine based disinfectant on demand using water and some standard sodium chloride table salt. But it's worth revisiting the technology, as it could be very useful if there was some sort of natural disaster.

This device used electrolysis to generate a potent chlorine sterilising agent from plain (or contaminated) water and salt. It could potentially be used to sterilise water for drinking, to preserve it or to make a stronger chlorine solution for cleaning and medical use.

A common method for deep sterilisation of medical establishments is to fog them with a hypochlorous acid solution. This is notable for being a potent disinfectant, while also being safe for skin contact and breathing at low concentrations. In some instances hypochlorous acid fog can be used for treating lung infections. These units do produce some sodium hypochlorite too, which makes them less suited to inhalation at high concentration.

Note that only a trace level of chlorine is needed for drinking water sterilisation. You can buy tiny soluble chlorine (Sodium dichloroisocyanurate) tablets for this use (Oasis water tablets). Sodium hypochlorite is commonly used for sterilising public water supplies, and you can sometimes get a slight smell or taste of it in tap water.

The nice thing about this module is that it can use any low voltage and low current source of electricity, so even a low power solar panel on an overcast day could give useful results.
There was a very useful correlation between mAh and chlorine strength, that could allow a typical USB monitor device to be used as a level indicator.

It could be viable to use a simple current regulator circuit to get predictable time based results.

The electrode material of the anode is critical, as the process can cause rapid degradation of most metals. For emergency improvised electrodes it may be viable to use graphite for that electrode and stainless steel for the cathode.

Here's a Wikipedia article that gives more information:-
https://en.wikipedia.org/wiki/Hypochlorous_acid

It's been a while since I bought this unit, but they are still commonly available.
Here's a link to a couple of types on AliExpress (not a sponsor).
These are affiliate links, but that will not affect the price you pay.

The most common type:-
https://s.click.aliexpress.com/e/_c2yRaJT1

A similar version to the one in the video:-
https://s.click.aliexpress.com/e/_c43qTXwB

A larger spray bottle version for making a disinfectant spray:-
https://s.click.aliexpress.com/e/_c3Hbcax5

The small units should cost around £5-£10 and the large spray unit should cost around £20.



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