Earth is 70 percent water, but of that water, only a small percentage of it is actually drinkable. Since a whopping 97 percent of the water in the world is from the ocean or other bodies of salt water, science and technology have struggled to find a way to convert that to drinking water that can sustain our swelling global population’s needs. The current method is reverse osmosis, which removes large molecules and ions from a solution, but it's expensive.
Graphene is a combination of different forms of carbon – charcoal, graphite, carbon nanotubes, and fullerenes. It is most commonly depicted as a kind of chicken-wire structure, linked together by its bonds. And it is incredibly useful: it has been used in everything from solar cells to killing bacteria. Recently, MIT researchers have discovered that it can also desalinate water – at up to 3 times the efficiency of reverse osmosis.
The study poured water twice as salty as seawater through graphene sheets punctured with nanopores, or holes, of various sizes. These holes were then strengthened with hydrogen atoms and hydroxyl groups. The smaller nanopores were large enough for the water to escape, but too small for the salt molecules – using essentially the same system as reverse osmosis. However, because single-layer graphene is just one atom thick, it is much more efficient than current methods of reverse osmosis, which requires usage of much thicker filters. In fact, it was 1,000 times faster than the present available methods.
While the study is extremely exciting, it is still not quite possible to desalinate water with graphene on a commercial scale. Production capabilities on measuring the exact size of holes in graphene are not exact yet – so it would still be difficult to make sure that the holes are the correct size to filter water but not salt. However, scientists say that the capacity is coming soon. The other problem is making sure that the filter is stable, but the researchers say that can be achieved using similar methods as the ones being used in present reverse osmosis plants.