Fantasma4500
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underrated ascorbic acid
ascorbic acid, quite strong reducing abilities, it can turn a solution of copper sulfate into copper mirror over time, i have confirmed this myself
although i had to heat up the solution a bit and it didnt coat glass with copper
ive used it for turning silver nitrate into silver metal, works very rapidly and even gave some crystalline silver somehow
im pondering whether ascorbic acid could be used for reducing nitrate into nitrite?? supposedly with a catalyst of some sort, well knowing that simply
mixing up the two (as done for pyrotechnical composition "golden powder") wont make the two react
i dont know much of the datalogical part in terms of reduction abilities of compounds, but turning copper sulfate into copper powder in aqeuous
solution should take some potential, shouldnt it? if so thats a starting point assuming there isnt much data out there for ascorbic acid in regards of
its ability to reduce
i dont quite get the whole idea of reductions, it appears to me that zinc chloride can be used as reduction agent just as zinc metal powder can, could
zinc ascorbate then not give an yet stronger reducing agent if both ionic zinc and ascorbate ion are able to reduce?
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clearly_not_atara
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The trouble with reducing nitrate in solution is that usually nitrite is a stronger oxidizing agent than nitrate in solution. For example bisulfite
reduces nitrite to hydroxylamine. I believe ascorbate will also react with nitrite as it is an alcohol and a nucleophile. This paper discusses some
ways of converting NO3- to NO2-:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.319...
Cadmium is very effective for this reduction. A pity it's toxic, although SMers use mercury all the time. Sulfuric acid / nitrate / Cl- will
apparently give good yields of nitrosyl chloride. This would be an attractive route if there were a way to avoid the release of chlorine.
ZnCl2 does not reduce anything, but it may make some substances more susceptible to reduction.
[Edited on 6-4-2017 by clearly_not_atara]
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tsathoggua1
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Can ascorbic acid reduce manganese salts from solution to the metal?
(chloride, sulfate) been attempting to recover the Mn content from batteries by digesting in acid to form salts) Would rather not go the thermite type
routes and stick to solution or fused salt-phase chemstry/electrolysis given the rather nasty toxicity of aerosolized Mn. Despite its being essential
in small quantities, manganese toxicity is particularly unpleasant in that even after successful reduction of Mn levels in the brain back down to
levels found in healthy people, the damage is degenerative and progressive, causing a kind of parkinsons disease. So not something I'd want spewing
out into the environment in a mini volcano.
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clearly_not_atara
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Look up the half-cell potentials:
DHA + 2 e- + H+ >> Asc- (V = +0.080)
Mn2+ + 2e- >> Mn (V = -1.185)
So no. Manganese metal is actually very reactive. However it will reduce Mn3+ to Mn2+.
https://www.pearsonhighered.com/tinoco5einfo/assets/document...
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Fantasma4500
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for nitrite i would take sodium nitrate and heat up with iron oxalate, the nano iron powder formed would instantly react and should make nitrite
nitrite stronger oxidizing agent, seems odd to me, it can be made using charcoal and molten nitrate, the mixture is then lit whereafter the charcoal
is oxidized, it did the time i tried it seem like i could just keep on adding charcoal however, and in molten state nitrite shouldnt be very good at
absorbing oxygen -- which it does to form nitrate again
dont worry about manganese in the atmosphere, commonly steel contains about 0.4% manganese, that means also all welding electrodes and wires contains
the same, and oftenly there is no absorbing of welding fumes, in short.. manganese gets out in the air all the time, it has indeed got neurotoxic
properties are excess amounts and will give you very aggressive behaviour if exposed to it, manganism they call it
just cover the thing up with a bucket to capture most of the smoke if you really think a bit of manganese is gonna make the world shred apart
as a bonus.. extremely high manganese exposure can cause acute "schizophrenic symptoms", that including hallucinations, even visual
says in the document "The standard electrochemical potential for the reduction
of nitrate ion (NO3
- + 3H+ + 2e- S HNO2 + H2O) is
E = +0.934. "
that paired with ascorbic acids half cell potential..
"DHA + 2 e- + H+ >> Asc- (V = +0.080)"
so +0.080 and +0.934
as i see it, testing for nitrite is taking sulfuric acid with iron sulfate in it, when this solution gets into contact with nitrite ions, the HNO2
formed creates nitrous oxide complex with the iron forming dark brown ppt, this is quite easy test to prepare, maybe adding sulfuric acid to solution
of ascorbic acid and nitrate would instantly form HNO2, which would then give off NOx, which HNO3 would not
maybe HNO3 and ascorbic acid would do something interesting, and now i think on exactly that reaction... ascorbic acid does produce NOx when it gets
into contact with HNO3? next question is reaction mechanism
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AJKOER
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I have used an aqueous high pH Aluminum based path, as discussed previously on SM (see https://www.sciencemadness.org/whisper/viewthread.php?tid=52... ), to reduce nitrate. The unexpected result was the experiment went well past
nitrite formation introducing a surprising buildup of NH3. An aqueous path based on Pb appears to behave similarly (per comments in same cited
thread).
Perhaps a new (yet to be perfected) method woud be to first employ, say H2C2O4, to act on nitrate creating a dilute solution of HNO3. Convert the
latter with Cu into NO. Combine the nitric oxide (a stable radical) with the hydroxyl radical (.OH) produced by, for example, the action of UV on
H2O2. Key reactions:
H2C2O4 + 2 KNO3 → 2 HNO3 + K2C2O4 (s)
H2O2 + UV → •OH + •OH
.OH + .NO = HNO2 ( see reaction 36 at https://books.google.com/books?id=qKoxBQAAQBAJ&pg=PA51&a... )
And the last reaction can definitely be reversed in the presence of UV, the first apparent issue with this path. Also, one must rapidly convert the
unstable nitrous acid (especially if not cold and dilute) into a nitrite salt.
Note, avoid excess H2O2 due to the unfavored reactions (or use another source for the needed hydroxyl radicals, like perhaps the action of solar light
on N2O gas dissolved in an aqueous suspension of ZnO per an ebook I recently browsed):
H2O2 + HNO2 → H2O + HNO3
•OH + H2O2 → •HO2 + H2O
•HO2 + NO → •OH + NO2 (see https://www.google.com/url?sa=t&source=web&rct=j&... )
NO2 + H2O → HNO2 + HNO3
HNO3 → H+ + NO3-
•OH + HNO3 → H2O + •NO3 (see https://www3.nd.edu/~ndrlrcdc/Compilations/Hydroxyl/OH_169.H... )
•NO3 + NO2- → NO3- + •NO2 (Reference, page 182, equations R24 in "Plasma Kinetics in Atmospheric Gases", by M. Capitelli, et al., link: https://books.google.com/books?id=2ofqCAAAQBAJ&pg=PA182&...
destroying nitrite.
-------------------------------------------
[Edit] Just found an interesting source. My take, per the comments cited below, one needs to form conc HNO3 and react with Cu to form largely NO2.
Then, pass the NO2 into a cold dilute solution of a sulfite. My guess on a balanced net reaction:
2 ·NO2 + SO3(2−) + H2O → 2 NO2− + SO4(2−) + 2 H+
Here is the referred to comments, to quote::
"Huie, R.E.; Neta, P.
J. Phys. Chem. 90, 1193-1198 (1986)
Reaction: ·NO2 + SO32− → products
Reference Reaction: ·NO2 + C6H5O− →
Solvent: H2O
k ~3.5 × 107(L mol−1 s−1), kreference = 8.6 × 106(L mol−1 s−1), pH = 12.1
Experimental method: Pulse radiolysis
Analytical method: vis-UV absorption
Data type: Relative value measured directly
Competition kinetics in soln. contg. nitrite ion; Overall reaction is 2 ·NO2 + SO32− → 2 NO2− + SO42−
-------------------------
Lee, Y.-N.; Schwartz, S.E.
Precipitation Scavenging, Dry Deposition, and Resuspension. H.R. Pruppacher, R.G. Semonin, W.G.N. Slinn (eds.), Elsevier, New York, NY, 1983, Vol. 1,
p.453-67
Reaction: ·NO2 + SO32− →
Solvent: H2O
pH range 5.8 to 6.4
k > 2 × 106(L mol−1 s−1), pH = 6.4, 5.8
Experimental method: Flow techniques
Analytical method: conductivity
Data type: Limiting value
Obs. acid production; products are H+, NO2− and SO42−; complex mechanism; gas-liquid system"
-------------------
Link: https://www3.nd.edu/~ndrlrcdc/Compilations/Ino/INO_791.HTM
[Edited on 9-4-2017 by AJKOER]
[Edited on 9-4-2017 by AJKOER]
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tsathoggua1
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The problem with (toxic degrees of) manganese via inhalational exposure is that damage can be progressive, with its causing a parkinsonian type of
toxicity, which continues to degenerate even after aggressive chelation therapy which brings manganese levels in the brain and CNS down to normal
levels. Once at that stage, as I understand it, your pretty well buggered.
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The Mad Plater
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Quote: Originally posted by Antiswat  | | ascorbic acid, quite strong reducing abilities, it can turn a solution of copper sulfate into copper mirror over time, i have confirmed this myself
although i had to heat up the solution a bit and it didnt coat glass with copper |
Very interesting - I wonder if it'd be of any use for electroless plating of nickel (or indeed, other metals).
In commercial use, the reducing agent in EN plating is either sodium hypophosphite or sodium borohydride (2 entirely different processes). Yes, these
are both drug precursors.
Strangely, not yet illegal around here - at least the hypo, of that I'm sure - but it's only a matter of time.
I'll have to mess around with this idea a bunch: sodium hypophosphite is the most "difficult" reagent for my purposes, since it's becoming
increasingly illegal everywhere in the world, and home-brewing it on a kg scale is not very feasible (as in, forget about it!).
Current chemistry WIP:
1. Mn phosphating of carbon steels:
- the phosphating step by itself works perfectly fine;
- currently working on surface prep & activation.
2. Zn phosphating of carbon steels:
- on backburner ATM;
- current status: brand new bath concentrate is ready for first phosphating tests!
3. Electroless nickel plating (>10% phosphorus content):
- on double backburner ATM;
- initial results (on carbon steel) VERY promising;
- plating on aluminium needs a lot more R&D (surface prep - zincating).
4. Electropolishing of stainless steels:
- IT WORKS! At least "well enough" for now;
- the process parameters could use a bit more refinement.
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Fantasma4500
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i'd still pick ascorbic acid and nitric acid to create NO2, its quite rapid of what i remember and i have a distant idea that its not as exothermic as
copper + HNO3
question is what else it may create
if it were to be used for electroplating nickel onto steel i would suggest adding a weak solution of ascorbic acid to the nickel salt solution,
ascorbic acid could indeed be useful in terms of reducing inorganics, where in electroplating you really dont want to depend on metallic reductants
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gatosgr
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Ascorbic acid also acts as a capping agent that's why you saw 'crystallization' you can use ascorbic acid to make Nanoparticles gold silver and
copper have a positive enough reduction potential but other metals need borohydride or stronger reducing agents.
Why make nitrite from nitrate?
[Edited on 13-4-2017 by gatosgr]
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Fantasma4500
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nitrite from nitrate? well why not
nitrite is expensive where nitrate is not, it has a bunch of uses
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clearly_not_atara
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Yeah it's common that people can get nitrate but not nitrite but the reduction is hard to control.
| Quote: | | electrodeless nickel plating |
First thing that comes to mind is sodium dithionite. Ascorbate is a reducing
agent but not actually that strong by the standards of inorganic reducing agents.
Using these data it does not appear that ascorbate will reduce nickel at any pH:
http://www.sciencedirect.com/science/article/pii/00220728940...
https://en.m.wikipedia.org/wiki/Standard_electrode_potential_(data_page)
If dithionite is not successful another possibility might be dihydrolipoic acid or a similar dithiol. Still another possibility are salts of chromium
(II), which if I'm interpreting the data right will reduce nickel to the metal while being oxidized to chromium (III). The acetate seems preferable.
Chromium (II) acetate is famously air-sensitive of course.
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Melgar
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Ascorbic acid has been most useful for me for two applications:
First, adding in small amounts to air-sensitive organic compounds when they need to be evaporated but it's clear they're slowly oxidizing when I
expose them to air. It's kind of laborious to evaporate many solvents in a vacuum, and some things that I'd need to evaporate, I'd rather not risk
damaging my vacuum pump. Not to mention, my vacuum pump is pretty noisy, and I haven't set up a control mechanism for it yet.
Second, if I need an iodide salt and only have elemental iodine and a hydroxide or carbonate of the metal. First, neutralize the base with ascorbic
acid. Second, add iodine bit by bit. It dissolves slowly at first, but as iodide ions become more concentrated, it dissolves faster. The ascorbic
acid reduces the iodine to iodide as it forms. You can make pretty much any iodide salt that way. I am curious how ascorbic acid manages to
neutralize lugol's solution though. That's iodine dissolved in an iodide solution, but there doesn't seem to be any cation formed. My only guess is
that the ascorbate ion is oxidized into a neutral compound, forming hydroiodic acid, essentially. Of course, hydroiodic acid is a reducing agent too,
so eventually there would be an equilibrium.
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Fantasma4500
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as i was producing some silver from impure silver nitrate (coins, 90 10 silver-copper?) i noticed a few things, the silver particles starts clumping
together when the solution is heated, very easy to clean with decantation
and as i kept adding more ascorbic acid i saw that the copper nitrate -- in diluted form which was originally blue turned into a strong green, which
persisted even when diluted
copper nitrate can be green in solution if its quite concentrated, but obviously the ascorbic acid reacted with the copper nitrate somehow, i'd like
to imagine my silver is impure with copper but it didnt seem like copper was actually coming out of solution as metal from the ascorbic acid and im
not sure if that would explain the green colour anyways
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Varmint
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So, if Mn02 is toxic, how does that square with KMnO4 being the most popular emergency water treatment chemical?
Seems to me there ought to be some product labeling requirements if there is clinically recognizable risk associated with its use.
DAS
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Melgar
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| Quote: Originally posted by Varmint | So, if Mn02 is toxic, how does that square with KMnO4 being the most popular emergency water treatment chemical?
Seems to me there ought to be some product labeling requirements if there is clinically recognizable risk associated with its use.
|
Anything is toxic if you ingest enough of it. MnO2 is much less toxic than chlorine, for instance, and chlorine is used even more frequently to
sterilize water. But what does that have to do with ascorbic acid?
@Antiswat: copper changes it's ion configuration and color based on what other ions are available in the solution. In this case, copper will form the
blue color if enough chloride ions are available, but if there start to be ascorbate ions interfering with that formation, it will fall back to the
green color.
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Fantasma4500
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you need manganese in your metabolism anyhow, so it can accumulate but.. your body will use it up over time, much differently than lead or fluoride
which both settles in bones and teeth, and parts of the brain that contains similar compound to bones or teeth
what means a lot in terms of accumulation is also whether compounds of the chemical element are insoluble as it will allow the compound to get into a
cell, thereafter become insoluble forming particles larger than the cell membrane
searching for something entirely different i found some "data" on ascorbic acid
"Cr(VI) is reduced to Cr(III) by ascorbic acid (reductive coefficient = 3.473*106 M-1*s-1) [3]."
https://pilgaardelements.com/Chromium/Reactions.htm
now next up would be to find a list of reductive coefficent to see how useful ascorbic acid really is, to see what kinda stuff we can replace with
quite OTC synth vitamin C
about the KMnO4 for water treatment, you only use a very small amount of KMnO4, extremely small, barely colouring the solution, its used for survival
and of what i understand not for common water treatment (maybe unless if some sort of agenda was to be provoked? nah!)
it would be desired to let the MnO2 fall to the bottom to then decant off the now microorganism-cleansed water
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