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Quaxo76

Storing bromine and iodine

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I'm trying to collect all the (non highly-radioactive) elements of the periodic table, in pure form. I already have about 65, and I just received 50g of iodine, and will soon receive 5ml of bromine. I'm having problems with storage of iodine though, and I suppose bromine will be even worse...

The iodine arrived in a glass container with a plastic/rubbery seal, and it was already slightly corroded. I put it in a borosilicate glass vial with a screw-cap with silicone seal, but it turned yellow pretty soon. Iodine smell didn't come out but I guess it was just a matter of time.

Then somebody told me to store it in a glass vial with glass cap (the ones with a "ground" glass at the interface between vial and cap, I don't know the English name), putting some silicon grease between bottle and cap... I did that, but after a few hours the grease layer between cap and vial started turning purple, and after 4-5 days all the grease is purple, and I can smell iodine again.

Now the lady at the shop where I buy lab supplies, sold me a glass vial with a plastic screw-cap but with a teflon seal. She said that teflon can indefinitely store both iodine and bromine, and that that's how they store them. Is this true? Can I use the teflon caps? If not, is there any other way? What about a tight, high-quality glass vial/glass cap? Maybe with some teflon inbetween?

(I don't have the means to make a sealed glass vial as I don't have a hot flame).

 

Thank you in advance,

Cristian

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Teflon inner layer should be good. It should be chemically inert to halogens, as it is already saturated with fluorine. Teflon is also called: tetra fluor ethylene.

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Teflon is PTFE or polytetrafluoroethylene.

 

Have you considered just ampouling the samples? with a little practice, this can be done somewhat crudely with a plain old borosilicate test tube and a propane plumbing torch. The halogens won't permeate solid glass. To do this with iodine, just keep the flame away from the iodine. For bromine, you should submerge the bottom of the tube in ice-salt brine to minimize volatility.

 

You can buy teflon sheeting and cut out a cap liner to stick in a tube with a screwcap. Tightening the cap converts this into an inert compression fitting. It will very slowly leak over time, but is readily openable if necessary.

 

If you don't need a shelf stable sample, seal the iodine in a HDPE jar with a tight fitting lid, place it inside a second jar containing sodium sulfite and sodium bicarbonate to absorb escaping iodine, and place the whole shebang in the freezer to keep volatility to an absolute minimum. Bromine is also best stored in the freezer inside a teflon-capped tube with the sulfite/bicarbonate secondary container if not ampouled.

 

Alternatively, you can buy some FEP or PFA plastic bottles, which are also fluoropolymers and entirely resilient to attack by the halogens.

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Teflon is also called: tetra fluor ethylene.

 

well thank god uc clarified this:

 

Teflon is PTFE or polytetrafluoroethylene.

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Yeah bad wording, sorry about that. I was right on the fluorine part though :doh:

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Teflon is PTFE or polytetrafluoroethylene.

 

Have you considered just ampouling the samples? with a little practice, this can be done somewhat crudely with a plain old borosilicate test tube and a propane plumbing torch. The halogens won't permeate solid glass. To do this with iodine, just keep the flame away from the iodine. For bromine, you should submerge the bottom of the tube in ice-salt brine to minimize volatility.

 

You can buy teflon sheeting and cut out a cap liner to stick in a tube with a screwcap. Tightening the cap converts this into an inert compression fitting. It will very slowly leak over time, but is readily openable if necessary.

 

If you don't need a shelf stable sample, seal the iodine in a HDPE jar with a tight fitting lid, place it inside a second jar containing sodium sulfite and sodium bicarbonate to absorb escaping iodine, and place the whole shebang in the freezer to keep volatility to an absolute minimum. Bromine is also best stored in the freezer inside a teflon-capped tube with the sulfite/bicarbonate secondary container if not ampouled.

 

Alternatively, you can buy some FEP or PFA plastic bottles, which are also fluoropolymers and entirely resilient to attack by the halogens.

 

Well, while the glass will keep the halogens in there, over time the glass does become brittle, especially in the thinner areas where it was melted. I had my bromine sealed in a glass ampoule, and for a long while there were no issues at all. About two years after it was ampouled, I started to notice that there was a very faint bromine-like odor in my cabinet. I figured the bromine was starting to slowly seep through the glass. I took the ampoule over to a friend's place and we went to re-seal the Br2 into the ampoule. When the top of the tube, where the glass was initially melted and sealed, was VERY lightly tapped, it just crumbled and fell apart. It wasn't like that when the sample was first ampouled. So over those two years, the glass did get a bit brittle. When the Br2 was re-ampouled, we also surrounded it with some acrylic resin so it's sealed in the glass tube which is sealed in the acrylic resin block. No notice of any Br2 leakage over the past few years.

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What? Really? Bromine corrodes GLASS?!? That puts an end to any hope I had of keeping it... I have no means of re-ampouling anything, nor any friends who can do that, and besides, if Br2 gets through the glass, I believe in the long term resin doesn't have a chance... :(

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It doesn't corrode the glass. It just seems to make it more brittle. So if you have it in a glass container that has a thinner than normal part to it, over a few years the bromine will make the glass more brittle and it can eventually leach through. If your glass is a standard thickness and doesn't have any thin spots in it, then it probably won't be a problem. I got mine re-ampouled and encased in an acyrlic resin since I never plan on using the bromine and want to keep it permanently encased for a long, long time.

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According to the Wikipedia article, bromine is shipped in steel containers that are lined with lead. Perhaps the lead is unreactive enough to resist corrosion by the bromine? Or perhaps it is just easily passivated... anyone have any thoughts?

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I have had some Br2 (200mls) for 20 yrs in glass/screw cap with teflon liner. Sure, infinitesimal amounts get through, but cant notice it unless one does a quantitative analysis on the entire amount. BUT, this was Reagen grade glass, and there is a difference.

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Bromine should be ambuled using borosilicate test tube and a propane plumbing torch. It should not be stored in any bottle with any type of lids. If we do so, the storage enviroment (switch box, fridge ,fan etc all will get corroded. AFter somtime, bromine will be no more in the bottle, but it leaves the effect of corrosion.

Iodine solid could be stored in a brown colour bottle with screwed lids and washers made of flexible plastic ( in gms).

The Iodine solid could be stored by keeping it in sealed high density polythene bag ( in kgs) .

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