I might have had a thread on these a while back, but I'm still baffled by them, and I'd like to put them to use.
On eBay, I picked up a dozen bottles and lids that are MACHINED from solid PTFE - teflon. These are not PFA/FEP bottles.
These are sweet in every way but one - they are stained and carry a really funky odor, something very organic. I've tried cleaning them with all
sorts of hot mineral acids, pirhana fluid, everything. They are still stained and still smell. This blows my mind. I thought PTFE was just about
immune to attack, and can be cleaned with ease.
What are they for? My best guess is that they were part of some very expensive biotechnology machine. Perhaps they were filled with proteins, or
something to do with automated DNA analysis. The other option is the semiconductor industry, which might suck because of toxicity concerns.
I'm afraid to use them due to the possibility of contamination.
unionised - 5-10-2012 at 08:53
I'm glad you are wearing gloves.
Those sorts of bottles are very expensive and so they only get used if there's nothing else that will do the job.
Whatever they were used for is probably rather corrosive (and the fact that it has stained the PTFE supports that).
I know it's not very green but the best suggestion I can give is that you take the lids off and leave them outside away from anyone for a while and
see if whatever it is dissipates.
Sunlight, oxygen, water and time makes for a pretty good cleaning agent.Swede - 5-10-2012 at 09:56
It terms of actual "stuff" in the bottles, there is none. All that is left is the staining, and the smell. As mentioned, I tried peroxide, sulfuric
and nitric acids, soaking them overnight in the cleaners, and nothing has touched the staining.
I even sectioned one of them, and the stain itself extends into the PTFE a good mm or two, so it's not surface staining. I doubt that the stains at
least will ever come out, so I guess it comes down to "what good are they?"
I can potentially mount them in a lathe and turn them into PTFE beakers by boring out the cruddy part, but as original containers, they're probably
toast, which is sad, because they are neat little bottles and probably very expensive when new.
I think they were part of an automated machjine. They have the rigidity so that a machine can select, manipulate and open them, which is something
that a much more flexible PFA bottle couldn't deal with. And the lids have very specific grooves that look to accept a flanged opening mechanism.Swede - 5-10-2012 at 10:00
Oh yes, just a little gloat - these were part of a huge lot of PTFE, PFA, and FEP lab bottles I picked up for something like $20. About 1/2 of these
were used, but the other half were brand spanking new, so now I have a nice collection of bottles from 100ml to 250ml that were probably $60 to $150
each when new.
ScienceHideout - 5-10-2012 at 11:07
It sounds to me that they may have contained bromine... Is it bromine like? Have you tried cleaning it with sodium thiosulphate? Looks like the right
color for bromine...watson.fawkes - 5-10-2012 at 11:44
They are still stained and still smell. This blows my mind. I thought PTFE was just about immune to attack, and can be cleaned with ease.
The chemical is inert, but the material is not impervious. Since PTFE doesn't take well to melt processing,
though it can be sintered under pressure. This, however, leads to less than 100% fill. But also, because PTFE is inert, even to itself, individual
grains don't bond much chemically, but rather mechanically, and with thermal cycling grain boundaries can open up transiently.Ozone - 5-10-2012 at 13:38
Bromine was my first instinct, as well.
O3woelen - 6-10-2012 at 01:52
I do not think it is bromine. Bromine stains are homogeneous, but as the picture shows, the stains in the bottle contain many little dark specks,
especially near the rim.
But of course, you can check easily. Just make a little bromine (e.g. take some chlorate, add to a solution of KBr or NaBr and then add some acid and
swirl, until you have a nice orange/red solution) and CAREFULLY compare the smell of the bromine with the smell of the bottles.kristofvagyok - 6-10-2012 at 03:45
Doesn't look like bromine to me as well. I have worked a lot with bromine and never ever saw a colorination like this on the PTFE. It could be a
million else compounds what has az orangeish color...
Simply just don't care what is it, wash it out. Use acetone/methanol/KOH+isopropanol, just get it out. Non of these will damage the teflon, they will
just get out the gunk.Swede - 6-10-2012 at 06:31
After a thorough cleaning, all identifiable solids are gone... long gone. All that remains is the staining and the smell. And if something is
embedded in the PTFE and volatile enough to be obvious to the nose, it's also going to interact with anything I store in there.
All I can think of is a protracted soak (weeks) in something potent, either 30% peroxide, or an organic solvent like acetone or MEK.
Odor
quinoxaline man - 6-10-2012 at 06:54
Why not store in a vacuum desiccator under vacuum? Since the odor is noticible at atms. pressure, perhaps it will completely volatize under a high
vacuum.
Henry Swede - 7-10-2012 at 03:01
That's a great idea, Henry, I'll give it a shot. Thanks!feacetech - 7-10-2012 at 13:45
Looks kind of like "crude HFA" staining, from a SSP fertiliser plants scrubber process.
The Crude HFA can have a lot of iodine in it, this coupled with the HFA can stain PTFE like this.
[Edited on 7-10-2012 by feacetech]Oscilllator - 8-10-2012 at 21:15
Tried sodium hydroxide? It is pretty good at cleaning. Other that that, the vacuum seems your best bet.
And yes, I am very jealous of your pot collection.niertap - 9-10-2012 at 16:21
The specks might be from microscopic cracks created during the machining or small bubbles(defects) in the block they were machined from. the compound
could penetrate all of it slightly and the defects much more so. It really does seem like a small halide compound. it's high vapor pressure seems
evident of the staining where it escaped through the threaded lid.zed - 11-10-2012 at 15:19
Well, you might be able to keep them intact, and hone them out with a brake cylinder hone attached to an electric drill.
Likewise, lathe attachments might be available that would allow you to re-machine the insides of your bottles.
Third, you might be able to Vacuum distill this stinky stuff out of your bottles. Think vacuum dessication + heat.
