i've seen the PTFE capped bottles on breckland scientific but they are hugely expensive. Does anyone have any suggestions?
thanks very much.Dr.Bob - 28-3-2019 at 18:39
The blue cap on this media bottle is polypropylene, might not last long. A glass stoppered reagent bottle might be safer and would vent any fumes if
pressure builds up. Either way I would be careful of storing that mixture for long terms.Deathunter88 - 28-3-2019 at 18:52
In my experience PP handles 98% sulfuric acid very well, I have the same media bottles and the caps are fine after 3 years of storage. PP handles 70%
nitric acid reasonably well as well, the insides of my caps are bleached white but they are still hold strong. Maybe get a few extra caps to replace
after a few years.
One thing to note is that some of those amber media bottles are actually clear glass bottles with an amber coating of some kind. This coating flakes
off after exposure to acid fumes for a while. The ones you linked to look like genuine amber glass ones so you should be fine. Herr Haber - 29-3-2019 at 05:39
I wouldnt use PP for nitric acid but it's perfectly fine for sulphuric acid.
My red PTFE Duran caps didnt like nitric acid so I went for Duran Premium. After 3-4 years they are all perfectly usable
so far I have found that
Sulaiman - 29-3-2019 at 06:02
69% Nitric acid stores well (at least a few years) in hdpe bottles with hdpe tops,
96% sulphuric acid does not escape much from hdpe bottles with caps,
but it does slowly discolour towards brown,
and the outside surface of the hdpe bottle gets 'dusty/crumbly' after a few years
(I think that the sulphuric acid VERY slowly creeps/diffuses through pores in the hdpe bottle wall ?)
whereas stored in glass it stays transparent and colourles.Rsambo - 30-3-2019 at 11:52
Thanks so much everyone. That's really helpful. I'll definitely get some and see how they fair short term and let you know. Could really do with
some ptfe caps I think for the nitric acid...draculic acid69 - 31-3-2019 at 04:37
The nitric and sulfuric I get come in the same type of bottle and if I had to store that combo I'd just use the sulfuric acid bottle.nimgoldman - 31-3-2019 at 12:54
I never had any problems with sulfuric using PP cap.
I purchased two PBT caps with PTFE liner from Duran especially for HNO3 and HBr.
Note that HNO3 will leak slightly even with this cap.
There are even more expensive PFA caps, there are all-fluoropolymer, but these I think are suitable only if you frequently use them, autoclave them
and there is a risk of breaking (since Teflon is not very resistant mechanically).Herr Haber - 1-4-2019 at 03:46
Note that HNO3 will leak slightly even with this cap.
If present on your bottle remove the pouring ring.
I destroyed one of those red caps because the pouring ring was letting vapors out.
Vapors did nothing to the PTFE liner but the cap itself...
