Technology to extract drinking water from the air using 'biodegradable hydrogel' made from discarded food and natural materials
A research group at the University of Texas at Austin has announced that they have succeeded in generating more than 14 liters of water from the air per kilogram of material per day using a 'molecularly functionalized biomass hydrogel' that can be made from natural materials such as discarded food, dead branches, and shrimp and crab shells.
Molecularly Functionalized Biomass Hydrogels for Sustainable Atmospheric Water Harvesting - Guan - Advanced Materials - Wiley Online Library
From Scraps to Sips: Everyday Biomass Produces Drinking Water from Thin Air
https://cockrell.utexas.edu/news/archive/10158-from-scraps-to-sips-everyday-biomass-produces-drinking-water-from-thin-air
Kitchen Scraps and Seashells Pull Drinking Water from Thin Air - ScienceBlog.com
https://scienceblog.com/kitchen-scraps-and-seashells-pull-drinking-water-from-thin-air/
The molecular functionalized biomass hydrogel developed by the research team acts as an adsorbent that captures moisture from the air and can be extracted as a liquid by applying mild heat. This is the same principle as desiccants such as silica gel, but since the biomass hydrogel is biodegradable, the environmental impact when it is disposed of is minimal.
And unlike existing synthetic adsorbents, which often use petrochemicals or require large amounts of energy to extract water, the new biomass hydrogels can be made from natural polysaccharides and require less energy to release water.
In field tests, the team found that the biomass hydrogel produced 14.19 liters of clean water per kilogram of material per day, compared with just 5 liters per kilogram of common adsorbents.
'This breakthrough provides a universal molecular engineering strategy that can transform a wide variety of natural materials into highly efficient adsorbents,' said Guihua Yu, professor of materials science and mechanical engineering at the University of Texas at Austin. 'This opens up an entirely new way to think about sustainable water harvesting and is a major step towards practical water harvesting systems for homes and small communities.'
What makes biomass hydrogels work so well is a two-step molecular engineering process that transforms natural materials like cellulose, which makes up plant cell walls, starch found in potatoes and corn, and chitosan, which is made from crustacean shells, into adsorbents.
In their approach, the team first endowed natural polysaccharide molecules with thermoresponsive groups, making them more responsive to temperature changes, and then added zwitterionic groups - molecules that have both positive and negative charges - to improve the material's ability to absorb and store water.
This enabled the research team to develop a hydrogel that can efficiently collect moisture from the air at room temperature and release it as clean water at a low temperature of 60 degrees, which is easily achievable using solar heat or waste heat.
The molecularly functionalized biomass hydrogel is part of Yu's long-term efforts to develop solutions for people without access to clean drinking water. The team previously developed a highly hygroscopic polymer film that can harvest water from the air using glucomannan, a component of konjac.
A new material that produces large amounts of water from desert air using 'konnyaku' is developed - GIGAZINE
The research team is currently working on designing practical systems to scale up production, including portable water collection devices, autonomous irrigation systems, and emergency drinking water supplies.
'Access to clean water should be simple, sustainable and scalable, and this material gives us a way to make water from air using one of nature's most abundant resources,' said Weixin Guan, lead author of the paper.
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