Crystalline Nets Harvest Water From Desert Air, Turn CO2 Into Liquid Fuel

Omar Yaghi, a chemist at the University of California, Berkeley, reported that he and his colleagues have created a solar-powered device that uses porous crystalline material, known as a metal-organic framework (MOF), to suck water vapor and carbon dioxide (CO2) out of the air and then release it as liquid water. Science Magazine reports: One recent market report predicted that sales of MOFs for applications including storing and detecting gases will balloon to $410 million annually over the next 5 years, up from $70 million this year. "Ten years ago, MOFs showed promise for a lot of applications," says Omar Farha, a MOF chemist at Northwestern University in Evanston, Illinois. "Now, that promise has become a reality." One application is Yaghi's, which he hopes will help provide drinking water for the estimated one-third of the world's population living in water-stressed regions. Yaghi and his colleagues first developed a zirconium-based MOF in 2014 that could harvest and release water. But at $160 per kilogram, zirconium is too expensive for bulk use. So, last year, his team came up with an alternative called MOF-303, based on aluminum, which costs just $3 per kilogram. In the desert of Arizona, Yaghi and his team placed their MOF in a small, clear plastic container. They kept it open to the air at night, allowing the MOF to absorb water vapor. They then closed the container and exposed the MOF to sunlight, which drove liquid water from it -- but the harvest was only about 0.2 liters per kilogram of MOF per day. At last week's meeting of the American Chemical Society and in the 27 August issue of ACS Central Science, Yaghi reported that his team has devised a new and far more productive water harvester. By exploiting MOF-303's ability to fill and empty its pores in just minutes, the team can make the new device complete dozens of cycles daily. Supported by a solar panel to power a fan and heater, which speed the cycles, the device produces up to 1.3 liters of water per kilogram of MOF per day from desert air. Yaghi expects further improvements to boost that number to 8 to 10 liters per day. Last year, he formed a company called Water Harvesting that this fall plans to release a microwave-size device able to provide up to 8 liters per day. The company promises a scaled-up version next year that will produce 22,500 liters per day, enough to supply a small village. "We're making water mobile," Yaghi says. "It's like taking a wired phone and making a wireless phone."Read more of this story at Slashdot.
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