Atmospheric Water Harvesting (AWH) is a technique that draws clean drinking water from humidity. Scientists have long sought a reliable water extraction method for it, though. There are “sponge-like” materials designed to soak up moisture, but their setback has always been the recovery step. Traditionally, these spongey systems rely on the Sun’s heat to evaporate the water and condense it. However, this process could take hours or even days.
MIT researchers may have found a faster solution that replaces thermal release with ultrasonic waves. According to the research team, their ultrasonic device vibrates at a high frequency to shake water from the spongy materials known as sorbents. Importantly, the water extraction apparently takes only minutes.
A Faster Way to Get Drinkable Water From the Air
Principal research scientist Svetlana Boriskina emphasized the importance of a faster recovery method. “Any material that’s very good at capturing water doesn’t want to part with that water, she said. “So you need to put a lot of energy and precious hours into pulling water out of the material.” Boriskina, graduate student Ikra Iftekhar Shuvo, and the rest of their team realized ultrasound could offer a breakthrough.
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“With ultrasound, we can precisely break the weak bonds between water molecules and the sites where they’re sitting,” Shuvo, who has a background in the field of ultrasound, explained. “It’s like the water is dancing with the waves, and this targeted disturbance creates momentum that releases the water molecules, and we can see them shake out in droplets.“
Researchers say the ultrasonic technique proved efficient. They calculated that their design is 45 times more efficient at extracting water compared to other techniques on the same material. Additionally, their system, which can operate on a small solar cell, automatically turns on when the sorbent is full, enabling it to run multiple extraction cycles in a day.
“The beauty of this device is that it’s completely complementary and can be an add-on to almost any sorbent material,” Boriskina emphasized.
There is immense potential for their water extraction device, particularly for communities that lack access to reliable water sources. According to the World Health Organization, in the U.S. alone, 1 in 4 people lack access to safe, drinkable water.
“People have been looking for ways to harvest water from the atmosphere, which could be a big source of water, particularly for desert regions and places where there is not even saltwater to desalinate,” Boriskina added. “Now we have a way to recover water quickly and efficiently.“