New research from the University of Manchester developed a graphene-based sieve that can filter out salt from seawater. The graphene oxide membrane could be a cheaper and more efficient filter for desalination plants to use.
Graphene oxide has proven effective for sieving out nanoparticles, organic molecules, and large salts. To filter out common salt, Nair and his colleagues used walls made of epoxy resin on both sides of a graphene oxide membrane. This prevented the graphene oxide from expanding when immersed in water. It also gave the researcher the ability to control these pores.
When dissolved in water, common salts form a “shell” of water molecules around the molecules of salt. Tiny capillaries from the graphene oxide membranes can then block these salts from flowing through. This also allows the water molecules to flow through the membrane much faster. “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,” Nair explained.
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