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I have a problem. I've been playing with ferrofluid, trying to make a display like pic related, but something weird happened. I filled a glass jar with 70% isopropyl alcohol (I read this would keep the ferrofluid from staining the glass), then added several drops of the ferrofluid. It worked perfectly at first, save for the isopropyl alcohol taking on a slight brown tinge. The ferrofluid behaved as you'd expect initially, but when I checked on the display a few weeks later, the ferrofluid had hardened into solid chunks of magnetite. The display was not in a magnetic field and the container was sealed. My chemistry is a bit rusty, but I think the isopropanol reacted with the carrier fluid in the ferrofluid, but I have no idea what or how. Help me understand, /sci/borgs.
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The carrier fluid is described as a "light hydrocarbon" in the MSDS, which most sources seem to interpret as mineral oil. The only list of light hydrocarbons I could find contained gases, so oil might be a good bet. I don't know what surfactant they used.
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>>7842456
Carrier fluid is oleic acid, OP shoulda just used water
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This is a guess ok so dont diss me for it.
You are, at a basic level making a battery by adding the alchohol. Thus there is anodic/cathodic reactions occuring even between minute particles. For me, that brown tinting is a classic sign of battery corrosion, its an indicator of same in electolyte. As I say, thats my SUGGESTION for it - i am no chemist. Dont shout at me !
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>>7842450
You likely dissolved either your solvent or surfactant in isopropyl alcohol.
Magnetite is almost as stable as rust, which is quite stable.
Try either water or oil and see what happens
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>>7842450
>I filled a glass jar with 70% isopropyl alcohol
>70%
That means there was about 30% water. And that water started the metal corrosion process.
>My chemistry is a bit rusty
Must ... resist ...
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>>7843566
I was thinking of some kind of oil, but what sort should I use? Is it safe to say this is the result of the surfactant dissolving and, thus, the nanoparticles agglomerating? Or could something have happened with the carrier?
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>>7843586
this
They make 99.9% pure alcohol, get it from janitorial supply companies.
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>>7844680
>already corroded
Could be a different form of oxide. Picture shows a black material, not red.
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I tried water again and it made a huge mess. The ferrofluid just floated on the surface. I tried pure ethanol and the outcome was somewhat better. Why would the behavior in water be so different from alcohol? Aren't they both polar solvents?
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>>7846101
It's still black. I don't think corrosion is the answer.
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>>7846115
Water is heavier than the ferrofluid and the ferrofluid is or closer to the ethanol in buoyancy.
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>>7844680
IIRC magnetite formally is Fe3O4 (ie. 1:1 mixed oxide Fe2O3 + FeO).
FeO can be further oxidized, yielding only magnetically inert Fe2O3 (red rust).
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>>7847973
It's still magnetic, it's just solid chunks instead of fluid.
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