Biomass Hydrogels Harvest Water From Air

Discarded food scraps, stray branches, seashells and many other natural materials are key ingredients in a new system that can pull drinkable water out of thin air developed by researchers from The University of Texas at Austin.

This new “molecularly functionalized biomass hydrogels” system can convert a wide range of natural products into sorbents, materials that absorb liquids. By combining these sorbents with mild heat, the researchers can harvest gallons of drinkable water out of the atmosphere, even in dry conditions.

“With this breakthrough, we’ve created a universal molecular engineering strategy that allows diverse natural materials to be transformed into high-efficiency sorbents,” said Guihua Yu, a professor of materials science and mechanical engineering and Texas Materials Institute at UT Austin. “This opens up an entirely new way to think about sustainable water collection, marking a big step towards practical water harvesting systems for households and small community scale.”

In field tests, the researchers generated 14.19 liters (3.75 gallons) of clean water per kilogram of sorbent daily. Most sorbents can generate between 1 and 5 liters per kilogram per day.

The new research was published in Advanced Materials.

This system represents a new way of designing sorbents, the researchers say. Instead of the traditional "select-and-combine" approach, which requires picking specific materials for specific functions, this general molecular strategy makes it possible to turn almost any biomass into an efficient water harvester.

Unlike existing synthetic sorbents, which use petrochemicals and generally require high energy inputs, the UT Austin team’s biomass-based hydrogel is biodegradable, scalable, and requires minimal energy to release water. The secret lies in a two-step molecular engineering process that imparts hygroscopic properties and thermoresponsive behavior to any biomass-based polysaccharide, such as cellulose, starch, or chitosan.

“At the end of the day, clean water access should be simple, sustainable, and scalable,” said Weixin Guan, a senior doctoral student and the study's lead researcher. “This material gives us a way to tap into nature’s most abundant resources and make water from air—anytime, anywhere.”

The latest innovation is part of Yu’s years-long quest to develop solutions for people lacking access to clean drinking water. He’s developed water-generating hydrogels throughout his career, adapting them for the driest conditions. He recently created an injectable water filtration system, and he has applied his hydrogel technology to farming.

The research team is now working on scaling production and designing real-world device systems for commercialization, including portable water harvesters, self-sustaining irrigation systems, and emergency drinking water devices. Since the beginning, the researchers have focused on scalability and the ability to translate this research into solutions that can help people around the world.

“The biggest challenge in sustainable water harvesting is developing a solution that scales up efficiently and remains practical outside the lab,” said Yaxuan Zhao, a graduate researcher in Yu’s lab. “Since this hydrogel can be fabricated from widely available biomass and operates with minimal energy input, it has strong potential for large-scale production and deployment in off-grid communities, emergency relief efforts, and decentralized water systems.”

Reference: Guan W, Zhao Y, Lei C, Wang Y, Wu K, Yu G. Molecularly functionalized biomass hydrogels for sustainable atmospheric water harvesting. Adv Mater. 2025:2420319. doi: 10.1002/adma.202420319

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