DIY magnetic fluid at home. DIY ferromagnetic liquid with a laser printer cartridge. Manufacturing magnetic fluid mechanically

To a person far from scientific discoveries, who said goodbye to physics or chemistry in school, many things seem unusual. Using, for example, electrical appliances in everyday life, we do not think about how exactly they work, taking the benefits of civilization for granted. But when it comes to something that goes beyond everyday perception, even adults are amazed, like children, and begin to believe in miracles.

How, besides magic, can one explain the phenomenon of the emergence of three-dimensional figures, flowers and pyramids, magical paintings replacing each other from a seemingly ordinary liquid? But it’s not magic, science provides a rationale for what’s happening.

What is ferrofluid?

We are talking about a ferrofluid - a colloidal system consisting of water or other organic solvent containing tiny particles of magnetite, and any material that contains iron. Their sizes are so small that it’s even hard to imagine: they are tens of times thinner than a human hair! Such microscopic size indicators allow them to be evenly distributed in the solvent using thermal movement.

For the time being, as long as there is no external influence, the liquid is calm, resembling a mirror. But as soon as you bring a directed magnetic field to this “mirror”, it comes to life, showing the viewer amazing three-dimensional pictures: magical flowers bloom, moving figures grow on the surface, changing under the influence of the field.

Depending on the strength and direction of the magnetic field, the pictures change before our eyes - from light, barely noticeable ripples appearing on the surface of the liquid, through needles and peaks that change sharpness and slope and grow into flowers and trees.

The ability to create color paintings using backlighting, truly mesmerizing to the observer, reveals an unknown world to him.

Unfortunately, metal particles, although called ferromagnetic, are not ferromagnetic in the full sense, since they cannot retain their resulting shape after the disappearance of the magnetic field. Because they do not have their own magnetization. In this regard, the use of this discovery, which, by the way, is not entirely new - it was made by the American Rosenzweig in the middle of the last century, has not found wide application.

How to make and where is ferromagnetic fluid used?

Ferrofluids are used in electronics and the automotive industry, and I would like to believe that their widespread use is not far off, and with the development of nanotechnology they will be used quite widely. In the meantime, this is mostly fun for the admiring public, spoiled by various types of spectacles.

Three-dimensional paintings make you watch them with bated breath, doubt whether this is a montage, and look for an explanation for what is happening, at least on the Internet. Who knows, maybe a little boy who today watches metallic “living” colors and figures with his mouth open will tomorrow find a fundamentally new application for this phenomenon, making a revolution in science and technology. But that’s tomorrow, but for now, watch and enjoy!

Tatyana Albertovna,
You are, of course, right - the ionic bond of the carboxyl group is stronger than the donor-acceptor bond of the amine. But in the latter case, the electronic structure of the surface layer of the particle is less disrupted, which is especially important for nanoobjects (with decreasing size, the proportion of atoms on the surface increases). Ethanolamines should not stabilize magnetite, because 1) a small molecule, the steric factor is insufficient 2) hydrophilic, does not interfere with the contact of the particle with water (and dissolved oxygen). Still, oleylamine can be an interesting stabilizer (or a mixture with olein). The question is off topic: have you tried producing magnetite (first stage, coprecipitation) in a magnetic field? There should be something ordered (sticks, for example) :))
Vladimir Vladimirovich,
According to the literature, Fe(III) can oxidize unsaturated fatty acids. In other words, with the help of oleic acid, hematite can be converted into magnetite. Here's a funny one (just for Angelina Valerievna:)

Alexander Borisovich, I absolutely agree with you about ethanolamines.
I tried to use them to stabilize magnetite 20 years ago, when approaches to the synthesis of magnetic fluids were just being explored. Attempts to create stable colloidal systems were accompanied by a constant search for something new. Without mistakes, even obvious ones from a theoretical point of view, there will never be results or understanding.

...the ionic bond of the carboxyl group is stronger than the donor-acceptor bond of the amine. But in the latter case, the electronic structure of the surface layer of the particle is less disrupted, which is especially important for nanoobjects...
What is important for us, first of all, is the energy of adsorption interaction. As I understand it, the greater the energy, the greater the changes in the electronic structure of the surface layer as a result of chemisorption, and vice versa. Everything is logical. Question: are such changes negative for magnetite particles with an average diameter of 10 nm? Or vice versa. Just in this case, changes in the electronic structure of the surface layer as a consequence of chemisorption make adsorption interactions even stronger, and therefore only help solve one of the primary tasks in the synthesis of MFs - stabilization of dispersed phase particles.

Still, oleylamine may be an interesting object (or a mixture with olein).
If there is an opportunity, we will definitely try it.

In other words, with the help of oleic acid, hematite can be converted into magnetite.
It turns out interesting. For magnetite stabilized by a surfactant, we obtain a ratio of 2- and 3-valent iron of 1:8. This is no longer magnetite!?
And if we adsorb oleic acid on hematite particles, will we get true magnetite?

It's been 52 years since NASA employee Steve Papell invented ferrofluid. He was solving a very specific problem: how, under conditions of weightlessness, to force the liquid in the rocket’s fuel tank to approach the hole from which the pump pumped fuel into the combustion chamber. It was then that Papell came up with a non-trivial solution - adding some kind of magnetic substance to the fuel in order to control the movement of fuel in the tank using an external magnet. This is how ferromagnetic liquid was born.

Papell used magnetite (Fe 3 O 4) as a magnetic substance, which he crushed using a special technology (ground in a mixture with oleic acid) for many days. The result was a stable colloidal suspension in which tiny particles of magnetite 0.1-0.2 microns in size stably existed. Oleic acid in this system played the role of a surface modifier, which prevented magnetite particles from sticking together. S. Papella's patent US 3215572 A (Low viscosity magnetic fluid obtained by the colloidal suspension of magnetic particles) is open and can be viewed on the Internet. The classic composition of a ferromagnetic fluid is 5% (by volume) magnetic particles, 10% surface modifier (oleic, citric or polyacrylic acid, etc.). The rest is organic solvent, including liquid oils.

Interest in magnetic fluids has revived in recent years, and today they have already found many applications. If you apply such a liquid to a neodymium magnet, the magnet will slide over the surface with minimal resistance, that is, friction will sharply decrease. Radio-absorbing coatings for aircraft are made in the USA based on ferromagnetic fluid. And the creators of the famous Ferrari use magnetorheological fluid in the car’s suspension: by manipulating the magnet, the driver can make the suspension harder or softer at any time. And these are just a few examples.

Magnetic fluid is an amazing material. Once you place it in a magnetic field, the scattered magnetic particles unite and line up along the field lines, turning into a completely solid substance. Today, tricks with magnetic fluid, which upon contact with a magnet turns into hedgehogs or cacti that are impeccable in terms of symmetry, are shown on many entertainment shows. Of course, you can buy ferromagnetic fluid, but it’s much more interesting to make it yourself.

We wrote about how to obtain a self-hardening magnetic fluid, which will allow you to examine the structures formed by magnetic particles under a microscope (“Chemistry and Life”, 2015, No. 11). And here is another recipe for a homemade ferromagnetic fluid. Take 50 ml of laser printer toner. This powder consists of at least 40% magnetite, the particle size of which is 10 nanometers or less. The toner also necessarily contains a surface modifier so that the nanoparticles do not stick together. Add 30 ml of vegetable oil (two tablespoons) to 50 ml of toner and mix thoroughly, sparing no time in this process. The result will be a black homogeneous liquid, similar to sour cream. Now pour it into a flat glass container with sides so that the layer thickness is at least a centimeter. Place a magnet under the bottom of the container, and a hard hedgehog will immediately appear in the liquid at this point. It can be moved using a magnet. If you bring a magnet to the surface of the liquid or from the side, the liquid will literally jump out towards the magnet, so be careful. To avoid this problem, you can place the magnetic fluid in a small glass conical flask, filling it halfway or a little less. Tilt the flask to create a layer of liquid along the side of the flask and hold the magnet close to the glass.

Success depends on the strength of the magnet (a small neodymium magnet can be purchased in stores) and the quality of the toner. In the latter case, you need to be sure that it contains magnetic powder.

The toners found in printer cartridges have interesting magnetic properties that you can experiment with at your leisure. The effect they produce is very interesting, because the liquid begins to be drawn towards the magnet, and moreover, individual elements form bizarre geometric shapes. True, not all toners are suitable for repeating this step-by-step instructions. Only dark-colored toners will be needed, since color toners are made without the use of dark magnetic particles.

Materials

To make magnetic fluid with your own hands, you will need:

• thick sheet of paper;
• protective gloves;
• protective mask;
• empty glass cup;
• plastic sticker for stirring;
• vegetable oil;
• spoon;
• a wide plastic container, such as a plate.

Step 1. Very carefully open the cartridge to pour the toner from it into a glass cup. In total you will need about 50 mm of liquid. To check whether the liquid you have chosen has magnetic properties, just run a magnet along the wall of the glass. If it is activated, the experiment can continue.

The toner liquid is not harmful to your health unless you inhale or drink it. That is why you need to wear protective gloves and a mask before doing this work. This way you will reduce the likelihood of poisoning if liquid accidentally gets on your hands.

Step 2. To the volume of goods you have already received, you need to add two tablespoons of vegetable oil. Using a plastic sticker, thoroughly mix the mixture you received. To continue the experiment, it must be homogeneous.

Step 3. You need to carefully pour the resulting magnetic fluid into a wide container. This is exactly what is needed to see everything that will happen to the resulting magnetic fluid.

Apply a magnet from the bottom of the plate to the outside. Pay attention to what is happening inside the container. At the point of contact of the magnet, the liquid should be collected in a voluminous tubercle in the shape of a hedgehog. These are the magnetic particles that manufacturers add to the toner. They can be smaller or larger, which again depends on the manufacturer.

Step 4. With this liquid you can make a magnetic pattern. To do this, you need to pour some of the liquid onto thick paper and hold a magnet on the back side. By moving it from side to side, you will draw.

If you stain any objects or furniture with toner, rinse everything off with cold water, you should be able to do this without any problems. Under no circumstances should you use hot water; it will fix the pigment and make it impossible to wash it out.

Have you ever seen magnetic fluid? It looks like liquid metal and expands with needles if you bring a magnet to it. Here you will find instructions on how to make ferromagnetic liquid with your own hands at home.

The theory is this: modern laser printers contain the mineral magnetite (Fe3O4). It is needed so that the paint particles stick to the paper. This mineral reacts to magnetic fields and is thus well suited for our experiment.

Step 1: Materials

• Protective gloves
• Protective mask
• Glass measuring cup
• Cartridge (old) from a printer or copier
• Stirring stick
• Small container and piece of paper
• Strong neodymium magnet

Step 2: Collect Toner

Carefully pour the toner from the cartridge into a glass cup. You need about 50 ml.
Run a magnet across the OUTSIDE OF THE CUP to make sure the toner is magnetic.

Be careful: The toner is relatively safe as long as you don't inhale or drink it, but it does spray very easily and creates a lot of mess, so wear protective gloves and a mask.

Step 3: Add Oil

Add two tablespoons of oil.

Step 4: Stir

Stir until the liquid becomes completely homogeneous.

Step 5: Magnet Reaction

1. Pour some liquid into a small container.
2. Place a magnet under the bottom of the container
3. The liquid will begin to expand!

If the result does not look like what you see in the photo, then there is most likely a problem with the toner. Some brands contain more or less magnetic components. You can also try adding a little more oil, or vice versa, removing it. Some brands do not contain ferrofluid at all - then you will need to find another cartridge.

Step 6: Magic Ink

1. Now pour some magnetic fluid onto the paper
2. Move the magnet under the paper
3. You get “magnetic drawings”!

If you stain everything around with toner, use a vacuum cleaner to clean or rinse with cold water. Do not use hot water or rub areas that are stained with toner - this may cause the toner to rub into the surface permanently.