Food waste, plant material and other biomass could potentially be converted into materials capable of extracting water from the atmosphere, according to researchers at the University of Texas at Austin, The Economic Times reported.
The researchers have developed a new class of biomass-based hydrogels that can absorb moisture from the air and release it as water using relatively mild heat. Their findings, published in the peer-reviewed journal Advanced Materials, could provide a more sustainable approach to atmospheric water harvesting.
The study, Molecularly Functionalized Biomass Hydrogels for Sustainable Atmospheric Water Harvesting, was authored by Weixin Guan, Yaxuan Zhao, Chuxin Lei, Yuyang Wang, Kai Wu and Guihua Yu.
Rather than relying on a single specialised synthetic material, the researchers developed a molecular engineering strategy that can transform naturally abundant polysaccharides such as cellulose, starch and chitosan into water-absorbing hydrogels.
In laboratory tests, the cellulose-based hydrogel captured 0.86 to 1.32 grams of water per gram of material at relative humidity levels between 15% and 30%. It could then release 95% of the captured water at 60°C, reducing the heat required to regenerate the material for another harvesting cycle.
Outdoor tests showed that the cellulose-based material produced up to 14.19 kg of water per kg of sorbent per day under the conditions tested, using electrical heating.
The material works by combining water-attracting and temperature-responsive molecular groups. These properties allow the hydrogel to capture moisture from relatively dry air and release the water when heated.
The researchers said the approach could potentially be used to develop portable water harvesters, decentralised water systems, self-sustaining irrigation systems and emergency drinking-water devices.
A key feature of the research is the use of biomass-derived materials. Cellulose, starch and chitosan can be sourced from a variety of biological materials, creating potential opportunities to use resources such as food waste, plant residues and other biomass as feedstocks.
However, untreated waste cannot simply be placed in a device to produce water. The biomass must first be processed to provide a suitable polysaccharide structure, which is then chemically modified to give the hydrogel its moisture-capturing properties.
The researchers said the strategy could reduce dependence on specialised synthetic sorbents and provide a renewable starting point for atmospheric water harvesting.
The technology is still at the research stage, and laboratory and controlled outdoor results do not establish commercial readiness. Future systems will need to address energy consumption, water collection efficiency, material durability and large-scale production costs.
The team is now exploring ways to scale up the technology and develop practical systems that could provide water in areas where conventional infrastructure is unavailable or difficult to build.
