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Neil
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Quote: Originally posted by AJKOER  | Caution, while the voluminous jelly substance is most definitely Al(OH)3, the white substance you saw could be an impurity from the Aluminum foil as
it is commercial grade Al, which is anywhere from 92% to 99% pure, or some alpha Al2O3, formed in a hardening process, which is not soluble in acids
or bases.
On impurities, we have mentioned Silicon, some foils have Fe for added strength, at times Mn, but would anyone believe a small amount of Lead (Pb
maybe country specific due to manufacturing process) as a possible impurity? See article reference below (I hope I am misreading).
"The effect of lead impurity on the DC-etching behaviour of aluminum foil for electrolytic capacitor usage" by W. Lina, , G. C. Tua,
C. F. Linb and Y. M. Pengb
a Institute of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan R.O.C., at Materials Research Laboratories,
Industrial Technology Research Institute, Hsinchu, Taiwan R.O.C.
Received 26 June 1995; revised 17 October 1995. Available online 16 February 1999.
"Abstract
The effects of lead impurity on the etched morphology of high purity aluminum foils for electrolytic capacitor
applications were investigated in this work. The lead impurity was either present in as-received aluminum foils or deposited purposely on the
foil surface through an immersion-reduction reaction. The amount and distribution of deposited lead varies with the lead content in as-received foil.
The as-received foil with higher lead content gave a higher concentration and a more uniform distribution of deposited lead."
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AJKOER
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Thanks Neil for the highlights.
I probably misread and now would say there maybe special purpose Al foils with added Pb, for example, for specific applications.
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IrC
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http://www.exo.net/~pauld/activities/AlAirBattery/alairbatte...
Using salt water has already been mentioned, but you could also power something while waiting for the reaction.
"Science is the belief in the ignorance of the experts" Richard Feynman
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blogfast25
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| Quote: Originally posted by AJKOER | Thanks Neil for the highlights.
I probably misread and now would say there maybe special purpose Al foils with added Pb, for example, for specific applications.
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Lead? In what is in all likelihood food grade Al foil? I think NOT!
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Bezaleel
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In all certainty food grade Al foil.
| Quote: Originally posted by Neil | In the first pictures it looks like there is more white material, a slime or gel?
Is it possible that some of the material was lost when you poured of the original liquid or during subsequent filtration/decantations?
I agree, the amount of material is to great. Ammonia is used in a number of anodizing mixtures for Al, is it possible it catylised the crystallization
of the aluminum hydroxide?
The oxide layer on the foil may have been thick enough to provide seed crystals.
Did you happen to handle the foil with your bare hands before it was added to the ammonia? |
No material was lost when I poured off the liquid, as it stuck a bit to the walls of the flask. It was a very thin layer, that broke into many pieces,
when I shook the flash after I added the HCl solution. In the 3rd pic you see the broken pieces of what grew on the flask walls in the 1st pic.
This is of course food grade Al foil, and I tore off a piece from the role by hand (so there are human lipids on it for sure).
The original question in this thread was a method to produce pure Al2O3. It seems, putting pieces of household Al foil in ammonia is a possible though
slow method. An interesting test might me to see whether the reaction speeds up when refluxing the ammonia.
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Neil
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Toss in a chloride to speed it up.
It would be interesting to see if it reacts without any salt/oil contamination from ones hands.
Do you have the capacity to reflux it in ammonia? That would be very interesting...
[Edited on 30-8-2011 by Neil]
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blogfast25
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| Quote: Originally posted by Bezaleel | | The original question in this thread was a method to produce pure Al2O3. It seems, putting pieces of household Al foil in ammonia is a possible though
slow method. An interesting test might me to see whether the reaction speeds up when refluxing the ammonia. |
Considering just how many quick and dirty methods there are to produce alumina this would definitely be a slow boat to China. And you still need to
prove the stuff you see is actually alumina.
An interesting but rarely discussed laboratory method for producing calcined alumina is the pyrolysis of pure ammonium alum (NH4Al(SO4)2.12H2O), which
on heating first loses its water, then the ammonium sulphate, then the SO3.
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