Sciencemadness Discussion Board

Polypropylene funnel considerations

Chemorg42 - 4-6-2020 at 15:13

So the first time I used it, like an idiot, I broke my one glass funnel!
:(
Now, all I have is this plastic (I think polypropylene?) funnel. My question is, can I use it to filter a hydrochloric acid containing solution?
Specifically, I am thinking of following the wiki's synthesis procedure for salicylic acid which requires 10% HCl solution. Can I pour this through my funnel, what can / can't I use with it?
Thanks for the help.

Sulaiman - 4-6-2020 at 18:49

Polypropylene and polyethylene are surprisingly inert,
The only problems that I've had are stains and heat damage.
Dilute HCl is definitely OK.
Strong oxidisers and some solvents could be a problem but the contact is so brief that any damage is negligible,
So you can consider polypropylene or polyethylene funnels safe with all common liquids.

In general, Google "polypropylene chemical compatibility"
or substitute any other substance for "polypropylene"

[Edited on 5-6-2020 by Sulaiman]

Chemorg42 - 4-6-2020 at 19:18

OK, thanks.
I looked at a compatibility table, but it was for exposure over a 48 hour period, so it did not provide a very accurate picture. I figured that, in this case, practical lab experience was probably better than abstract tables (as useful as they can be.)

Refinery - 4-6-2020 at 23:01

I haven't yet faced a chemical that eats polyethene at NTP, and not quite sure about polypropene either. Even styrene is stated to be not compatible with PE, but a container I have has PE cap on it without any additional seals and it just sits there forever, so it can't be that bad. I've used PE siphon to transfer 98% H2SO4, 35% HCL, ammonia solution, NaOH and practically all solvents and never had an issue.

Biggest issue with plastic funnels is staining like said. They get stained easily and are difficult to clean, so if you are doing amateur chemistry, trace contamination should not be an issue in general.

RedDwarf - 5-6-2020 at 02:39

I generally assume if I can't remove a stain, then it's also unlikely to contaminate anything either.

Refinery - 5-6-2020 at 03:26

Well there's that, too. I've got some parts that are contaminated by carbon, but it basically doesn't react with anything under 600C, so it really doesn't matter.

Chemorg42 - 6-6-2020 at 08:08

98% H2SO4?
Wow, that is impressive.
Nitric acid is not compatible, though, correct?

CouchHatter - 6-6-2020 at 09:20

I've used mine with 52% nitric acid and not noticed any staining. I also poured 40 mL sulfur chloride through one and it almost completely swole the stem shut in seconds. Not going to use that one for much else.

Refinery - 6-6-2020 at 10:00

Polyethene and other same group stuff in general needs superacids to react. Polyethene handles sulfuric acid in ntp like everyday - it's sold in it.

Mateo_swe - 16-7-2020 at 08:34

For these situations its good to have some compability charts for plastics and chemicals.
Here is 2 that i have used.

Attachment: chemicalresistance.pdf (199kB)
This file has been downloaded 307 times

Attachment: Plastics chemical resistance guide.pdf (1.6MB)
This file has been downloaded 363 times