Büchner Funnel Filtration Troubles

Hello, I am having trouble with my 500 mL Büchner funnels. They seem to be filtering through far too slow, taking 25-30+ minutes to pull 1000mL, in comparison to how fast it looks in the videos on YouTube and from what I’ve read in others posts.

My last few attempts consisted of laying down a coffee filter over the fritted disc, then a whatman 2.5 micron filter paper. Then I would pour some ethanol in and turn on vacuum. Next, I would mix a slurry of either T5 or AC, then dump that into the funnel. The first few seconds after applying vacuum, the ethanol would come through pretty fast, but after ~30 seconds or so, it became agonizingly slow. I started to see ethanol evaporating underneath the fritted disc.

I would come back 10 minutes after filling the 500ml funnel with about ~300mL of AC/T5 slurry and it looked like it barely went down, and what was coming through came through in drips, it was constant drips but still drips. Very slow.

Is there something in my procedure I’m doing wrong? I know my vacuum is strong enough. Is it the two papers? I’m trying to get the AC/T5 out of my extract, would I just need to keep filtering in another Büchner (or maybe the same one) over a bed of Celite? I didn’t have any Celite in hand at this time, I was trying to follow the LostBiologist’s Tek, the part where he describes making the filter cakes.

Please help! Any info is much needed and greatly appreciated.

T5 is incredibly slow. What kind of vacuum are you using?

I can funnel about 8liters in 4 hours through a bed of t5 and carbon. Using 750ml funnel

300ml of a slurry in a 500ml bruchner funnel? Pretty sure your using way to much. You want like a 3/8in t5 and 1/4in of carbon. If your vacuum is sufficient and your not getting a consistent pull you wont be able to seat your paper. If your vacuum is able to pull consistently the paper should be seated and therefore no consumables should make it past that. No need for more then 1 filtration. I’ve never had issues and only use 1 watman filter.

Always run small amount of clean ethanol through cake/filter. Take off vacuum, clean flask. Then,begin to filter your tinture.

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I should have been more specific about the slurry - I mix enough T5 in 300mL of ethanol to make only a ~1/4” cake once the 300ml of ethanol has been pulled through. Is that too much for making the cake?

Also, is a #1 whatman paper enough for keeping out AC/T5? I thought I read somewhere around here a 2.5 micron paper would work but it seemed to still make it past that.
Is Celite not necessary for filtering out AC/T5? After my latest troubles, I had figured it was necessary, but the tek I read here said something along the lines of-
Continuing to pour ethanol over the AC/T5 cake and filter paper below it until you no longer see sediment in the flask.

What is the case with that? Do I need Celite? If I do, would I need to keep filtering my extract over Celite multiple times to assure that there’s no leftover Celite in my extract solution?

I appreciate your answer!

You put a coffee filter over the frit and then a 2.5 micron membrane filter? Pretty sure a coffee filter is >greater than 2.5 micron …

2.5 micron membrane should be kinda slow with that setup its not unusual. Buy some whatmann 15-30 micron filters and try them and note the difference.

2 micron should keep AC out

EDIT: 2.5 micron → 2

I spoke to soon, I get what your saying now. I think you’ve confused the part where thelostbio describes making the cakes. Your not using an Etoh tinture when making the cake. Your simply make a slurry with the powder with clean solvent to add to your bruchner funell to make a cake. Jumped the gun on replying. Feel free to DM I love to help ya out. I also use thelostbios bucket Tek.

Edit: Okay your doing I right, I’ve never had any sediment get past a whatman 1, maybe that would do the trick

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Use a puck of glass wool on surface.

Yeah, a coffee filter over the fritted bed and then a 2.5 inside of that coffee filter. I was trying to keep as much AC/T5 out of my extract solution. I had read 2.5 micron would be sufficient.

What I am attempting to do is carbon scrub and also T5 scrub, and I had read that these powders make it past most filter papers, and that Celite was needed. If I am using Celite to filter AC, wouldn’t I need to filter solution again to filter any Celite making it past the fritted disc bed?

The coffee filter isn’t doing anything its about (20 micron)- the 2.5 micron filter has already grabbed everything

Stage the filtration so your Product passes through a 20-40 micron filter and then the 2.5 micron and see if that makes a difference

Make the DE cake on top of the 2.5 membrane and skip the coffee filter

Ahh I see. So changing to a porcelain non fritted style Büchner wouldn’t speed anything up much? Is a porcelain Büchner more or less superior to a fritted disc funnel? The disc is a pain in the ass to clean. I just broke my only two trying to bake the AC out of the discs.

Honestly they’re both fragile, bench scale implements I would look for something like stainless steel. In my opinion at that scale fritted funnel vs Büchner its preference, I choose fritted funnel. There are many alternatives to Buchner there are others here that know more about those options than me. Use the search bar and you will see too. The search bar can lead you to a land of milk and honey.

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