

Nanoporous Graphene Could Outperform Best Desalination Techniques - pwg
http://www.wateronline.com/doc.mvc/nanoporous-graphene-could-outperform-best-commercial-water-desalination-techniques-0001

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Scramblejams
Impressive find. However, given that the toxicity of graphene is not well
understood[1], shouldn't there be significant concern for now about using
graphene in processes which involve contact with food products? It's easy to
envision a scenario in which a microscopic chunk of the stuff breaks off and
ends up in the air or your stomach. The article only hints at this, where it
mentions "mechanical stability."

[1] <http://en.wikipedia.org/wiki/Carbon_nanotube#Toxicity>

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ChuckMcM
_"In their simulations, the scientists strengthened the nanopores by
passivating, or shielding, each carbon atom at the pore edge with either
hydrogen atoms or hydroxyl groups."_

Filed under the heading, "If someone knew how to build this stuff in volume,
boy would it be useful."

This is good follow on work to other micropore work with graphene but as far
as I can tell its just a simulation which points to areas that might lead to
useful products.

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DennisP
Another cheap new desalination idea was recently presented at Google's Solve
for X: <http://www.youtube.com/watch?v=R63zYZZuRvQ#>!

Instead of a fancy membrane it uses some nifty chemistry. Doesn't take much
energy and the chemicals are in a closed loop.

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riledhel
Thank you for the link. The McGinnis's talk was very interesting, but there
are some other more just as good.

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WiseWeasel
I wonder if that flow rate would be high enough to build this membrane into a
drinking straw, so you could take a safe drink right out of the ocean with a
cheap, compact device. This seems like it has the potential to revolutionize
camping and survival in the near-term, and eventually the availability of
clean water everywhere.

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confutio
Wouldn't the water have to be sanitized first? It sounds as if it only filters
sodium, not other dangerous particles.

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WiseWeasel
The pore size is very slightly bigger than a single water molecule, and
smaller than a single sodium ion. Heavy metal atoms are much larger than
sodium atoms, and would not go through the membrane. Any kind of virus or
bacteria is much, much larger than this molecular scale, and have no hope of
traversing. I am not aware of any harmful water-soluble substances as small as
a water molecule.

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ScottBurson
Hydrogen fluoride comes to mind, but it's probably not an important pollutant
in most of the water sources we care about.

I can't think of anything else that small that would be a problem.

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WiseWeasel
Wouldn't hydrogen fluoride just be fluoride ions in solution? Water molecules
tend to clump around charged ions, which might impede traversal of the
membrane.

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fpp
There are already technologies beyond reverse osmosis in large scale
industrial use (and I'm not referring to brine or similar high energy
approaches)

Siemens has built a desalination plant in Singapore that works similar to
dialysis (mimicking kidneys) and is using a fraction of the energy required
for a comparable RO solutions
(<http://www.desalination.biz/news/print.asp?id=6008>).

The key issue with all membrane / filter based desalination solutions still is
the lifetime / service requirements of the filters.

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ajb
I thought Reverse Osmosis was already close to its thermodynamic limit (in
terms of efficiency)?

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ctdonath
Estimated time to product?

Why not sooner?

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ctdonath
This is an honest question. Millions would like such a product yesterday. I'd
like to know how long it might take to market, and understand why it could not
be done sooner.

Didn't expect such questions be downvoted on a business/product startup site.

