electrolysis

26 Articles

Using Electrolysis For More Than Just Generating Hydrogen

June 5, 2026 by 6 Comments

When the topic of ‘electrolysis’ is mentioned, people typically think of just splitting plain old dihydrogen monoxide (hydric acid: H2O) into its constituent atoms, but this barely scratches the surface of what is going on during electrolysis. Once you understand the full picture it also becomes obvious how electrolysis can be used for other tasks, including metal refining, flow batteries and more, as covered in a recent video by [NightHawkInLight].

On a fundamental level electrolysis is what it says on the tin: a way to lyse (i.e. split apart) using electrons, which is what the anode and cathode provide or remove. This can be used to break down the bonds between hydrogen and oxygen, but also those of iron ore, like Fe3O4. Stripping the oxygen from the iron atoms is commonly done in a reduction process using the CO from coke or hydrogen,

Setup for electrolysing iron ore. (Credit: NightHawkInLight, YouTube)
Setup for electrolysing iron ore.

By instead dissolving the iron ore in acid, electrolysis can then be used to separate the two. In the example, the acid is created by one side of the electrolytic cell, with both electrodes separated by an ion-exchange membrane barrier that prevents the chemical processes on each side of the cell to affect the other side while still enabling the cell to work. How to make these membranes is also demonstrated in the video.

Through a careful arrangement of these membranes and the electrodes, you can guide which reactions can occur where, and which – negative or positively charged – ion can pass through which membrane, giving a lot of control. It can also be used to prevent undesirable reactions from happening, such as in this case the generating of chlorine gas from the NaCl being lysed.

Acidity indicator dye is used to show in great detail how the cell works, including its preparation of getting the acidity just right before the crushed iron ore is mixed with some of the generated acid and the resulting liquid added to the cell. Following this you get a closed-loop chemical process to which only fresh iron ore slush has to be added and electrodes swapped out for fresh ones as the build-up of iron becomes sufficiently thick. In addition to supplying the cell with electricity, naturally, though you can even invert the cell and use it as a chemical battery akin to a lead-acid one if that’s more your thing.

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DIY Electrolysis Machine Removes Hair Permanently

May 7, 2026 by 38 Comments

If you talk to the FDA, there’s only one permanent method of hair removal—electrolysis. This involves sticking a needle into a hair follicle, getting it very hot or running a current through it, and then letting heat and/or the lye generated kill the root of the hair dead. Normally, you’d pay someone with a commercial machine to do this for you at great expense. Or, you could do it yourself with a home-built machine, as [n3tcat] did.

Based on the available information out in the wild, [n3tcat] decided to build a galvanic electrolysis machine. This specifically passes current through a needle in the hair follicle to generate lye at the hair bulb, which kills it. The amount of lye generated depends on the amount of current and the time over which it is applied. More lye is more likely to kill a follicle permanently, though there are limits with regards to avoiding scarring, other skin damage, and excessive pain.

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A cylindrical neodymium-iron-boron magnet in shown on a grey background. A white line of boiling liquid surrounds the top edge of the magnet, and a cloud of condensing vapor hangs over it.

Homemade Liquid Oxygen Demonstrates Paramagnetism

March 2, 2026 by 6 Comments

Liquid nitrogen isn’t exactly an everyday material, but it’s acquired conveniently enough to be used in extreme overclocking experiments, classroom demonstrations, chemistry and physics experiments, and a number of other niche applications. Liquid oxygen, by contrast, is dangerous enough that it’s only really used in rocket engines. Nevertheless, [Electron Impressions] made some of his own, and beyond the obvious pyrotechnic experimentation, demonstrated its unusual magnetic properties. Check out the video, below.

The oxygen in this case was produced by electrolysis through a proton-exchange membrane, which vented the hydrogen into the atmosphere and routed the oxygen into a Dewar flask mounted at the cold end of a Stirling cryo-cooler. The cooler had enough power to produce about 30 to 40 milliliters of liquid oxygen per hour, enough to build up an appreciable amount in short order. As expected, the pale blue liquid caused burning paper to disappear in a violent flame, and a piece of paper soaked in it almost exploded when ignited.

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Blue Alchemist Promises Rocket Fuel From Moon Dust

September 22, 2025 by 16 Comments

Usually when an alchemist shows up promising to turn rocks into gold, you should run the other way. Sure, rocket fuel isn’t gold, but on the moon it’s worth more than its weight in the yellow stuff. So there would be reason to be skeptical if this “Blue Alchemist” was actually an alchemist, and not a chemical reactor under development by the Blue Origin corporation.

The chemistry in question is quite simple, really: take moon dust, which is rich in aluminum silicate minerals, and melt the stuff. Then it’s just a matter of electrolysis to split the elements, collecting the gaseous oxygen for use in your rockets. So: moon dust to air and metals, just add power. Lots and lots of power.

Melting rock takes a lot of temperature, and the molten rock doesn’t electrolyse quite as easily as the water we’re more familiar with splitting. Still, it’s very doable; this is how aluminum is produced on Earth, though notably not from the sorts of minerals you find in moon dust. Given the image accompanying the press release, perhaps on the moon the old expression will be modified to “make oxygen while the sun shines”.

Hackaday wasn’t around to write about it, but forward-looking researchers at NASA, expecting just such a chemical reactor to be developed someday, proposed an Aluminum/Liquid Oxygen slurry monopropellant rocket back in the 1990s.

That’s not likely to be flying any time soon, but of course even with the Methalox rockets in vogue these days, there are appreciable cost savings to leaving your oxygen and home. And we’re not biologists, but maybe Astronauts would like to breathe some of this oxygen stuff? We’ve heard it’s good for your health.

A cylindrical red furnace is in the center of the image. To the left of it is a black power supply. A stand is in front of the furnace, with an arm extending over the furnace. To the right of the furnace, a pair of green-handled crucible tongs sit on an aluminium pan.

The Hall-Héroult Process On A Home Scale

July 22, 2025 by 8 Comments

Although Charles Hall conducted his first successful run of the Hall-Héroult aluminium smelting process in the woodshed behind his house, it has ever since remained mostly out of reach of home chemists. It does involve electrolysis at temperatures above 1000 ℃, and can involve some frighteningly toxic chemicals, but as [Maurycy Z] demonstrates, an amateur can now perform it a bit more conveniently than Hall could.

[Maurycy] started by finding a natural source of aluminium, in this case aluminosilicate clay. He washed the clay and soaked it in warm hydrochloric acid for two days to extract the aluminium as a chloride. This also extracted quite a bit of iron, so [Maurycy] added sodium hydroxide to the solution until both aluminium and iron precipitated as hydroxides, added more sodium hydroxide until the aluminium hydroxide redissolved, filtered the solution to remove iron hydroxide, and finally added hydrochloric acid to the solution to precipitate aluminium hydroxide. He heated the aluminium hydroxide to about 800 ℃ to decompose it into the alumina, the starting material for electrolysis.

To turn this into aluminium metal, [Maurycy] used molten salt electrolysis. Alumina melts at a much higher temperature than [Maurycy]’s furnace could reach, so he used cryolite as a flux. He mixed this with his alumina and used an electric furnace to melt it in a graphite crucible. He used the crucible itself as the cathode, and a graphite rod as an anode. He does warn that this process can produce small amounts of hydrogen fluoride and fluorocarbons, so that “doing the electrolysis without ventilation is a great way to poison yourself in new and exciting ways.” The first run didn’t produce anything, but on a second attempt with a larger anode, 20 minutes of electrolysis produced 0.29 grams of aluminium metal.

[Maurycy]’s process follows the industrial Hall-Héroult process quite closely, though he does use a different procedure to purify his raw materials. If you aren’t interested in smelting aluminium, you can still cast it with a microwave oven.

Mining And Refining: The Halogens

January 21, 2025 by 25 Comments

I was looking at the periodic table of the elements the other day, as one does, when my eye fell upon the right-hand side of the chart. Right next to the noble gases at the extreme edge of the table is a column of elements with similar and interesting properties: the halogens. Almost all of these reactive elements are pretty familiar, especially chlorine, which most of us eat by the gram every day in the form of table salt. As the neighborhoods of the periodic table go, Group 17 is pretty familiar territory.

But for some reason, one member of this group caught my attention: iodine. I realized I had no idea where we get iodine, which led to the realization that apart from chlorine, I really didn’t know where any of the halogens came from. And as usual, that meant I needed to dig in and learn a little bit about the mining and refining of the halogens. At least most of them; as interesting as they may be, we’ll be skipping the naturally occurring but rare and highly radioactive halogen astatine, as well as the synthetic halogen tennessine, which lives just below it in the group.

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Simple Hydrogen Generator Makes Bubbles And Looks Cool

November 21, 2024 by 18 Comments

Hydrogen! It’s a highly flammable gas that seems way too cool to be easy to come by. And yet, it’s actually trivial to make it out of water if you know how. [Maciej Nowak] has shown us how to do just that with his latest build.

The project in question is a simple hydrogen generator that relies on the electrolysis of water. Long story short, run a current through water and you can split H2O molecules up and make H2 and O2 molecules instead. From water, you get both hydrogen to burn and the oxygen to burn it in! Even better, when you do burn the hydrogen, it combines with the oxygen to make water again! It’s all too perfect.

This particular generator uses a series of acrylic tanks. Each is fitted with electrodes assembled from threaded rods to pass current through water. The tops of the tanks have barbed fittings which allow the gas produced to be plumbed off to another storage vessel for later use. The video shows us the construction of the generator, but we also get to see it in action—both in terms of generating gas from the water, and that gas later being used in some fun combustion experiments.

Pedants will point out this isn’t really just a hydrogen generator, because it’s generating oxygen too. Either way, it’s still cool. We’ve featured a few similar builds before as well.

(Pedantic editor’s note: Because this build doesn’t separate the H2 from the O2, what you get is a stoichiometric mix, or HHO, or “Oxyhydrogen“. By virtue of being in exactly the right ratio to combust, this stuff is significantly more explosive than pure H2. Be careful!)

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