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  • Graphene is the sexy new wonder material that seems to have a million and one uses.

  • From thin flexible screens to solar cells that work when it's raining, people are

  • finding all sorts of potential applications for this one-atom thick sheet of carbon.

  • Now scientists have added another trick to graphene's repertoire; making seawater drinkable.

  • Desalination is not a new concept; Israel gets over a quarter of its fresh water from

  • the mediterranean sea.

  • But graphene could make the whole process much more efficient.

  • The main technique used for large scale desalination is called reverse osmosis.

  • Normal osmosis is where water flows across a semipermeable membrane to areas of higher

  • saltiness, if you were one of those kids that poured salt on snails, causing the snail to

  • shrivel up as the water leaves its body, you've seen it in action and also, dude, c'mon.

  • The reverse osmosis used for desalination, however, is when pressure is applied to saltwater

  • to force it in the directions it doesn't normally flow, through special membranes to

  • areas of lower salinity, separating the H2O and telling the salt Na Na Na Na, hey hey

  • hey, goodbye

  • Get it because sodium is

  • NA.

  • Anyway, this all sounds great but it's not perfect: water from desalination is very expensive,

  • costing anywhere from $1,000 to $2,500 per acre foot, which is about the amount of water

  • 10 people use in a year.

  • Generally it's cheaper to just use less water and recycle the water you do use, but

  • for some particularly dry places there's no other option.

  • Part of the expense comes from pre-treating the water, but pumping the water through the

  • jelly-roll-like plastic membranes uses a lot of energy.

  • Computer models have predicted that if we could use super-thin graphene sheets instead

  • of these thicker membranes, the amount of energy needed for reverse osmosis could be

  • reduced anywhere from 15-46%.

  • Less energy used for pumping means less expensive water, and that could make a huge difference

  • to people in the world's poorer and drier places.

  • Unfortunately reality doesn't always cooperate with computer models, and making graphene

  • that can separate water from salt isn't as straightforward as it appears.

  • Researchers found that when their graphene oxide membranes were submerged in water, they

  • swole a little bit.

  • They would still filter nanoparticles, organic molecules, and even larger salts but not the

  • common salts found in seawater, which are dangerous to drink because they just lead

  • to more dehydration.

  • That's normal osmosis at work again.

  • But now new findings from the same group of researchers have figured out how to prevent

  • the swelling and control the pore size.

  • Now the dissolved salts and the water molecules they bind to can't get through the pores,

  • but free water molecules can, and do so surprisingly fast, which is a good thing when you're

  • trying to make fresh water as quickly as possible.

  • The researchers hope that their discovery can make desalination more affordable, which

  • would be a huge boon to poorer drought stricken countries who can't afford to build billion-dollar

  • desalination plants.

  • With climate change threatening to make droughts even worse, graphene could do more than just

  • make flexible screens, it could help saves lives.

  • Oh graphene you're my hero.

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  • Do you think desalination is the answer to solving drought or is the problem to huge

  • to make a dent in?

  • Let us know in the comments and don't forget to subscribe while you're down there.

  • If you're worried that making graphene is still too expensive and hard to make to fulfill

  • it's promises, good news!

  • Scientists accidentally found out how to make it cheaper, and Trace tells you about that

  • right here.

  • Thank you guys for watching Seeker.

Graphene is the sexy new wonder material that seems to have a million and one uses.


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B2 中高級 美國腔

石墨稀(Graphene Could Solve the World's Water Crisis)

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    joey joey 發佈於 2021 年 04 月 13 日