Graphene: The perfect water filter | ExtremeTech
Researchers from the home of graphene, the University of Manchester in England, have discovered — seemingly by chance — one of the most important properties of graphene yet: It’s impermeable to everything but water. It is the perfect water filter.
In an experiment, the University of Manchester researchers filled a metal container with a variety of liquids and gases and then covered it with a film of graphene oxide. Their most sensitive equipment was unable to register any molecules leaving the container, except water vapor. The graphene oxide filter even prevented helium gas from escaping, which is notoriously finicky.
This fantastical feature joins a huge list of properties that have led graphene to be called a “wonder material.” Graphene, which is merely a single layer of carbon atoms, is the most conductive material in the world, both electrically and thermally. It is incredibly strong, and yet the thinnest material in the known universe. Graphene enables CPUs that can operate at 300GHz or higher, batteries that last 10 times as long, and petabit and exabit network transmission speeds. It even creates electricity when struck by light!
Now, technically graphene oxide isn’t quite the same thing as graphene, but in a good way: graphene oxide is much easier to make. Basically, graphene oxide forms into single-atom-thick sheets, like graphene, but it then likes to stack up, layer after layer, to form a laminate. The University of Manchester researchers think that it is this laminate form that allows water molecules through. “Graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules,” says Dr Rahul Nair, who leads the project. “If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules.”
In another experiment, Dr Nair & Co. sealed a bottle of vodka with the graphene filter. This allowed just the water to evaporate, effectively distilling it into super-vodka. Beyond silly experiments, though, it’s easy to see the awesome potential of this new filter. With an ever-increasing strain on the world’s water supplies, water filtration is one of the hottest (and most valuable) topics at the moment — and by the sound of it, if graphene oxide really is completely impermeable to everything except water, this new filter would make clean water out of anything. Sea water, gray water, sewage…
Read more at ScienceDaily