Graphene Oxide Could Have the Power to Make Seawater Drinkable
Could Have the Power to Make Seawater Drinkable
Graphene-oxide membranes are well known for their filtering capabilities. A new research study suggests that they might be able to turn seawater into safe and clean drinking water.
The possibility of this breakthrough came via a just-published paper by scientists at the University of Manchester (United Kingdom). It appeared in the journal Nature Nanotechnology in an article coauthored by Jijo Abraham and Kalangi S. Vasu.
These unique membranes have previously been found to be very useful when attempting to isolate organic molecules, large salts and small nanoparticles. They have also been used for gas separation. Using them to remove smaller salts such as those that naturally appear in seawater has been a technical dilemma so far. The reason is that when these membranes are immersed in water, the graphene-oxide structures begin to swell. When the membranes swell, even though larger ions or molecules are successfully blocked, the swelling is sufficient so that both water and the smaller salt molecules can flow through the material. It is also further complicated because when seawater is present, the dissolved salts in it are surrounded naturally by a “shell” of water molecules that protects the salt and blocks the efficacy of any separation membrane.
The trick involved in the University of Manchester group’s research involves manufacturing graphene-oxide sieves with far more precisely controlled membrane structures. It also involves creating membrane openings that have a uniform pore size down to the atomic scale, in a more-or-less tunable manner.
With these new structures in place, the tiny capillaries of the graphene-oxide membranes keep the salt from passing through the membrane along with the much smaller molecules of water. The result is a sustained fresh-water output flow without any trace of the original incoming saltwater sources.
The value of this breakthrough could be immense. Thanks to global warming and related continuing worldwide drought patterns, the United Nations estimates that by 2025 some 14% of the world’s population could be dealing with a major scarcity of fresh water. These potentially quite inexpensive graphene-oxide sieves could be just the innovation needed to save the world – from itself – again.