In the Earth's atmosphere, there is water that can fill almost half a trillion Olympic swimming pools. But it has long been overlooked as a source for potable water. Researchers now have created a substance that extracts water from air without any external power source.
The team created a type of aerogel — a solid material that weighs almost nothing. Under the microscope, it looks like a sponge but it does not have to be squeezed to release the water it absorbs from the air. It also does not need a battery. In a humid environment, one kilogram of it will produce 17 liters of water a day.
The trick is in the long, snake-like molecules — known as polymers — building up the aerogel. The long-chain polymer consists of a sophisticated chemical structure that can continuously switch between attracting water and repelling water. The smart aerogel autonomously gathers water molecules from the air, condenses them into a liquid, and releases the water. When there is sunshine, the smart structure can further boost the water release by transitioning to a complete water-hating state.
Ninety-five percent of the water vapor that goes into the aerogel comes out as water. In laboratory tests, the aerogel produced water nonstop for months. The researchers tested the water and found that it met World Health Organization standards for drinking water.
Other scientists’ work previously devised ways to extract water from air but the designs had to be powered by sunlight or electricity and had moving parts that had to be opened and closed.