Low-cost film can pluck drinking water from desert air

More than a third of the world’s population lives in drylands, areas that experience significant water shortages. Scientists and engineers at the University of Texas at Austin have now developed a novel material that could help people in these areas access clean drinking water.

The team developed a low-cost gel film made from abundant ingredients that can pull water from the air in even the driest climates. The ingredients that facilitate this reaction cost a mere $2 per kilogram, and a single kilogram of the film can produce more than six liters of water per day in areas with less than 15% relative humidity and 13 liters in areas with up to 30% relative humidity. The team reports this new material in a paper in Nature Communications.

This research builds on previous breakthroughs from the team, including the ability to pull water out of the atmosphere and the application of that technology to create self-watering soil. However, these technologies were designed for relatively high-humidity environments.

“This new work is about practical solutions that people can use to get water in the hottest, driest places on Earth,” said Guihua Yu, professor of materials science and mechanical engineering in the Department of Mechanical Engineering. “This could allow millions of people without consistent access to drinking water to have simple, water-generating devices at home that they can easily operate.”

The researchers used renewable cellulose and a common kitchen ingredient, konjac gum, as the main hydrophilic (attracted to water) skeleton. The open-pore structure of the gum speeds the moisture-capturing process. Another primary component – thermo-responsive cellulose with hydrophobic (resistant to water) interaction when heated – helps to release the collected water immediately so that the overall energy input to produce clean water is minimized.

Other attempts at pulling water from desert air are typically energy-intensive and do not produce much. And although six liters does not sound like much, the researchers say that creating thicker films, absorbent beds or arrays could drastically increase the amount of water they yield.

The reaction required to produce the film is a simple one, which reduces the challenges of scaling it up and achieving mass usage. “This is not something you need an advanced degree to use,” said Youhong ‘Nancy’ Guo, the lead author of the paper and a former doctoral student in Yu’s lab, now a postdoctoral researcher at the Massachusetts Institute of Technology. “It’s straightforward enough that anyone can make it at home if they have the materials.”

The film is flexible and can be molded into a variety of shapes and sizes, depending on the need of the user. Making the film involves simply pouring the gel precursor, which includes all the relevant ingredients, into a mold.

“The gel takes two minutes to set simply. Then, it just needs to be freeze-dried, and it can be peeled off the mold and used immediately after that,” said Weixin Guan, a doctoral student on Yu’s team and a lead researcher of the work.

This story is adapted from material from the University of Texas at Austin, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.