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NATURESCIENCE

New prototype is created to obtain drinkable water from the desert air

Water gel balls. Small gel ball in the hand at sunrise. Polymer gel. Silica gel. Balls of hydrogel. Crystal liquid ball with reflection. Texture background

Water is essential for people’s lives and everything around us. Although it may seem as an inexhaustible resource, if it’s not taken care of, it can become one of the biggest problems in the next decades. In all freshwater existing on our planet, only 3% is freshwater, but not all of it is drinkable or even accessible. In addition to this, if we take all the water consumed on planet Earth, we can see only 8% is destined for domestic consumption. The rest is destined to Agriculture or industrial uses.

Researchers have spent years trying to find a way to get drinking water in areas where it is a scarce resource. Such as the biggest desert areas on our planet. To this day, there are 1,500 million people on the earth who do not have access to drinking water. That is why it’s a main priority for international politics. The increase in population is associated with greater water consumption on the planet and the UN is estimating this growing rate. By the year 2050 there will be more than 5,000 million people who won’t be easily accessing drinkable water.

Researchers from KAUST (King Abdullah University of Science and Technology) in Saudi Arabia have developed a device that’s capable of absorbing water from the air. This type of progress could be invaluable in saving lives where water is a scarce resource.

How does the prototype work?

It’s operated using low cost calcium chloride hydrogel. Which is capable of capturing the vapor that exists in the air, even in areas where humidity is low. Then said hydrogel is heated to release the water it contains. These types of experiments involving calcium chloride to get water had already been done many times. But there’s a complicated part, which is combining it with materials like hydrogel to be able to store water properly.

The most remarkable aspects of the hydrogel are its high performance and low cost” in the words of Renyuan Li, a student on Wang’s team. It is estimated that there are more than 10 trillion tons of water in the atmosphere. So the future evolution for these prototypes would be a breakthrough in the fight against the global drought. Especially in those areas where drinking water is scarce or has low accessibility.

Where is the secret?

Calcium chloride absorbs any vapor surrounding in the air. Being a deliquescent compound, it transforms that water vapor into a liquid solution. This salt has been combined with a polymer called hydrogel, which can store large volumes of water while remaining solid.

This device has a calcium chloride mixture with hydrogel inside. In addition, it’s coated with a series of nanotubes able to absorb sunlight, transforming it into heat. So it can warm up the hydrogel enough to release the liquid.

For the tests, 35 grams of hydrogel were used, which captured 37 grams of water, with an ambient humidity of 60%. The next day, the device was exposed to the sun for two and a half hours. Thus heating the hydrogel and releasing 20 grams of potable water, ready to drink.

Once water is released, hydrogel can be used again to continue the collecting process.

Study conclusions

According to researchers on this study, it’s a “cheap and affordable” device. It doesn’t need electricity to function and it also works in low humidity conditions, thanks to calcium chloride properties. Therefore, it could be used to produce drinking water in deserts. The basic idea is to collect all the possible vapor from the air at night and transforming it into water during the day.

Although these advances are encouraging, there is still a long way to go. One of the obstacles that they want to overcome is that the water is released continuously as the vapor of the air is trapped, and not intermittently.

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