A new device that harvests water from the atmosphere using solar power could be used to provide for the world’s driest nations.
Scientists developed the atmospheric water harvesting technology using a super hygroscopic gel with remarkable swelling and salt-trapping qualities.
The resulting prototype device, complete with desorption and condensation chambers, was found to be able to retain an unparalleled amount of clean water even when the sun was at its weakest.
The researchers, from China, hope the device could be used to provide water to dry, water-stressed countries that struggle to obtain sufficient clean water.
More than 2.2 billion people currently live in water-stressed countries vulnerable to severe water shortages, with the United Nations estimating that 3.5 million die every year from water-related diseases.
Many water-stressed nations are simultaneously located in some of the sunniest regions on the planet – hence the fervent interest from scientists to develop technology harnessing sunlight to help obtain clean water.
Researchers from the Shanghai Jiao Tong University in China have now developed exciting new solar-powered, atmospheric water harvesting technology that could help provide enough drinking water for people to survive in these difficult, dryland areas.
Previous attempts to develop similar technology have often struggled when injecting salt into hydrogels, as the higher salt content reduces the swelling capacity of the hydrogel due to a ‘salting-out’ effect which leads to leakage and a reduction in water absorption capacity.
However, researchers in this study synthesized a super hygroscopic gel using plant derivatives and hygroscopic salts that was capable of both absorbing and retaining an unparalleled amount of water whilst limiting salt leakage.
One kilogram of dry gel was found to adsorb – or hold – 1.18 kilograms of water in arid atmospheric environments and up to 6.4 kilograms in humid atmospheric environments.
This hygroscopic gel was additionally simple and inexpensive to prepare, and would therefore be highly suitable for large-scale preparation.
“This atmospheric water harvesting technology can be used to increase the daily water supply needs, such as household drinking water, industrial water, and water for personal hygiene,” study author Dr. Ruzhu Wang explained.
“We were impressed that even when up to five grams of salt was injected into one gram of polymer, the resulting gel maintained good swelling and salt-trapping properties.”
The research team constructed a prototype device with desorption and condensation chambers which also employed a turbofan in the condensation chamber to increase the recovery of desorbed – or released – water to more than 90 percent.
In an outdoor demonstration, the prototype released adsorbed water even in the morning or afternoon when the sun was at its weakest, showing the device could also gather water during the daytime.
The team behind the promising study, published in the journal Applied Physics Reviews, now aims to achieve simultaneous adsorption and desorption using renewable energy to maximize daily water yield per unit mass of adsorbent to further optimize the system’s performance for practical applications in water generation.
In addition to daily water production, sorbent materials that harvest water from the atmosphere water could also play an important role in applications such as dehumidification, agriculture irrigation, and thermal management for electronic devices.
Produced in association with SWNS Talker
