pichoro - 11-6-2014 at 20:07
So I'm currently attempting to prepare some ferrofluid with an advanced high school chemistry class meeting for a few weeks over the summer, and have
run into a couple of issues.
First, the procedure in brief:
Prepare and combine 4 mL of 1M Iron(III) Chloride solution and 1 mL of 2M Iron(II) Chloride solution.
Add 50 mL of 0.5M Ammonium Hydroxide dropwise while stirring to form Magnetite nanoparticles.
Concentrate Magnetite in bottom of flask with a strong magnet, decant, and rinse multiple times with distilled water.
Add 1 mL of 25% Tetramethylammonium Hydroxide solution to stabilize.
I've run into two matters I wish to seek comment on.
First off, I've tried this several times with mixed results. After a failed first attempt, I had success and got a spiking ferrofluid. I had success
a couple of more times, and then I've not been successful since. My first attempt was two years ago, and I'm using the same bottle of
tetramethylammonium hydroxide. I'm concerned about the shelf-life, and if it can go bad. There is definitely some sediment in it now, but I didn't
pay enough attention when I got it to see if there was sediment then. So, does anyone know if this stuff has a short shelf-life? Google has not been
helpful with this question.
Second, ferric chloride. I thought I was going to leave the Iron(III) chloride solution sit over night yesterday and come back to it today and
continue the process, only to learn that iron(III) ions undergo a reaction that causes the solution to become acidic, and they form a polymer of
sorts. This was explained very hastily to me by an instructor-turned-colleague who is far more knowledgable than myself. However, I've gotten home,
and have found I have more questions and holes in my understanding of this than I realized at the time. I won't be back there for a couple days, and
in the meantime, have failed to find anything helpful using google. Does anyone know of any good resources or have some insight into this process?
I'm really kind of curious about the polymer, as I intend to talk to this group of students about polymers later on in the summer.
Thanks in advance!
IrC - 11-6-2014 at 22:37
I don't remember the site as it was a long time ago but I remember reading a very good writeup on the subject of ferric chloride chemistry. It was
about etching circuit boards so even though I cannot give a link at least I can suggest you search the subject of etchant chemistry. It was very
thorough and covered the HCl formation. Hopefully using this search term will help. If I have time this week I'll try to retrace my steps even if it
only exists on wayback and post a link.
CHRIS25 - 11-6-2014 at 23:33
Decomposition:
Paragraph 12 ....exposed to
air....https://snf.stanford.edu/SNF/materials-and-chemicals/msds-std-chemicals/images-msds/tetramethylammonium-hydroxide-tmah
Product shelf life: http://www.hunan-chem.com/organic_chemicals/TDS_Tetramethyla...
FerroFluid:
The best ferrofluid video that I have ever found, (except for its lack of meticulous information on molarities and concentrations, very very good)
http://technyou.education.csiro.au/module/properties/page/11...
Extra Info basic quick and easy:
http://education.mrsec.wisc.edu/background/ferrofluid/index....