Development of a material that sucks up nearly 6 liters of water from the air every day

Scientists have developed a salt hydrogel that can draw large amounts of fresh water from the air in conditions of just 30% humidity.

Lack of drinking water is a serious problem in many parts of the world, while large amounts of water are always suspended in the air. To solve this problem, researchers at the University of Texas, Austin, developed salt hydrogel materials that can draw fresh water from the air in conditions of low relative humidity, New Atlas reported on March 3. The new study was published in the journal Angewandte Chemie.

Drinking water can be extracted from the air thanks to a new salt hydrogel.

Hydrogels (a form of polymer) are primarily made of water, but that doesn't stop them from absorbing more. Their excellent absorbency makes them useful in the manufacture of diapers and dressings, and even has the potential to be used as dehumidifiers and devices for drawing drinking water from the air.

The application of making a device to draw water from the air will be very practical, but the disadvantage is that the process is a bit slow and inefficient. Adding desiccant salts - effective water absorbents - can be helpful, but these salts do not mix well with the hydrogel.

So, in the new study, the scientists worked to find a way for them to combine favorably. They used a polymer made of "zwitterionic" molecules - they contain ions that carry both positive and negative charges. This allows the polymer to hold the hygroscopic salts more firmly, thereby creating a hydrogel that effectively draws water from the air.

The water capture process requires a cycle of absorption and extraction. First, the team let the material absorb moisture from the surrounding air for an hour. They then dry it in a condenser to capture water, which is then used for absorption. Repeating this cycle several times does not appear to reduce the material's ability to absorb or release water.

In tests, the salt hydrogel performed very well. The team of experts was able to extract 5.87 liters of fresh water per kilogram of material per day with air with 30% humidity. When further improved, these zwitterionic hydrogels will be very useful in providing drinking water to developing and drought tolerant areas.