New material to make seawater drinkable

Engineers have found a material for cost effectively removing salt from seawater. The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out. The process is called desalination.

"Even though we have a lot of water on this planet, there is very little that is drinkable. If we could find a low-cost, efficient way to purify sea water, we would be making good strides in solving the water crisis," said study leader professor Narayana Aluru from University of Illinois at Urbana-Champaign.

The team modelled various thin-film membranes and found that MoS2 showed the greatest efficiency, filtering through up to 70 percent more water than graphene membranes.

"Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials," Aluru added.

Most available desalination technologies rely on a process called reverse osmosis to push seawater through a thin plastic membrane to make fresh water.

The membrane has holes in it small enough to not let salt or dirt through, but large enough to let water through. They are very good at filtering out salt, but yield only a trickle of fresh water.

"Reverse osmosis is a very expensive and energy intensive process. A lot of power is required to do this process, and it's not very efficient. In addition, the membranes fail because of clogging," Aluru said.

"So we'd like to make it cheaper and make the membranes more efficient so they don't fail as often. We also don't want to have to use a lot of pressure to get a high flow rate of water," he said. (The study was published in the journal Nature Communications.)