UT-Austin researchers develop low-cost gel that absorbs water from desert air

Leila Saidane, News Reporter

A new low-cost, sustainable polymer gel film produced by UT researchers may hold the key to aiding water scarcity in two-thirds of the global population.

The thin and porous film, made out of the cooking ingredient konjac gum, renewable cellulose and water-absorbent salt, can rapidly capture large amounts of water under arid conditions, according to the study.

“The amount of atmospheric water vapor … is another source of fresh water that cannot be overlooked,” said Youhong Guo, lead author of the paper and UT doctoral graduate. “Our previous efforts mainly focused on the seawater desalination, wastewater treatment and water disinfection, but in this research we seek the alternative solution to water scarcity — from the air.”

The flexible film, which can be molded into any shape and size, is simple to make, Guo said. The material costs only $2 per kilogram and is set in a mold with a gel precursor and freeze dried until it is ready to use. Once it is ready, the gel is able to produce roughly 1.5 gallons of water a day in environments with less than 15% relative humidity. Most homes ideally sit at a range of 30-50% relative humidity. 

“You just need to put the film outside, exposed to the air and after an hour you can take it back and put (it) on the heating plate to evaporate the water and condense it,” lead researcher Weixin Guan said.

UT researchers previously developed a hydrogel to absorb water from high humidity environments and a solar-powered moisture harvester to collect and clean atmospheric water. But this recent invention does not require vast amounts of energy like the others and works in the hottest and driest conditions.

“Compared to other (atmosphere moisture absorbing) material, our gel has much faster absorption and desorption kinetics, which also allow the more operation cycles which means a higher water yield per day,” Guo said.

Guo said the next step in the process is creating a device to efficiently condense and collect the water from the new material. The project, funded by the U.S. Department of Defense’s Defense Advanced Research Projects Agency, was developed in part to aid soldiers in securing drinking water in arid climates.

“Our group (was) aiming to develop hydrogel-based materials to overcome the global water shortage,” Guo said. “Besides using the traditional water purification technologies, people can obtain more water resources daily using our material … The synthesis of the gel is very simple, which means everyone can make it easily for a massive usage.”