A device can now absorb water from the air
Even at the lowest humidity of 7% and a temperature over 80 degrees Fahrenheit, the device can produce six ounces (0.2 litres) of water per kilogram of MOF per day.
If we can extract water from the air, it will solve a lot of difficulties related to carrying water. Scientists have developed a device that can help extract water from the air. The newly updated device can extract enough water to survive. The device is equivalent to a microwave in size and can extract water from hot air, including deserts.
The Previous Versions:
Researchers developed the first water-absorbing MOF in 2014. They developed the second version of the device in 2018. It was capable of collecting 0.07 litres of water per day, per kg of MOF during one night-cycle.
Yaghi, who is involved in the project and works as UC Berkeley professor of chemistry says, “This is not like a dehumidifier, which operates at high relative humidity. Some people say that 0.7 litres is not a lot of water. But it is a lot of water if you don’t have water.”
The 2019 model of the device measures 10 inches wide and 5 inches thick and works with the help of solar power. It can continuously absorb water throughout the day. A battery included in the device gets charged during the day using solar power and helps absorb water during the night.
The latest version of the water version produces 10 times more water than the previous version and 100 times higher than the initial concept launched in 2014. According to researchers, the water is good enough to drink and contains no traces of organics or metal.
Why is it difficult to extract water from the air?
If you want to extract water from air with low humidity, the air needs to be cooled down below freezing (zero degrees Celsius) temperature and then once the water present in condenses you can get water from it by heating. However, this device doesn't require the air to be cooled at such temperatures.
How the device works:
Scientists are using extremely porous compounds called Metal–organic frameworks (MOFs) to absorb water from the air. A gram of the compound has a surface area equivalent to a football field. The compound follows a process called adsorption.
Adsorption is a property in which the atoms, ions or molecules of a gas, liquid or dissolved solid stick to the surface of a particular material surface.
In this case, water gets absorbed to the internal surface of the MOFs and increases the humidity inside the MOF. This increase in humidity helps water condense even at room temperature. A simple example that we all witness every day is on a water bottle taken out of the fridge. The surface of the bottle has water droplets on it because the air near its surface cools down and condenses as water.
Even at the lowest humidity of 7% and a temperature over 80 degrees Fahrenheit, the device can produce six ounces (0.2 litres) of water per kilogram of MOF per day. The latest version can pull more than five cups (1.3 litres) of water from low-humidity air per day for each kilogram of the water-absorbing material.
When is it coming to the market?
Water Harvester Inc., a startup owned by Yaghi, is expected to introduce devices that are about the size of a microwave oven. These devices will be capable of supplying 7 to 10 litres of water per day. A larger version with a size similar to that of a small refrigerator will provide 20,000 litres of water per day. Both of these devices are expected to run on solar power.
Yaghi says, “This water mobility is not only critical to those suffering from water stress, but also makes possible the larger objective — that water should be a human right.” He added, “The atmosphere has almost as much water at any one time as all the rivers and lakes. Harvesting this water could help turn dry deserts into oases.”