Access to clean water remains one of the greatest challenges facing mankind. Breakthroughs by engineers at the University of Texas at Austin may offer a new solution to absorb moisture from the air through solar technology and return it as clean and usable water.
The breakthrough described in the most recent issue of Advanced Materials can be used for disaster situations, water crises or poor areas and developing countries. The technology relies on hydrogels, gel-polymer hybrids, designed as "super sponges" that retain a large amount of water.
The research team led by Guihua Yu at the Copleel School of Engineering in UT Austin combines hydrogels that are highly absorbent and release moisture when heated. This unique combination has been proven to work in wet and dry weather conditions and is essential for producing clean, safe drinking water from the air.
The atmosphere contains approximately 50,000 cubic kilometers of water, and this new system can take advantage of these reserves and may result in small, inexpensive and portable filtration systems.
"We have developed a completely passive system, all you have to do is leave the hydrogel outside and collect the water," said Fei Zhao, a team researcher at Yu, co-author of the study. “The collected water will remain in the hydrogel until it is exposed to the sun. After about five minutes in natural sunlight, the water will be released.”
This technology is based on Yu and Zhao's 2018 breakthrough, using hydrogels to develop an innovative solar water purification technology that uses only solar energy to clean water from any source. The team's new innovations make this work a step further by using water already in the atmosphere. For both hydrogel technologies, Yu and his team developed a method that combines materials that are hygroscopic (absorbent) and thermally responsive (the ability to release water during simple heating).
"This new material is designed to collect moisture from the air as well as clean water in the sun, avoiding strong energy consumption," said Yu, associate professor of materials science and mechanical engineering.
Collecting water from water is not a new concept. Most refrigerators are kept cool by steam condensation. However, ordinary refrigerators require a lot of energy to perform this action. The technology of the UT team only needs solar energy, is compact, and can still produce enough water to meet the daily needs of ordinary families. Prototype testing showed daily water production of up to 50 liters per kilogram of hydrogel.
This technology represents a new strategy for improving existing atmospheric water harvesting technologies and can replace the core components of existing solar water purification systems or other moisture absorbing technologies.
Yu and his team have applied for a patent, and Yu is working with UT's Technology Commercialization Office to develop licensing and commercialization of this innovative hydrogel. The study was funded by the Alfred P. Sloan Foundation, the Camille & Henry Dreyfus Foundation and the National Science Foundation.
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