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Old 04-04-2017, 10:53   #1
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Another way to create drinkable seawater?

Came across this. In a way it is the same old idea, but the methodology may hold promise of improvement over the existing way to convert seawater to drinkable water. We can only wait and see.

https://www.sciencedaily.com/release...0403193120.htm
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Old 04-04-2017, 15:30   #2
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Re: Another way to create drinkable seawater?

Quote:
Originally Posted by buzzstar View Post
Came across this. In a way it is the same old idea, but the methodology may hold promise of improvement over the existing way to convert seawater to drinkable water. We can only wait and see.

https://www.sciencedaily.com/release...0403193120.htm
Interesting possibilities, but it will be a while before it is commercially viable

And I'm sick and tired of seeing every scientific press release from a university these days include an unsubstantiated and irrelevant hook: "As the effects of climate change continue to reduce modern cities' water supplies..."
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Old 04-04-2017, 16:09   #3
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Re: Another way to create drinkable seawater?

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Interesting possibilities, but it will be a while before it is commercially viable

And I'm sick and tired of seeing every scientific press release from a university these days include an unsubstantiated and irrelevant hook: "As the effects of climate change continue to reduce modern cities' water supplies..."
No argument from me. I am close to the point of expecting to see a "scientific" article that will suggest nuclear winter is the only way to even out climate change.
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Old 04-04-2017, 16:26   #4
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Re: Another way to create drinkable seawater?

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No argument from me. I am close to the point of expecting to see a "scientific" article that will suggest nuclear winter is the only way to even out climate change.
Could always drop about a 30 mt or.so unit into a caldera volcano on the sly and.say it was natural. Same effect without near the.fallout.
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Old 05-04-2017, 08:33   #5
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Re: Another way to create drinkable seawater?

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Originally Posted by buzzstar View Post
Came across this. In a way it is the same old idea, but the methodology may hold promise of improvement over the existing way to convert seawater to drinkable water. We can only wait and see.

https://www.sciencedaily.com/release...0403193120.htm
The posters ahead of me have already made some good points. These articles never talk about details. How is this more efficient than what we do now and how much more efficient? How much does it cost now? What do they realistically feel the costs can be reduced to with mass production? How durable is it? What is the effect of disposing of these? The list of questions goes on.

The article is basically summed up as "We have something new. It may be practical and beneficial but right now we don't have any real world uses for it."
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Old 05-04-2017, 09:01   #6
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Re: Another way to create drinkable seawater?

I'm not sure what the big deal is about this. It's simply another membrane technology. Any membrane technology has the same physics problem to deal with and that is osmotic pressure. The pores in the membrane are bidirectional and water molecules will always move from the side with the lower concentration of solutes (fresh water side) to the side with the higher concentration of solutes (salt water side). This will occur until the physical pressure on the salt water side overcomes the ability of the water molecules to move through the pores. This pressure is called osmotic pressure. In order to move the water molecules to the fresh water side additional physical pressure must be applied to the salt water side. Of course as water molecules move from the salt water side to the fresh water side the concentration of solutes on the salt water side increases requiring even more physical pressure to force the water molecules through the membrane. This is called reverse osmosis and is the way all modern RO systems work. Sea water has an osmotic pressure of a bit over 400 psi, but increasing solute concentrations on the salt water side and to get a practical flow rate about 800 psi is required. If this new membrane technology has a higher concentration of pores than current membranes one might be able to get a practical flow rate at something less than 800 psi but it will still require a physical pressure higher than the osmotic pressure of the salt water and from any increase in osmotic pressure caused by the increasing concentration of solutes on the saltwater side as water is forced to the fresh water side. While there may be some energy saving it will not eliminate the need for high pressure pumps, pressure vessels, high pressure hoses and the other things that we associate with current reverse osmosis technology.
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Old 05-04-2017, 11:08   #7
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Re: Another way to create drinkable seawater?

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Originally Posted by StuM View Post
Interesting possibilities, but it will be a while before it is commercially viable

And I'm sick and tired of seeing every scientific press release from a university these days include an unsubstantiated and irrelevant hook: "As the effects of climate change continue to reduce modern cities' water supplies..."
Much more likely to be increasing population causing the problem . But yes , it is fashionable to blame climate change until the next " Truth " comes along .
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Old 05-04-2017, 21:54   #8
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Re: Another way to create drinkable seawater?

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I'm not sure what the big deal is about this. It's simply another membrane technology. Any membrane technology has the same physics problem to deal with and that is osmotic pressure. The pores in the membrane are bidirectional and water molecules will always move from the side with the lower concentration of solutes (fresh water side) to the side with the higher concentration of solutes (salt water side). This will occur until the physical pressure on the salt water side overcomes the ability of the water molecules to move through the pores. This pressure is called osmotic pressure. In order to move the water molecules to the fresh water side additional physical pressure must be applied to the salt water side. Of course as water molecules move from the salt water side to the fresh water side the concentration of solutes on the salt water side increases requiring even more physical pressure to force the water molecules through the membrane. This is called reverse osmosis and is the way all modern RO systems work. Sea water has an osmotic pressure of a bit over 400 psi, but increasing solute concentrations on the salt water side and to get a practical flow rate about 800 psi is required. If this new membrane technology has a higher concentration of pores than current membranes one might be able to get a practical flow rate at something less than 800 psi but it will still require a physical pressure higher than the osmotic pressure of the salt water and from any increase in osmotic pressure caused by the increasing concentration of solutes on the saltwater side as water is forced to the fresh water side. While there may be some energy saving it will not eliminate the need for high pressure pumps, pressure vessels, high pressure hoses and the other things that we associate with current reverse osmosis technology.
Bill, I have been following the development of graphene water filters for some time and what struck me about them was that they are "transparent" to H2O molecules. Pour water into the filter, water goes right through like the graphene wasn't there but impurities don't pass. A cleaning cycle is obviously necessary to wash off the gunk but no more high pressure forcing through an RO membrane. Hype vs reality? Who knows what the final products will look like but the patents were snapped up by Lockheed/Martin immediately. That should say volumes about when we might expect to see them in this segment.
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Old 05-04-2017, 22:16   #9
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Re: Another way to create drinkable seawater?

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Could always drop about a 30 mt or.so unit into a caldera volcano on the sly and.say it was natural. Same effect without near the.fallout.
The difficult part is the correct caldera. I opposed Yellowstone and Long Valley, and these in the area of Indonesia have their own problems. I like the Italians, and while I like the Greeks too, but Santorini / Crete might take care of a few problems. Darn. I - I - I guess it is up to mother nature.
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Old 05-04-2017, 22:38   #10
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Re: Another way to create drinkable seawater?

Trifan, I'd say Bill's analysis is spot-on. Permeability of membranes has practical implications for the speed and energy costs of reverse osmosis, but the basic physics (Second Law of Thermodynamics) is unchanged.
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Old 05-04-2017, 23:38   #11
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Re: Another way to create drinkable seawater?

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Originally Posted by Captain Bill View Post
I'm not sure what the big deal is about this. It's simply another membrane technology. Any membrane technology has the same physics problem to deal with and that is osmotic pressure. The pores in the membrane are bidirectional and water molecules will always move from the side with the lower concentration of solutes (fresh water side) to the side with the higher concentration of solutes (salt water side). This will occur until the physical pressure on the salt water side overcomes the ability of the water molecules to move through the pores. This pressure is called osmotic pressure. In order to move the water molecules to the fresh water side additional physical pressure must be applied to the salt water side. Of course as water molecules move from the salt water side to the fresh water side the concentration of solutes on the salt water side increases requiring even more physical pressure to force the water molecules through the membrane. This is called reverse osmosis and is the way all modern RO systems work. Sea water has an osmotic pressure of a bit over 400 psi, but increasing solute concentrations on the salt water side and to get a practical flow rate about 800 psi is required. If this new membrane technology has a higher concentration of pores than current membranes one might be able to get a practical flow rate at something less than 800 psi but it will still require a physical pressure higher than the osmotic pressure of the salt water and from any increase in osmotic pressure caused by the increasing concentration of solutes on the saltwater side as water is forced to the fresh water side. While there may be some energy saving it will not eliminate the need for high pressure pumps, pressure vessels, high pressure hoses and the other things that we associate with current reverse osmosis technology.
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Trifan, I'd say Bill's analysis is spot-on. Permeability of membranes has practical implications for the speed and energy costs of reverse osmosis, but the basic physics (Second Law of Thermodynamics) is unchanged.
Egad. Can you not understand there is a difference between basic physics and the application of technology using the basics? Maybe a simple example is the gasoline powered internal combustion engine. Yep. People harnessed the basics well over a century ago. Technology, not the basic principles have improved since. I doubt I need to even attempt to enumerate the ways, and I could not hit more than a relative few if I tried. If this troubles you, just attempt to compare the engines on a 1917 Ford Model T, with that on a 1965 Ford Mustang. Principle is the same for both, but the improvement is immense. The laws did not change, but the technology did. For reasons that should be clear similar improvements apply to creating a satisfactory consumable version of fresh water from seawater. IF the graphene membranes perform as described in the original article, one heck of a lot less energy is required for the process when compared to present methods.. I think we all realize the cost of producing a commercially viable version may be an impediment, but that does not make it impossible or a violation of the laws of physics.

Just to add an example more in keeping with this form. When I started sailing a small pram in the early 1950's the sail was, I believe, cotton/canvas. Now it would be Dacron, probably lighter, stronger, more durable, and would keep its shape better. The result is that if I were the the age now that I was then, I could probably sail faster although my skills and the rest of the boat remained unchanged. The same laws of physics would still be there. Think of cotton/canvas as present water distillation technology, and Dacron as the graphene, although it may turn out to be as expensive as Kevlar and as useful as newsprint sails. [Too tired to correct this, but the idea is there.]
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Old 05-04-2017, 23:52   #12
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Re: Another way to create drinkable seawater?

I'm curious to know what the saturation point is and how quickly it will become clogged up with impurities.

Water water everywhere but not a drop to spare....
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Old 06-04-2017, 00:08   #13
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Re: Another way to create drinkable seawater?

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I'm curious to know what the saturation point is and how quickly it will become clogged up with impurities.

Water water everywhere but not a drop to spare....
A more reasonable question than attempting to figure out how the second law of thermodynamics would apply to water poured through a filter. If I read the post by trifan correctly, since the particles such as sea salt (still sodium chloride) and the other things dissolved or suspended in sea water are trapped on one side of the filter, while the water passes through to the other side, once the concentration is heavy enough to interfere with the flow, all that needs to be done is wash off the particles. Presumably, it could even be done with sea water. Again, relying on triton, the filter itself does not trap the particles in the filter,. but rather on its surface. Please do not ask me to defend this understanding in any scientific way, but perhaps triton or someone else can.
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Old 06-04-2017, 00:20   #14
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Re: Another way to create drinkable seawater?

That's understandable, but there most certainly has to be a lifespan for the membrane even if zero pressure was used. The article said it was drinkable, not containing no salts at all. Then there has to be an issue of microorganism control as well. I'm skeptical that this would even be within a decade of production.
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Old 06-04-2017, 11:25   #15
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Re: Another way to create drinkable seawater?

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The difficult part is the correct caldera. I opposed Yellowstone and Long Valley, and these in the area of Indonesia have their own problems. I like the Italians, and while I like the Greeks too, but Santorini / Crete might take care of a few problems. Darn. I - I - I guess it is up to mother nature.
New Zealand's Taupo caldera would be a possible choice big enough to cool theplanet significantly but not cause to much loss of life . Would make fresh water more readily available justt melt the ice in the yard.
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