ChocolateStirBar
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Retort for sulphuric acid distillation?
Hi, I'm looking for advice on how to source a retort for sulphuric acid distillation. I guess quartz would be the ideal, but the ones I found weren't
quite right due to having a ground glass joint in the top of the retort.
I'm looking for a retort in which the *only* hole is the outlet of the air condenser, to cut down on sulphuric acid fumes. The fumes are entirely the
reason I've not been unable to do any distillations of the acid yet. I could not do it outside either.
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LearnedAmateur
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Welcome to the forums. Simply closing off the retort with a glass stopper should do the job, there are several videos online of people manufacturing
and distilling nitric acid using jointed retorts and fumes don't appear to be an issue there. You shouldn't need quartz as long as care is taken when
heating, bringing the flame up to touch the glass after a minute or two, circling around the bottom to ensure even temperature.
Sorry I can't be of much help with your actual inquiry, hopefully some other members can find sources of plain retorts if that's the only way you want
to go.
Also, have you considered generating SO3 gas and leading it into ice water? I'll link a procedure for the former which can be modified. This has the
advantage of being conducted at a lower temperature than boiling sulphuric acid, and can further create oleum in the same flask. It must be done
slowly and on a small scale though since the generation of H2SO4 is extremely exothermic - active cooling is necessary too.
http://www.sciencemadness.org/member_publications/SO3_and_ol...
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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j_sum1
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I'm no expert on this one LA, but I believe it is extremely inadvisable to add SO3 to water. The better procedure is to add SO3 to
concentrated sulfuric acid and then dilute that.
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Vosoryx
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I've used a ground glass distillation setup for sulfuric acid. No retort is required, and the joints leaking is not an issue so long as they are well
greased and attached. Since plastic keck clips will melt off at those temp, It might be better to use metal ones, or (if you don't, like me, have any
metal ones) fashion some out of copper or steel wire for the two joints before the condenser.
Retorts are cool, but seriously limited in use.
Good luck and be safe - I know it's been said before, but boiling H2SO4 is certainly not an easy walk in the park. I highly recommend boiling stones
such as smashed glass or sand if you are distilling large amounts at once, and a vacuum if you have access.
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ChocolateStirBar
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Cheers for the welcome!
If I remember correctly, you grease joints with sulphuric acid itself due to the incredibly high temperatures and acidity levels involved, yes?
I also assume no-water condensing is used, or perhaps two leibigs joined together and only running water through the latter.
Whilst I do appreciate the SO3/Oleum tip, it sounds simply much too dangerous for me to even think about at the present time. I'll definitely read up
on it just for the knowledge but carrying out procedures like that isn't likely due to me having to stay indoors.
Part of the reason I was gonna go with quartz was the fact that my entire setup of other glassware is chinaware, which call me paranoid but I don't
know if I trust it for something as dangerous as 300c+ distillation of anything let alone H2SO4!
How do you achieve those temperatures anyway? Mantles?
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JJay
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I don't really trust borosilicate with boiling sulfuric acid either, so I use one of these for distilling sulfuric acid: https://www.ebay.com/itm/500ml-Customized-Quartz-Distilling-... I use 10,000 BTU (i.e. about 3000 watts) propane camp stove as a heat source and
an ordinary borosilicate Vigreux adapter as a condenser. That seller does custom quartz labware.
It does leak a bit from the joint where it interfaces with the borosilicate condenser but it is fine in a fume hood. It doesn't seem to leak much from
the top; I am quite sure that the stopper is quartz, but the stopper seems to have a slightly higher coefficient of expansion than the rest of the
flask, and it grips tightly while hot. I've been meaning to have them make me a quartz condenser (something like a jointed quartz tube that I could
wrap with copper tubing)....
I haven't managed to obtain sulfuric acid that is stronger than 92% from it yet, but I haven't made any special effort to keep moist air out of the
apparatus.
https://www.sciencemadness.org/whisper/files.php?pid=488723&...
[Edited on 31-10-2017 by JJay]
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LearnedAmateur
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Quote: Originally posted by j_sum1  | | I'm no expert on this one LA, but I believe it is extremely inadvisable to add SO3 to water. The better procedure is to add SO3 to
concentrated sulfuric acid and then dilute that. |
Yes, the reaction will create localised hotspots in a glass flask containing water, this is especially problematic since SO3 is a liquid at room
temperature so will drip in as opposed to diffusing through the water evenly. It will probably crack the glass if the proportions are right, sometimes
to the point of a small explosion.
However, if you were to bubble it into cold water in an open container that is cooled in an ice bath or with dry ice, the reaction should become far
more controllable. Production of gas can also be closely varied as long as it's kept within ~10C of the decomposition temperature of the pyrosulfate.
---
I've never distilled sulphuric acid or worked with SO3 before so I can't give you any tips from experience, but yes it would be a good idea to use
sulphuric acid in the joints. Temperature wouldn't be a problem for other lubricants but they will instantly char so you'd have a fun time getting the
joint back out. It's probably your best bet to avoid the procedure I recommended, I'm in the same situation as you where I can't work outside and you
definitely don't want corrosive vapour and flying glass indoors.
Yeah I wouldn't trust Chinese glassware much, I've bought several pieces now but they're never heated - pipettes, syringes, filters; quartz is
definitely your best and safest bet, even Chinese glass will be up for the job, just make sure it's not an obscure manufacturer with an unmarked
product. You'll probably need a propane torch (the ones with the bottles and screw on nozzles), camping stove is also a good suggestion, I'm not sure
that there are many mantles that can go hot enough and they'll be hundreds of dollars if they can. If direct flame isn't your fancy then a sand bath
should work, this can be heated from underneath and ensures even temperature distribution but will take a lot longer.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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ChocolateStirBar
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| Quote: Originally posted by JJay |
I haven't managed to obtain sulfuric acid that is stronger than 92% from it yet,[Edited on 31-10-2017 by JJay] |
Oh...the stuff I was wanting to get to 96%+ is a very lurid purple 91%~ concentration drain cleaner, so I'm not sure what to do if this is the case. I
can't really think of much use for heavily dyed H2SO4 that's probably 8%+ water. I'm a bit of a purity obsessive, plus it feels much nicer to have the
choice to dilute azeotropic acid (carefully!) down to the required concentration.
I wonder if Ave369 (I believe that's her name) will fly into the thread and offer advice, using TFSE led me to her indoor distillation via retort
thread, and the logic and results were sound.
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XeonTheMGPony
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So far I've distilled over 3L of the stuff, it can be a pain as it really likes to bump! I do 450ml batches in a 1 L flask with a hand full of crushed
beaker.
Chinese glass is fine just test it first by dry heating care fully then cooling and look for any bubbles or defects.
Do not use a 3 way adapter, no point and odds are it will crack just use a 45* distilling adapter.
Get metal clips (It likes to bump and your sealed system will no longer be!)
if it is really wet run it for a while on a Vigruex column and just heat it till the dense while fums just start to appear near the top and that will
help to reduce actual distill time.
Go slow and don't rush, I use a 300 mm water cooled Leibig with a water to gas exchange (Radiator) to cool it. once at a steady boil you need to tune
the heat to be hard enough to keep it steady with out bumping then it will coast along to near the end befor bumping
I usually leave a 50ml tailing those get stored separated, then I use the tailings to make SO3 now for when I need very concentrated acid.
[Edited on 31-10-2017 by XeonTheMGPony]
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hissingnoise
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| Quote: | | Oh...the stuff I was wanting to get to 96%+ is a very lurid purple 91%~ concentration drain cleaner |
Shopping around for clean acid (local hardware?) is usually worthwhile, though you'll need to check that what you're buying is water-white
─ battery acid, too, is an option, though the prolonged boiling (cough!) can be a pita...
Sulphuric acid distillation should really be a last retort if you can't vacuum
distill.
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Aqua-regia
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H2SO4 purification under vacum. Thats the key. Buy a cheap pump with 20 mbar capacity. If you have simple tap water pump and the water
temperature enough cold (winter) and sufficient pipe pressure exist also good. In this case the normal borosilikate equipment is everlasting. When i
was younger, destillated a lot from battery quality acid. It was really a piece of cake. Note: Between the electric pump and equipment advised a
trap for acidic humidity avoid the pump. If the boiling point raises the maximum, you have in the collecting flask 97-98% concentrate of the acid.
Under vacuum likewise preferable the air condenser than Liebig condenser.
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ChocolateStirBar
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Good advice, thanks guys.
I haven't looked too hard, but OTC sulfuric acid isn't that easy to get here, hence why I went with the purple stuff.
As a less than subtle hint, the government seemingly does not like nitric acid, nor peroxides, nor perchlorates (admittedly I have absolutely 0 use
for the latter, EM aren't an interest of mine).
The fact those chemicals are banned, even for uses as benign as producing silver nitrate or piranha fluid, makes me think perhaps H2SO4 will go the
way of the dodo as well soon.
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Vosoryx
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Depends on the country, but yes. I know one store where I can find the H2SO4 drain cleaner where I live, but I know that other people have trouble
depending. When I did find the one store, I bought a crap ton just in case they stop carrying it.
Finding cheap nitrate salts for making HNO3 is also a PITA. Using the Potassium Nitrate that CAN be found in SOME stump removers makes most a little
sticker shocked. Ammonium Nitrate in cold packs is hard to find nowadays. I work for a company that has a license to buy NaNO3 as an industrial
fertilizer, and I bought a 50 lb bag through their license.
With the overpricing and limited availability of some of the most commonly required things for amateur chem, I wouldn't be at all surprised to see
easy Sulphuric acid vanish in the years coming...
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