Sand Desert

Cheap harvested drinking water from dry desert air

Researchers have developed an inexpensive gel film that can extract water from the air even in arid climates such as the desert.

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

The researchers developed an inexpensive gel film made up of abundant materials that can extract water from the air even in the driest climates. The materials that enable this reaction cost as little as $2 per kilogram, and a single kilogram can produce more than 6 liters (~1.6 gallons) of water per day in areas with less than 15% relative humidity and 13 liters (~3 .4 gallons) in areas with relative humidity up to 30%.

Film water collection bag

An example of another form that the water-trapping film can take. Credit: The University of Texas at Austin/Cockrell School of Engineering

The research builds on the research team’s past breakthroughs, including the ability to: remove water from the atmosphere and the application of that technology to create self-watering soil† However, these technologies are designed for environments with relatively high humidity.

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

The new article was published in the magazine . on May 19, 2022 nature communication

Water Catching Film Forms

The water-trapping film can be easily molded into many different shapes. Credit: The University of Texas at Austin/Cockrell School of Engineering

The researchers used renewable cellulose and a common kitchen ingredient, konjac gum, as a major hydrophilic (attracted to water) skeleton. The open-pore structure of chewing gum speeds up the moisture absorption process. Another engineered component, thermo-responsive cellulose with hydrophobic (resistant to water) interaction when heated, helps to immediately release the captured water, minimizing the total energy input to produce water.

Other attempts to extract water from desert air tend to be energy-intensive and ineffective. And while 6 liters doesn’t sound like much, the researchers say creating thicker films or absorbing beds or arrays with optimization can dramatically increase the amount of water they yield.

Process of making waterproof films

The process of making the water catching film from the ingredients. Credit: The University of Texas at Austin/Cockrell School of Engineering

The response itself is simple, the researchers said, which reduces the challenges of scaling up and achieving mass utilization.

“This isn’t something you need an advanced degree for,” said Youhong “Nancy” Guo, the paper’s lead author and a former doctoral student in Yu’s lab, now a postdoctoral researcher at the Massachusetts Institute of Technology. “It’s so easy that anyone can make it at home if they have the materials.”

The film is flexible and can be molded into different shapes and sizes depending on the user’s needs. To make the film, only the gel precursor is needed, which contains all the relevant ingredients in a mold.

Device for collecting water from the air

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

“The gel takes 2 minutes to harden easily. After that, it just needs to be freeze-dried, after which it can be unmoulded and used immediately,” said Weixin Guan, a doctoral student on Yu’s team and a principal investigator on the work.

Reference: “Scalable Superhygroscopic Polymer Films for Durable Moisture Absorption in Dry 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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