Sulaiman
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How to filter hot potassium permanganate solution?
I intend to purify some potassium permanganate by recrecrystalisation,
scaling Wikipedia solubility data: 25 g/100ml @65oC, 7.6 g/100ml @ 25oC
I'm unfamiliar with the oxidising power of a saturated 65oC solution,
and I have only household filtering capabilities.
What can I use with a funnel to gravity filter the hot permanganate solution - that I want to purify, not add impurities to.?
(OTC materials only)
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Fluorite
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You can cut a glass bottle and use it as a funnel and add acid washed sand to make a diy fritter funnel? The sand should hold itself I guess
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Fery
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Sulaiman such conc KMnO4 sol oxidizes everything even when cold (brown spots on skin, destroys cellulose fiber so filter papers...)
if you allow sat sol to stay at 25 C for few days, then decant, cool to 0 C, almost 2/3 will crystallize and 1/3 stay in mother liquor
you can reuse the mother liquor for next crop with somewhat lower purity
cannot you use sintered glass funnel or buy it pure?
it is used as a local treatment for mycotic infections of skin, especially on feet, in my country you can buy it in pharmacy for such a treatment,
very pure, pharma grade, here is also an chem eshop where you can buy it few kg in pure quality, and maybe aquarium suppliers probably technical
purity (I remember it was used as aquarium water disinfection)
good luck in purification, please report your practical observations then, I suppose the purification to be too messy to try it by myself, I'm not so
brave, I know well what KMnO4 is, but I understand there are countries where you cannot easily buy it
sat KMnO4 solutions:
2,74% at 0 C
4,12% at 10 C
5,96% at 20 C
7,06% at 25 C
8,28% at 30 C
11,11% at 40 C
14,42% at 50 C
18,16% at 60 C
also here:
https://sci-hub.st/10.1021/ja01976a004
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Boffis
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You can nearly always buy fibre glass filter papers off Ebay at a reasonable price and if you get the ones without an organic binder they are
perfectly resistant to KMnO4 solutions, even hot, but they don't like being folded so you will need an aqppropriate sized Buchner funnel.
Alternatively a No4 glass fritted Buchner funnel can be used. The later can be cleaned by back flushing and washing with bisulphite solution as is
usual for MnO2 stained kit.
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Texium
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Get some glass wool if you can. Use it just as you would use cotton.
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Sulaiman
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I expect the potassium permanganate that I have is quite pure,
but I want to be more confident of its purity before I retry an experiment that is probably sensitive to impurities.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
I doubt that sand or glass wool would 'catch' suspended MnO2 etc.
I have a porcelain 90mm dia. Buchner finnel at home and I'm trying to not duplicate equipment and chemicals here,
so I'll look into getting a sintered glass vacuum assisted filter funnel.
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teodor
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I think that potassium permanganate is that thing which even being pure in crystalline form (but I doubt it is often the case) is changed much in
solution. But after staying for a while and being filtered after that I believe it becomes stable and at this point could be tested.
Otherwise you should deal with absolute purity of everything which is contacting it. I would think about that the same way as about 98% H2O2, the only
difference is that the last could explode and the former only deposit MnO2, but the precautions against their reducing on manipulations should be
basically the same.
[Edited on 8-12-2020 by teodor]
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Sulaiman
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I've soaked the glassware to be used in water with HCl and H2O2 and rinsed with diy distilled water,
and I have some (presumably) fairly pure sulphuruc acid that I recently distilled.
I'll probably buy this kit on 12/12/2020 https://www.lazada.com.my/products/2440lab-suction-filtratio...
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zed
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Yup! KMnO4 solutions are Good for cleaning up ulcerations on the feet and ankles. In the U.S., it may be considered a prescription item. Too bad.
A little piece of glass wool in the bottom of a beaker. Press it with the tip of a hypodermic needle. Just draw your solution through it. Works
well.
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Texium
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You'd be surprised by what
properly packed glass wool can do.
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macckone
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glass fiber filter media - https://www.sterlitech.com/gd-120-glass-fiber-membrane-filte...
Also available from amazon and ebay.
Celite is very fine silica from diatomaceous earth.
Diatomaceous earth which is mostly silica with some calcium carbonate can be soaked in nitric acid and then rinsed repeatedly with distilled water.
This will leave basically the same thing as celite except that uses a defined grade of diatomaceous earth and uses a float process to separate iron
contaminants before treating with nitric acid. Sulfuric acid won't work right as it will bond with calcium and form a solid mass. HCl will remove
everything but the usual insoluble chlorides.
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