Carbon Nanotubes Strengthen Desalination Membranes

Adding carbon nanotubes to reverse osmosis membranes helps them withstand chlorine exposure without reducing their desalination abilities.

AsianScientist (Apr. 24, 2018) – In a study published in Scientific Reports, researchers in Japan have described how carbon nanotubes help reverse osmosis membranes to resist chlorine. Their findings could lead to more robust membranes that can endure large-scale water desalination.

“Since more than 97 percent of the water in the world is saline water, reverse osmosis desalination plants for producing fresh water are increasingly important for providing a safe and consistent supply,” said study corresponding author Professor Morinobu Endo, a distinguished professor of Shinshu University and the honorary director of the Institute of Carbon Science and Technology.

Reverse osmosis membranes are typically thin film composite systems, with an active layer of polymer film that restricts the movement of salt and other unwanted substances across a permeable porous substrate. Such membranes can turn seawater into drinkable water, as well as aid in agricultural and landscape irrigation, but they can be costly to replace.

To meet the demand for potable water, there is a need for more robust membranes that can withstand harsh operating conditions and cleaning treatments.

In the present study, Endo and his team used multi-walled carbon nanotube-polyamide nanocomposites to strengthen reverse osmosis membranes. The carbon nanotubes stabilized the polyamide, preventing it from reacting with chlorine, which is one of the main causes of degradation in reverse osmosis membranes.

“Carbon nanotubes and fibers are already superb reinforcements for other applications in materials science and engineering, and this is yet another field where their exceptional properties can be used for improving conventional technologies,” Endo said.

The researchers are working to stabilize and expand the production and processing of multi-walled carbon nanotube-polyamide nanocomposite membranes. They are also planning a collaboration to produce the membranes commercially.

“We are currently working on scaling up our method of synthesis, which, in principle, is based on the same method used to prepare current polyamide membranes,” Endo said.

The article can be found at: Ortiz-Medina et al. (2018) Robust Water Desalination Membranes Against Degradation Using High Loads of Carbon Nanotubes.


Source: Shinshu University; Photo: Shutterstock.
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