Researchers have tapped into graphene-oxide membranes as a new source to produce clean water.
A team from The University of Manchester have demonstrated the real-world potential of creating adequate clean water sources using graphene-oxide for new filtration technologies.
Graphene-oxide membranes have previously shown potential for gas separation and water filtration and graphene-oxide membranes developed at the National Graphene Institute at The University of Manchester have already demonstrated the potential of filtering out small nanoparticles, organic molecules and large salts.
However, prior to this study, graphene-oxide membranes could not be used for sieving common salts used in desalination technologies, which require very small sieves.
Previous research at The University of Manchester found that if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water but larger ions or molecules were blocked.
The research team have now further developed the 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, allowing the sieving of common salts out of salty water, making it safe to drink.
Because the effects of climate change continue to reduce water supplies, many countries are investing in desalination technologies, as well as looking increasingly to alternative water solutions.
When common salts are dissolved in water, they form a ‘shell’ of water molecules around the salt molecules, which 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, ideal for application of these membranes for desalination.
“Realization 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,” professor Rahul Nair, of The University of Manchester, said in a statement. “This is the first clear-cut experiment in this regime.
“We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes.”
By 2025 the United Nations expects that 14 percent of the world’s population will encounter water scarcity. However, the researchers believe that this technology has the potential to revolutionize water filtration across the world, particularly in countries that cannot afford large-scale desalination plants.
The researchers are hoping that graphene-oxide membrane systems can be built on smaller scales to make this technology accessible to countries that do not have the financial infrastructure to fund large plans without compromising the yield of fresh water produced.
The study was published in Nature Nanotechnology.
