Sciencemadness Discussion Board

Questions about pleated filter paper.

PYRIDINEyade - 21-9-2023 at 04:53

Please tell me why pleated filter paper is not suitable for filtration to collect residue?

j_sum1 - 21-9-2023 at 14:17

Never heard of this.
I do it all the time.
(Ok. Not all the time. But whenever I can be bothered to pleat the paper.)

Sulaiman - 21-9-2023 at 20:21

Before I had my 'vacuum' filtration system I used many packs of filter papers,
that I mostly pleated,
because pleating can significantly increase the rate of flow of the filtrate,
but sometimes I got tiny fibres from the centre of the filter paper in the recovered filter cake.
My pleating damaged the structure of the paper,
especially at the centre where all of the pleats meet.

If funds permit, I can really recommend 'vacuum' filtration;
. Much faster
. Much smaller/cheaper size papers required
. Quicker drying of filter cake
. Less likely to shed fibres into your product

If you do a lot of filtering you will really appreciate 'vacuum' filtration.
I use a porcelain Buchner funnel, conical filtration flask, 12v 'vacuum' pump and power supply.
A stand clamp is necessary to reduce the probability of accidents.
So quite an investment, but I feel it is worth it.
(a more modern version would be a sintered glass Buchner funnel, I've not tried so can't comment)

I used 'vacuum' above to represent "reduced pressure"
Very low pressures (such as due to a rotary vane pump) are not good as most liquids will boil/vapourise.
A water aspirator is more than good enough,
My pump's - 70 kPa relative to atmospheric pressure (was - 80 kPa when new) is more than adequate.
Some members use a small hand operated vacuum pump.

PS if you do get a vacuum filtration kit,
before buying check what size (and grades) of filter paper are cheap and obtainable in your location or online.

choose size based on your expected type of usage,
and get a filter flask with a ground joint as it can then be easily converted to a gas generator etc.

[Edited on 22-9-2023 by Sulaiman]

PYRIDINEyade - 21-9-2023 at 20:50

Thanks for the reply.
I've looked online and consulted the literature several times, but none of them gave me a clear reason for this.
I asked my professor about it and he replied that there was no problem, so I will use the pleated filter paper from now on when collecting residues that are slow to filter.

Thanks for the reply.
It's very nice that it's hard for fibers to get mixed in.
I'll give that a try too.