
Carbon Nanotubes Excluding Salt from Seawater - meri_dian
https://www.sciencedaily.com/releases/2017/08/170824182653.htm
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ResearchAtPlay
Perhaps this membrane is also interesting for electricity production. From the
abstract:

 _CNTPs block anion transport, even at salinities that exceed seawater levels_

High salinity levels that occur in some mining processes could produce
electricity via pressure-retarded osmosis. Reaching adequate flow rates
through membranes has been a barrier to this tech in the past [1].

As a slightly off-topic question: Does anyone know of any industrial processes
where high volumes of fluids with high salinity concentrations occur? I am
doing some research on where this technology could be applied.

[1] www.nature.com/articles/nature11477

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DontGiveTwoFlux
Anyone read the paper to see what kind of flux this technology might have
compared to materials used in existing membranes?

I often hear about desalination as an energy problem, since the plants use so
much to run. I'd be interested to know if this technology would lower the
energy requirements of desalination. Anyone read the paper?

~~~
Dylan16807
"because osmosis is a simple matter of thermodynamics, it's possible to
calculate exactly how efficient we can make the process. And, as it turns out,
we're really quite close as these things go. A state-of-the-art facility is
now within a factor of two of the theoretical energy minimum, and only 25
percent higher than the realistic minimum for the current reverse osmosis
process."

~~~
claudius
Hm, I’m not sure I buy this argument, as it relies on the entire procedure
being in equilibrium at all times. For the same reason that the human body can
operate at much higher efficiency than a steam locomotive (or even the
"perfect" Carnot engine), it should be possible to devise a desalination
process which is much more efficient than the thermodynamic optimum by relying
on catalysts and other non-equilibrium effects.

~~~
theptip
> the human body can operate at much higher efficiency than ... the "perfect"
> Carnot engine

Can you expand on what you mean by this please? The ideal Carnot cycle
describes the fundamental thermodynamic maximum for extracting work from heat.

I thought that applied across all state changes (i.e. not just in equilibrium
situations)?

~~~
claudius
Of course it applies if you wish to extract work from _heat_. However, it does
not apply when extracting work from chemical, nuclear or electrical energy,
_only_ if you first transformed that other energy into heat and then
transformed the heat into work.

