Unimpeded permeation of water through helium-leak-tight graphene-based membranes
1–10 of 46 posts
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#2Can we get a simpler overview of what this means for a layperson?
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#3Can we get a simpler overview of what this means for a layperson?
It makes me excited that there might be some kind of new science that could mean low power desalination.
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#4Can we get a simpler overview of what this means for a layperson?
Helium is very hard to store since it's a noble gas and so monatomic; I think it's smaller even than H2. So storing it (and H2 for that matter) is hard.
Strangely, their material is able to do that while also passing water, H20, which is a much larger molecule. They suggest in the summary that there's more going on than just the size of the porosity. Haven' read more.
Maybe someone else will know how useful this is for He or H2 in solution.. I'd imagine they'd vaporize out.
Might also be useful for drying H2 after electrolysis
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#5Can we get a simpler overview of what this means for a layperson?
It sort of seems like a bag that can hold a small object, like a golf ball, but something larger like a watermelon would "fall through" the bag without it tearing/breaking.
Pretty interesting stuff but I'm not too aware of the research field, just live in a place that's wet.
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#6Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#7Can we get a simpler overview of what this means for a layperson?
It makes me excited that there might be some kind of new science that could mean low power desalination.
No, it can't.
Desalination by reverse osmosis requires certain force to push water through the filters which is dictated by osmotic pressure. It is unavoidable.
To imagine it, think about it this way: to overcome osmotic pressure you only need to pump the water above the filter to a certain height. The height you need is only dictated by the magnitude of the pressure and not the filter. And as the water flows, you only need to top up the water column which is your only energy expenditure. The only thing that the filter dictates is how quickly the water will flow -- which is how much filter area you need to filter a certain amount of water in a unit of time. But pumping the water to certain height requires always exactly the same amount of energy regardless of the properties of the filter.
For sea water the pressure is 25-33 bar (at 25C) which translates to column of water 250-330 m high.
In practice building a column 1/3km in height would not be practical so you can start imagining other configurations. For example, you could come up with a piston that is pushed by a spring to maintain roughly constant pressure and you inject water from time to time to maintain piston position.
But you will always be working against this pressure you have to overcome for the sea water to start getting separated from salt in one go, or you could use multiple stages to reduce pressures at the cost of more complex processing. Whatever you do there is minimum cost in energy you have to expend that does not depend on the filter.
But there is still a possibility for cheaper/lower maintenance filters and so studying materials that can pass water and stop everything else can still provide a lot of value.
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#8This is bollocks!
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#9Are there any companies focused on mass-production of graphene material?
Re: Unimpeded permeation of water through helium-leak-tight graphene-based membranes
#10Can we get a simpler overview of what this means for a layperson?
It sort of seems like a bag that can hold a small object, like a golf ball, but something larger like a watermelon would "fall through" the bag without it tearing/breaking. Pretty interesting stuff but I'm not too aware of the research field, just live in a place that's wet.
In particular[0], the bigger stuff (water) blocks the smaller.
> Diffusion of other molecules is blocked by reversible narrowing of the capillaries in low humidity and/or by their clogging with water.
So in the absence of the water, the He would escape.
[0] heh