Researchers at the Massachusetts Institute of Technology have developed a device that collects moisture from the air and turns it into drinkable water within minutes. The research team hopes that the technology could eventually be used to provide clean water to areas lacking natural resources.
Atmospheric water recovery (AWH) systems work by extracting moisture from the air and condensing it into liquid water. This typically involves cooling moist air or using sponge-like materials called “adsorbents” that absorb water vapor and then release it and condense it into droplets.
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But MIT’s new device uses ultrasound (ultrasound) to shake water out of the adsorbent. The released moisture exits through a small nozzle at the bottom of the device, where it can be collected and used.
According to the researchers, the ultrasound prototype is 45 times more efficient at extracting trapped water compared to evaporation alone. They detailed their findings in a paper published November 18 in the journal Nature Communications.
“People have been looking for ways to harvest water from the atmosphere, which could be a major source of water, especially in desert regions or places where there isn’t even seawater to desalinate,” study co-author and MIT principal investigator Svetlana Boriskina said in a statement. “We now have a way to recover water quickly and efficiently.”
Drinking water — days to minutes
MIT’s approach uses ultrasound (sound waves that travel at frequencies above 20 kilohertz, above the range of human hearing) to release water from adsorbents.
The heart of the AWH device is a flat ceramic ring that vibrates when voltage is applied. The researchers found that radiofrequency pulses are ideal for breaking the weak bonds between absorbed water and the material surface.
“It’s like the water is dancing with the waves, and this targeted disturbance creates a momentum that releases the water molecules, and we see them flying out into droplets,” lead author of the study and MIT graduate student Iqra Iftekhar Shuvo said in a statement.
The researchers tested the device by placing quarter-sized samples of adsorbent inside humidity chambers set at different levels. Once the sample is saturated, it is placed on an ultrasonic actuator and vibrated at high frequency. In each case, the instrument dried the sample in just a few minutes by shaking it.
A potential challenge is that new devices require a power source, unlike AWH systems that use only sunlight. The researchers suggest that the device could be combined with a small solar cell that also acts as a sensor to detect when the adsorbent is full. This can trigger a release cycle that allows the system to collect and release water multiple times a day.
The researchers envision a compact home setup that combines highly absorbent materials with a window-sized ultrasonic actuator that vibrates to release trapped water.
“The advantage of this device is that it is completely complementary and can be added to almost any adsorbent,” says Boriskina. “What matters is how much water you can extract in a day. Using ultrasound, you can quickly collect water and circulate it many times. This can be how much water you can extract in a day.”
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