Sciencemadness Discussion Board

Fritted glass filtration question

NEMO-Chemistry - 29-5-2016 at 18:27

I only have a very small funnel with a glass frit on the bottom. Reading the forum I see a number of questions regarding the cleaning of the frit.

Would using a decent filter paper on top of the frit help prevent the need to clean these with things like Piranha solution? I would like to filter a few solutions but the thought of having to use Conc acids etc to clean the frit after puts me off a bit.

Metacelsus - 29-5-2016 at 20:14

Usually the point of the frit is so that you don't need filter paper. However, using filter paper with the frit would likely be fine, as long as the stuff you're filtering doesn't damage the paper (and then clog the frit with paper degradation products).

crazyboy - 29-5-2016 at 21:27

It depends, as Metacelsus notes one of the reasons to use fritted glass is that you don't need filter paper. In my experience the issue is not having a material adhere to the top of the frit requiring scraping. The problem is more often the product or impurities that are partially dissolved in the liquid fraction will not wash out with water but only with copious amounts of warm solvent or harsh treatments like Piranha.

For many filtration the material comes right off the frit and is very soluble in hot water, or perhaps dilute acid or base so harsh methods are not required. Anyway sulfuric acid is cheap and a little goes a long way.

NEMO-Chemistry - 29-5-2016 at 21:50

Ok thank you, I might invest in a Buchenar funnel and save some of the headache ;).

ave369 - 31-5-2016 at 03:45

I only use the fritted funnel for stuff that reacts with paper, such as ferrates or sulfuric acid. This kinda defeats the purpose of having paper in your fritted funnel. For everything else, I use paper and a common funnel.

NEMO-Chemistry - 31-5-2016 at 04:09

Quote: Originally posted by ave369  
I only use the fritted funnel for stuff that reacts with paper, such as ferrates or sulfuric acid. This kinda defeats the purpose of having paper in your fritted funnel. For everything else, I use paper and a common funnel.


I need to stop being cheap and using coffee filters! the bottom drops out of them. Its all a mute point now as I dropped the funnel!