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#Post#: 6807--------------------------------------------------
Desalination with Renewable Energy
DIR By: AGelbert
Date: April 3, 2017, 1:35 pm
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[center]Graphene sieve turns seawater into drinking water
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April 3, 2017
[center]
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[center]A graphene membrane. Credit: The University of
Manchester [/center]
Graphene-oxide membranes have attracted considerable attention
as promising candidates for new filtration technologies. Now the
much sought-after development of making membranes capable of
sieving common salts has been achieved.
New research demonstrates the real-world potential of providing
clean drinking water for millions of people who struggle to
access adequate clean water sources.
The new findings from a group of scientists at The University of
Manchester were published today in the journal Nature
Nanotechnology. Previously graphene-oxide membranes have shown
exciting potential for gas separation and water filtration.
Graphene-oxide membranes developed at the National Graphene
Institute have already demonstrated the potential of filtering
out small nanoparticles, organic molecules, and even large
salts. Until now, however, they couldn't be used for sieving
common salts used in desalination technologies, which require
even smaller sieves.
Previous research at The University of Manchester found that if
immersed in water, graphene-oxide membranes become slightly
swollen and smaller salts flow through the membrane along with
water, but larger ions or molecules are blocked.
The Manchester-based group have now further developed these
graphene membranes and found a strategy to avoid the swelling of
the membrane when exposed to water. The pore size in the
membrane can be precisely controlled which can sieve common
salts out of salty water and make it safe to drink.
As the effects of climate change continue to reduce modern
city's water supplies, wealthy modern countries are also
investing in desalination technologies. Following the severe
floods in California major wealthy cities are also looking
increasingly to alternative water solutions.
When the common salts are dissolved in water, they always form a
'shell' of water molecules around the salts molecules. This
allows the tiny capillaries of the graphene-oxide membranes to
block the salt from flowing along with the water. Water
molecules are able to pass through the membrane barrier and flow
anomalously fast which is ideal for application of these
membranes for desalination.
Professor Rahul Nair, at The University of Manchester said:
"Realisation of scalable membranes with uniform pore size down
to atomic scale is a significant step forward and will open new
possibilities for improving the efficiency of desalination
technology.
"This is the first clear-cut experiment in this regime. We also
demonstrate that there are realistic possibilities to scale up
the described approach and mass produce graphene-based membranes
with required sieve sizes."
Mr. Jijo Abraham and Dr. Vasu Siddeswara Kalangi were the
joint-lead authors on the research paper: "The developed
membranes are not only useful for desalination, but the atomic
scale tunability of the pore size also opens new opportunity to
fabricate membranes with on-demand filtration capable of
filtering out ions according to their sizes." said Mr. Abraham.
By 2025 the UN expects that 14% of the world's population will
encounter water scarcity. This technology has the potential to
revolutionise water filtration across the world, in particular
in countries which cannot afford large scale desalination
plants.
It is hoped that graphene-oxide membrane systems can be built on
smaller scales making this technology accessible to countries
which do not have the financial infrastructure to fund large
plants without compromising the yield of fresh water produced.
HTML https://phys.org/news/2017-04-graphene-sieve-seawater.html
Agelbert NOTE: PLEASE, spare me the, "but, but, you need fossil
fuels to make graphene" argument. What you NEED is ENERGY. And
there are MILLIONS of places on planet earth that you can
HARVEST that (RENEWABLE) energy for an on location graphene
factory that does not use ANY fossil fuels, EVER!
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#Post#: 6820--------------------------------------------------
Re: Desalination with Renewable Energy
DIR By: AGelbert
Date: April 3, 2017, 9:13 pm
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--- Quote from: Palloy2 link ---
>
> [quote]
>
HTML https://phys.org/news/2017-04-graphene-sieve-seawater.html
> Graphene sieve turns seawater into drinking water
>
> Agelbert NOTE: PLEASE, spare me the, "but, but, you need
fossil fuels to make graphene" argument. What you NEED is
ENERGY. And there are MILLIONS of places on planet earth that
you can HARVEST that (RENEWABLE) energy for an on location
graphene factory that does not use ANY fossil fuels, EVER!
--- End Quote ---
You also need Energy to make the water cross the membrane,
because you are reversing Entropy, (there is more Entropy in
seawater, a mixture of water and chemicals, than there is in
pure water here and a bunch of chemicals there). In the
desalination efforts currently up and running, that Energy is
input by applying pressure to the seawater with
electricity-power pistons. The cost of the Energy to do this
makes desalination plants in Australia (Brisbane and Sydney) too
expensive, white elephants - used only during extreme long-term
droughts.
So the third world is never going to get fresh water this way.
[/quote]
The Palloy reading comprehension difficulties, AGAIN. This new
desalination filter will NOT require PRESSURE, either osmotic or
otherwise. THAT MEANS that there will be ZERO energy REQUIRED
for the separation of the major part of the ions from the H2O.
If you had a grasp of biosphere math, enzymatic catalysts in
nature and all the various shortcuts the biosphere uses to avoid
the STUPID and inefficient HEAT, BEAT and TREAT method humans
prefer due to a preference for brute force approaches (as if
THAT ruinously energy intensive approach is "IT" in
thermodynamics - it's actually the WORST approach!), I would
discuss this issue with you.
But since you are routinely deliberately obtuse and selective in
the way you measure the COST of energy invested to run processes
in civilization and energy returned from those investments
(UNETHICALLY DENYING the Social cost of Carbon CONTINUOUSLY), I
have nothing but pity for your inflated self confidence in these
matters.
You do not have the remotest idea of what you are talking about.
Have a nice deluded, ARROGANT, CLOSED MINDED, DAY.
#Post#: 6826--------------------------------------------------
Re: Desalination with Renewable Energy
DIR By: AGelbert
Date: April 4, 2017, 4:16 pm
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--- Quote from: RE link ---
>
> [quote author=Palloy2 link=topic=559.msg128449#msg128449
date=1491272168]
> So you are going to undo Entropy without using Energy? That
will be a first for the Universe.
>
--- End Quote ---
If you built a seawall in a cove with high tidal differences,
you could use the pressure of the water against the wall at high
tide to push it through desalinating membranes.
Of course, you still would have pumping to do since the fresh
water you would be collecting would be below sea level. You
probably could do the pumping with windmills though. In fact,
you could use windmills to pump seawater through desalinating
membranes directly.
RE
[/quote]
Thank you, RE, for trying to inject some reality into Palloy's
selective thermodynamics fun and games. You see, Palloy is about
as objective on these matters of energy in general (AND FOSSIL
FUELS IN PARTICULAR) as Putin. Palloy thinks fossil fuels are
IT. Of course he pretends to "like" renewable if they, uh, would
"only" be as "efficient" as those GLORIOUSLY "energy dense"
fossil fuels. It's like talking to a wall. He never stops his
wishful thinking about that crap called fossil fuels. His
concepts of scientific terms like entropy and thermodynamics and
maybe brownean movement and molecular diffusion, etc. are so
twisted to defend polluting fuels and ALWAYS find fault with ANY
Renewable Energy, that he continues to come up with fascinating
bits of erudite sounding irrelevance to try to persuade the
uneducated that isn't full of S H I T.
He COMPLETELY missed the point of the graphene filter. Yeah, it
takes a LOT of energy to make graphene. BUT, the filter itself
will EASILY separate Na and Cl ions associated with water
molecules by gravity alone. Old Palloy likes big factories and
scaled up monstrocities that he can point to as being "more
efficient". ::)
These graphene filters will be distributed to individuals and
will probably NEVER be part of some big desalination facility,
although that option is available. And entropy doesn't have
beans to do with all this because a solar powered water pump can
easily dump sea water into a graphene filter. Gravity will, alas
for Palloy, defeat part of all that entropy that poor Palloy is
obsessing about (deliberately on purpose, of course
HTML http://www.createaforum.com/gallery/renewablerevolution/3-311013201314.png).<br
/>The forces inside a graphing filter take care of other entropy
caused energy gradient factors by dislodgling the normal charge
on a clump of sea water by their whiplashing (graphene isn't
perfectly flat - it has a modified chair structure like
graphite, but more ordered) around of positive and negative
charges in the graphene structure. It's AMAZING STUFF!
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But thanks again for showing how CFS can be applied to the
graphene filter to overcome any minor problems. If Palloy wants
to make entropy mountains out of gravity assist molehills,
that's his problem. I think he takes his talking points from
Pruitt and/or Putin.
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