A new low-cost gel film can pull drinking water from arid desert air

For every three people, one calls drylands home. 

Though they contain some of the world's most valuable and rarest biodiversity in addition to being major contributors to the world's breadbasket, drylands are characterized by water scarcity and erratic rainfall.

Dryland communities primarily depend on groundwater as they don't have access to alternative freshwater sources. Additionally, climate change-related impacts have only worsened the situation.

But, fret not.

A low-cost gel film that can pull water from the air even in the driest climates has come to the rescue.

Scientists and engineers at The University of Texas at Austin have developed an innovative solution that could help people in these areas access clean drinking water. The research paper appears in Nature Communications.

It's not magic, it's simple and powerful science

The low-cost gel is made of abundant materials which help in facilitating this reaction. They cost a mere $2 per kilogram, and a single kilogram can produce more than six liters of water per day in areas with less than 15 percent relative humidity and 13 liters in areas with up to 30 percent relative humidity.

The team had earlier come up with solutions that could 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 Cockrell School of Engineering’s Walker 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.”

Renewable cellulose and konjac gum, a common kitchen ingredient, were used as the main hydrophilic skeleton. The open-pore structure of gum accelerates the moisture-capturing process. Another designed component, thermo-responsive cellulose with hydrophobic interaction when heated, helps release the collected water immediately so that overall energy input to produce water is minimized.

The film is flexible and can easily be molded into a variety of shapes and sizes, as per the need of the user. Only the gel precursor is required to make the film, and it includes all the relevant ingredients poured 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.

Mass usage around the corner

There have been attempts at pulling water from desert air. But they are typically energy-intensive and do not produce much. Though six liters may not sound like a lot, creating thicker films or absorbent beds or arrays with optimization could drastically increase the amount of water they yield, as per the researchers.

The reaction itself 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 research was funded by the U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA), and drinking water for soldiers in arid climates is a big part of the project. The researchers hope to see the low-cost gel as something that will be available at a hardware store and can be used in homes.