bigredox - 11-10-2017 at 19:10
I have a very expensive glass Buchner funnel with a coarse frit filter disk. A student used it to filter a mixture containing red P without celite or
any other filter aid. Now the frit is contaminated throughout with red P.
How do we get the frit clean again? I'm to the point of trying to burn it out.
JJay - 11-10-2017 at 19:19
Burning it out might be bad for the frit since it could cause concentrated phosphoric acid to form... I'd probably try an aqueous oxidizer... perhaps
bromine water?
Texium - 11-10-2017 at 19:24
Bromine water is a good idea, just be cautious. Phosphorus and bromine can get kinda sparky. And make sure to do it with good ventilation as you'll
get HBr as a byproduct.
bigredox - 11-10-2017 at 19:39
I just read about using chlorine water. I can make either Cl or Br water easily enough.
How about 5% sodium hypochlorite instead. That we have on the shelf already.
Note: Our lab has excellent fume hoods. Besides that I would probably capture the acidic vapor in a dilute aqueous base for disposal instead of
blowing out pollution.
[Edited on 10/12/2017 by bigredox]
JJay - 11-10-2017 at 20:19
Sodium hypochlorite was my first thought, but I wasn't 100% sure if it would work. Let us know?
woelen - 11-10-2017 at 22:29
Simple bleach works perfectly fine. Just soak it with bleach and wait until no more phosphorus can be seen. Then rinse with distilled water.
MeshPL - 12-10-2017 at 10:43
Nitric acid should work too, just as aqua regia.
woelen - 12-10-2017 at 22:46
Bleach works better, fasster. And wasting precious nitric acid for this is not a good idea, unless you work in an institutional lab and have no issues
obtaining nitric acid.