Graphene as a Water Sieve
Graphene is basically a carbon lattice one atom layer thick. It’s been around for only a few years and the guys who made it got a Nobel prize for it. And we’re figuring out how great that material is about once a month. This time, they’re telling us we can use it to desalinate water, to purify it, a thousand times faster than current methods.
The explanation goes something like this: because of one interesting property of graphene, we can make a sheet of it with holes at any size we want, like the size of a water molecule.
It goes like this, this is a water molecule.
This is a salt molecule. (It’s not an actual molecule but stay with me for this)
Salt, when it’s in your salt shaker, looks more like this.
But when it dissolves in water, it looks like this.
The salt compound is made from more massive atoms than water. And with the graphene sheet, we can make holes that let water through and keep salt out. Which basically means that you can pour salt water through a simple filter and get pure water on the other side. Yes, this ideal is still a ways off, there is still work to be done, but this idea is just super cool! Science is awesome! :)
Posted in High-Tech, Less Interesting News by Eran with 7 comments.
The main challenge of desalination is biofilms- organisms that latch onto the filter and clog its holes. How is Graphene better at avoiding this problem?
Can you cool organisms before hand by boiling them or something?
Probably, but the whole idea of this type of desalination is not to do it by heating.
otherwise you could just boil the water and condense the steam.
maybe you could do it with UV but that takes electricity and organisms develope immunity over time.
Well, we’re talking about possible ways to do this while they are probably also thinking the same thing. :)
In that case, I think it would be possible to just change the top sheet if it gets too clogged. They won’t use just one sheet because they need it to be strong to take all the pressure.
Of course, they use entire rolls, but they still clog up.
Also, tere is no need for too much pressure, salt water flow though thin tubes of the membran and that normal pressure push it out- allowing you to collect the water from the outside of the tubes.
they tried all kinds of antibiotic agents on te membrane to prevent biofilm from forming. so far, not good enough to be economical long term.
Well, they have to remove the sheets to get the salt that has accumulated, excess organisms will be included.
they don’t need to remove the salt as crystals, it stays dissolved in a highly concentrated solution and flows out like any water. this concentrated solution can maybe used later in batteries but for now its enough simply t dry it in the sun for the salt.