Researchers at the University of Texas at Austin have developed biomass-based hydrogels that can capture moisture from the atmosphere and release it as water using relatively low heat, potentially offering a more sustainable approach to water harvesting, The Times of India reported.
The research, published in the peer-reviewed journal Advanced Materials, uses natural polysaccharides such as cellulose, starch and chitosan to create water-absorbing materials. The approach could allow agricultural and organic waste materials to be converted into components for atmospheric water-harvesting systems.
The study was conducted by Weixin Guan, Yaxuan Zhao, Chuxin Lei, Yuyang Wang, Kai Wu and Guihua Yu.
Rather than developing a single specialised synthetic material, the researchers developed a molecular engineering method that can modify different biomass-based materials to give them the properties needed to absorb and release water.
In laboratory tests, the cellulose-based hydrogel captured between 0.86 and 1.32 grams of water per gram of material at relative humidity levels of 15-30%. About 95% of the captured water could be released when the material was heated to 60°C.
The researchers modified the natural polysaccharide structure by adding thermoresponsive and zwitterionic groups. This molecular design allows the material to attract moisture from air while facilitating the release of captured water at relatively low temperatures.
The ability to regenerate the material using modest heat is important because atmospheric water harvesting involves two stages: capturing water vapour and subsequently releasing it as liquid water. Lower regeneration temperatures could help reduce the energy required to operate such systems.
The team also tested the hydrogel outdoors. Under the conditions of the experiment, the cellulose-based material produced up to 14.19 kilograms of water per kilogram of sorbent per day using electrical heating.
The researchers said the strategy could be applied to a range of naturally abundant biomass materials. The University of Texas at Austin highlighted potential sources including food waste, discarded branches and seashells.
The approach could therefore provide a way to turn materials commonly treated as waste or agricultural by-products into useful components for water-generation technologies.
Atmospheric water harvesting could be particularly useful in areas where conventional water infrastructure is difficult or expensive to establish. The researchers’ work points towards the development of portable water harvesters and decentralised systems capable of producing water from atmospheric moisture.
However, the reported water-production rate was achieved under specific experimental conditions, and further development would be needed to determine how the technology performs across different climates and humidity levels and at larger scales.
The research suggests that combining renewable biomass materials with molecular engineering could open a new route to atmospheric water harvesting while reducing dependence on specialised synthetic sorbents.
