Molecular sponge soaks up water from desert air

A team at the Advanced Research Centre of the Royal Scientific Society (RSS) in Amman, Jordan has incorporated their technology into a compact and portable water harvester device. 

They say their process, when conducted on-the-grid, produces water at a cost per litre that is 46% less than the price of commercially available bottled water.

Jordan is the world’s second most water scarce country. “Secure access to water is an existential crisis, [so] we sought to exploit the untapped reservoir of the atmosphere, which contains an immense amount of water in the form of humidity,” says RSS Executive Director of Scientific Research and materials chemist, Kyle Cordova. 

The process uses a metal-organic framework (MOF), a hybrid material composed of metallic centres held together by organic (carbon-based) linker groups. MOFs have highly porous, three-dimensional structures. Varying the metallic components and the linker groups offers great structural variety, which chemists worldwide are exploring for their abilities in molecular separation and catalysis, among other applications.

The MOF used by Cordova and colleagues has pores that can selectively capture water molecules from the air and then be induced to release the harvest as liquid water.

The team found that fluctuations in humidity and temperature had a big impact on the water-harvesting efficiency and power needed to drive their device. This led them to develop control algorithms that automatically optimize the water harvesting cycles in line with environmental conditions. This self-adapting facility refined the performance to produce up to 3.5 litres of water per kilogram of MOF per day.

“This is a 169% increase in production efficiency compared to the next best-performing device,” Cordova says. 

MOF researcher, Professor Yue-Biao Zhang at ShanghaiTech University, China, who was not involved in the work, describes it as “a breakthrough that propels MOFs for atmospheric water harvesting one step further to real applications”. He says he is excited that MOF materials “will change the world by pulling drinking water from desert air in the Middle East and other arid areas”.

The Advanced Research Centre at the RSS is a product of the Global Science initiative², which began at the University of California, where Cordova previously worked. The initiative allows experienced scientists to develop centres of excellence in countries with relatively weak research bases. Researchers, such as Cordova, provide mentorship to emerging scholars. “It’s about providing opportunities and democratizing access to scientific research around the world,” Cordova says.

The team is now hoping to move quickly into commercialization and widespread application of their device. Fabricating the MOFs accounts for the bulk of the device’s production costs, so the team is working with domestic and international partners to manufacture these materials at scale. They are currently testing a prototype commercial version and hope that support from the Jordanian government will assist in manufacturing individual household units by next year.

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