Scientists at the University of Texas in Dallas, who learned how to collect water from living organisms such as rice leaves and pitcher plants, developed and tested a combination of materials that can do the same but faster.
The shells of certain desert-inhabiting beetles can catch and direct water droplets, as well as textures on rice leaves and pitcher plants. With this natural blueprint, researchers at UT Dallas, in collaboration with Penn State University, developed a surface and infused it with a liquid lubricant that is hydrophilic ̵
Their results appear online on March 30 in the journal Science Advances .
Existing processes for producing fresh water, such as desalination, rely on the transition from steam to water, "said Dr. Simon Dai, a mechanical engineering lecturer at the Erik Jonsson School of Engineering and Computer Science." We wanted to create a surface that can efficiently detect and direct water droplets. "
If a surface encloses a drop of water too tightly, it can not move fast enough to be picked up at an efficient speed, Dai said The droplet is firmly attached and takes a long time to reach the bottom of the glass This time consuming process means that some water may be lost due to evaporation before it can ever be trapped.
To design a suitable material, Dai and his associates had to meet several criteria, including creating a surface that made it possible to keep the lubricant even. In addition, the surface chemistry for the lubricant needed to be more favorable than for the water to wet solid structures, and the lubricant and water could not mix.
The "hydrophilic directed slippery rough surfaces" of the researchers, or SRS combines the best water harvesting design elements from several natural products. They wanted a surface that could capture tiny water droplets and combine them into big droplets. They adapted this property to the slippery function of pitcher plants.
"We found through simulations that molecules attracting water- or hydroxy-functional groups capture water droplets most efficiently, which is why we used hydrophilic lubricant," said Dr Steven Nielsen, Associate Professor in the Department of Chemistry and Biochemistry at UT Dallas , and a study author.
"We have provided our rough surfaces with a hydrophilic, liquid lubricant that is molecularly mobile so that the collected water can coalesce larger drops," said Dai. "In addition, the material is scalable, unlike beetle-inspired surfaces where dripping occurs only in certain areas, we can create small or large surfaces with the ability to quickly capture and move water anywhere on the surface."
Another key component of the SRS is that it can be optimized and customized for specific applications. These are suitable for a wide range of industries such as air conditioning, power generation, desalination and water use in arid regions.
"We are confident that these surfaces can be scaled up or down as needed," Dai said. "The next steps include improving water-harvesting capabilities at lower humidity levels."
Researchers have filed a patent for the technology.
An artificial surface dissolves sticky water droplets
X. Dai el al., "Hydrophilic Directed Slippery Rough Surface for Water Recovery" Science Advances (2018). fortschritt.sciencemag.org/content/4/3/eaaq0919