Transforming Air Into Pure Drinking Water Is Finally Possible, Here’s How

Deserts are not particularly welcoming environments, and yet at least a hundred million people live in desert regions around the world, according to the UN. They have to make do with less than 25 cm of rainfall each year, and for many, even that minuscule water supply is under threat as climate change is making dry areas even drier. So scientists at UC Berkeley have been experimenting with materials that can pull drinking water out of thin air. The compound they’ve devised is one of a family of materials called Metal-Organic-Frameworks, or MOFs. MOFs are, well it’s pretty much right in the name, frameworks of metal atoms connected to each other with organic linkers.

This structure makes them porous like a sponge, giving them incredible surface areas; a single gram of a MOF can have the surface area of a football field. And depending on the metal and organic molecules they’re made of, they can be tailored to capture different things in their pores. MOFs have potential uses capturing CO2 and turning it into the fuel methanol, or neutralizing nerve agents like sarin gas. The function the Berkeley scientists tuned their MOF for was extracting water vapor that’s present in the air. The first one they made in 2014, called MOF-801, was zirconium-based. When tested in a water harvester it worked entirely passively, absorbing and condensing water overnight and giving it up again when the sun warmed it up.

So the concept worked and used a lot less energy than the other way of extracting water from low humidity air, which involves cooling the air below freezing. In any case, Zirconium is costly, so the researchers set to creating MOF-303 dependent on the lot less expensive component aluminum. Not only is the new MOF cheaper, but it also performs much better. It can hold 30% more water and fill up and empty in just 20 minutes in the right conditions. And because the MOF was designed to leave no traces of organic or inorganic material in the water, it’s completely pure and drinkable right away.

Utilizing a similar latent procedure in a reaper left medium-term in the Arizona desert, one kilogram of MOF-303 collected 0.2 liters of water. Now I know what you’re thinking. That doesn't sound like a lot of water. And you're right. But the good news is the aluminum-based MOF’s ability to fill and empty in minutes can be exploited. The scientists changed up their design. Instead of passively relying on a day-night cycle, their latest harvester relies on solar-powered fans and heaters to run dozens of cycles a day.

Ideally, it can make more than 1.3 liters of water per kilogram of MOF each day, and the researchers hope to get that number as high as 8 or 10 liters per kilogram. The lead analyst behind this has begun a privately owned business called Water Harvesting. The plan is to launch a microwaved sized device that can supply 2 adults with enough drinking water for their daily hydration and cooking needs. Eventually, they envision a harvester big enough to supply a small village.

If the devices are affordable, safe, and reliable enough, these metal-organic frameworks have the potential to turn even the driest deserts into oases. Clean drinking water has always been a challenge for humanity, and sometimes we make mistakes. Like when we chose lead funnels were a smart thought. Thankfully, researchers are developing ways to render the poisonous pipes harmless.