Graphene-based sieve that can filter salt out of seawater, a development that could provide drinking water to millions of people around the globe. Scientists has created a graphene-based sieve capable of removing salt from seawater.
The promising graphene oxide sieve could be highly efficient at filtering salts, and will now be tested against existing desalination membranes.
What is Graphene?
Graphene — an ultra-thin sheet of carbon atoms organized in a hexagonal lattice — was first identified at the University of Manchester in 2002 and has since been hailed as a “wonder material,” with scientists racing to develop inexpensive graphene-based barriers for desalination on an industrial scale.
It has previously been difficult to manufacture graphene-based barriers on an industrial scale.
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.
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.
But it has been difficult to produce large quantities of single-layer graphene using existing methods, such as chemical vapour deposition (CVD). Current production routes are also quite costly.
In the new technology “graphene oxide can be produced by simple oxidation in the lab”.
As an ink or solution, we can compose it on a substrate or porous material. Then we can use it as a membrane.
“In terms of scalability and the cost of the material, graphene oxide has a potential advantage over single-layered graphene.”
Graphene oxide membranes have already proven their worth in sieving out small nanoparticles, organic molecules and even large salts. But until now, they couldn’t be used to filter out common salts, which require even smaller sieves.
Previous work had shown that graphene oxide membranes became slightly swollen when immersed in water, allowing smaller salts to flow through the pores along with water molecules.
Boosting global access to water is critical. By 2025, 14% of the global population will suffer from water scarcity, the United Nations predicts. In addition, climate change is expected to wreak havoc on urban water supplies, with decreased rainfall and rising temperatures expected to fuel demand.