A Device Invented To Capture Clean Drinking Water

It may be possible to capture drinking water from the air using simple equipment even in the aridest desert regions. According to researchers, with this new invention, water can be captured from thin air and released when warmed by daylight.

There are nearly 13 trillion tonnes of water, a vast supply of clean drinking water that can be produced, in the Earth’s air across the whole world. Many types of equipment have been developed and tested to make use of this water resource. However, they are not effective, cost-incentive and impractical. To tackle this issue, scientists at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia invented a prototype utilizing stable, nontoxic and inexpensive salt, known as calcium chloride.

By capturing the air's moisture, this salt can dissolve itself. Calcium chloride has a great potential in capturing water. However, after it absorbs water, the substance changes its state of matter from solid to salty liquid. This is still a problem that scientists have to deal with if they want to have a water capturing device, said Renyuan Li, a Ph.D. student at KAUST.

Therefore, researchers found a solution to this problem, that is to combine the salt with a hydrogel which can hold a significant volume of water while still retaining its form as a solid. To ensure the release of water vapor, researchers also added in some tiny bit of carbon nanotubes (0.42% by weight). This substance can take the light of the sun in and turn the solar power into heat.

To test this prototype device, the team added 35 grams of this substance in it then left it outside for one night. As a result, they collected 37 grams of water with the humidity level reaching about 60%. On the next day, 2.5 hours of sunlight exposure was enough to produce most of the water, which was collected in the device.

The most significant benefits of the hydrogel are its high effectiveness and cost savings, according to Li. Scientists said the cost for hydrogel can be about half a cent a day when increasing the productivity of this machine to 3 liters of water a day, which is the minimum volume of water that an adult needs.

According to researchers, they will adjust the hydrogel to let it produce clean drinking water continuously instead of in batches.