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  4. Can you use capillary action to clean water or reduce salinity
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Can you use capillary action to clean water or reduce salinity

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Offline championoftruth (OP)

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Can you use capillary action to clean water or reduce salinity
« on: 30/07/2022 13:34:02 »
I have seen videos of capillary action as below but the question can it be used make dirty water into clean drinking water?

Would it remove bacteria, viruses and protozoa?

Would it remove or reduce salinity if using seawater?


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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #1 on: 30/07/2022 19:48:37 »
Quote from: championoftruth on 30/07/2022 13:34:02
the question can it be used make dirty water into clean drinking water?
No.
It might remove a lot of impurities  but not all of them.
Essentially, that's just a slow complicated way to filter the water.
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Offline championoftruth (OP)

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #2 on: 30/07/2022 21:07:52 »
Quote from: Bored chemist on 30/07/2022 19:48:37
Quote from: championoftruth on 30/07/2022 13:34:02
the question can it be used make dirty water into clean drinking water?
No.
It might remove a lot of impurities  but not all of them.
Essentially, that's just a slow complicated way to filter the water.

Complicated? 2 cups and a tissue.

Does not answer the question I ASKED
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Offline evan_au

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #3 on: 30/07/2022 23:47:18 »
Quote from: championoftruth
can it be used make dirty water into clean drinking water?

Complicated? 2 cups and a tissue. Does not answer the question I ASKED
The average human adult needs about 2 liters of drinking water per day (if they are willing to give up sanitation).

"2 cups and a tissue" will not produce 2 liters of fresh water per day, so "No" is still the answer.

Reason: It takes real energy to separate water from impurities.
- Capilliary action is driven by surface tension (which operates once) and/or evaporation (which doesn't deliver drinkable water).
- Extracting fresh water from sea water takes energy. In lifeboats, additional fresh water can be produced by a solar still or by a semi-permeable membrane and muscle power.

https://www.usgs.gov/special-topics/water-science-school/science/desalination
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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #4 on: 31/07/2022 10:38:21 »
Quote from: championoftruth on 30/07/2022 21:07:52
Quote from: Bored chemist on 30/07/2022 19:48:37
Quote from: championoftruth on 30/07/2022 13:34:02
the question can it be used make dirty water into clean drinking water?
No.
It might remove a lot of impurities  but not all of them.
Essentially, that's just a slow complicated way to filter the water.

Complicated? 2 cups and a tissue.

Does not answer the question I ASKED
I think you will find that I did answer; and the answer was "no".
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Offline alancalverd

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #5 on: 31/07/2022 12:56:58 »
Or "yes, but".

Having just failed a COVID test I can report that solid/liquid chromatography still works. The principle is that the solvent permeates (by capillary action) the column faster than any solute or suspension, so if you built a long chromatography column and put some contaminated water in at one end, the first liquid to appear at the other would indeed be clean water. It would be quickly followed by salty water and eventually by viruses, bacteria and whatever else you don't want, but the first few molecules would be pure H2O. Not a practical procedure.
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Offline evan_au

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #6 on: 31/07/2022 22:28:51 »
Quote from: alancalverd
Having just failed a COVID test
So you are saying that you failed, but the test method was a success...
- Get well soon!

PS: In Australia, demand for PCR capacity has dropped, so some laboratories are now routinely checking for COVID, Influenza (A & B) & RSV; several respiratory viruses circulating in our winter.
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Offline alancalverd

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #7 on: 31/07/2022 22:37:22 »
My favorite t-shirt says "I'm not stupid. I got A+ on my blood test."

Apropos COVID, I've been working for some time with a group developing a rapid electronic breath test to replace nasal swabs and chromatography. I'd almost given up hope of making any money from the project a couple of months ago, but COVID has suddenly become fashionable again and is sweeping Europe like Beatlemania. It's an ill wind, as they say.
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Offline Petrochemicals

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #8 on: 31/07/2022 23:31:49 »
The capillary action shown in the video could be said to be a syphon, thus gravity assist. A gravitational impetus can be used as a source of energy in any filter. Capillary action uphill would be creditable as a theory.
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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #9 on: 01/08/2022 10:02:55 »
Quote from: Petrochemicals on 31/07/2022 23:31:49
Capillary action uphill would be creditable as a theory.
If capillary action made water run uphill and drip into a beaker it would be a perpetual motion machine.
So, those of us who are not Petrochemicals will see that it's impossible.
Petrochemicals won't see that...
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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #10 on: 01/08/2022 10:11:20 »
Quote from: alancalverd on 31/07/2022 12:56:58
Having just failed a COVID test I can report that solid/liquid chromatography still works. The principle is that the solvent permeates (by capillary action) the column faster than any solute or suspension,
No it's not.
Plenty of materials "run on the front".
The process of chromatography uses an equilibrium (or near so) system.
What you are talking about is using it as a sieve.

You can strip a lot of stuff out of water using reverse osmosis.
The pressures involved are fairly high (40 to 60 PSI according to "the first reference I found with google") but, in principle could be generated using gravity.
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Offline evan_au

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #11 on: 01/08/2022 11:49:47 »
Quote from: Bored Chemist
If capillary action made water run uphill...
That's what trees do - a fine capilliary in the trunk raises the water quite high, and transpiration does the rest...

But it uses solar power to drive the water cycle.
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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #12 on: 01/08/2022 11:59:49 »
Quote from: evan_au on 01/08/2022 11:49:47
Quote from: Bored Chemist
If capillary action made water run uphill...
That's what trees do - a fine capilliary in the trunk raises the water quite high, and transpiration does the rest...

But it uses solar power to drive the water cycle.
Let me know when you get one to drip water into a beaker at the top.
This, BTW, doesn't count because it's not powered by capilliary action.
https://en.wikipedia.org/wiki/Guttation
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Offline Petrochemicals

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #13 on: 01/08/2022 14:28:05 »
Quote from: evan_au on 01/08/2022 11:49:47
Quote from: Bored Chemist
If capillary action made water run uphill...
That's what trees do - a fine capilliary in the trunk raises the water quite high, and transpiration does the rest...

But it uses solar power to drive the water cycle.
I  tried squeezing  tissue and liquid came out.
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Offline Bored chemist

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #14 on: 01/08/2022 14:38:06 »
Quote from: Petrochemicals on 01/08/2022 14:28:05
I  tried squeezing  tissue a
So, you made a force move through a distance.
You did work on the system.

Did you understand that in the context of of a perpetual motion machine?
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Offline Deecart

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #15 on: 01/08/2022 17:17:15 »
Quote from: Bored chemist on 01/08/2022 10:02:55
Quote from: Petrochemicals on 31/07/2022 23:31:49
Capillary action uphill would be creditable as a theory.
If capillary action made water run uphill and drip into a beaker it would be a perpetual motion machine.
So, those of us who are not Petrochemicals will see that it's impossible.
Petrochemicals won't see that...

It depends on the fluid you use.
So no "perpetual machine" problem (at least i dont like this kind of "proof" : "It would be a perpetual machine so it cant exists"; i think that it is not how scientists are reasoning).

Here the example that contradict your belief :
Superfluid helium

But you are right, for liquid water at standard temperature, capilarity cant make a liquid flow beyond the top of the tube.
« Last Edit: 01/08/2022 17:22:32 by Deecart »
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Offline championoftruth (OP)

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #16 on: 01/08/2022 17:36:24 »
Quote from: alancalverd on 31/07/2022 12:56:58
Or "yes, but".

Having just failed a COVID test I can report that solid/liquid chromatography still works. The principle is that the solvent permeates (by capillary action) the column faster than any solute or suspension, so if you built a long chromatography column and put some contaminated water in at one end, the first liquid to appear at the other would indeed be clean water. It would be quickly followed by salty water and eventually by viruses, bacteria and whatever else you don't want, but the first few molecules would be pure H2O. Not a practical procedure.

That is what i was going to suggest but you stole the reply after the useless info by Borad Chemist.

The question was that by using a combination of capillary and chromatography.you could purify and reduce salinity.

There is no reason to limit the length of the connecting capillary tubes which could be wound in a spiral and then passing through a chromatography column.

The question is there ANY reduction in salinity by capillary action alone?

« Last Edit: 01/08/2022 17:45:40 by championoftruth »
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Offline championoftruth (OP)

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #17 on: 01/08/2022 17:39:19 »
Quote from: evan_au on 30/07/2022 23:47:18
Quote from: championoftruth
can it be used make dirty water into clean drinking water?

Complicated? 2 cups and a tissue. Does not answer the question I ASKED
The average human adult needs about 2 liters of drinking water per day (if they are willing to give up sanitation).

"2 cups and a tissue" will not produce 2 liters of fresh water per day, so "No" is still the answer.

Reason: It takes real energy to separate water from impurities.
- Capilliary action is driven by surface tension (which operates once) and/or evaporation (which doesn't deliver drinkable water).
- Extracting fresh water from sea water takes energy. In lifeboats, additional fresh water can be produced by a solar still or by a semi-permeable membrane and muscle power.

https://www.usgs.gov/special-topics/water-science-school/science/desalination

I never specified the size of the cups. They could be giant beakers or giant tanks or containers.

semi permeable membranes are hard to get and very expensive.
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Offline championoftruth (OP)

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #18 on: 01/08/2022 17:40:30 »
Quote from: Petrochemicals on 31/07/2022 23:31:49
The capillary action shown in the video could be said to be a syphon, thus gravity assist. A gravitational impetus can be used as a source of energy in any filter. Capillary action uphill would be creditable as a theory.

So capillary theory is fake your saying?
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Offline Deecart

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Re: Can you use capillary action to clean water or reduce salinity
« Reply #19 on: 01/08/2022 17:55:22 »
In my opinion, the na+ and cl-, so the common salt you can find in water, are very tiny "particles (ions)" (around the size of water molecules)
Also, they interact strongly with water and tend to stay around water molecule due to van der waals forces.
Therfore, if you have some "capilarity flow", i prefer to say "adsorption" of liquid by some "sponge" (some matter with wide surface), permitted (the flow could be permitted to persists after fully adsorbed) by the evaporation of water (water evaporate and is replaced by the liquid water that stand around), then the diffusion of "salt" is much greater then the flow.
So, no gradient of water with less or more salt because salt diffusion is much greater than the flow.

I think we here do some confusion between the capilarity and the filtering possibility due to the tiny "pores" (they are not pores but some grid) you could have with some materials (here some paper towel).
What it sure here : The paper towel has not "pores" (or grid of cellulose) small enougth to permit only water to flow trought and not "salt".

And if it were the case (the pores are small enought), then you would have some salty water separated by some pure water and ... this would lead to some osmosis pressure that would lead water to counteract the water salinity, so a flow at the other direction counteracting the flow in the "capilarity" direction.
« Last Edit: 01/08/2022 18:04:40 by Deecart »
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