Sciencemadness Discussion Board

TCCA purification, strange things happen

Refinery - 27-4-2020 at 12:16

I have TCCA that has 50-75% of it and 25-50% of NaCO3.

I attempted to purify it by powdering the tablets, and dissolving 100g of powder with 200ml of acetone.

A white, milky sludge formed, that filtered clear at first. The sludge quickly clogged the filter.

Then, the solution began turning greenish and bubbles started to evolve. When I had filtered part of it, the filtrate was noticeably green, and it darkened as time passed. I crashed 1:1 volume of water to filtrate, and white mass instantly formed. When I re-filtered this, more white mass formed in the second filtrate, and I thought to test and add more water, and more of it formed. Strange is, the more water I added, the more it expanded like a sponge.

Then I started to feel burning in my eyes, and I decided to abort and discard the whole process.

So, was there cloroacetone formed?

I thought purifying TCCA was an easy task, but I once again lost my faith in my skills. What should be the right way to do it? I could not find descriptions on purifying TCCA properly, only just claims that it is one of the most easily available otc chemical. But what can you do with it when it's all impure?

EDIT: now that I think it (before bed), couldn't I just have crushed the tabs, dissolve the whole junk in water, let it settle/filter it and let it evaporate to dryness? There is this other brand that dictated it has ~5% copper sulfate, ~5% Al sulfate and min 89% of TCCA. Should there be issues with water purification?

I need it for styrene oxidation.

[Edited on 27-4-2020 by Refinery]

morganbw - 27-4-2020 at 12:49

Process for purifying trichlorocyanuric acid

I have never purified TCCA so cannot offer real advise other than the link.
One possibility is to pulverize it and slurry it in H2O. The water should dissolve the Na2CO3 leaving most of the TCCA undissolved. Strain it through a piece of cloth or filter and dry what you have.

You possibly made some chloroacetone.


[Edited on 4/27/2020 by morganbw]

Refinery - 27-4-2020 at 22:46

It appears to me that Al and Cu sulphate do not interfere with the reaction, hence the other brand tablets could be used directly, possibly with minimal decanting, due to them being insoluble in acetone. Any residues would react with NaOH phase and turn into water and sodium sulphates.

njl - 28-4-2020 at 08:50

I'm not too aware of the process, but I don't think any appreciable amount of Chloroacetone was formed both due to the lack of an acid in the solution and because it is a strong lachrymator that you would likely notice in the air.

Refinery - 28-4-2020 at 10:52

I had to leave the proximity due to my eyes burning. So, something was there.

UC235 - 28-4-2020 at 13:27

I've always just used TCCA for chlorine generation with HCl, for which contaminants are mostly irrelevant except carbonate would introduce CO2 to the gas stream. Some brands are 99% and I think it's worth trying to track down because the stuff is a potent oxidant and reacts with lots of the things you'd like to try purifying it with.

If you really need it pure, I am under the impression that it is not that hard to produce by leading chlorine gas into a solution of trisodium cyanurate. Cyanuric acid itself can be recrystallized from boiling water (though very large volumes are needed since its solubility is low even at boiling) but probably the white paste left from a chlorine generator can be boiled with some HCl (outside!) once or twice, and after a water wash be more than good enough.

[Edited on 28-4-2020 by UC235]

Fyndium - 25-9-2020 at 10:34

There are brands that contain a very large amount of sodium carbonate as filler. It does something weird with acetone indeed. Perhaps there was also something else.

Other brand contains about 10% of copper sulfate and other acetone insoluble stuff that leaves behind when TCCA is dissolved. It is easy to filter out to result in crystal clear solution. This could be used to crystallize pure TCCA, but I've always prepared this solution in situ and used immediately after determining the amount of impurities above. If these are the impurities, they have nil effect on chlorine production.

NitratedKittens - 7-8-2021 at 09:06

Quote: Originally posted by morganbw  
Process for purifying trichlorocyanuric acid

I have never purified TCCA so cannot offer real advise other than the link.
One possibility is to pulverize it and slurry it in H2O. The water should dissolve the Na2CO3 leaving most of the TCCA undissolved. Strain it through a piece of cloth or filter and dry what you have.

You possibly made some chloroacetone.


[Edited on 4/27/2020 by morganbw]


Have just carried out the procedure in the link on some hot tub TCCA tablets. No noticeable hydrogen chloride was evolved. Got a very low yield (9g of TCCA from 100g of tablets) because i did not crush my tablets fine enough and the binders they put in them to make them slow release mean they don't dissolve readily unless crushed to a very fine powder.

macckone - 7-8-2021 at 17:47

Get pure cyanuric acid. Put it in solution. Bubble chlorine from the tcca through the pure stuff.
Otherwise, sodium carbonate is much more soluble than tcca in water.

Yes even tiny amounts of chloroacetone are a lacramator.

Fluorite - 8-8-2021 at 16:16

cyanuric acid should also be mixed with sodium hydroxide to make sodium hypochlorite in situ?

macckone - 9-8-2021 at 09:23

Fluorite,
Base of your choice.
Probably do not want excess base.
Just enough to keep in neutral.

Fyndium - 9-8-2021 at 14:27

The pool tablets are hard af, and when I handled them ages ago, I just took pliers and crushed them to granular consistency and put them in handheld blender to pulverize it. Tip: use an actual respirator mask, because you will be breathing what is like powdered chlorine that goes everywhere, and the odor will linger your nose for a long. Non-powdered TCCA will take forever to dissolve in acetone, and boiling it seem to encourage chloroacetone formation, perhaps because by a catalysis caused by presence of metal ions. If TCCA powder smells nasty, even trace amounts of chloroacetone will just burn your eyes and nose and make you run away from the place.

There seem to be a brand that consists over 90% of TCCA and rest of some chlorides and sulfates, which do not go into acetone and can be removed fully by simple filtration.