Water harvesting hydrogel

Materials World magazine
25 Mar 2019

A new hydrogel can absorb moisture in the air and turn it into clean water. Idha Valeur reports.

A new technology that can convert air moisture into potable water and is powered by solar energy could open up access to safe water supplies, according to researchers from the University of Texas at Austin (UT), USA. The technology could make a difference in disaster situations, during water crises, or in developing countries, by providing a source of safe and accessible water.

Led by UT Austin’s Cockrell School of Engineering Professor Guihua Yu, the research team combined absorbent and water-releasing hydrogels to successfully craft a combination that would be effective in humid and dry weather conditions.

With as much as 50,000km3 of water in the atmosphere, this system could potentially act as a small, cheap and transportable water filtration method.

‘We have developed a completely passive system where all you need to do is leave the hydrogel outside and it will collect water. The collected water will remain stored in the hydrogel until you expose it to sunlight. After about five minutes under natural sunlight, the water releases,’ said UT Austin PhD Researcher and co-author of the study, Fei Zhao.

In 2018, the research team created a technology where hydrogels were used to clean water from its source, powered by solar energy. This time, the team has developed it further by targeting water readily avaliable in the atmosphere.

‘The new material is designed to both harvest moisture from the air and produce clean water under sunlight, avoiding intensive energy consumption,’ Yu said.

The test of the prototype showed the hydrogel, which is shaped into pellets and stored in a mesh bag, is capable of producing 50 litres of water per kilogram of hydrogel per day. As well as providing a standalone solution, this technology could replace existing water purification methods powered by solar energy, or even other technologies absorbing moisture.

Zhao told Materials World the main obstacle for commercialising the hydrogel is large-scale fabrication, as ‘there are some fundamental differences between lab-scale fabrication and industrial production.

‘Moreover, while the raw materials of our super moisture-absorbent gel (SMAG) are commercialised chemicals, there is no industrial production of them, and hence we are not able to fairly estimate the cost of our SMAG at this stage. But certainly, as they become critically useful in certain technologies, the cost of producing them may quickly become economical’.

The paper, Super moisture-absorbent gels for all-weather atmospheric water harvesting, was published in Advanced Materials.

Read more about the project here: bit.ly/2ulLdVT