Efficient Approach to Water Desalination
The availability of fresh water is dwindling in many parts of the world. One promising source of potable water is the world's virtually limitless supply of seawater, but desalination technology has been too expensive for widespread use. MIT researchers Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering in MIT's Department of Materials Science and Engineering, and graduate student David Cohen-Tanugi have come up with a new approach using a different kind of filtration material - sheets of graphene, a one-atom-thick form of the element carbon, which they say can be far more efficient and possibly less expensive than existing desalination systems.
Transcript
00:00:05 Fresh water is running in short supply in many parts of the world, and our research group at MIT has been looking at how entirely new materials could help us get more affordable clean water from the ocean, where more than 97% of the world's water resides. The key is the water desalination process, and I'm working with Prof. Jeffrey Grossman in the Materials Science department at MIT on the design of new membranes for water desalination. One of the membranes that we're studying is made of
00:00:30 graphene, which is a fascinating material. It's only one atom thick, and we've found that it has tremendous potential for drastically improving the water permeability. Water desalination today often uses filtration membranes that effectively reject salt ions, like sodium and chloride, but at the cost of sluggish water output, and a very high energy footprint. Using a computational tool called Molecular Dynamics, we've modeled the behavior of salt water flowing across
00:00:56 graphene membranes at the atomic scale. Our simulations show that graphene could let water through at more than 100 times the permeability of existing membranes, while still rejecting salt. The way to achieve this is to introduce small pores, on the order of 1 billionth of a meter in the structure of graphene. If the pores are wider than water molecules, but still narrower than solvated ions, our calculations demonstrate that water is able to flow across them while salt is blocked. And because graphene
00:01:20 is one of the strongest materials known, this membrane could withstand the pressures required for water desalination. The enhanced water permeability of nanoporous graphene could be an important advantage over existing water desalination technology. So while there's still a lot of work to be done on this topic, we're very encouraged by our existing results and we're excited to see the role that nanoporous graphene could play in the future of global water resources.