Some say future wars will be fought over water, and a billion people around the world are already struggling to find enough water to live on. Now researchers from the National University of Singapore (NUS) are coming to the rescue.
The NUS team created a substance capable of extracting water from the air without any external power source.
An airgel to extract water from the air
There is so much water in the Earth's atmosphere that it fills nearly half a trillion Olympic swimming pools. But the simple atmosphere has long been overlooked as a source of drinking water. To extract water from this underused source, a team led by Professor I have Ghim Wei of the Department of Electrical and Computer Engineering of the NUS created a type of airgel, a solid material that weighs almost nothing.
Under the microscope it looks like a sponge, but it doesn't need to be squeezed to release the water it absorbs from the air. It also does not require a battery. In a humid environment, just one kilogram of airgel is capable of extracting water from the air for 17 liters per day.
Water from the air with an airgel: how does it work?
The trick is in the long snake-like molecules, known as polymers, that make up the airgel. The special long-chain polymer consists of a sophisticated chemical structure that can continuously switch from water attraction to water repulsion.
This "smart" airgel extracts water from the air, condenses it into a liquid and releases the water. When it's sunny, the smart structure can further increase water release by moving into a state of total water repulsion. And it is very effective in this. 95 percent of the water vapor that enters the airgel comes out as water. In laboratory tests, the airgel provided water continuously for months.
The researchers tested the water and found that it met the World Health Organization's standards for drinking water.
The first device that does not require power
Other scientists have previously come up with methods of extracting water from the air, but their designs had to be powered by sunlight or electricity and had moving parts that needed to be opened and closed. The NUS researchers published their creation in the journal Science Advances ("MOF matrix of autonomous atmospheric water infiltration"). They are now looking for industrial partners to expand the device for home or industrial use. Perhaps it could even find a place in endurance sports or survival kits, for example." As atmospheric water is continually replenished by the global hydrological cycle, our invention offers a promising solution for achieving sustainable freshwater production in a variety of climatic conditions, at minimal energy cost, "said Prof. Ho.
