# How could an absorbent material be emptied?

I have been thinking about this for quite some time: Given a foam or other absorbent material saturated with a solvent, how could you draw all the solvent to the top of the foam (basically how could you 'empty' the foam and draw all the liquid out of it)? I think a strong enough vacuum at the top of the foam should do the trick, but am not sure. If there are any publications regarding this problem, please link them in your answer as well; I have not been able to find any.

• Papers don’t always exist for things or methods that don’t work. Use the answer and progress from there. – Solar Mike Dec 3 '20 at 4:53

The vacuum could find easy pathways in the matrix of foam that could leave the hard-to-reach pockets alone like wet islands.

The best way is to take advantage of the gravity or centripetal force, acting on every single molecule of the fluid.

A container with porous bottom either tspinning by a machine or just sitting on top of a sloped drain would do.

• Thanks for the insight. How do you think I might be able to counteract that issue with the vacuum? – a43nigam Dec 2 '20 at 17:34
• I’d use a centrifuge. – Eric S Dec 2 '20 at 23:38
• @EricS, that's the Idea. The vacuum is never going to be completely effective. It's like expecting rain washing down the slope of meadows washing it in a perfect sheet form. No, it will carve creeks and leave the peaks alone. – kamran Dec 2 '20 at 23:52
• The OP wants the solvent reach a certain portion of the foam and the answer adresses that. One should add that in a vacuum, the solvent will also evaporate and that evaporation will certainly dominate after some point (basically when the volume is drained, but the surfaces are still wet). In a foam with large internal surface area surface tension will also play a huge role. – mart Dec 4 '20 at 8:41