Published: Sun, April 16, 2017
Science | By Carlton Santiago

A Revolutionary New Material Pulls Drinking Water From Thin Air

A Revolutionary New Material Pulls Drinking Water From Thin Air

Their device works at low power and in arid conditions, which means it could help remote desert communities without constant access to fresh water. Video by Roxanne Makasdjian and Stephen McNally, UC Berkeley. MIT photo from laboratory of Evelyn Wang.

You can't squeeze blood from a stone, but wringing water from the desert sky is now possible, thanks to a new spongelike device that uses sunlight to suck water vapor from air, even in low humidity.

The device designed by Evelyn Wang (the other senior of the paper) and her students at MIT uses a kilogram of the dust-sized crystals of the MOF.

Yaghi, a chemistry professor at University of California, Berkeley, envisions a future where the water is produced off-grid for individual homes and possibly farms using the device. Her team of students was able to produce nearly three liters of water using 2.2 pounds worth of MOFs in just 12 hours, drawing the water from the air and not having to use any solar panels for their device. "There are desert areas around the world with around 20 percent humidity", where potable water is a pressing need, "but there really hasn't been a technology available that could fill" that need, Wang says.

"It's not just that we made a passive device that sits there collecting water; we have now laid both the experimental and theoretical foundations so that we can screen other MOFs, thousands of which could be made, to find even better materials", he told Berkeley News.

The technology opens the door for what co-author Omar Yaghi called "personalised water". In the last 20 years, researchers have created over 20,000 different MOFs for a wide variety of applications, such as separating methane and water from other gasses. Metal organic frameworks got invented some two decades ago.

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To collect the water, scientists turned to metal organic frameworks, or MOFs. Many firms are using these MOF to produce water. UC Berkeley, Berkeley Lab image.

Some MOFs can capture carbon dioxide (CO2) from flue gases, separate petrochemicals within processing plants, or catalyze the reactions of absorbed chemicals. Also, water is one of the key factors needed for basic survival. The team also observed that the water vapor molecules often form cubes, in groups of eight. The team found that when this material is placed between a top surface that is painted black to absorb solar heat, and a lower surface that is kept at the same temperature as the outside air, water is released from the pores as vapor and is naturally driven by the temperature and concentration difference to drip down as liquid and collect on the cooler lower surface.

It's not that hard to collect condensation in a humid climate, but squeezing H20 from arid, thin air is another story.

Taking a page out of science fiction playbooks, scientists have demonstrated breakthrough technology capable of generating water out of dry air using the power of the sun.

The harvester sitting atop a roof at MIT. Sunlight heats the device, which causes the water to condense into a tank. The yellow and red condenser sitting at the bottom is covered with water droplets.

But it's conceivable that someday if you're visiting Death Valley, one of the driest places in the United States, you'll be able to wet your whistle with a device based on Wang and Yaghi's concept.

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