Illinois researchers identify ultra efficient membrane material

University of Illinois engineers have claimed to have identified a nanoporous material that could be deployed in desalination with greater efficiency promise than graphene.

Using supercomputing, the Illinois team modelled various thin-film membranes and found that molybdenum disulphide showed the greatest efficiency, filtering through up to 70% 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. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time,” said study leader Narayana Aluru, professor of mechanical science and engineering at the University of Illinois. The research was published in Nature Communications.

“Reverse osmosis is a very expensive process,” Aluru said. “And it’s not very efficient. In addition, the membranes fail because of clogging. 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.”

The thinnest membranes are likely to be the most efficient because the force needed to push water through is proportional to membrane thickness. The Illinois researchers have looked at nanometre-thin membranes including graphene. They found that a single-layer sheet of of the substance outperformed its competitors through its combination of thinness, pore geometry and chemical properties.

Molybdenum disulphide is, according to the researchers, a robust material, so even a thin sheet is able to withstand the pressures and water volumes encountered in desalination.
The Illinois researchers are establishing collaborations to test molybdenum disulphide in desalination and to test its rate of fouling.