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. Reverse osmosis used for desalination, however, is when pressure is applied to saltwater to force it in the direction it doesn't normally flow, through special membranes to areas of lower salinity, separating the H2O and salt.
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. 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.
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