Technology
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Removing water from the air can make places more comfortable, and it can also provide a vital resource when water is scarce. However, the process is more laborious than it might seem at first, and different techniques have different drawbacks. Polymers have been used to efficiently remove water from the air, but getting the water back out of the polymers is not a cheap task – or it wasn’t. A breakthrough might change that.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.The polymers used in this breakthrough make up an adsorbing material. That's not a typo: Absorbing material gets soaked through, but an adsorbing one keeps molecules on its surface. Still, the release (or desorbing) is the problem. Usually, these polymers need to be heated to around 100°C (212°F) to release the water. A team of researchers has now developed a liquid moisture adsorbent that releases water at a temperature of around 35°C (95°F).
This new approach is made possible by using two polymers. One is polyethylene glycol, which is used in several industrial applications and even in some medicines – for example as a laxative (it works by increasing the amount of water in the stool because it is such a good adsorbent). The other one is polypropylene glycol, which is similar but not as good as adsorbing water and is actually a main component of paintballs.
The difference in their ability to trap water is the crucial breakthrough of this work. As they fight over water molecules, they create a transfer mechanism that allows them to break down water clusters so that the precious liquid can be more easily extracted.
“This technology has the potential to be applied not only to water supply in arid regions and places with limited energy resources, but also to ensuring access to water in times of disaster and emergency,” co-author Assistant Professor Arisa Fukatsu, from Osaka Metropolitan University, said in a statement.
“Improvements to this technology are also expected to lead to reductions in greenhouse gases and more efficient use of water resources,” added co-author Professor Masahide Takahashi, also at Osaka Metropolitan University “From now on, we will aim to improve the liquid moisture adsorbent and increase the efficiency of the entire system in order to make it practical.”
The paper is published in the journal ACS ES&T Water.
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