• Researchers, including one of Indian origin, have developed a graphene-based sieve capable of removing salt from seawater, an advance that may provide clean drinking water for millions of people.
• When immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, while larger ions or molecules are blocked.

More Details:

• Researchers from University of Manchester in the U.K. have now successfully developed graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water.
• The pore size in the membrane can be precisely controlled, which can sieve common salts out of salty water and make it safe to drink, they said.
• When the common salts are dissolved in water, they always form a ‘shell’ of water molecules around the salt molecules.
• This allows the tiny capillaries of the graphene-oxide membranes to block the salt from flowing along with the water.
• Water molecules are able to pass through the membrane barrier and flow anomalously fast which is ideal for application of these membranes for desalination.
• “Realisation of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology.
• “The membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.

Source: The Hindu