Low cost frost harvests drinking water from dry desert air

Low cost frost harvests drinking water from dry desert air

sand desert

Researchers have developed a low-cost gel film that can extract water from the air even in dry climates like the desert.

More than a third of the world’s population lives in arid areas, areas that experience significant water shortages. Engineers and scientists at the University of Texas at Austin have developed a unique solution that could help people in these areas access safe drinking water.

Researchers have developed a low-cost gel film made from abundant materials that can extract water from the air in even the driest climates. Materials that facilitate this reaction cost only $2 per kilogram, and a single kilogram can produce more than 6 liters (~1.6 gallons) of water per day in areas with relative humidity below 15% and 13 liters (~3.4 gallons) in areas up to 30% relative humidity.

Water Catch Film Bag

An example of a different shape that the water-capturing film can take. Credit: University of Texas at Austin / Cockrell School of Engineering

The research builds on the research team’s previous breakthroughs, including the ability to extract water from the atmosphere and the application of this technology to create self-watering soil. However, these technologies were designed for relatively humid environments.

“This new work is about practical solutions people can use to get water in the hottest and driest places on earth,” said Guihua Yu, a professor of materials science and mechanical engineering at the department. of Mechanical Engineering from the Cockrell School of Engineering. “It could enable millions of people without constant access to clean water to have simple water-generating devices at home that they can easily operate.”

The new article was published on May 19, 2022 in the journal Nature Communication.

Forms of water-capturing film

Water catching film can easily be molded into many different shapes. Credit: University of Texas at Austin / Cockrell School of Engineering

The researchers used renewable cellulose and a common kitchen ingredient, konjac gum, as the primary hydrophilic (water-attracted) skeleton. The rubber’s open-pore structure speeds up the moisture-locking process. Another engineered component, heat-sensitive cellulose with hydrophobic (water-resistant) interaction when heated, helps release collected water immediately so that the overall energy input to produce water is minimized.

Other attempts to extract water from the desert air are usually energy-intensive and do not produce much. And while 6 liters might not seem like a lot, the researchers say that creating thicker films or optimized absorbent beds or networks could significantly increase the amount of water they produce.

Process of creating a water capture film

The process of creating the water-capturing film from its ingredients. Credit: University of Texas at Austin / Cockrell School of Engineering

The reaction itself is simple, the researchers said, reducing the challenges of scaling it up and using it on a massive scale.

“It’s not something you need an advanced degree to use,” said Youhong “Nancy” Guo, the paper’s lead author and a former doctoral student in Yu’s lab, now a postdoctoral researcher. at Massachusetts Institute of Technology. “It’s simple enough that anyone can do 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 needs of the user. Making the film only requires the gel precursor, which includes all the relevant ingredients poured into a mold.

Device for capturing water from the air

A prototype device for capturing water from the air using the new film. Credit: University of Texas at Austin / Cockrell School of Engineering

“The gel takes 2 minutes to simply set. Then you just need to freeze-dry it and take it out of the mold and use it immediately afterwards,” said Weixin Guan, a doctoral student in Yu’s team and principal investigator of the work.

Reference: “Scalable Super Hygroscopic Polymer Films for Sustainable Moisture Harvesting in Arid Environments” by Youhong Guo, Weixin Guan, Chuxin Lei, Hengyi Lu, Wen Shi, and Guihua Yu, May 19, 2022, Nature Communication.
DOI: 10.1038/s41467-022-30505-2

The research was funded by the Defense Advanced Research Projects Agency of the United States Department of Defense ([{” attribute=””>DARPA), and drinking water for soldiers in arid climates is a big part of the project. However, the researchers also envision this as something that people could someday buy at a hardware store and use in their homes because of its simplicity.

Yu directed the project. Guo and Guan co-led experimental efforts on synthesis, characterization of the samples, and device demonstration. Other team members are Chuxin Lei, Hengyi Lu, and Wen Shi.

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