funnel with built in filter???

[auntyjack]

ok, i've got this funnel here that i bought on impulse(it was only ten bux and it looked so groovey) and i thought maybe some of you tech heads might be able to tell me a bit about it.....the big bit where you pour stuff is not conicle, it is a slightly tapered cylinder and becomes conicle at the bottom where it meets the spout...inside the funnel, across the conicle bit at the bottom is a slightly convex, six mill thick, glass or ceramic filter...i guess i'm asking has anyone had experience with these and can you tell me the specifications of such a filter...the only markings on it say,"pyrex-made in england" and a number 3 next to a little rectangle...thanks

[politoxicomania]

Yes i know this very well but i dont know the name in english. In german we call it "Fritte". Its made to collect crystalls or other solid material. Normally there are some gas inlet or outlets to work under inert conditions. The Number written on it describs the filter. There are 4 categories  1 is very crude ond 4 is very fine filter.
If the Filter shows dust on it clean it with HCL/H2O2 mixture, till it shows a white surface. Dont use it to filter amorphe precipitate or Bariumsulfat.
Always clean it conscientiously.

[Un_Chambered]

I think thier called sintered glass funnels,but thats probably wrong.Do you know what size? coarse,meadium,or fine.swim found the meadium to bee good for most of his purposes but the coarse still needed paper.

[pickler]

I believe they are called fritted filters.

[Un_Chambered]

Thanks pickler,my gut was telling me that wasn't it but my mouth disagreed .
So wtf is a sintered glass funnel then?

[terbium]

So wtf is a sintered glass funnel then?

I believe that the terms fritted glass and sintered glass are both used to mean the same thing.

[abolt]

Make sure you use filter papers with these type of funnels or the sintered/fritted glass can become clogged up with shit that renders them useless.

[Rhodium]

I disagree. When I opt for a fritted glass filter in a lab procedure is because whatever I am filtering has a tendency to clog a regular paper filter and hence I use a glass funnel instead. This if I want to keep the precipitate. If I instead want to keep the filtrate, I add a centimeter thick layer of Celite in the fritted glass funnel to prevent clogging.

[Un_Chambered]

Swic says he found his very usful without using paper(except the coarse size)and without clogging being a problem,esspecially w/vacuum applied.
And no lost product traped in paper fiber .
Peace,chambered.

[yellium]

I disagree. When I opt for a fritted glass filter in a lab procedure is because whatever I am filtering has a tendency to clog a regular paper filter and hence I use a glass funnel instead. This if I want to keep the precipitate. If I instead want to keep the filtrate, I add a centimeter thick layer of Celite in the fritted glass funnel to prevent clogging.


And then there's the shitty situation where you need to go for a sintered glass filter because the solution you need to filter is way to aggressive for paper filtering, but the only sintered glass filter you have is F-4 or F-5, meaning that the moment you pour the solution you want to filter on it the filter gets clogged up immediately.

And then you find out that there's no way you can get thet filtrate out of your filter.

[terbium]

And then there's the shitty situation where you need to go for a sintered glass filter because the solution you need to filter is way to aggressive for paper filtering, but the only sintered glass filter you have is F-4 or F-5, meaning that the moment you pour the solution you want to filter on it the filter gets clogged up immediately.
This is a situation where Whatman glass fiber filter "papers" are useful.

[abolt]

If I instead want to keep the filtrate, I add a centimeter thick layer of Celite in the fritted glass funnel to prevent clogging.

Chief..........Swim saw the performance of a sintered glass funnel decline when using it as a Buchner, sans filter paper or Celite, with the dreaded Al sludge.

Swim no longer has this problem as Swim has since acquired Celite.

Luckily for Swim, another bee advised him to drop it into Hcl, which seemed to clear it up.

[Osmium]

Where Os worked these thingies, up to 125ml size were considered 'expendable', if they appeared to be clogged or dirty they were immediately discarded. Obviously Os' employer used to get better glassware prices than most bees  

Do NOT use them for Al sludge filtration! Al sludge MUST be filtered through paper, repeatedly, because it will clog them in seconds!

Inorganic shit is best dissolved using acids or bases, or whatever reagent will dissolve the precipitate in question.

Organic shit can be removed with solvents. If it doesn't want to go away, adding THF and a little red HNO3 will burn the shit out of every contamination (Don't do this inside! Fume hood only! Nasty cloud of NOx!)
H2SO4/H2O2 works equally well, but make sure that no acetone is trapped in the filter funnel).

[Rhodium]

Do NOT use them for Al sludge filtration! Al sludge MUST be filtered through paper, repeatedly, because it will clog them in seconds!

Or - you can use a centimeter or two of Celite in any kind of filter funnel. If the filtration slows down, scrape the Celite surface carefully to expose a "new" unclogged surface (but never as deep as to touch the filter), increasing the filtration speed again. Wash the filter cake with IPA or THF, then remove all the sludge, taking care not to take too much of the celite with it, boil the sludge in some IPA for a few minutes, then filter it all again. Rinse cake with THF or IPA. This to ensure that no product stays attached to the Al sludge.

The same general procedure can very successfully be used with Lithium Aluminum Hydride post-reaction sludge after it has been decomposed with IPA and aqueous NaOH solution as described in

https://www.thevespiary.org/rhodium/Rhodium/chemistry/lah.reduction.html

[abolt]

General Cleaning

A new fritted filter should be washed by suction with hot hydrochloric acid and then rinsed with water before it is used. This treatment will remove loose particles of foreign matter such as dust. It is advisable to clean all Pyrex® brand fritted filters as soon as possible after use. This will prolong their life.

Many precipitates can be removed from the filter surface simply by rinsing from the reverse side with water under pressure not exceeding 15 lbs/square inch. Drawing water through the filter from the reverse side with a vacuum pump is also effective. Some precipitates tend to clog the pores of a fritted filter. Treatment here must be by chemical means.

A few suggestions found generally useful follow:

Material           Cleaning solution

Fatty materials - Carbon tetrachloride

Organic matter* - Hot concentrated cleaning solution, or hot concentrated sulfuric acid plus a few drops of sodium or potassium nitrite
 
Albumen - Hot ammonia or hot hydrochloric acid
 
Glucose - Hot mixed acid: H2SO4 + HNO3

Copper or iron oxides - Hot hydrochloric acid plus potassium chlorate

Mercury residue - Hot nitric acid

Silver chloride - Ammonia or sodium hyposulfite

Viscose - 5 to 10% NaOH, followed by cleaning solution

Aluminous and siliceous residues - 2% hydrofluoric acid (EDIT: Hydroflouric acid is very dangrous, newbees take care)followed by concentrated sulfuric acid; rinse immediately with distilled water followed by a few mL of acetone. Repeat rinsing until all traces of acid are removed.



*Cleaning solution containing bichromate will tend to permanently stain fritted ware. This is undesirable for biochemical or pharmaceutical work, and hence the sulfuric-nitrite solution is suggested.

Operating Pressures
 
Fritted glassware is designed primarily for vacuum filtration or for gas flow at relatively low pressures. If used for pressure work, the MAXIMUM differential on the disc should not exceed 15 pounds per square inch. Care should be taken when preparing sample solutions to avoid trapping air. If dissolved air is present, the flow rate may be reduced by up to 50%

Thermal Limitations
 
The resistance to thermal shock of fritted ware is less than that of non-porous Pyrex brand labware. Therefore, articles of fritted ware should not be subjected to excessive temperature changes or to direct flame.

Dry fritted crucibles at room temperature may be placed into a drying oven operating at 150°C (302°F).

Fritted ware may be safely heated in a furnace to 500°C (932°F) without ill effect, provided that the cycle of heating and cooling is gradual.