MIND BLOWERS

A Membrane That Sucks Impurities From Water

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RODNEY PRIESTLEY, XIAOHUI XU PROFESSOR, POSTDOCTORAL RESEARCHER, PRINCETON UNIVERSITY

MORE THAN 800 MILLION people worldwide lack access to safe drinking water. Over half the U.S. population drinks from water with detectable lead levels, studies suggest. And even as the pandemic reminded us of the importance of frequent handwashing with soap and water, three in 10 people around the globe can’t do that in their own homes. The World Health Organization and UNICEF warn that these numbers are likely to get worse in the next decade unless societies create and improve water infrastructure—a vast and expensive proposition.

A new tool for meeting this challenge has emerged from the laboratory of Princeton University chemical engineers Rodney Priestley and Xiaohui Xu. They have created a material that removes impurities in drinking water, requires no additional energy source beyond sunshine and is potentially cheap to manufacture.

The two engineers stumbled on their new approach while working on a project to make artificial skin to help heal wounds. Skin typically acts as a selective shield—keeping pathogens out of the body, while still permitting water to pass through it. To make artificial skin, they created a hydrogel (a complex polymer that will not dissolve in water) with a molecular structure that would permit the passage of water and block contaminants.

As they developed and tested this material, Xu realized the hydrogel might potentially have another application: water purification. That spurred a new project, in which the two researchers modified their hydrogel in a few key ways so it would not only filter impurities, but actively draw water in as well.