Sciencemadness Discussion Board

Interesting filtering idea - Using a string/wick to siphon/filter solution via gravity??

RogueRose - 7-6-2016 at 21:05

I had a strange thought and I'm not sure I have ever seen or heard of this before so please tell me if this is a usable practice or if there is a better method/tweek to what I am explaining.


Let's say there is something in solution and there is particulate matter of all sizes in the solution. The particulate, no matter how small, does not dissolve into the liquid but the liquid is holding some dissolved substance.

The mixture is allowed to settle and preferably placed in a tall narrow column to allow the particulate to sink to the bottom. A string/wick is wetted and then placed in the solution and the other end is allowed to hang outside the holding cylinder at a lower level than the bottom of the holding cylinder.

As far as I can tell there should be capilary action that will allow the liquid to travel up and then down the wick.

IDK if it would be beneficial to put the wick in tubing I guess it depends upon what the liquid is.

Now my question is, if the wick is placed all the way to the bottom of the solution/particulate, will the particulate travel up the wick as well?

Anyone ever hear of this, use it or anything else? Any food for thought on this idea?

Thanks for any suggestions or info.

j_sum1 - 7-6-2016 at 22:19

Volume flow rate will be small. But for a set-and-forget that you leave overnight it would probably work.
The other thing to consider is that you will probably not get rid of the very last bit of your liquid. There is likely to be some remaining unless you manage to get the end of your wick to the very lowest point.

TinSandwich - 7-6-2016 at 22:21

I remember seeing a similar system being used in a video on the youtube channel Cody's Lab (great channel btw). I think it was in a video about extracting nitrates from dung.

It didn't work for him but he seemed pretty confident about it so I'll assume he knew it could work in theory. I'll see if I can find the video.

https://youtu.be/VaGykqoNhJk?t=187


[Edited on 8-6-2016 by TinSandwich]

NeonPulse - 8-6-2016 at 17:08

This does work but very slowly. Very slow. It's not a new idea but it is a working concept if the wick and receiving vessel are positioned right. You do lose liquid through spilling drops and evaporation but any particulates are left behind. Also if you have a substance dissolved in the liquid it can crystallise on the wick and slow the process further or even halt it altogether. Filtration is a much better option.

macckone - 8-6-2016 at 22:32

Yes this can work. It is slow but works moderately well for things that tend to clog filter paper. Calcium compounds are one good example.

Eddygp - 10-6-2016 at 07:34

The wick would not lose as much water from evaporation if inside some tubing. What material are you thinking about for the wick?

RogueRose - 12-10-2016 at 19:49

Quote: Originally posted by Eddygp  
The wick would not lose as much water from evaporation if inside some tubing. What material are you thinking about for the wick?


Well a lot of things I guess, usually solutions (close to saturation) like FeSO4, CuSO4, CaNO3, etc..

An example is FeSO4 that has either rust (Fe2O3) or ferric sulfate (Fe2(SO4)3) in it and it passes through paper coffee filters (the brown rust like color) fairly easily. There are also some copper compounds like CuCl2 and a Cu + (NH4)2SO4 (which has a similar color to the light blue CuCl2) that pass through paper filters much too easily.

I'm wondering what kind of string/wick/cloth can be used to do this.

[Edited on 13-10-2016 by RogueRose]

CuReUS - 13-10-2016 at 10:26

I have another idea how this might work
1.take a waste container with a flat bottom and make lots of holes in the bottom
2.take strings of moderate thickness (ex- shoelaces) and pass them through the holes
3.Now tie a big fat knot at the end of the string inside the container so that it does not come out of the hole
4.Use a tiny amount of silicone sealant around the holes from the outside of the container to make the holes waterproof
5.Finally,place this container over a bowl and pour in the solution you want to filter

you could use an empty pringles container and make holes in the plastic cap.After putting the strings and waterproofing the holes,you could pour in your solution,shut the lid tightly and turn the container upside down over a bowl or beaker.


[Edited on 13-10-2016 by CuReUS]