Sciencemadness Discussion Board

Failed Experiments with Ferrofluids

jtalmodovar26 - 1-1-2011 at 19:57

Hey , I'm new to this forum (And Amateur chemistry in general)
Not sure if this is in the wrong forum :(:o
For my Science fair project for school I was going to change the surfactant in Ferrofluids (Ferrofluids being a dispersement of tiny magnetite nano-particles in a carrier fluid with the surfactant sort of encasing it ; The ferrofluid is basically a liquid where when a magnetic field is introduced ton's of hardish spikes pop up). Due to tons of stuff my project failed (I only produced one batch that worked and the spikes were way to small to be measured).
I've learned only one thing from this project ; If you need ferrofluids ; Buy It. At least in my experience it's a hassle to make.

Making the Magnetite actually wasn't hard (You combine 5ml of Iron (III) Chloride solution and 1ml of Iron (II) Chloride ; Then you just add 50ml of Ammonium hydroxide while it's in a magnetic stirrer).
But, then the hard part was filtering out excess liquids and then just filtering it several times to get pure magnetite . :mad:

Sedit - 1-1-2011 at 20:39

I have considered this experiment many times just never put it into practice.

Since it sounds as if you are dealing with alot of loss or lost time in the filtering process perhaps attempt to decant the liquid first and then follow this with a filter or perhaps a wash or two.

jtalmodovar26 - 1-1-2011 at 20:58

That's what I did. Because the magnetite is (Duh) Magnetic . I placed a Magnet under the solution for a few minutes. The solution separates quite nicely. Either way it does still take awhile for it to filters. The real problem is that once it''s been filtered you need to get the magnetite out from the filter paper using a wash bottle. At least in my run of the experiment the magnetite was extremely sticky and was ingrained to the paper.

I definitely think I will do this Experiment later on down the road on my own time (I had to use the Lab at my High School So, It was on borrowed time) and Without the pressure of Science Fair Breathing down my neck :P

nitric - 1-1-2011 at 23:53

What kind of filter did you use, gravity filter or buchner filter, as a buchner would have saved time if you were filtering a thick magnetite solution as it would have partially dried some of the magnetite and would have less product in contact with the paper. The magnetite was so "sticky" due to the fact that it was percipitated out, so it was such an extremely fine powder that a lot of it likely embedded in the paper.

Sedit - 2-1-2011 at 10:31

Be sure to pre-wet your filter paper first as this will stop the particals from clogging up the filter thru capilary suction.

Would it not be possible to wash it with acetone or something simular to remove the last of the water and allow it to dry quickly?

jtalmodovar26 - 2-1-2011 at 12:07

Nitric - I used a Gravity filter (Is that like a normal filter (I'm New))
Sedit - I did but now looking back I only put enough for it to keep and "Stick" to the Funnel. I feel really dumb for not even thinking about using something like acetone to get rid of the excess water :o

In Retrospect I should've gone to you guys before I started or officially ended my sciencefair project :(

nitric - 2-1-2011 at 12:25

Quote: Originally posted by jtalmodovar26  
Nitric - I used a Gravity filter (Is that like a normal filter (I'm New))
Sedit - I did but now looking back I only put enough for it to keep and "Stick" to the Funnel. I feel really dumb for not even thinking about using something like acetone to get rid of the excess water :o

In Retrospect I should've gone to you guys before I started or officially ended my sciencefair project :(


a Buchner Funnel is a funnel that is used when you usually want to keep the solid in the liquid, and is much faster than a gravity filter, and washing your product with some low boiling solvent that forms a azetrope with water like sedit said would help a lot (acetone, iPrOH, EtOH)

[Edited on 2-1-2011 by nitric]

jtalmodovar26 - 2-1-2011 at 12:27

That makes sense now. Thanks!

Twospoons - 2-1-2011 at 14:35

I've been interested in ferrofluids for a while. I seem to recall reading somewhere that you don't want to let the magnetite dry out, otherwise the particles will clump and you wont be able to suspend them later on. So its better to settle and decant than filter. Then add the surfactant to the wet magnetite.
If you are trying to separate from other trash, put the magnet at the side of the beaker, instead of on the bottom. You end up with crap on the bottom, magnetite on the side.

jtalmodovar26 - 2-1-2011 at 18:13

That is true . Thanks to my own Noobishness to chemistry in general. I came back a few hours later to find the magnetite caught in the filter flaking and making a really weird grid formation from drying (The thing looked like a circuitboard).