06 April 2017

Desalination using a sieve

A sieve that will entrap molecules of salt, letting water through:
Reporting their results in the journal Nature Nanotechnology, scientists from the University of Manchester, led by Dr Rahul Nair, show how they solved some of the challenges by using a chemical derivative called graphene oxide.

Isolated and characterised by a University of Manchester-led team in 2004, graphene comprises a single layer of carbon atoms arranged in a hexagonal lattice. Its unusual properties, such as extraordinary tensile strength and electrical conductivity, have earmarked it as one of the most promising materials for future applications...

When 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 through along with the water.

"Water molecules can go through individually, but sodium chloride cannot. It always needs the help of the water molecules. The size of the shell of water around the salt is larger than the channel size, so it cannot go through," said Dr Nair.


  1. The filters would clog up fast but.
    Mind you if they were inclined belts you could have double filtration and recuperate the salt as the belts go over the top roller.

  2. The technology of nanopore filtration is not new but the application of graphene oxide, which is much thinner than other materials for the equivalent strength, is.

    Cleaning would be carried out by reverse flushing or by applying an electrical current across the membrane.


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