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A new graphene sieve developed at the University of Manchester has just been proven to successfully turn seawater to drinking water by efficiently filtering out even the tiniest salts during the desalination process.

The scientists led by Dr. Rahul Nair and the National Graphene Institute have previously developed graphene membranes that can sieve particles ranging from large salts to nanoparticles but not the common salts which require smaller sieves. The common salts were let through the old sieve because they tend to swell or expand when immersed in water, Phys.org reported.

Dr. Nair and his team improved on that technology by attaching both sides of the graphene membrane to walls of epoxy resin to limit the expansion. They observed that when common salts are dissolved in water, it is surrounded by a layer of water molecules. The more rigid sieves block the salts because the shell of water around it is too big for the small tubes it has to pass through, the BBC reported.

While this is a welcome development, it is still not possible to produce this graphene-based membrane at an industrial scale. To turn seawater to drinking water is still very expensive with the current technology of using polymer-based membranes. They also need to create graphene membranes which can stand prolonged contact with saltwater.

Affluent countries are now investing in technologies to turn seawater to drinking water as climate change has started to limit water supplies in major cities. The severe drought in California was a prime example of where the technology could be used. If developed into new desalination technology, they can also use seawater for irrigation.

The ability of the developer to control the size of the pores of the graphene membrane can also be very useful in developing membranes that can selectively filter out ions or particles according to their size.