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Homemade Ferrofluid

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Part Scavenger
Mon Feb 27 2006, 03:25AM Print View
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 661
OK, I tried Andrew's ferrofluid tutorial and I've got some problems. I created the ferrous chloride from the ferric chloride and that part looks right. I was very careful with my measurements, I don't know if that has to do with anything. Here's what happened:

After I combined the ferrous choloride and the ferric chloride, I was supposed to add ammonia which was supposed to create magnetite which I was expecting to be black. In my first batch I never saw any black that I can remember, just looked like VERY iron rich water(rusty). Nobody on the net had pics of this stage, so I thought maybe that was normal and as I evaporated the ammonia it would change to black. So, I was supposed to cook it down until the ammonia smell went away, but after the ammonia had all dissolved in the red sludge, there was no smell any more even after heating. I have since learned that this red sludge is ferric hydroxide?

Starting over again, I was able to create black(magnetite?) by adding the ammonia to the ferrous/ferric chloride solution, but it turned red as soon as I saw a little trace of it. This is not what is supposed to happen right?

It might be important to note that I am using olive oil instead of oleic acid, but that doesn't seem to be the problem. I was able to finally work some ferrofluid out of the "ruined" batches by adding ammonia after the mixture was covered in kerosene( the carrier) and then boiling it(which was not recommended). I also now had the ammonia smell and I boiled it until it was gone. This resulted in ferrofluid that works, but no spikes and it gets clumpy, but it does slide around and follow a magnet. I think this (clumping) is because my particles are too big and I think that's because I didn't succeed with the initial precipitation. But, the olive oil in place of the oleic acid seemed to work fine.

Thanks
-Part Scavenger
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Michael W.
Mon Feb 27 2006, 04:07AM
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Location: Vernon, B.C, Canada
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I made it at school with exact molar solutions and it took two tries to get it to work and even then it wasn't very spectacular....
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Part Scavenger
Mon Feb 27 2006, 04:27AM
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 661
Although any input would be greatly appreciated, I think I found the answer to the "red" problem. It seems that you need to add the ammonia over a period of several minutes, stirring, and this yields and initial "red" solution that is eventually overcome by the magnetite precipitate. I'll try that Tues if I've got time. I just slowly poured it in there while stirring. I finally found a pic, their precipitate looked really nice, black and orderly. Their product looked quite a bit better than mine too due to small particles. Maybe this will give me what I want...
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Nik
Mon Feb 27 2006, 05:34AM
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Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
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My girlfriend has been attempting ferrofluid for a few days now and has been getting better and better results. I will talk to her tomorro and find out if she has any tips on making it work.
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Part Scavenger
Mon Feb 27 2006, 03:57PM
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
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That'd be great! Wow, a girl who actually knows what ferrofluid is. Lucky!
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Bored Chemist
Mon Feb 27 2006, 06:19PM
Registered Member #193
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Location: sheffield
Posts: 912
Olive oil really isn't the same as oleic acid. It may work, but I somehow doubt it.
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Part Scavenger
Mon Feb 27 2006, 06:56PM
Registered Member #79
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I know. It's 83% oleic acid according to my friend who is a chem teacher and a pharmacist I talked to. She said to go ahead and try it. I don't think that's the problem (at least not yet). The the crappy ferrofluid I got after I added ammonia to the "finished" batch and boiled was attached just fine to the kerosene. I made one batch without the oil to see if it was interfering with the ammonia thing, and the kerosene behaved completely differenty(It just floated on top). Duh, I know, but I was testing something and just went ahead and poured in the kerosene to see what would happen.
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robert
Mon Feb 27 2006, 07:58PM
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Not quite, ist a glycerin ester of oleic acid (and others).
The fact that ist a ester and not the free acid makes a huge difference.
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Part Scavenger
Tue Feb 28 2006, 01:57AM
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 661
Huh. Didn't know that. Can I get the oleic out? I'm having trouble finding it in my area. BTW I'd prefer not to do it this way: (They said it's from the middle ages or something)

"To procure oleic acid, treat oil of bitter almonds with caustic potash, and to the soap formed add hydrochloric acid; this separates the oleic and other acids. To the decomposed mixture add about half its weight of oxide of lead, and digest for 2 or 3 hours, at a temperature of 100° C. (212° F.), by which means oleates of the fatty acids are formed. Ether is now added, which dissolves only the oleate of lead; the ethereal solution is mixed with an equal volume of water, to which hydrochloric acid is added as long as is required for decomposition, and the mixture is then well shaken. The ether rises to the surface, holding the oleic acid in solution; decant it and distill it off; there remains a compound of pure oleic acid with oxidized acid. By subjecting this compound to a temperature of about -7.2° C. (19° F.), the pure crystals of oleic acid form, while the oxidized acid remains in solution. "

EDIT+> Are you getting the idea I don't know much about chemistry? Learning more about the oleic acid in olive oil... Only 1% of extra virgin olive oil is free oleic acid, oleic acid still makes up 83% of olive oil, but like robert said, it's the ester and it's tied up in there somehow. Rancid olive oil is up to 24% free oleic acid. Oleic acid can be made from olive oil supposedly easily, but I've yet to find the answer on the internet. Everybody just seems to know how to do it. This much I know: something about HCl, mix it in making sure the solution is acidic, add kerosene? Something about purifying the mixture with the crap you just poured off and something about carboxylic acids. I guess, I don't know, it's kind of put together at this moment. I know it can't be hard to make, people have been making soap with it since dirt apparently. But I can't stand to buy it it's kinda expensive for the 5mL I need. Maybe I need to talk to Granny Clampett...

Another Edit+> Over at the chem fourms, someone suggested filtering the finished ferrofluid with filter paper. According to him, he's made "spikey" ferro-fluid at home and this is the only way to make it work. He says "any magnetite that doesn't have a death grip on the oleic acid is gonna make your ferrofluid clump and cause a mess in your container" Something to that effect.
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Heiders
Tue Feb 28 2006, 03:05AM
Registered Member #268
Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48
I am "the gf who knows what ferrofluid is" and I have managed to purchase some real oleic acid from chemistrystore.com and have far more than I can ever use. If you would like, I can sell you some. However:

I had the same problem, the magnetite didn't react. I ended up getting ferrous chloride crystals from my ever-helpful chemistry teacher. With some math, I made up a 1.5M solution and added it to the ferric in the appropriate amounts (2:1).

I did some more research and found another way to make ferrofluid, but some of the basic reactions are the same. It is a .pdf, and can be found here. (chem.wisc.edu) When I added the ammonia, it turned black, but with stirring disappeared. I ended up added about 100mL extra - VERY slowly - to completely react it all. It turned out really dark, but surprisingly brown and not black, however I ran out of time to finish it that night.

The next day the extra ammonia had separated and was sitting on top. I poured off the ammonia and cooked the remainder, but it all clumped into a blob in the middle surrounded by what looked like water with a yellowish tinge. I dont know whether this was supposed to happen or a result of from overcooking or too much/not enough oleic... Any ideas?

After pouring the "water" off, I added the kerosene, which made about 97% of the clumps break up. This solution was kind of responsive to the magnet, but settled a bit overnight. No spikes yet though!

Good luck with yours.
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Part Scavenger
Tue Feb 28 2006, 03:22AM
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 661
Thanks for replying!
Do you have a sis?

Nah, um, have you seen this? A couple of people on there seem to know what they're doing. The "Caver" guy claims to have make "spikey" ferrofluid at home, and recommends filtering the homemade ferrofluid.

Have you tried the tetra..whatever hydroxide as a carrier? I saw another couple of sites use it. Several places said the amount of carrier fluid was important to spikes. How do you know what this is? Is it just what sticks to the magnetite or if you have too much is that bad?

Oh, and thanks for the pdf! I haven't seen that one yet. I wonder what the ONE DROP or less does to enhance the spikes...
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...
Tue Feb 28 2006, 03:27AM
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2374
welcome to the forum!

Here is a lab procedure for making it... There are a few diagrams there, and the procedure seems simpler; might be worth a try...

Good Luck!
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Heiders
Tue Feb 28 2006, 04:26AM
Registered Member #268
Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48
Two sisters, both taken.

First I've seen of that thread. Thanks! No, I haven't used that tetra-something hydroxide as a carrier.

I actually split the latest batch into 2 parts, separated before cooking. After cooking, I added the amount of kerosene called for in the instructions to one portion. Results: Just blobby on the sides, no spikes.

To the second, I added about 25mL of kerosene, instead of 100mL. There were more clumps left, but I'm going to filter it now. What amounts have you tried?

What are you using to hold it? I have it in a not-very-watertight glass spice jar with some electrical tape. I'm wondering if it is too thick (either glass or fluid) to respond to the magnet properly, though I can drag it up the side no problem. I might be able to get a petri dish from the previously-mentioned chem teacher... Might that help?

I used lemon-scented yellow ammonia. What did you use? The thread you referenced said "no colours or scents" so I'm not sure.

Yes, I have seen the procedure from UCLA but it used a different surfactant. I'm not too sure whether rinsing it will work, and/or how much you lose per rinse. Could be interesting to see where to get the tetramethylammonium hydroxide and ammonium hydroxide, though. Good stuff.
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Mike
Tue Feb 28 2006, 05:59AM
Registered Member #58
Joined: Thu Feb 09 2006, 05:40AM
Location: Tri-Cities, Washington, US
Posts: 317
Well regular ammonia is in many household cleaners, however ammonium hydroxide (NH4OH) is in many Industrial Cleaners. However there is no need to search for these. Ammonium Hydroxide has the ability to dissociate in water so, NH3 + H2O ⇌ NH4+ + OH-
It is the name given to an aqueous solution of Ammonia. So you should be able to create your own.
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Bored Chemist
Tue Feb 28 2006, 06:18PM
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 912
"I know. It's 83% oleic acid according to my friend who is a chem teacher and a pharmacist I talked to."
This is true in the same way that salt is about 64%chlorine- that doesn't mean that roughly 2/3 of it escapes from the salt cellar as a green gas.

I wouldn't do all the messing about with lead compounds as given in that article (There are errors in it anyway). Since all you need is a surfactant then the mixture of fatty acids from olive oil would probably do. If you want I will sort out a method for getting this.

Ammonium hydroxide very nearly doesn't exist. ammonia disolves in water- very little of it get's ionised.
I'm not sure about getting hold of quaternary ammonium compounds - a few get used as bactericides and IIRC "bitrex"- the denaturant used in some alcohol is another example. That's no guarantee that they would work in this case.
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Part Scavenger
Tue Feb 28 2006, 06:48PM
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 661
I wasn't planning on messing with that lead stuff anyway, but thanks for the concern. You're right about the oleic acid in the olive oil, but couldn't I "pull it out"? I plan to look into the soapmaking stuff, apparently you can add HCl to olive oil and do something else to get the pure-ish oleic acid. I borrowed a book from my chem friend today that I believe will tell me how to do it, but I won't have time to do anything with it until Friday probably. Am I headed the right direction with the HCl and soapmaking process?




UPDATE: Ok, I think I figured it out. Here's what I plan to do:

1 Hydrolyze the olive oil using HCl in the form of muratic acid.
2. Ok, so now I’ve got excess HCl, glycerol, and fatty acids most of which are oleic acid carboxylic chains?
3. Then how do I get rid of everything except the fatty acids? Do they just dissolve in the water and pour off? This seems right because glycerol is soluble in water, as is HCl. That would mean I now have a mixture of carboxylic acids that is something like 83% oleic acid and a couple of other fatty acids that look like they’d do the same job.

Water is needed for hydrolysis, but do I need to add any because that's what muratic acid is already, right? Still I might need to add water?

And how do I figure out how much of each I need? I know it has to do with the molecular weight and the ratio of the way they bond, but VOLUME doesn’t seem to matter. It has to do with the concentration. Can I just dump it together? The “extra” stuff would be all soluable in water I think, so it should just pour off right? That way I wouldn’t have to do titration to figure out the amounts I need.



In response to Heidi, I think I'm getting the same stuff you are. Your description is almost exactly the same as mine looks.

I'm using super-grande, bottom of the shelf, good old sinus openin' ammonia. I read to buy it cheap because scents and flavors(or lack thereof) could interfere. That's good for me because my family uses the cheapest they sell.

I'm holding it in a glass baby-food jar, but it coats the inside with a black mess. It doesn't do that in a peanut butter jar though. I guess it likes the glass. I don't figure that that would happen as much if the ferrofluid was made properly, but I've never had the real stuff, so I don't know. I didn't keep it in there because one time I left acetone in a PB like jar... Didn't know about kerosene.

I filtered it last night through some T-shirt (redneck filter paper), and it got much smoother, still no spikes. Keep in mind I made this ferrofluid the horribly wrong way, so it might not reflect your results. I plan to make a new batch asaic.

Kerosene. Um, 100mL and "dump it in and see"

Off to take a speech test... Yippie. Sigh... I can't wait to take micro or something stimulating.


ANOTHER UPDATE: After my speech test, I ran to the shop to get my notes for my Philosophy test. While I was there I poured some muratic acid, and distilled water into some olive oil and swirled it up. At first I thought nothing was happening, but then the bubbles on the bottom of the olive oil started puffing into the water/HCl below. After letting it settle, I now have three layers. One is the bottom watery layer, a opaque-ish pee yellow thick substance, and a translucent or clear (haven't decided, it hasn't completely settled out.)

I'm pretty sure the middle layer is fatty acids, the bottom is the water and the other stuff, and heck if I know what the top layer is. (getting clearer) It's thin, but not quite as thin as water. Glycerin/glycerol? Got me. I thought that stuff would dissolve in the bottom layer. Anybody know? Is the yellow stuff what I think it is?

Oh, and the yellow stuff is pretty smooth and opaque. The original olive oil was slightly greenish and transparent. It did something!

Be back after my other test...


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Bored Chemist
Wed Mar 01 2006, 07:52PM
Registered Member #193
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Acid hydrolysis of the oil will work but it's slow.
If you have a book on soapmaking that's a good start. Make soap from some olive oil- no colour no perfumes of course.
Most soap making methods I have seen add lots of salt to the hydrolysed fat to precipitate the soap. Don't bother with that- just add the HCl at that point. The oleic (and other) acids will come out of solution- they don't disolve in water. You can tell when you have enough acid because when all the soap is used up the stuff isn't bubbly any more (well it's a lot less bubbly). Pure oleic acid is liquid at room temp so cool the resulting mess in the fridge (if it settles out into 2 layers then it's the top stuff you want. You may be able to pour it off and save fridge space) filter it quickly- paper towels usually work quite well. The next thing is to wash it to get rid of other junk- HCl glycerine etc so mix it with hot water. It should settle down into 2 layers; again you want the top one. The easy way to get this is to put it in a screw top jar, turn it upside down then put it back in the fridge. The acid goes solid so you can open the jar and let the water out (from under it). That should give you a fairly clean sample of oleic acid. The biggest impurity in it will be water (which doesn't really matter here).
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Part Scavenger
Thu Mar 02 2006, 01:33AM
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Thank You!!! I really appreciate it! I will try it as soon as I can. I love this forum.
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Omicron
Thu Mar 02 2006, 02:10AM
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Why not just buy it? Its pretty cheap, and I have made ferrofluid before try using a technical grade oleic acid.
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Heiders
Thu Mar 02 2006, 04:01AM
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Posts: 48
It's not cheap! I paid about $40 CDN for 1 gal (about 4L) and couldn't get a smaller size. *edit* I was referring to oleic here, sorry. I thought you were too! */edit*

Great layers Part Scavenger! I have a waste jar because I'm not too sure what I can pour down my drain, it has layers like that from all the crap I poured in there. It's neat.

Also: I respect you for wanting the fun of making your own oleic. Good luck *laughs*

I am attempting to filter mine through proper filer paper, but im losing so much to the paper and the rest to evaporation, it has been sitting 48hrs now (laziness and lack of chance to get at it again, but I checked it before school this AM) and still isnt all the way filtered. I did cover the whole unit with plastic wrap and it's in a cool dark area to limit evaporation, but still.

I'm going to transfer it to a new filter paper and see what happens.

Mostly I have seen ammonia as blue (windex) or yellow (household cleaner). What colour is it really? Clear? Google was unhelpful...
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Part Scavenger
Thu Mar 02 2006, 04:10AM
Registered Member #79
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Mine's clear. That's all I've ever seen my mom buy.

About the filter paper, I wonder what that guy was using. I had similar problems (although I didn't have any "filter paper") but he says it "flowed right through." I hope to try all this stuff out on friday. I will by Sunday or it's gonna kill me.
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Omicron
Fri Mar 03 2006, 02:05AM
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$40 CND that’s about $50 USD and for a gal that’s cheap, United Nuclear wants $15 for 30 ml. Where did you get yours? What was the quality like?
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Michael W.
Fri Mar 03 2006, 02:40AM
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I do believe there talking about oleic acid, not ferrofluid....
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Chris
Fri Mar 03 2006, 08:28PM
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Has anyone tried forming magnetite from the FeCl2/FeCl3 solution with sodium hydroxide? It should work with any base, and a faster reaction with stronger solution should yield smaller (better) particles. The ammonia is not important until it comes time to coat the magnetite with oleic acid, so forming the magnetite first with sodium hydroxide and then adding ammonia should be a far better method.
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Part Scavenger
Sun Mar 05 2006, 01:55AM
Registered Member #79
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Cool. I'll try that. I didn't get a chance to work on anything today or yesterday. But Sunday I have time. Yeah! I'll see what that does. I have noticed that the olive oil/HCL combo I left sitting on my desk the last several days has changed. The "big yellow layer" has almost completely turned into the "little layer above the yellow" I guess this is what Bored Chemist meant by "It would take forever." My chem friend also pointed out that too much HCl could mess up the resulting oleic acid if done this way, so I'll just pitch the stuff sitting on my desk and go for BC's method.
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Carbon_Rod
Sun Mar 05 2006, 03:05AM
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Suspension of material in water needs a surfactant no matter what:
2FeCl3 + FeCl2 + 8NH3 + 4H2O -> Fe3O4 + 8NH4CL

Oleic acid C17H33COOH is somewhat easily confused with linoleic acid C17H31COOH. However, tetramethylammonium hydroxide N(CH3)4OH is known to work well as a surfactant for this process. IIRC it is pretty toxic so look at the MSDS.

Have fun,
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Chris
Sun Mar 05 2006, 03:54AM
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Suspension of material in water needs a surfactant no matter what:
2FeCl3 + FeCl2 + 8NH3 + 4H2O -> Fe3O4 + 8NH4CL

What do you mean here? That reaction doesn't have anything to do with the surfactant, which is oleic acid.

Anyway, the Fe3O4 can be added from any source to the surfactant, which uses ammonia to break it down and bond it to the magnetite. I quote from Andrew's website:
THE OLEIC ACID REACTS WITH THE AMMONIA TO FORM AMMONIUM OLEATE, A SLIGHTLY SOLUBLE SOAP. THE HEAT CAUSES THE AMMONIUM OLEATE TO BREAK DOWN, AND THE OLEATE ION ENTERS SOLUTION WHILE THE AMMONIA ESCAPES AS A GAS. THE OLEATE ION ATTACHES TO A MAGNETITE PARTICLE, AND IS RECONVERTED TO OLEIC ACID.

I simply propose the magnetite be formed first using this reaction below, since no one seems to be able to get the reaction above to work at all, and they get poor results when it does (probably because a fast reaction will form smaller particles before larger crystals can form, which is necessary to get spiking, and household ammonia is only 5%-10% NH4OH, plus other additives).

2FeCl3 + FeCl2 + 8NaOH => Fe3O4 + 8NaCl + 4H2O

Once the magnetite is formed here, ammonia and oleic acid would be added in to coat the particles as described above.

It's a rather common idea that "homemade ferrofluid will not spike" or "homemade ferrofluid is not as good as 'real' ferrofluid" but is there some real reason for this? If people who have been attempting to make it at home are getting poor results, obviously we have been doing it wrong. Surely there is nothing magical about making "real" ferrofluid and it's a process that can be replicated. Trying to get the magnetite to precipitate out quickly and uniformly with a small particle size is the first step in trying to produce a quality fluid - commercial ferrofluids are actually available with a variety of particle sizes, where all the home attempts so far seem to have trouble even getting particles to precipitate, much less out of a clear solution.

It might we worth looking into other carrier solvents as well, with different viscosities and surface tension than kerosene. Also has anyone started with anhydrous or a better grade of FeCl3? The PCB etchant you buy could contain additives that interfere. Steel wool is a rather dirty source of iron for the FeCl2 as well, how about washed scrap iron turnings (yes probably a little slow to react) or pure iron powder?

I think I will try the NaOH magnetite sythesis when I go home next weekend for spring break if no one else has tried it by then, just to see how well it works (but I won't be able to get any farther than that because I don't have any oleic acid now ).
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Part Scavenger
Sun Mar 05 2006, 06:06PM
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Here's another useful link I found:

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Chris
Sun Mar 05 2006, 06:36PM
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Location: Harlowton, MT, United States
Posts: 213
Cool. That's an aqueous based ferrofluid rather than a non-polar solvent, but the idea remains similar. Look at it spike beautifully too! Again the Fe3O4 synthesis itself should work with about any hydroxide, but I see an acidic solution must be what everyone has been missing, and why iron hydroxide was formed. But, umm, what keeps a side reaction between ammonia and HCl from occurring? They can react to form NH4Cl if it doesn't react with the iron chlorides first.
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Carbon_Rod
Mon Mar 06 2006, 01:14AM
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
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Posts: 1009
Chris, I think you know what I meant. ;op

Here is some low yield crud holding a magnet showing creep. I would say about 2/3 of the probable yield was lost because it was made a little differently.

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