Sciencemadness Discussion Board

Sulfur

UnintentionalChaos - 15-3-2007 at 12:38

Any brillant suggestions for purifying some elemental sulfur? Someone mentioned hot toluene a while back, but I don't have any toluene lying around. Thanks. I've seen 2H2S + SO2 done, but I'd really rather not mess with the lethal gas and a cloud of rotten-egg stink.

Elawr - 15-3-2007 at 15:27

you could purify it by sublimation. I think that is how the medicinal product "flowers of sulfur" is manufactured from impure native sulfur.

not_important - 15-3-2007 at 19:23

Or by distillation in a current of CO2.

You should know what the likely impurities are. Some garden sulfur - marked 'wettable' - has a fair amount of organics - surface agents - and will generate a lot of H2S when heated.

It doesn't hurt to stir the sulfur with cold water for awhile, decant or filter and repeat. This removes the surface active stuff as well as some of the CaSO4 that's in some ag grade sulfur.

Sauron - 15-3-2007 at 20:17

Brauer's book probably has details on preparing ultrapure sulfur

But first of all, how pure do you need it?

Why not buy the grade you need and skip all the grunt work?

Alfa has grades purer than AR and pharm.

Some of Brauer's referenced procedures are laborious and others not so. I included the material on plastic sulfur and colloidal suflur. See attachment below (341-343.pdf)

[Edited on 16-3-2007 by Sauron]

Attachment: 341-343.pdf (89kB)
This file has been downloaded 1436 times

Per - 18-3-2007 at 01:03

Pure sulfur, hmm, I´ve here some kg with a purification of min. 99,9%, you could have a kg for only 7€, to bad that you live in the USA and I in Germany.

Nicodem - 18-3-2007 at 02:02

Quote:
Originally posted by UnintentionalChaos
Any brillant suggestions for purifying some elemental sulfur? Someone mentioned hot toluene a while back, but I don't have any toluene lying around.

I don't understand why you can not get toluene, but you could at least try with xylene. It should work even better as it has a higher boiling point while the solubility of sulphur at the same temperature is probably quite similar.

Sauron - 18-3-2007 at 11:02

I suppose we would all be less confused if you would define for us:

1. What level of purity you require (and maybe why)

2. How much S you need to purify

3. Why you just don't buy pure S of required grade as it is cheap.

USP sulfur is not pure enough?

Brauer's procedures that I posted detail how to rigorously purify sulfure a Kg at a time to a very high purity.

So pls define your requirements and we can be more helpful perhaps.

More Methods

BeanyBoy - 22-3-2007 at 09:10

I have a copy of Perrin, Armarego, & Perrin's "Purification of Laboratory Chemicals". It describes one very long procedure by Murphy, Clabaugh, & Gilchrist, which appears to be meant to take fairly pure sulfur to "99.9999 moles per cent purity", but it is *way* long. Only by request.

Also mentioned: "crystallization from CS2, benzene, or bezene-acetone, followed by melting and degassing."

And: "Has also been boiled with 1% MgO, then decanted, and dried under vacuum at 40deg for 2 days over P2O5".

Mention is also made of an ACS monograph by Bartlett, Cox, & Davis, for purification of S6, recrystallization of S8, and "Bacon-Fanelli sulphur", JACS, v83, p103-109.

I have page one of the monograph...

hth,
-the beantificator

UnintentionalChaos - 22-3-2007 at 12:28

I didn't even realize this thread had been going anywhere, but thanks for looking into it. I'm as much into prepping my own chems from OTC sources as I am about anything else and the only sulfur I can find is the 90% garden sulfur garbage (though a wash in water probably brought it up several percent) Right now, I don't have a particular use in mind, but would like to have some should the need arise, so the cleaner the better. I can get xylene, but I'm at college right now and everything is on hold for another two months anyway. :(

Sauron - 22-3-2007 at 14:47

Ah. So this is a wild goose chase. You aren't interested in ultrapure sulfur but in getting the crap out of garden grade sulfur.

Sorry, decrapping inappropriate materials isn't really indexed in the lit. too often.

Really, you ought to just buy some "real" sulfur when you find a need for it. Most large pharmacies still sell USP grade flowers of sulfur which is as OTC as you get and quite pure.

UnintentionalChaos - 22-3-2007 at 21:41

I have been in more pharmacies than you can shake a stick at and no sulfur. I found USP KNO3 once, but that was an odd stroke of luck. Sauron, you need to calm down. I'm sorry I didn't check the thread for a few days to clear up what was being asked. If I had enough equipment to pursue ultrapure sulfur or to just sublime the crap, I wouldn't have asked. I was looking for an alternate to lots of hydrocarbons for my case, but I guess there isn't a practical one. Please note that this is in beginnings for a reason. :mad:

Sauron - 22-3-2007 at 22:36

I am perfectly calm. Perhaps you are too touchy.

Pyridinium - 23-3-2007 at 04:31

Quote:
Originally posted by Sauron
Ah. So this is a wild goose chase. You aren't interested in ultrapure sulfur but in getting the crap out of garden grade sulfur.


Bah. This board is full of tortuous routes for purifying things that could just be bought.

IIRC, Chaos, the solubility of sulfur in xylene is quite a bit lower than it is in toluene.

Eclectic - 23-3-2007 at 04:49

To purify agricultural sulfur, why not try an agriculture related method. Make lime/sulfur solution by dissolving as much sulfur as possible in boiling hydrated lime and water (calcium polysulfide solution). Decant and filter liquid after cooling, then precipitate sulfur with muriatic acid (brick cleaner, HCl solution).

Probably a nasty, stinky process that really should be done in a barnyard, but better than poisoning yourself with aromatic solvents. Watch out for H2S.

not_important - 23-3-2007 at 09:23

It is not so common for pharmacies in much of the US to carry sulfur, the old home remedy uses have faded and shelf space is too valuable to take up with a very slow moving item.

Cleaning ag grade sulfur up usually means several good washes, perhaps extractions would be a better term. with water to remove the wetting agents. Don't let the sulfur dry out between washes, once the wetting agent is gone it's tough to wet the sulfur. One or two washes with wet alcohol, the 70% rubbing grade for example, might be a good finish. After that melting the sulfur and filtering it is perhaps the simplest cleanup that doesn't take too much equipment.

Pyridinium - there are parts of the world, including sections of the USA, where it is difficult to by one chemical or another, even everyday ones. Business licenses may be required, in the more urban areas it is not uncommon to find only various proprietary mixtures available to the public instead of pure solvents and chemicals.

Pyridinium - 23-3-2007 at 09:35

Quote:
Originally posted by not_important
Pyridinium - there are parts of the world, including sections of the USA, where it is difficult to by one chemical or another, even everyday ones.


I know, I was just being facetious. I'm fascinated with primitive methods for chemistry, partly because that's how it was done for centuries. Hence, I'm rather glad to see tortuous routes for making common things, or any routes for that matter. Today's common reagent is tomorrow's hyper-regulated no-no, thanks to encroaching chemophobia and other reasons.

Aqua_Fortis_100% - 23-3-2007 at 18:14

I have now some sulfur here.. 200g as "100% pure sulfur" from pharmacy and another amount of 700g of farm grade.

Is strange for me how in US the sellers can sell many "pure" solvents as toluene, xylene, acetone, MEK, etc and the simple elemental pure sulfur is a bit more hard to find...
if one day i find here a OTC place which can sell me these solvents without suspicion, i will be very happy :-)
(here these substances are normally out of commerce because of use in drugs world)

Eclectic method for refining farm grade sulfur seems very OTC , cheap and easy to reproduce in backyard instead buy aromatic solvents, etc .. although i think which the product isn't pure as the product from recrystalization method, and also the procedure should release poisonous H2S as Eclectic says.

[Editado em 23-3-2007 por Aqua_Fortis_100%]

16MillionEyes - 1-4-2007 at 06:00

Funny thing you ask for elemental sulfur and I have some myself but I don't know what to do with it. I haven't really thought of an interesting reaction with sulfur.

indigofuzzy - 2-4-2007 at 01:01

How would buying native sulfur from a mineral store work out, as far as being able to purify it?

Just as an example, one has native sulfur of unknown purity, and wants 90%+ purity. Or what if one wants 99.9%? How would one get there?

not_important - 2-4-2007 at 03:12

Quote:
Originally posted by indigofuzzy
How would buying native sulfur from a mineral store work out, as far as being able to purify it?

Just as an example, one has native sulfur of unknown purity, and wants 90%+ purity. Or what if one wants 99.9%? How would one get there?


Mineral samples tend to be an expensive way to get sulfur, the agricultural grade is likely to be much cheaper. Gardening supply shops often carry it

It all depends on the exact sample of native sulfur. In general you'll need to melt it away from the rock. Using agricultural/gardening grade starts with a a good washing with water to remove the organic wetting agents, this may mean multiple washes.

After that melting the sulfur and filtering it while hot will get rid of bits of rock or limestone/gypsum that is sometimes in Frasch method sulfur.

Sulfur from the Frasch process or recovered from petroleum processing is otherwise reasonably pure, 99 percent or higher. Volcanic deposit sulfur, as most proper native sulfur specimens are, requires distillation or solution-filtration-crystallisation - which often leaves solvent trapped in the sulfur and so is followed by distillation.

Agricultural sulfur starts off as fairly pure sulfur, then has wetting agents and other stuff added. Once those are removed, which water washing and melting + filtering seem to do a decent job of, the remaining sulfur is pretty clean.

Beyond that level of purity come the various methods already discussed - refluxing with MgO and filtration, embedding a quartz heater at 700 C in the molten sulfur and leaving it for some days; those have to be done under a CO2 or N2 atmosphere. That's to reach greater than 99.5% purity.

Diablo735 - 10-4-2007 at 03:34

What about sulfur that comes in those trains? I live near train tracks and there are small piles of everything all over the tracks. There are nice piles of sulphur, its yellow and it smells like it.(Haven't done any experiments to confirm. But pretty sure it is sulphur) Would that be high purity? And how do I know the purity, any tests?

not_important - 10-4-2007 at 03:59

Wiki sez that Alberta is doomed to ne covered with sulfur from hydrodesulfurization of petroleum and natural gas, converted to the elemental form by the Claus process.

This is a pretty good grade of sulfur. It should be free of mineral impurities, dissolving some would so if there were any insoluble trash; as you're collecting spillage it could pick up dirt. It likely contains trace amounts of organic carbon compounds and sulfur oxides or sulfuric acid, extraction with water and testing the pH of the extract would tell you if there was much oxidised sulfur.

I'd guess that for most purposes it will be pure enough, I'd do an acid removal wash before using it in pyrotechnics or at least test it for acid content.

So head out to the tracks with your shovel and pail, and start stockpiling this resource.