Harvesting fresh water from the sea with hydrogel

Researchers from the National University of Singapore (NUS) found a way to harvest water from the humid air over water surfaces using a water-absorbing hydrogel.

About 70 per cent of the earth is covered in water. Unfortunately, most of this water is located in seas and oceans, and therefore not suitable for consumption. With climate change, more and more areas around the world have to deal with water scarcity.

The research team from NUS found a way to recover ‘lost’ water from water surfaces. They developed a zinc-based water absorbing hydrogel, which is over 8 times more absorbent than commercial drying agents. When placed over a glass plate on a floating device, the hydrogel absorbs more than 4 times its original weight of water vapour.

Once saturated, the pieces f hydrogel were transferred to an enclosed glass box during the trial, which was exposed to sunlight. This caused the water to evaporate from the hydrogel and condense against the wall of the glass box. After use, the hydrogel can be reused.

Unlike processes like desalination, which are highly energy intensive, water collected using the new methods requires less treatment for different uses. The invention has the potential to be scaled up to be used in a floating water-capturing farm in areas with water scarcity.

Photo: NUS