Water desalination picks up the pace

July 18, 2018, King Abdullah University of Science and Technology

A membrane made of porous carbon-fiber structures grown on a porous ceramic substrate is more efficient at filtering seawater than existing similar membranes.

Engineered could help recover freshwater from heavily polluted groundwater and seawater, which is of critical need in developing countries and arid environments like the Arabian Peninsula. Conventional water desalination processes rely on polymer membranes. However, if these membranes achieve very good salt rejection, they can fall short of the necessary high freshwater flux.

Zhiping Lai and colleagues from KAUST have developed carbon-composite membranes that consist of a network of carbon fibers deposited on a porous, hollow ceramic tube. These membranes are "the first that can be used in all three membrane-based desalination processes, namely membrane distillation, reverse osmosis and forward osmosis," says Lai. These membranes can simultaneously reject all the salt plus let large quantities of freshwater through their nanoscopic pores while consuming little energy. The water fluxes are up to 20 times higher than for commercial membranes.

These results come from a unique interfacial salt sieving effect, which differs from a solution-diffusion mechanism observed in , explains Lai. One side of the is immersed in salt water while the other is in contact with freshwater, creating a gap between two liquid surfaces. "Water evaporates from the water and quickly passes through the carbon gap before condensing at the freshwater side. Thanks to the excellent thermal conductivity of , most of the energy can be recovered, which reduces energy consumption by more than 80 percent," adds Lai.

Explore further: Scientists use carbon nanotube technology to develop robust water desalination membranes

More information: Wei Chen et al. High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes, Nature Nanotechnology (2018). DOI: 10.1038/s41565-018-0067-5

Related Stories

From seawater to freshwater with a nanotechnology filter

June 1, 2011

In this month's Physics World, Jason Reese, Weir Professor of Thermodynamics and Fluid Mechanics at the University of Strathclyde, describes the role that carbon nanotubes (CNTs) could play in the desalination of water, providing ...

Recommended for you

New traffic rules in 'Graphene City'

December 6, 2018

In the drive to find new ways to extend electronics beyond the use of silicon, physicists are experimenting with other properties of electrons, beyond charge. In work published today (Dec 7) in the journal Science, a team ...

Artificial synapses made from nanowires

December 6, 2018

Scientists from Jülich together with colleagues from Aachen and Turin have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell. The component is able to save and ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.