Singapore taps into water-capturing innovation with new hydrogel

Singapore researchers have developed a new hydrogel that uses sunlight to harvest fresh water from the sea.

Marking the potential for floating water-capturing farms, the technology taps into Singapore’s leading work in developing sustainable urban solutions, including innovations in water treatment and management

The team from the Department of Materials Science and Engineering at the National University of Singapore (NUS) Faculty of Engineering has found an innovative way to harvest water from the humid air above water surfaces. It claims its zinc-based material is more than eight times more absorbent than existing drying agents such as silica gel and calcium chloride. The material does not require intensive energy to get the water back out of it, plus the gel can be reused over 1,000 times.

Lead scientist Asst. Prof. Tan Swee Ching says: “Due to the hot climate in Singapore, about 45 million cubic metres of water is lost from reservoirs through evaporation each year. Our hydrogel can convert moisture present in humid air to water without the need for any external energy input. By harnessing the moisture-rich air that is commonly found above water surfaces, we can collect water, which would otherwise be lost to the environment, for different uses.”

In field tests, floating devices containing the hydrogel were placed on the surface of the ocean. As water vapor subsequently evaporated out of the salt water, tiny airborne droplets of that vapor were collected by the gel. The water saturated hydrogels were transferred to an enclosed glass box which was then exposed to natural sunlight. Upon being heated to between 45 and 50 ºC (113 and 122 ºF) the gel released its stored fresh water in the form of vapor. That vapor condensed on the walls of the box, and was collected in liquid form.

In its current form, if used repeatedly throughout the day, the gel can produce over 10 litres of fresh water per kilogram of material daily.

The salt content of the water harvested from the hydrogels was found to be almost negligible.

“Unlike processes like desalination which are highly energy intensive, water collected using the novel hydrogel requires less treatment for different uses. Our invention also has potential to be scaled up considerably to function as a floating water-capturing farm. This approach could benefit rural communities where access to clean water remains a challenge. By creatively applying novel solutions, we hope to contribute towards mitigating the global water crisis,” said Asst Prof Tan.

The team is now looking at ways to optimise the performance of the hydrogel and the water harvesting process.

In a previous study, the same hydrogel was also shown to be effective at lowering relative humidity within rooms.

In 2020 Singapore will again host Singapore International Water Week, which in 2018 hosted more than 24,000 participants from 110 countries and brought together more than 500 business leaders. The biennial event  global platform gathers stakeholders from the global water industry to share best practices, showcase the latest technologies and tap business opportunities to share and co-create innovative water solutions. 



(via: National University of Singapore via AlphaGalileo, New Atlas, Visit Singapore)