As we know, some parts of the world lack access to clean drinking water. One approach to providing people with drinkable water is the treatment of seawater. Desalination plants are often used for this purpose. However, they consume a large amount of energy, which presents a major drawback in terms of cost and sustainability. Researchers at the Hong Kong Polytechnic University have now developed a new method: a 3D-printed aerogel that uses only sunlight to turn saltwater into drinking water.
The scientists based their new method on an existing technique. It involves using solar-powered evaporators made from porous materials. The saltwater evaporates, and the vapor is collected. Once the vapor cools, it becomes desalinated, drinkable water. But there’s a catch: scalability. Although attempts have been made to scale up these evaporators, the output doesn’t increase at the same rate. That’s because in large, thick materials with tiny pores, the vapor also gets trapped. As a result, this method is not very efficient and works very slowly.
Credit: ACS Energy Letters, Xiaomeng Zhao, Yunfei Yang, Xuemin Yin, Zhuo Luo, Kit-Ying Chan, Xi Shen
The researchers at the Hong Kong Polytechnic University, led by Xi Shen, took things a step further. They developed an aerogel made from cellulose nanofibers and carbon nanotubes. The gel is shaped using a process known as “frozen 3D printing.” As usual, the material is printed layer by layer, but each layer is immediately flash-frozen. Once a layer has solidified, the next one is added. This process creates structures with continuous vertical channels and ultra-thin walls. The resulting material resembles a sponge, with vertical holes that are each about 20 microns wide.
Solar Power and 3D Printed Aerogel Structures Provide Clean Drinking Water
According to a study published in ACS Energy Letters, the researchers tested square-shaped aerogel structures in various sizes. These were put through outdoor testing by placing the “sponges” in cups of seawater and covering them with transparent plastic. Sunlight heated the surface, causing the water, but not the salt, to evaporate. The water vapor collected on the plastic surface and was funneled into a container using a small funnel.
The results so far are extremely promising. The researchers were able to produce several tablespoons of drinking water, and its quality remained stable over an extended period. They also found that water vapor escaped quickly through the structure, even when the surface area of the aerogel was increased. This means the approach is truly scalable. In one test, the performance loss from scaling was only around 5 percent, compared to more than 40 percent with other materials.
Credit: ACS Energy Letters, Xiaomeng Zhao, Yunfei Yang, Xuemin Yin, Zhuo Luo, Kit-Ying Chan, Xi Shen
The next step is to conduct tests under real-world conditions. For the researchers, it’s crucial to determine how often the aerogel material needs to be replaced and how well it performs over the long term. You can find more about this study HERE.
What do you think about 3D-printed aerogels for producing drinking water? Let us know in a comment below or on our LinkedIn or Facebook pages! Plus, don’t forget to sign up for our free weekly Newsletter to get the latest 3D printing news straight to your inbox. You can also find all our videos on our YouTube channel.