7 replies to this topic

[pyrotrev]

I've been trying to make a few interesting chems (copper benzoate etc), but have problems collecting precipitates since the filter paper goes so soggy it's difficult to scrape all the ppt off it without it tearing and getting muddled up. Does anyone know of any filter paper that has agod wet strength please?

[GalFisk]

I've been trying to make a few interesting chems (copper benzoate etc), but have problems collecting precipitates since the filter paper goes so soggy it's difficult to scrape all the ppt off it without it tearing and getting muddled up. Does anyone know of any filter paper that has agod wet strength please?

I used three layers of regular coffee machine filters when making copper benzoate, since it tends to dissolve the glue in the filter seam. I didn't bother trying to scrape all the benzoate out of the filter, instead I squeezed out as much water as possible and let it dry inside the filter. It's much easier to get the benzoate out once it's dry.

[YT2095]

make 10g batches at a time and dry it in the filter as mentioned above, it comes out very nicely afterwards.
DO wear a dust mask when removing though, the particles are quite fine and it crumbles Very easily.

[Arthur Brown]

There were glass filter circles from Whatman once GF-A and GF-B these were strong and very acid resistant. very limited for sizes and had to be used flat -use a Buchner funnel. There always were grades of Whatman paper in the 54x series that were good at retaining fine ppts and hard enough to stay strong in use.

Also available are sintered glass discs and funnels. You may need a vacuum filtration setup.

http://www.dixonglas...dard/index.html and look for sintered

Check with them about porosity and the retention of fine ppts.


Sometimes fine ppts need to be floculated into something bigger so that they will filter, we used to filter in a 2 inch depth of filter pulp then burn the paper off in an oven but you can't do that with organics!

added link;

http://www.camlab.co...ecategoryid=307

Edited by Arthur Brown, 10 March 2008 - 10:02 PM.

[pyrotrev]

I think I'll try some of that Whatman 54 stuff - looks just the ticket - thanks!

[YT2095]

don`t waste your Money!

go to ASDA and buy a pack of 40 Coffee filter papers by Rombouts.
I`v used them in my Lab for YEARS and never once had an issue with them!

if you want to keep ALL PPTs then simply get some rockwool (any fish tank aquatic shop) and roll it into a ball that fits nicely into the stem of your funnel, then proceed as normal, being sure not to pack it in TOO tightly.

Edited by YT2095, 11 March 2008 - 01:48 PM.

[Arthur Brown]

Papers from the 42 series are slow with good retention of fine ppts Papers from the 542 range are also hardened paper for resistance to acid and alkaline media.

Coffee filters will pass much of the fine ppts as they are usually too coarse.

[pyrotrev]

don`t waste your Money!

go to ASDA and buy a pack of 40 Coffee filter papers by Rombouts.
I`v used them in my Lab for YEARS and never once had an issue with them!

if you want to keep ALL PPTs then simply get some rockwool (any fish tank aquatic shop) and roll it into a ball that fits nicely into the stem of your funnel, then proceed as normal, being sure not to pack it in TOO tightly.

Not quite so easy with a Buchner funnel! But the idea of something you can wash/squeeze stuff out of is nice