Newly created sieve could make seawater drinkable
3 May 2017 by Evoluted New Media
Scientists from the University of Manchester have created a sieve that can filter common salts, providing drinking water from seawater.
Scientists from the University of Manchester have created a sieve that can filter common salts, providing drinking water from seawater.
The sieve — a graphene-oxide membrane — has already demonstrated an ability to filter small nanoparticles, organic molecules and large salts. However, common salts removed in desalination technologies have been too small to be filtered —until now.
These membranes usually swell when they are exposed to water but the researchers have found a way to prevent this, maintaining the uniformity of the pore size. Due to the changes implemented by the scientists the graphene membrane allows only water to pass though, filtering out common salts in addition to larger molecules.
When common salts are dissolved in water, a shell of water molecules are formed around them. The tiny capillaries of the membrane allow water to pass through, leaving salt and other impurities behind.
Professor Rahul Nair, from the University and co-author of the paper published in Nature Nanotechnology, said: “Realisation 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. 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 UN predicts 14% of the world’s population will be troubled by scarcity of water, resulting in millions of people struggling to find adequate clean water sources. If graphene-oxide membranes could be built on smaller scales, it’s hoped this technology could be made accessible to countries without the financial infrastructure for funding large plants.
Mr Jijo Abrahama, one of the lead authors on the paper, said: "The developed membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes."
To help combat the effects of climate change that’s reducing water supplies in cities such as California, a number of more wealthy cities are investing in a number of desalination technologies.
