CycloRook
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Questions about piranha solution.
I have watched several videos on this mixture. I have some questions.
Does this solution destroy all organic molecules ?
To what degree does this solution destroy organic molecules ?
What is the mechanism of action on organic molecules ?
If you put a sample of aspirin or Tylenol into piranha solution what would happen ?
I would like to know how all this works but can't find any mechanism of action online.
Thanks
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B(a)P
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This is a bit simplistic, but not a bad start.
Piranha solution
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CycloRook
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Yeah. It seems like there solution wasn't as concentrated as some videos I've seen. I doubt the berry would have lasted longer.
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macckone
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There are a bunch of reactions going on, one is dehydration of organics with OH groups,
Another is addition of sulfate groups in place of other groups.
Then there is persulfate which is one of the most potent oxidizers known.
It will oxidize pretty much anything, including carbon.
answering the other questions
does this destroy all organic molecules? I haven't found any that it doesn't with the exception of fluorocarbons and things like carbon
tetrachloride.
To what degree does this solution destroy organic molecules? To CO2 and H2O and what ever hetero atom oxides, with the exception of fluorocarbon
groups and some chlorine compounds like phosgene and carbon tetrachloride.
Mechanism was already discussed. It is oxidation, like fire.
Paracetamol and acetyl salicylic acid will be completely oxidized.
With paracetamol, there is a nitrogen, It will leave as either nitrogen or form nitrosylsulfuric acid.
With nitrosylsulfuric acid being an oxidizer in its own right.
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CycloRook
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I just had a thought. Can piranha solution used to recover precious metals like platinum palladium or gold ?
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Tsjerk
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From what?
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arkoma
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HCl + clorox work pretty well
"We believe the knowledge and cultural heritage of mankind should be accessible to all people around the world, regardless of their wealth, social
status, nationality, citizenship, etc" z-lib
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CycloRook
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anything I guess. Catalytic converters or anything that's an organic mix
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Bedlasky
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Catalytic converter isn't organic mix. It's mixture of various oxides and precious metals (Pt, Pd, Rh). And I personally never heard about organic
mixture containing precious metals.
And to your question - no, piranha solution isn't suitable for extracting precious metals. For extraction of Pt, Pd and Au you need presence of
chlorides, Rh and Ir can't be recovered by aqueous methods (Rh can be dissolved in molten NaHSO4, Ir in molten hydroxide with some strong oxidizer
like KNO3 or Na2O2) and Ru and Os cannot be dissolved in acids, but they are attacked by highly oxidizing alkaline solutions or melts (NaClO etc.).
If you are interested in precious metals recovery, read something about industrial process of separation of precious metals.
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CycloRook
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I really need to do more reading on this. My thought was that piranha solution would essentially oxidize everything except the precious metals. Thanks
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Dr.Bob
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I have tried Piranha solution for some frits and other very dirty glassware, and it works on somethings, but not on everything, some frits it barely
cleans at all. But they are dirty from a wide variety of things, and I don't know which ones are dirty with what, which makes things harder.
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macckone
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piranha is good for organics.
It is bad for inorganics as a lot of oxides and sulfates are insoluble.
For inorganics peracetic acid is my go to followed by nitric and aqua regia.
Obviously aqua regia can't be used on lead or silver contamination.
Those need straight nitric.
Peracetic acid is basically glacial acetic with 30% hydrogen peroxide.
It will convert most things to the acetates.
It is very good with insoluble hydroxides and carbonates.
Nitric acid will work on a lot of stuff and aqua regia will work on the rest.
Some insoluble oxides require chloric or perchloric acid (chrome oxide)
If you have sulfates stuck in a frit things get more complicated.
calcium sulfate requires soaking and drying to work it out of the frit.
barium sulfate, good luck with that. Don't use a frit for barium sulfate.
Na-EDTA can be used to dissolve really stubborn stuff.
Good paper on cleaning frits from back in the days before computer aided analysis (GC/MS, OES-ICP, etc).
https://pubs.acs.org/doi/pdf/10.1021/ac60044a602
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unionised
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No it isn't.
For a start, it smells different.
Also it's capable of oxidising manganese salts to permanganate.
The real problem with trying to use peroxides to get precious metals into solution is that they typically catalyse the decomposition of the peroxide
before it has a chance to do any oxidising..
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macckone
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Unionised,
peracetic acid really is glacial acetic acid with hydrogen peroxide.
That is one of two methods for making it.
Notice I specifically mentioned using it with carbonates and hydroxides.
precious metals are better handled with nitric or aqua regia depending on the metal.
But gold and silver work with peracetic acid, numerous videos available on the process.
I don't work with platinum very often, I don't have that kind of money.
You really need to know what is on the frit before cleaning it.
If you don't then the order peracetic acid, nitric, aqua regia will work for all but the sulfates and water will work on a number of those.
Na-EDTA will work on sulfates according to the linked paper but a frit clogged with sulfates might be a total loss.
Lead and calcium can be slowly worked out with water, but barium sulfate is very stubborn.
It depends on how clean you need it and how much time you have.
Another trick is soaking with sodium bicarbonate, then hitting the frit with acetic acid.
You can get a small mount of sulfate to convert to carbonate and then the carbonate to acetate since these are equilibrium reactions.
But these take time.
It may be cheaper to buy a new fritted funnel if you factor in the time cost, the reagents are generally cheap.
Back to your manganese to permanganate, permanganate is pretty soluble while manganese oxide is not.
Peracetic acid has removed manganese oxide from glass for me.
Patent where manganese oxide is removed from denim with peracetic acid which leaves the blue dye in place:
https://patents.google.com/patent/WO1992013987A1/en
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Triflic Acid
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Manganese oxides also react with hydrochloric acid but produce Cl2 gas, so this must be done outdoors or in a well-ventilated area. This is how I
clean my manganese-oxide-covered glass, by adding some HCl and then letting it sit in a plastic box with liquid hydroxide drain cleaner at the bottom
outdoors for a couple of days. It removes the stains pretty well, and there is practically no chlorine smell.
There wasn't a fire, we just had an uncontrolled rapid oxidation event at the power plant.
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macckone
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Quote: Originally posted by Triflic Acid  | | Manganese oxides also react with hydrochloric acid but produce Cl2 gas, so this must be done outdoors or in a well-ventilated area. This is how I
clean my manganese-oxide-covered glass, by adding some HCl and then letting it sit in a plastic box with liquid hydroxide drain cleaner at the bottom
outdoors for a couple of days. It removes the stains pretty well, and there is practically no chlorine smell. |
Peracetic acid is really better for this one.
It is very fast and no Cl2 gas.
Just good old oxygen and manganese acetate.
Sulfuric acid is also good for manganese oxide.
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