A breakthrough in solar water harvesting technology, which uses innovative gels and system designs to efficiently extract water from the atmosphere. This technology could revolutionize water use in arid, sunny areas to meet critical needs for drinking water and other uses.
Atmospheric water collectors use hygroscopic gels and salts to supply water to arid areas. More than 2.2 billion people currently live in water-stressed countries, and the United Nations estimates that 3.5 million people die each year from water-related diseases. Since the areas most in need of improved drinking water are also located in the sunniest places in the world, there is a strong interest in using sunlight to help access clean water.
Researchers at Shanghai Jiao Tong University in China have developed a promising new solar-powered atmospheric water harvesting technology that could help provide enough drinking water to people in these harsh arid regions. They published their findings in the AIP-published journal Applied Physics Reviews.
This atmospheric water harvesting technology can be used to increase daily water supply needs, such as domestic drinking water, industrial water, and personal hygiene water.
Overcoming traditional challenges
Historically, researchers have faced challenges when injecting salt into hydrogels, as higher salt content can reduce the swelling capacity of hydrogels due to salting out effects. This leads to salt leakage and a decrease in water absorption.
We were impressed by the fact that even with up to 5 grams of salt injected into 1 gram of polymer, the resulting gel retains good swelling and salt trapping properties"Researcher Wang Ruzhu said.
Schematic diagram of the atmospheric catchment cycle during the day. Material**: Wang Ruzhu.
Innovative hygroscopic gel and system design
Using plant derivatives and hygroscopic salts, researchers synthesized a super-hygroscopic gel that absorbs and retains large amounts of water. In an arid atmosphere, one kilogram of dry gel can adsorb 118 kg of water, and in a humid atmosphere, it can adsorb up to 64 kg of water. This hygroscopic gel is simple and inexpensive to prepare, making it suitable for large-scale preparation.
In addition, the research team adopted a prototype with a desorption chamber and a condensation chamber, configured in parallel. They used a turbofan in the condensation chamber to increase the desorption of water to more than 90%.
In an outdoor prototype demonstration, the team found that it released adsorbed water even in the morning or afternoon when the sun was low. The system also enables adsorption and desorption at the same time during the day.
Future applications and optimizations
The research team will strive to achieve simultaneous adsorption and desorption using renewable energy to maximize the daily water production per unit mass of adsorbent, thereby further optimizing the performance of the system and making it practical in the field of water production.
In addition to daily water production, adsorbent materials that collect atmospheric water can play an important role in future applications such as dehumidification, agricultural irrigation, and thermal management of electronic devices.
Reference: "Daytime Air-Water Collection Based on Simultaneous Adsorption-Desorption of Superhygroscopic Porous Gels," by Chengjie Xiang, Xinge Yang, Fangfang Deng, Zhihui Chen, and Ruzhu Wang, December 5, 2023, Review of Applied Physics.
doi: 10.1063/5.0160682
Compilation**: scitechdaily