This unit uses an electrochemical reaction to convert water with salt into a sanitising liquid called hypochlorous acid. This type of device is sometimes called a chlorine generator.
In the event of a disaster, something like this could be improvised to sterilise water using low level solar energy.
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A while ago, i made a video about a device that was just basically a spray bottle that you plugged into usb and it turned salty water into hypochlorous, acid or diluted, bleach cleaning agent and at the same time i ordered a few different ones from ebay. But i didn't want to make too many videos about the same thing so now it's time to take a look at another one, and this one is called the household we'll use disinfectant generator. Five minutes use salt and water with our procult. You can make disinfectant by yourself five minutes: excellent, sodium hypochlorite generator 99.99 disinfectant.

When we open it up, we find a set of instructions in chinese and english reasonably acceptable, english and the device itself. Obviously i chose the pink one. Did i choose a pink one, or is that just what i got, but it is a pink one. I probably chose it as being pink as the usb connector.

You can see through the side electrodes inside which i'll take this apart later on. I don't know if there's any active electronics in it, we'll find out when i take it apart, but you get the unit and you get a scoop of salt and it basically says in instructions put water into a glass for every 100. Milliliters. Add one scoop of salt: i've measured the scoop with table salt and the scoop actually measures three grams, so they suggest two percent salt.

This is actually making a three percent solution and for comparison uh to this disinfecting or water sanitizing solution. I got some of these little tablets that are chlorine, water purification tablets. I think they're chlorine are these chlorine. Oh one moment, i'm just going to check this.

Ah, yes, it does release chlorine. Its ingredients are sodium, trochlear, seen otherwise known as sodium dichloroazocyanurate lovely and when you dissolve one of these 8.5 milligram tablets in one liter of water, it makes a density of, but it gives about five parts per million of chlorine. I exaggerated that i dissolved one in just uh 100 milliliters, which is a tenth of a liter, and i dipped a stripping it because i've got these chlorine test strips here and the level is extremely low when you dip the strip in there's a very slight color Change keep in mind. This is 10 times as the strength that it would normally be and when compared to the chart, it comes in about 2.525 milligrams per liter, so it'll be a tenth of that so 25 to 50 milligrams a day or so will effectively be 2.5 to 5 milligrams.

A liter, okay right. I should put that strip out the way that is a reference. It's very weak. It barely smells bleachy right.

Tell you what let's begin the test. So here is a little scoop. I'm going to add the one spoon where's, a teaspoon. I've not got a teaspoon, so one scoop of salt to this i'll, just use this to stir them to mix it up.

I don't think it needs to be all dissolved anyway, but that water is now completely undrinkable and to see how much current this unit draws. I have a power bank and i have a plug-in meter. So let's do this. Let's uh get this cable untied and i shall plug it in to this.
Nothing will happen, probably because i honestly don't think there's much in the way of circuitry ammo dunk it in the water, but i'm going to time it i'm going to put it in for five minutes um and then once it's been in for five minutes, i'm going To measure the strength of that, the salt is not all dissolved. This is not really surprising the current it said it would be an amp. Let's start the timer start, it's only 300 milliamp, it's drawing. I can see the bubbles coming out, though uh.

So they said, it'd be an amp, i feel cheated, but maybe this is good. No sure it's in here now what's in here and we will open up later, are two electrodes. I get the feeling, i don't think, there's a resistor in here or anything but we'll find out. We open it, but uh.

There are two electrodes and it causes an electrolytic reaction where it kind of the salt. The sodium chloride in the water reacts with the oxygen hydrogen and you can see it bubbling here in the bubble: smeared. Well, let's zoom down, so you can see it bubbling, let's just zoom down, so you can see absolutely everything. This is what this is.

What it's supposed to be about here, um and since we're more interested what's down there, we'll focus down on that and right now maybe yeah swamping it out, but we can actually see what's happening now with the power right table uh, so it separates that. Can i smell it? Oh yeah, god that is so bleachy smelling that is making a very, very bleachy liquid right table. I'll give it it's five minutes at the 300 milliamps and i shall return and then we'll stick the strip in and we'll see what strength of a stuff we've got with this test and see you know, what's a result we get. I shall be back in three minutes and 30 seconds and start so uh current is up to 400 milliamps.

Let's turn the power off swish this about a bit in here. So that's it had five minutes. What strength are we going to get? I think it's going to be quite high. Am i going to be dripping stuff everywhere here? Yes, i am.

Let me just grab a bit of paper towel. I didn't think this through. Did i? No? I never do it's not a surprise. So here is our uh liquid.

Oh, that just smells like like a swimming pool, exploded, let's put the strip in that's a lot stronger. Okay! So let's see what this comes in at actually on there, i would say it comes in at somewhere between 200 to 300. Probably close to 300 milligrams per liter, okay, that's quite strong um and i'd guess that if i gave it another uh five minutes, it would yeah. Let's give it another five minutes so i'll, just bang it back.

In again i mean by the magic of youtube. We can do this so in it goes again. The bubbles are fizzing out of it. Let's give it a shake to make sure that uh it's making connection, let's start the timer again and uh yes, i'll, be back in five minutes and the next test.
Five minutes later, let's turn the power off again. It's up to 400 bullets waving around about 400 milliamps. Let's do another test on this and see what the concentration is now, so i shall uh swoosh around with this tap it on the side, put it over on the paper towel, which is in place now, and i have to give it another swirl just because i Feel the need to swirl it for some reason, just to make sure everything's mixed in. I shall dip.

Is this a new bit? Yes, it is a new bit of strip. I shall dip this in even darker, oh yeah, let me show you the original strip. This is closer to the hold on i'll. Just let i'll let you guys decide i'll.

Let you guys decide here by focusing up there, what do you reckon 500? That would bear outrage, wouldn't it that is kind of doubled the strength, and there was the original one that i did the first pass through. So that was the two to three hundred. I think it's actually lightened a little bit since uh, probably because the bleaching effect of chlorine - but i would say, yeah this one's in the region heading in the region of 500., so uh it does produce a fair concentration. Now the question is what, if i was wanting to use this to actually sterilize drinking water? To me, that would mean getting one liter of water, putting a pinch of salt in and then maybe testing it just to see um.

Oh that's going to be quite tricky to test. I shall maybe right give me one moment: i'm just going to do some experiments, okay, random, wild experiment, time. I have put two pinches of salt into one liter of water. That's that much! I'm gon na drop the electrode and see how conductive it is it's showing about 50 milliamps, and i can see the stuff bubbling out of that already.

I'm not sure if you're going to see that it's also doing its best to float out the water um. Are you able to see that i shall move over to that side? No, it doesn't want to move over to that side. It just wants to do its own thing, so i'm going to leave it for five minutes in this level of water. So, let's start the timer again uh and then when i come back uh i shall taste the water and see if i can actually taste the chlorine in it.

I'm not sure if you can see that i'm going to move this to the middle of the shot and actually, let's get a focus target at round about the same height which will be about there and i'll move this to the middle of the shot. Uh. Put that about the same height, it's really not want to play ball, because it's floating about, partly because it's filling itself up with gas and the next part of this experiment after tasting this i'll zoom down this. This is just to show you.

There are bubbles coming out of it. Can you see the bubbles? Yes, you can see the bubbles coming out of it, so once i've done this i'll taste it and then after that, i'll just take this thing apart. I've already noticed that the little pink rubber band thing may be covering a screw because well i've not lifted it, but it is a sort of flexible rubber sleeve that's been put over, so i shall be back shortly and resume so this is still drawing about the 35 to 40 milliamps, depending on how many bubbles are in it, uh i'm not getting a huge smell of chlorine. I wouldn't expect it.
There is a tiny. Ah, let's try the stripping it and see if it changes color at all. Ah, no color change, but then that's what i got with the first test. I did uh with the tablet dissolved in the in one liter of water.

I'm not sure, but can i taste the chlorine? Oh i'm just going to taste it not sure. I think it may require a bit of experimentation to determine how much how long you'd have to leave it in the water, but it certainly was doing something right. Tell you what i'm gon na take this out the way before i spill it everywhere, i'll be back in a moment all cleared up. Let's open this up.

Does this thing come off it does it's a sleeve? Is there a screw? No there's not a screw. It's just a little rubbery sleeve. Is it holding it together? So the point of that experiment was really to suggest that perhaps in the event of an apocalypse you might be able to sterilize drinking water. Oh this does just unclip apart.

That's quite nice! Is it just gon na be two electrodes straight on, let's zoom down for this, for the for the reveal, but in the event of a super mega apocalypse, maybe you could improvise uh water sterilization two of those electro plates. These have some fancy coating on them. Oh one of them has the fancy coating. You can't just use stainless steel or aluminum, because uh there's a certain.

The reaction is quite vicious, so one of these plates may be some special coating on it. People say platinum, but i'm not sure they'd be using platinum and cheap products, although i suppose it's possible, this plate could be coated. Platinum and they've got the polarity in the exact way for it. Uh.

Is this going to split open any further? I don't think there's going to be any circuitry in this. Is there i think this. This is chewy they've, actually kind of molded that in there i think, tell you what then we could improvise this um. I shall just do a quick test.

What can i do here? I shall do a quick test i'll just pause moment of momentum. I'll do this, because i don't think it'll be that quick. One moment please test complete there, there's no circuitry. It is literally just the five volts being applied across these two electrodes.

There are specific distance apart. The coated one is connected to positive and the uncoated one that just looks like just bare metal, not sure what metal is it's not easily attracting hold on i'm just going to scratch that i'm going to scratch it with a sharp probe one probe. Is it aluminum not sure that is, it could be stainless, not sure it's certainly not attracting a magnet um. Now nothing really magnetic about that.
Although there are some stainless alloys that are slightly magnetic and some that aren't, it could be stainless and that other one well a coated stainless in the case of that one, although i do noting the edge, is like they've cut it from a sheet that has just Been coated in the surface and the edge is fairly sort of dirty in the sense, it's just a bare metal edge in that it's not got the coating all the way around. So i'm not sure that is the coating they've put in it, but it is one apparently optimized for creating the hypochlorous acid uh when you apply a voltage across this current flows through the salty water so yeah. I guess ultimately it's interesting to know this. Just in case somehow, in the end, in the future that you somehow find yourself in a scenario that you need to create some sort of hygienic way to treat water, including drinking water, but uh interesting little thing.

I can't immediately think of any use for other than that camping. Maybe that would be quite handy, but there we go that. Is it it's the little uh? What do they call it again? They called it. The household will use disinfectant generator.

It's your little usb powered one with no circuitry at all, just the two electrodes in the usb supply in a fairly neat little container, and that is about it, but interesting, well worth testing.

13 thoughts on “Testing a usb water steriliser”
  1. Avataaar/Circle Created with python_avatars Nigel Johnson says:

    I suggest you compare its strength with Milton sterilising fluid, this is commonly used to clean babies bottles. Neat from the bottle is is a very strong sodium hypochlorite solution. It was once possible to buy Domestos, which was an even stronger hypochlorite solution, which I used to use as a ready source of chlorine gas, by mixing it with acid. One of my favourite chemical demonstrations, was the spontaneous ignition of turpentine rags, when exposed to a gas jar filled with chlorine.
    Unfortunately the ingredients were change, initially with the addition of soap. I think the reason was that there were a number of accidentally poisoning when Harpic when used in combination with Domestos. Harpic being a strong hydrochloric acid solution. Mixing the two produced dense clouds of chlorine gas. I believe there were even explosions reported when Domestos was used together with scrubs ammonia solution, which produced the explosive nitrogen trichloride.

    With regard to the electrolysis cell, powered by USB. It does seem dangerous not to have included a fuse, maybe even a poly fuse. Is it assumed that all USB power supplies have built in short circuit protection?

  2. Avataaar/Circle Created with python_avatars chrimony says:

    If those electrodes are stainless steel, that's bad news. Using that in electrolysis produces hexavalent chromium, which is toxic. Seems like a completely useless product. In an apocalypse scenario, I'd just boil the water and save whatever batteries I had left for a flashlight. Having a reliable source of fire would be a million times more useful than stupid gadget products.

  3. Avataaar/Circle Created with python_avatars Michael Moorrees says:

    Promised 1A, but draws only 0.3A. Sounds about right. I bought some "12V 1A" DC switching "wallcubes" from China, a couple of years ago. Put a varying loads on them, and the voltage dropped below 10.8V (10% drop off 12V), at about 350mA. So I concluded that a "Chinese Amp" is about 1/3 of an Amp, used elsewhere in the world. Even here in the US, where we use an "English Amp" instead of a "metric Amp". People say, all Amps are metric, but don't tell that to anybody in Merica !

  4. Avataaar/Circle Created with python_avatars UpLateGeek says:

    It's common after a major flood for tap water to become contaminated. Not 100% sure why, possibly excess runoff in the catchment area puts a lot of organics into the water supply, which is too much for the regular water treatment systems to cope with.

    So this could be helpful for that situation, if you can figure out how to make it put a reliably safe level of chlorine into the water. Although it's possible just leaving the water to outgas for some time afterwards would be allow the chlorine to dissipate.

  5. Avataaar/Circle Created with python_avatars Katyushas Lab says:

    If you leave one of these running in a saturated salt solution for a couple of weeks, you end up with a decent crop of sodium chlorate (after disproportionating by boiling for a bit to finish the reaction). Always useful to know.

    The anodes on these seem to be MMO for the most part, cathode is either Ti or stainless steel. Theres a few varieties of them out there.

  6. Avataaar/Circle Created with python_avatars The Rest Home, Croxton says:

    Hi big Clive! I used to work in swimming pools and some places use this process on a larger scale to produce Sodium hypochlorite for swimming pool treatment. Is safer to buy and store salt and convert it on site where it is needed. I use on of these plug-ins and I use it to make steriliser for my brewing gear (wine & beer) – it's way cheaper than buying steriliser powers, and I always have salt at hand.

  7. Avataaar/Circle Created with python_avatars ShirtFrontAuthoritarianism says:

    From memory you need 4ppm available Chlorine for disinfection (15 min rate?) . You can only drink 500 mg/L NaCl in water by AU standards. 1mg/L is 1 ppm so it would be feasible to make sterilized water with your 0.3g salt in 1 L water (300ppm) . But it would take considerably longer . As another suggested use 5 g of salt in 100 mL and then dilute it . At least you can get current flow at that concentration. Sea water is about 35,000 ppm or 35g/L so you could use 10mL of sea water and then add that to grey water . Though the additional oxygen would also be a disinfectant .

  8. Avataaar/Circle Created with python_avatars Fearmylogic says:

    While the concentration for drinking may be too high ( per the instructions. Would want to dilute it with more water ), I wonder how good this would be for making a home-made disinfectant. For cleaning up in the kitchen or bathroom. I imagine it would work fairly well, as you are basically creating bleach, which has a ton of uses. And while bleach is pretty cheap, a pinch of salt and some tap-water is even cheaper. Having something like this to sterilize silverware and plates when camping would be a great use for this.

    Do you have a link to where to buy it? While I've done my own electrolysis, and could do this myself, having something pre-made that uses the correct metals, in an single cable that can be stored easily sounds convenient.

  9. Avataaar/Circle Created with python_avatars Stan Burton says:

    Water purification tablets release not chlorine, but chloramines which are longer acting. They release chlorine much slower and therefore more thoroughly sanitize contaminated water by maintaining an adequate chlorine supply for a longer period instead of creating a big spike of chlorine that then evaporates quickly.

  10. Avataaar/Circle Created with python_avatars Daryl Cheshire says:

    You can melt some caustic soda flakes in a nickel crucible and electrolize it with a car battery charger. You can use a spirit burner to melt the NaOH, sodium metal is formed at the cathode.
    I noted that the current draw was 12 Amps. Molten caustic soda is very dangerous, if spilt will consume a paper notepad instantly. It is one of the few things that will dissolve carbon or soot.
    Irrelevant, I know.

  11. Avataaar/Circle Created with python_avatars Greygleam says:

    the anode is MMO (mixed metal oxide) usually a mix of Iridium/ruthenium or Iridium/tantalum on a titanium substrate. This is done so the anode does not dissolve in the reaction while produching the chlorine compound. The cathode is ideally bare titanium but they could have gone cheaper and used some 316l or such stainless steel. The anode cannot be pure titanium because you will just "anodize" it and this will create a electrically insulating oxide film on it which would stop the reaction . Hence the anode is coated with this metal oxide mix that stays conductive and does not dissolve into the solution. Platinum or platinum coated titanium would also work as an anode but is not used because MMO is usually cheaper.

  12. Avataaar/Circle Created with python_avatars Michael Wood says:

    Thanks – nice to see your "tear-down"! In South Africa its common to see salt water chlorinators in swimming pools pools. I made my own unit using titanium aanode electrode and an iridium plated titanium cathode. It worked well but one had to add quite a lot of salt fairly regularly. (I seem to remember the system drawing around 15 amps)

  13. Avataaar/Circle Created with python_avatars Rick Nelson says:

    Just to note. The water plants I work at as an I&C tech here in Florida. The target CL2 concentration for finished drinking water leaving the water plants is no more than 3ppm. Above that, there will be complaints. In the most distant from the plant areas of distribution, I believe that the minimum concentration is 0.2ppm. I am not a licensed water plant operator, but I do calibrate and repair the instruments.

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