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watson.fawkes
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I can guess, but only guess, that if it's SiO2 it's there as a nucleation agent for evolved gas. The combination of bumping and
enclosed pipes is not a good thing.
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Luftwaffe
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I am curious as to what impurity that is and if non-distilled H2SO4 would be unsafe to use in chemical synthesis's specifically nitrations.
I have recently been thinking of purifying sulfuric acid using a very indirect but possibly successful route which would include vacuum distilling
HNO3 from the raw drain cleaner sulfuric acid and a recrystallized nitrate salt found in fertilizers (which in my case is KNO3). I would then use the
nitric acid to oxidize SO2 by creating a sulfur dioxide gas generator and bubbling it through the nitric acid which would produce in theory pure
diluted sulfuric acid which you could then boil to concentrate. This process assumes that no impurities boiled over in the nitric acid distillation
for it to work and from what everyone is saying it seems to have a low volatility which leads me to believe it would not boil over.
Minus the liberation of NO2 when oxidizing SO2, it seems like it would be safer than distilling the raw H2SO4 at high temperatures, even if you were
to vacuum distill it. Perhaps I am blowing things way out of proportions and over-complicating the whole purification process. I just want to make
impurity free sulfuric acid in a safe manner and whether that be distilling and separating those mystery crystals or doing the whole procedure I lay'd
out, I don't know, which I guess is why I'm here! 
This is my first post here on Sciencemadness, hopefully I didn't break any rules! 
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windchime
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Interesting that the liquid lightning brand drain cleaner up here in Canada is 94% vs. 44% by weight in the states. There is no mention of inhibitors
on the Canadian bottle label either.
http://liquidlightning.net/template.php?go=msds
I purchased a bottle the other day. The contents have a bit of a dark brown colour to them, not sure if that's a result of age (oxide buildup) or
contaminants/additives. I'm going to try the heating method first to see if i can clear it up.
Amusing the regional differences in product content. I'd make a joke about canucks being more responsible... but I'll save the bad karma for after
working with the acid.
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freedompyro
holmes1880
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After further testing I have confirmed that the cleaning of H2SO4 by the addition of 5% H2O2(30%) works somehow...
I first brought a mostly clear solution of Rooto to a full boil which took me about 30 minutes with a propane burner. It turned to pure black with a
hint of red when a bright light was shined through it.
It was cooled back to room temperature and maintained it's black color. I poured into another flask. To the original flask I added H2O2(30%) in an
amount equal to 5% of the weight of the H2SO4. The H2SO4 was poured slowly back into the original flask and some light boiling occurred in a few
spots.
After being heated for 5 minutes the solution had turned clear with a slight hint of yellow and lots of light bubbling. After being brought to a full
H2SO4 boil emitting clouds of white fumes after 20 more minutes and being lowered to a simmer for 5... It still maintained the clear color with a
slight hint of yellow. No change on cooling... When fully cold it actually appears 100% clear on first glance with 900ml in a 1000ml flask, but if you
look at with an angle in a tall clear bottle you can see a very slight yellow tint.
One question I need to ask is... What is the concentration of H2SO4 brought to a full boil for a couple minutes? Is it 98% or is it around 96% or so?
Note: The top half of the flask was insulated with aluminum foil both times. The H2SO4 seemed to radiate so many BTU's that it could not be brought to
or held at a boil without the flask being insulated and the heat held against it's lower sides with the use of aluminum foil sheets surrounding the
burner.
[Edited on 15-2-2012 by freedompyro]
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Neil
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Quote: Originally posted by freedompyro  | After further testing I have confirmed that the cleaning of H2SO4 by the addition of 5% H2O2(30%) works somehow...
I first brought a mostly clear solution of Rooto to a full boil which took me about 30 minutes with a propane burner. It turned to pure black with a
hint of red when a bright light was shined through it.
It was cooled back to room temperature and maintained it's black color. I poured into another flask. To the original flask I added H2O2(30%) in an
amount equal to 5% of the weight of the H2SO4. The H2SO4 was poured slowly back into the original flask and some light boiling occurred in a few
spots.
After being heated for 5 minutes the solution had turned clear with a slight hint of yellow and lots of light bubbling. After being brought to a full
H2SO4 boil emitting clouds of white fumes after 20 more minutes and being lowered to a simmer for 5... It still maintained the clear color with a
slight hint of yellow. No change on cooling... When fully cold it actually appears 100% clear on first glance with 900ml in a 1000ml flask, but if you
look at with an angle in a tall clear bottle you can see a very slight yellow tint.
One question I need to ask is... What is the concentration of H2SO4 brought to a full boil for a couple minutes? Is it 98% or is it around 96% or so?
Note: The top half of the flask was insulated with aluminum foil both times. The H2SO4 seemed to radiate so many BTU's that it could not be brought to
or held at a boil without the flask being insulated and the heat held against it's lower sides with the use of aluminum foil sheets surrounding the
burner.
[Edited on 15-2-2012 by freedompyro] |
Sounds like you had organics which were consumed by your impromptu piranha solution. Take the density to determine the concentration.
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AJKOER
Radically Dubious
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Here is a somewhat more complex and expensive route, but no distillation of H2SO4 and perhaps interesting to some.
1. For the given amount of H2SO4, calculate how to divide it to produce equimolar amounts of hydrated ferrous sulfate and ammonium sulfate, and also
have some residual H2SO4 as well.
2. Prepare the hydrated Ferrous sulfate by dissolving Fe in H2SO4, and separately, bubble pure NH3 into H2SO4 to form Ammonium sulfate. For Ferrous
sulfate, follow preparation at:
http://www.crscientific.com/ferroussulfate.html
For Ammonium sulfate, per Wikipedia:
2 NH3 + H2SO4 → (NH4)2SO4
"A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2 to 4% of
free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat of
reaction keeps reactor temperature at 60 °C."
3. Mix the equimolar amounts of hydrated ferrous sulfate and ammonium sulfate with the residual H2SO4 to make Ferrous ammonium sulfate. See procedure
at: http://motion.kodak.com/motion/uploadedFiles/US_plugins_acro...
4. Dilute and crystallize out the Ferrous ammonium sulfate to form light green crystals.
5. Combine green crystals, distill water and Oxalic acid dihydrate (costs about $2.64 a mole), and heat forming a yellow precipitate of Iron Oxalate,
and also some Ammonium oxalate. Separate out the Iron salt and cool to collect the Ammonium oxalate crystals. Boil the solution to remove any
remaining Oxalic acid and/or Ammonium oxalate. Reactions:
(NH4)2[Fe(H2O)2(SO4)2]*4H2O + H2C2O4*2H2O --> FeC2O4 (s) + H2SO4 + (NH4)2SO4 +8H2O
(NH4)2SO4 + H2C2O4*2H2O --> (NH4)2C2O4 + H2SO4 + 2H2O
H2C2O4 + H2SO4 --Boil--> H2SO4 + H2O + CO2 + CO
The remaining solution is H2SO4 purified essentially by crystallization and some boiling. Side products are Iron oxalate and Ammonim oxalate.
[Edited on 27-2-2012 by AJKOER]
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chucknorris
Hazard to Self
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Oh well.. Sulfuric acid boiling temp at 5 pascals(which is the max vac my pump will make) seems to be 62C. Can it be distilled in order to purify it
or does it decompose?
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