This Graphene Sieve Makes Clean Drinking Water From Seawater
Water scarcity is a global problem, but a new innovation could help turn saltwater into clean drinking water by using a graphene-based sieve.
In a paper published in the journal Nature Nanotechnology, scientists from the University of Manchester revealed how they were able to create a graphene-based filter that can make saltwater drinkable.
According to a report from BBC News, this new graphene oxide sieve can actually remove salt from seawater. Manufacturing graphene-based barriers on a large scale used to be very challenging, but the team, led by Dr. Rahul Nair, used a chemical derivative called graphene oxide to solve a few of the challenges with the material.
Industrial amounts of single-layer graphene are very difficult and expensive to produce, but graphene oxide can be created in a laboratory just with simple oxidation.
"As an ink or solution, we can compose it on a substrate or porous material," Nair said. "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."
Previous studies have already shown that graphene-oxide membranes exhibit potential for filtering small nanoparticles, organic molecules and large salts. However, when these membranes are immersed in water, they swell up, causing smaller salts to flow through the membrane with the water while larger ions or molecules are blocked.
Nair's team avoided the swelling by putting walls of epoxy resin on the sides of the graphene oxide membrane.
Common salts dissolve in water and create a "shell" of water molecules around the salt molecules, according to a report from Phys Org. Then, the capillaries of the membrane can keep the salt from flowing with the water.
"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," Nair explained. "This is the first clear-cut experiment in this regime."