Elemental sulfur from CS2

Yeah, the average price I could find with a Google search was around 300 USD per liter. There weren't many companies even selling this chemical, and it is restricted to ground shipments.

[Edited on 3/6/2025 by chempyre235]

This is pure blasphemy given that CS₂ is an incredibly unique, expensive, and hard to acquire solvent, while elemental sulfur is so cheap and plentiful that every amateur chemist probably has at least a kilo sitting around that they don’t know what to do with!

Also, carbon disulfide is really nasty stuff. If you’re going to play around with it, at least use it for something worthwhile. Figuring out a way to turn it into something as cheap and dull as elemental sulfur is not worth the risk to your health.

[Edited on 3-6-2025 by Texium]

opinions (of a non-chemist that can be ignored)

Quote: Originally posted by Precipitates

Heat, and an oxygen-free environment, but it's probably not easy.

Quote: Originally posted by unionised

Sell CS2: buy sulphur. Seriously, CS2 is more valuable.

Quote: Originally posted by Texium

This is pure blasphemy given that CS2 is an incredibly unique, expensive, and hard to acquire solvent, while elemental sulfur is so cheap and plentiful that every amateur chemist probably has at least a kilo sitting around that they don’t know what to do with!

Quote: Originally posted by Sulaiman

If you are considering taking waste off site then there may be liability problems for the lab. (assuming that you are not a registered waste disposal company) In either case you should have a quiet word with your supervisor before expending too much effort. I have usually found no problems when asking for stuff of little/no/negative value. Sometimes a nominal sum may be involved just to keep paperwork tidy. So, although your intentions are excellent, you should get at least tacit approval - for your own 'safety' PS imagine sitting in your car, in a traffic jam, in summer, with a few litres of CS2 in the trunk/boot. bp 46oC, autoignition at 102oC (eg the exhaust system)

Quote: Originally posted by teodor

Why not use it to prepare thiocarbonates and purify them by recrystallization to get rid of impurities.

Quote: Originally posted by teodor

Why not use it to prepare thiocarbonates and purify them by recrystallization to get rid of impurities.

Quote: Originally posted by Eithern

Quote: Originally posted by teodor   Why not use it to prepare thiocarbonates and purify them by recrystallization to get rid of impurities. Uhm but I have no uses for them, while solid sulfur, although cheap, is "cool" and I don't have it. Suggestions?

Quote: Originally posted by Eithern

Ahah I know! But of course the CS2 I'm talking about is more or less contaminated with volatile compounds and therefore worthless, that's why I liked the idea of converting a toxic waste in a common but safe substance.

Second attempt would be short path distillation done, you know, as an actual short path distillation. That is, distillation at below boiling temperature from the vapour pressure alone.

By all means, attempt to recover something useful from what would otherwise be a toxic and volatile waste material. But I think attempts to make sulfur or react with fluorine are misguided.

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RU_KLO - 20-3-2025 at 01:52

The substance can be contacted with the iron either directly or indirectly. Such contacting includes passing the substance through a permeable body of iron.
Iron, generally zero-valent iron, destroys carbon disulfide by a chemical redox reaction

Methods of carbon disulfide treatment
https://patents.google.com/patent/WO2003095118A1/en

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Sulaiman - 20-3-2025 at 04:47

I would probably take some (100ml?) and 'have a play' with it.
boil it, burn it, do like the ether demo - put in a (remote) flat surface a burning candle then nearby a small dish of CS2, prepare for soot!
Do all kinds of stupid stuff that you could not do at work.
(ppe, safety, blah blah blah. just use small quantities, and keep the larger quantity far away)
Sounds frivolous or unwise BUT not really that hazardous if you have (maybe not so) common sense,
and you will have a more realistic idea of the risks.
One exposure to a little CS2 vapour will not kill you.
Judge for yourself the fire risks.
I dislike the smell and the fire risks but if you want it .....
or
leave it alone

not much to be learned inbetween.

PS out of curiosity I checked my favourite online shopping site
500ml carbon disulphide with p&p equivalent USD40

[Edited on 20-3-2025 by Sulaiman]

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teodor - 20-3-2025 at 05:26

I don't have much interest here, but noticing that Sulaiman wrote something here and having 5 minutes to read
- why wouldn't use good old "decolorising carbon" to remove most of organics before further treatment
- stay away from distillation if you don't know exactly how to deal with fire on your workplace
And I of course enjoy the way how Sulaiman frames safety standards here.

[Edited on 20-3-2025 by teodor]

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Eithern - 25-3-2025 at 14:32

Thank you all for your interest in the topic, I should add that unfortunately I don't have an adeguate setup at home for using toxic volatile substances, and at work I can only do something when I've a free moment.
Obviously my superiors are not interested in recycling or re-valuating chemicals, we're an analysis laboratory not a place of research, so a delicate procedure like distillation is off limits. Making thiocarbonates seems easier but like I said before I don't know what to do with them, but if someone here is interested to buy some I could make a try
Joking aside, as Sulaiman suggested, I indeed took a few milliliters and ignited them with a lot of precautions to see if the reaction is like I saw on YT, can confirm that it's nothing special, blue faint flame with a strong smell of SO2, and a yellow deposit was effettively formed on the container edges... yeee that's my sulphur! Too bad it's only a few milligrams! Very inefficient
Could I capture and bubble the SO2 in hydrogen peroxide to make sulfuric acid? I don't know, maybe I should just let it be disposed of as usual and focus on recovering other things, but argh this bothers me!
If you have any other ideas they are welcome.

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Precipitates - 25-3-2025 at 20:02

Quote: Originally posted by Eithern

Could I capture and bubble the SO2 in hydrogen peroxide to make sulfuric acid?

Yes, an old video now, but still good on the subject:

Make Sulfuric acid (metabisulfite/oxidizer method)

Instead of a sulfur candle, carbon disulfide could, at least theoretically, be burned alternatively.

A method of capturing sulfur dioxide gas is shown in the following video, also by Nurdrage:

3 Ways to Make Sulfur Dioxide Gas

Just note the extreme flammability of carbon disulfide (as mentioned previously) - fire safety protocols should be in place.

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