Mixell
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SO2 collection
Anyone gt a method or a device that can collect SO2 from burning sulfur?
I need something that will gather the SO2 but will let fresh air enter the system and sustain the burning reaction.
I thought about burning it in a glass vessel and blowing air into the vessel, but that may not be so efficient.
Basically I would like to dissolve the sulfur dioxide in a solution of sodium hydroxide and make sodium sulfite. Or react the SO2 with chlorine and
make sulfuryl chloride.
Any suggestions?
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Contrabasso
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I'd be looking at an arrangement of a thistle funnel inverted over the flame of sulphur burning in air with several dreschel bottles collecting the
SOx and containing the reactants you need for the products you want, then more dreschel bottles to scrub the gasses to protect the vacuum aspirator
(or fridge pump)
You could make this with glass tube and rubber bungs or use ground glass fittings.
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garage chemist
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You can wash out the SO2 from the gas stream in cold water (medium solubility) or in alcohol (high solubility) followed by desorption of the gas by
heating.
Absorption in aqueous NaOH always entails losses due to oxidation of the sulfite ion by oxygen (a quite rapid reaction).
I would recommend to forget about a sulfur burner for now, and use a reaction that produces pure sulfur dioxide gas instead of a mixture with an
excess of air.
My method of heating sulfur with sulfuric acid in presence of ferric sulfate is cheap and convenient, and the gas stream is very uniform.
If you don't want to use H2SO4 as raw material, you can heat sulfur with MnO2, giving MnS and SO2. 1g SO2 from 1g sulfur- do you really need more than
that?
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dann2
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There is a thread on this somewhere.
It's good to mix the sulphur with something like perlite? so that it will keep burning
Go search!
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watson.fawkes
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Quote: Originally posted by garage chemist  | | I would recommend to forget about a sulfur burner for now, and use a reaction that produces pure sulfur dioxide gas instead of a mixture with an
excess of air. |
I'll second that. Getting rid of that excess gas requires a lot of gear. Above some threshold
it's feasible, but it's not a particularly small scale. If you really want to experiment with a sulfur candle, run it on tank oxygen. Then, if you're
doing solution absorption of the SO2, you'll know you've got complete absorption when there's no excess gas. You might also use an oxygen
concentrator, but that's only about 95% O2 (the rest is Ar and residual N2) and you'll still have a waste gas problem, albeit a much smaller one.
The practical problem with excess gas is that it will be contaminated with SO2 at some significant fraction of the vapor pressure of SO2 if you use
only a single absorption stage. You're trying to react at a gas-liquid interface, so you want tiny bubbles, long tubes, and multiple stages. Tiny
bubbles increase the surface area of contact. Long tubes and multiple stages increase the contact time. Multiple stages also provide a higher
concentration of reagent with each stage.
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peach
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NurdRage has a video up on youtube to do with extracting manganese from batteries and he makes a mention of using a sulphur candle.
He uses a glass funnel turned upside down over a tin of burning sulphur. There's some tubing from the funnel to a wash head, which dips into the flask
of his washed paste. A vacuum is connected to the outlet on the wash head, sucking the gas through the solution.
I would suggest steering clear of the sulfuryl chloride until you've had a fair bit of practice piping things around and getting them to dissolve or
react without clogging something up, having bottles syphoning back or it escaping into the room. It can be a real pain at times!
If you're after SO2 and are not bothered about it being anhydrous, you can forgo a lot of the expensive gear by doing it outside in the garden. Given
that you're bubbling it through a basic solution, I would expect a fair amount of it will stay in said solution; but some will escape as the bubbles
pop at the surface.
For a candle, you will need a pump of some sorts to get the gas moving. The absolute simplest method I can think of would be to connect an aquarium
pump to the upturned funnel and then dip it's 'blow' tube into a beaker of the hydroxide. You could seal the outlet tube off and poke lots of holes in
the sides with a pin to create a frit of some sorts. Precisely how long the pump will last I don't know.
You will also have to play around with it to get it working nicely I expect. But all gas stuff requires it to some extent. Which is why so many labs
end up using cylinders instead.
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Mixell
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The MnO2 + S sounds like the best method, since I have a lot of MnO2 mix from batteries.
I thought about it a bit further, and I would like to create stable, or at least pure compounds, oxidation of the sulfite ion to the sulfate is quite
disturbing.
I thought about making SO3 too, and I can get my hands on vanadium pentoxide if necessary, but that will requires a source of oxygen, and that
complicates things...
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