vanBassum
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Filtration setup options
Hello,
I want to buy a decent filter setup, but I notice they come in 3 different flavors. See the attachment. What should I keep in mind when choosing
between the 3?
I have used a funnel style filter with a fritted disk, so I know they are prone to clogging. Especially if you put the wrong things in there. I do
like the idea of the round filter papers, I would assume this catches the particles before they can go to the fritted disk.
I have seen sets with a little hand vacuum pump, this seems very practical.
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metalresearcher
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I have such a setup with a Büchner funnel. I put a piece of filter paper in it (even a piece of a coffee filter cut out to the right circular size
wlrks as well), put the wet KClO3 crystals in it and lower the pressure in the flask with the hand pump.
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Sulaiman
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For many years I used just the type on the right.
If you choose this type check what sizes of filter papers are easily available to you before purchasing.
(eg. I chose 90mm paper size)
The minor negatives are:
. Top heavy - I recommend some type of stand/clamp
. Expensive papers required for some filtrations
. I never know if the inside is clean
I recently bought a couple of fitted glass filters (60ml, G3 and G5)
and I like them too.
The minor negatives are:
. Cleaning - need to choose your solutions appropriately.
. Sometimes papers may give less overall mechanical loss than frits
As I recently mentioned in a different thread,
I like small cheap mechanical vacuum pumps (typically 12 Vdc) for filtration.
IF you know what you are likely to be filtering in future then recommendations are easier,
but who knows which way our interests will take us.
Overall I think that the porcelain types are good for larger volumes,
and frits for smaller volumes.
I'd l ike a 90mm fitted filter to get the best of both options.
Other members will probably have diverse opinions, horses for courses.
CAUTION : Hobby Chemist, not Professional or even Amateur
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XeonTheMGPony
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I got a set up similar to A
But I just use a large Erlenmeyer Flask, a in line gas take off adapter then just standard Büchner funnel.
The reason is every thing can be taken apart and cleaned and should I need to move to a second flask due to volume I can easily do it
All so I can use the inline gas take off adapter as a securing point for the whole set up, and using shim can swap flasks with out disturbing the
funnel.
Added to that should I break the hose connection point it is easier to replace
[Edited on 24-8-2024 by XeonTheMGPony]
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vanBassum
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Is it possible to clamp a filter paper between the glass joint on the B style filter?
I assume the different styles are more suitable for specific applications?
I like the idea of separate parts, in that case the parts can also be used for other things. The problem with B is that all glassware is 'special' or,
at least, I can't think of anything I can attach to it. But I do like the easy access to the fritted glass for cleaning.
[Edited on 24-8-2024 by vanBassum]
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Dr.Bob
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A the glass frits are really nice, as they don't require filter paper, but it can be used to protect the frit from clogging as easily. But I have
dozens of dirty frits that i am trying to clean currently, and they can be very hard to clean once dirty. There are entire forum topics on how to do
that well.
Type B are membrane filter frits, they are typically used with thin nylon or pTFE membrane filters that are very fine, so they work best for filtering
out small amounts of fine particles. They clog easily if overloaded. But the membrane mostly protects the glass frit in the bottom piece.
Type C Buchners are very practical. They are quite non-porous, so they don;t clog much, the paper may clog, but it is easy to replace. The filters
are easily cleaned with almost anything, and the funnel is able to be cleaned with acid or base or solvent well. They are also the cheapest one.
There are multiple varieties of all three and even other variations, plus tools like Celite which can help filter fines better and protect the frit
better. I have examples of all of these available, should you want to buy any.
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vanBassum
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Thanks for the information,
For my purposes, I think the A style is the most useful.
I just bought this:
https://nl.aliexpress.com/item/32966117013.html
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Sulaiman
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Very nice!
That kit should cover almost all requirements.
I strongly recommend the use of or investment in a clamp/stand for filtration.
Although the wide base of the conical flask gives good stability,
accidents happen,
eg the pump accidentally drops, pulling over the setup via the air tube.
eg a clumsy elbow knocks over the filtration setup.
A clamp/stand (or one more) finds many uses.
CAUTION : Hobby Chemist, not Professional or even Amateur
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Keras
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As indicated, sintered glass funnels are nice, especially if you want to filter coarse crystals. Beware, filtering smaller crystals or powders can
result in very long filtration times, as well as clogging of your filter. Sometimes, the clogging particles can be cleaned using, say, acids, bases or
even piranha solution in extreme cases, but sometimes they can’t be pushed away (plaster is a good example of a compound that’s extremely hard to
clean once it has got into the pores). If you suspect your final product might clog your filter, then use a porcelain Büchner with suitable filter
paper. A porcelain Büchner has large holes and cannot be clogged. There’s a whole collection of filter papers to choose from, I recommend getting
glass fibre filters because they’ll resist about everything, comprising very oxidising compounds such as potassium chlorate or bleach which would
destroy standard cellulose types. You can choose between various 'speeds' which correspond to the thickness of the pores. As mentioned, in case you
want to filter out very small particles or tarry substances that sometimes stain aromatic compounds, use diatomaceous earth over your paper filter.
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