New Hydrogel Material Allows Atmospheric Water Harvesting; Device Could Provide Refreshment in Desert Environments
Potable water is a basic need, but it's not accessible in some areas, especially in arid places. However, a new technology was recently developed that allows atmospheric water harvesting.
New Hydrogel Water Harvesting Device
Researchers at the University of Texas at Austin used a new hydrogel material to collect water from thin air at temperatures low enough to be achieved by sunlight. Hence, drawing water from the air's humidity is possible.
According to the study, if the humidity is high enough, a system can condense the moisture and gather liquid water by cooling the air below the dew point or passing fog through a mesh. However, water vapor must be directly drawn out of the air as a gas in arid regions and low-humidity environments.
It functions as a dehumidifier to gather the water in the first of its two major steps, after which it releases it for use. Other researchers have looked into similar approaches for extracting water vapor using silicas and metal-organic frameworks. However, per Guihua Yu, a professor of engineering at UT Austin who led the research, those materials come with pros and cons.
One notable drawback of the other materials used to remove humidity from the air is that it takes a lot of energy to release the water once it has been absorbed. Yu's team has created a novel synthetic material to address this significant issue. They use hydrogel, a network of polymers that naturally holds a lot of water. However, compared to other hydrogels, the new substance needs less energy to release that water, allowing the system to run on sunshine alone.
They aim to use the new technology in desert regions. The new study came after a previous research funded by the Defense Advanced Research Projects Agency (DARPA), a division of the Department of Defense, that seeks to give soldiers stationed in desert environments access to drinking water.
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How Does Atmospheric Water Harvesting Work?
The novel hydrogel is more effective in its intake and release of water due to its structure. It connects two separate segments - a network of sites that absorb and store water and thermoreactive segments that aid in the release of liquid water,
The benefit of immobilizing salt ions in the polymer structure on the absorption side. Conventional hydrogels are similar to "bulky Jell-O" and have salt ions added to them to aid in liquifying and drawing in vapor. However, Yu warns that they risk spilling those salts every time they release water and that their capacity to absorb water may eventually be compromised. The new hydrogel avoids these problems by anchoring the salt ions in specific locations.
Meanwhile, the held water must be released due to the gel's thermoreactivity. The material switches from keeping water to expelling it when warmed above a threshold temperature. This substance produces water at a relatively low temperature possible with only solar energy by distributing thermoreactive segments across smaller absorption areas.
At a temperature of 40 °C, the hydrogel can release more than 80 percent of the absorbed water in about 20 minutes, which is common in desert conditions.
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