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Wash U engineers develop a foam that can clean dirty water

Provided by Washington University in St. Louis
An artist's rendering of nanoparticle biofoam developed by engineers at Washington University in St. Louis. The biofoam makes it possible to clean water quickly and efficiently using nanocellulose and graphene oxide.

The future of clean water may depend on developing technologies that aim to clean dirty water. With that in mind, engineers at Washington University are using nanotechnology, the manipulation of materials on a molecular level, to develop a foam that can remove salt and contaminants from water.

Their findings were published recently in the journal Advanced Materials.

According to the World Health Organization, about one in 10 people lack access to water. As the global climate continues to warm, scientists predict that drinkable water will become less available.

University researchers are working on foam that consists of two materials: cellulose, a substance found in most plants, and graphene oxide, which conducts heat. When the foam is suspended in a container of water and sunlight shines on it, the graphene oxide will convert light into heat, which evaporates water. The cellulose moves the water to the surface, while the contaminants and salt settle in the container.

The process works like a sponge, said Srikanth Singamaneni, an associate professor of mechanical engineering and materials science.

“If you can imagine a sponge being suspended on the water, the sponge is able to draw the bulk underneath and draw it to the surface,” he said.

Singamaneni said the materials are inexpensive and can be produced in large quantities, since the cellulose is produced by bacteria. The next step for his research team is to scale up the technology to see if it can help populations of people who are in dire need of drinking water.

“We want to make bigger shapes of the bi-layered biofoam and see if it can evaporate quantities of water that are realistic,” Singamaneni said.

The foam will work the best in places, such as India, that receive plenty of sunlight. After scientists have shown that they can scale the technology, it could be market-ready within a couple years, he said.


Eli is the science and environment reporter at St. Louis Public Radio.