Fantasma4500
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Removing SO3 from air
I think i might just have found out how to remove SO3 from air easily (in case of special setup / accidents etc)
what i did was that i tried making citric acid out of lemon juice + Ca(OH)2 to get calcium citrate blah blah blah sulfuric acid.. heat.. and suddenly
i felt the presence of SO3..
ive been playing about around with making a nasty mess with HCl + NH4OH which forms NH4Cl in air, aswell as i removed Cl2 from air with ammonia aswell
so i thought why not try ammonia on SO3? it should form either NH4SO3 or (NH4)2SO4
either way it worked as i put a few millilitres of 25% ammonia to a boil and walked around with.. after just a few seconds i could feel there wasnt
much SO3 if any in the air anymore..
more practical use for this might be putting some 25% ammonia or less next to a beaker with +70% H2SO4 boiling (starts to form SO3 after 70% AFAIK)
the formed SO3 would then react with the ammonia to form a not that harmful compound, and thus not needing any special air venting apparatus etc.
what do you guys think.. could this react fast enough to remove all the SO3 or at least enough for boiling H2SO4?
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woelen
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In theory this works, but in practice it is not very reliable. What if there is bad mixing? How do you know that you have enough NH3?
You should avoid getting H2SO4/SO3 in the air by means of a scrubber, or you should work outside/in a fume hood.
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Fantasma4500
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well perhaps i could lead the SO3 into a smaller flash via PTFE with 25% ammonia, but the point of this is being able to concentrate H2SO4 without
using anything to lead the SO3 away but simply just making it into less harmful compounds as i would need to get a SO3-resistant plug for my PTFE
tube, with ammonia its just easier.. perhaps heated ammonia?
but yes its not the best solution for dealing with sulfuric acid i agree.. but if you can get enough ammonia for the SO3, and you use an excess and
youre standing next to it all the time it should work..
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woelen
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I would do this outside. Alternatively, you can use a simple flexible PVC tube, which you lead through water or simple household ammonia. No need to
use 25% NH3. The PVC tube may get eroded, but it's cheap, just a few dimes per meter, so you can discard it.
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AndersHoveland
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Your original post is very confusing.
NH3 gas reacts with SO3 to form sulfamic acid. The reaction is fairly violent. Sulfamic acid can actually be considered an adduct, in fact so too can
concentrated sulfuric acid.
Heating ammonium sulfate mostly causes it to decompose, resulting in nitrogen and sulfur dioxide. The reaction is more complex than this, but suffice
to say SO3 cannot be obtained from heating this salt.
One possible way to remove SO3 fumes from the air would be to buy a water filter (like the venta airwasher), and add some sodium bicarbonate into the
water.
As you know, SO3 is very acidic and dehydrating.
[Edited on 12-2-2013 by AndersHoveland]
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Fantasma4500
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Quote: Originally posted by woelen  | | I would do this outside. Alternatively, you can use a simple flexible PVC tube, which you lead through water or simple household ammonia. No need to
use 25% NH3. The PVC tube may get eroded, but it's cheap, just a few dimes per meter, so you can discard it. |
yes that could be an idea, i have thought about it aswell to just use something cheap, but the problem is that i think it will erode too fast with
SO3, fall into solution and i will have SO3 fumes everywhere, but this part could be aided by ammonia reacting with the SO3 meanwhile changing tube
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Fantasma4500
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| Quote: Originally posted by AndersHoveland | Your original post is very confusing.
NH3 gas reacts with SO3 to form sulfamic acid. The reaction is fairly violent. Sulfamic acid can actually be considered an adduct, in fact so too can
concentrated sulfuric acid.
Heating ammonium sulfate mostly causes it to decompose, resulting in nitrogen and sulfur dioxide. The reaction is more complex than this, but suffice
to say SO3 cannot be obtained from heating this salt.
One possible way to remove SO3 fumes from the air would be to buy a water filter (like the venta airwasher), and add some sodium bicarbonate into the
water.
As you know, SO3 is very acidic and dehydrating.
[Edited on 12-2-2013 by AndersHoveland] |
hm.. yes.. i didnt know if the reaction was violent, but if the reaction is going on in the air and not as NH4OH + solid SO3 would that matter that
much?
sulfamic acid is described as a simple irritant, and also i couldnt feel it in the air at all, which tells me that its not as bad as SO3..
about obtaining it, i dont have much use in that as its what im trying to avoid, but removing it is what i need to, so i can get to concentrate my
sulfuric acid past 70%
for removing it by leading it into a solution i think the best would be to use a weak solution of sulfuric acid (37%?) which would then become more
and more concentrated as the formed oleum would break down into sulfuric acid
SO3 is SAID to explosively react with water, i would need to test if this is real and HOW explosive it does react before leading it through just water
at all..
if i could get to lead SO3 through something and it wouldnt react explosively i would probably go with a carbonate as its cheap and you would get
something useful out of it aswell
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woelen
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| Quote: Originally posted by Antiswat | [...]
SO3 is SAID to explosively react with water, i would need to test if this is real and HOW explosive it does react before leading it through just water
at all..[...] |
It DOES so. I tried this, by pouring appr. 1 ml of 65% oleum in cold water. There is a loud
and very scary crackling noise as soon as the oleum touches the water.
But, if you lead air, containing some SO3 in the form of white smoke through water, then you don't have to worry about explosions. The amount of SO3
simply is too small for that and the SO3 is finely dispersed over a large volume and finally, most of the SO3 will not be true SO3, but it will be
H2SO4, since you make it by boiling H2SO4, which gives off H2O + SO3, which recombine quickly to give H2SO4.
[Edited on 13-2-13 by woelen]
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Fantasma4500
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oh.. well thats very good news to me (:
perhaps i could put a beaker or some other container with ammonia in the solution where the SO3 is supposed to go then..
also if i made a plug, where my PTFE tubing is for a erlenmeyer flask and covered the not-so-resistant plastic parts (screwlid from soda bottle) with
telfon/PTFE tape shouldnt that make it resistant? teflon tape should be somewhat cheap and possible to find..
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Johnny Cappone
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Has any progress been made on this topic? I have the same problem. The "outdoor" area I have available to concentrate my H2SO4 is a small space
surrounded by high walls, so that the air circulation is very poor. In the final stages of boiling, when the acid is > 80%, the acid mist has
already spread enough to be perceived as a pungent odor. I have avoided the procedure, out of respect for the welfare and safety of my neighbors (and
mine, of course). I was wondering if some towels soaked in NH4OH around the boiling flask would prevent the problem.
Any escaping ammonia gas would be a problem in itself. Still, infinitely smaller than the mist of sulfuric acid.
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RustyShackleford
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| Quote: Originally posted by Johnny Cappone | Has any progress been made on this topic? I have the same problem. The "outdoor" area I have available to concentrate my H2SO4 is a small space
surrounded by high walls, so that the air circulation is very poor. In the final stages of boiling, when the acid is > 80%, the acid mist has
already spread enough to be perceived as a pungent odor. I have avoided the procedure, out of respect for the welfare and safety of my neighbors (and
mine, of course). I was wondering if some towels soaked in NH4OH around the boiling flask would prevent the problem.
Any escaping ammonia gas would be a problem in itself. Still, infinitely smaller than the mist of sulfuric acid. |
suck up the mist with an aspirator with sodium bicarb water running through it? or just distill the acid so the the mist goes into water
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