The gel is made from two main, cheap and common ingredients: cellulose, which comes from plant cell walls, and konjac gum, a widely used food additive. These two components work together to form a gel film capable of absorbing water from the air and then releasing it on demand, without requiring much energy.
First, the porous structure of the rubber attracts water to condense in the air around it. Cellulose, on the other hand, is designed to respond to gentle heat by becoming hydrophobic, releasing the captured water.
Making the gel is also quite simple, according to the team. The basic ingredients are mixed and then poured into a mold, where it sets in two minutes. After that, it is freeze-dried, then unmolded and ready to use. It can be made into virtually any shape needed, and scaled quite easily and at low cost.
In tests, the gel film was able to squeeze an amazing amount of water from the air. At 30% relative humidity, it could produce 13 L (3.4 gal) of water per day per kilogram of frost, and even when the humidity dropped to just 15% – which is low, even for l desert air – it could still produce more than 6 L (1.6 gal) per day per kilogram.
It’s a huge improvement over other water collectors we’ve covered over the years. The highest was previously 8.66 L (2.3 gal), but that was in air with much higher humidity. Others reached 5.87 L (1.55 gal) at 30% humidity, or as little as 1.3 L (0.3 gal).
And the effectiveness of the new gel film could be further improved, the team says, by creating thicker films, absorbent beds or other matrix formations of the material. Perhaps most importantly, the material is extremely inexpensive to produce, costing just US$2 per kilogram. This is another major factor in scaling up technology and getting it to remote areas and developing countries, where it is most needed.
The research was published in the journal Nature Communication.
Source: UT Austin