mr.crow - 18-5-2012 at 10:28
So I bought a fritted buchner funnel on eBay and it appears to be clogged. It holds a vacuum but no liquid flows through it. The surface is white and
smooth and doesn't look very porous. Maybe clogged with silica?
How would I best clean this?
Yes I searched the googles, but would still like a personal answer to my problem. Thanks!
Mailinmypocket - 18-5-2012 at 10:33
What about trying to run something more volatile through it like methanol just to see if that makes it through? Or perhaps trying to run something
through in reverse to flush whatever is in there out the other way?
mr.crow - 18-5-2012 at 10:52
I tried using it with isopropanol when I discovered it was clogged. Really annoying because of the mechanical losses trying to get the wet crystals
out.
I was thinking of soaking it in NaOH/ethanol for a few hours
S.C. Wack - 18-5-2012 at 11:42
(Di)chromate in sulfuric acid is wonderful for many purposes.
There should be some writing on it unless it's gone, but if it's smooth it's a fine filter. Which normally could require a little vacuum, and would
hold some vacuum for some time.
And then, someone could have filtered (edit: or soaked it in) a very alkaline solution at some point, and that's that.
[Edited on 18-5-2012 by S.C. Wack]
99chemicals - 18-5-2012 at 17:12
I would avoid the Chromic acid solution as much as possible. That solution is carciogenic, toxic, volitile, corosive, horible to human flesh, and very
difficult to dispose of. I would first go with the NaOH and ethanol. Then wash if it still does not work use HCl.
mr.crow - 19-5-2012 at 11:38
It is indeed a Fine funnel. How much reduced pressure do I need? the pump does about 23 inHg (cheap gauge, goes up to 30).
Don't worry I wont be using chromic acid!
EDIT: Ok guys, false alarm! I tried it with a different filtering flask and it does indeed work! My 1L one doesn't make a good enough seal.
[Edited on 19-5-2012 by mr.crow]