All it takes is a bit of darkness, sunlight and a few photoreactive, highly porous materials.
The idea of converting seawater into drinking water is by no means new. Such projects have been operating for many years in the United States, Israel, China, Spain, Australia and Dubai. The biggest problem when it comes to desalinating water remains the cost of the process.
The authorities of such Dubai can afford to acquire 99 percent. drinking water precisely by desalinating sea water. Annually, however, they spend around $ 1.6 billion, producing around 182 million liters of water per day. Less wealthy countries unfortunately have to get along with the taste.
Water desalination is an increasingly desirable technology
However, scientists are still looking for cheaper ways to separate salt from water. The latest, very promising idea is to use a very porous material and sunlight. This solution was developed by a team of scientists from China and Australia.
By using super-porous material to suck salt from salt water, scientists were able to sustainably produce nearly 150 liters of clean drinking water per kilogram of porous material used for desalination. Moreover, the drinking water obtained in this way was cleaner than required by official WHO guidelines.
The study’s lead author, Huanting Wang, a professor of chemical engineering at Monash University in Australia, says his team’s approach uses the planet’s most abundant resource: sunlight. Their solar method desalinates brackish or stagnant water more sustainably than current desalination methods.
– Thermal evaporative desalination processes are energy intensive, and other technologies such as reverse osmosis, in addition to being energy-intensive, also require the use of chemicals to clean and dechlorinate membranes. Our process uses sunlight, which is the most widespread and renewable energy source on Earth. Says Huanting Wang, professor of chemical engineering at Monash University in Australia, lead author of the study.
How it’s working?
This type of energy produced by our star makes the salt-absorbing material able to regenerate and be ready to absorb water from salt again. Initial absorption takes place in the dark, but four minutes of exposure to sunlight causes the material to release the accumulated salt and restart the absorption process for many consecutive cycles. The material itself is poly (spiropyran acrylate) (PSP) bonded to an organometallic MIL-53 framework. This connection was named by scientists PSP-MIL-53.
Water salted in this way is also extremely clean. By analyzing its composition, scientists measured its total dissolved solids (TDS) to less than 500 parts per million – a standard even higher than the WHO recommendation, which classifies pure drinking water as having a TDS of no more than 600 parts per million. .
"This study successfully showed that photoreactive [metal compounds] is a promising, energy-saving and durable desalination adsorbent," said Wang.
The aim of this project was to create a solution that will enable the creation of clean drinking water in communities with a weak energy structure. However, the authors of this idea do not exclude further work on their solution and adapt it to the absorption of other compounds and minerals from the liquid. However, this is a song of the future, for now Wang and his team need to figure out how to get this technology out of the lab and put it into practice.
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A new method of water desalination has just been developed. It does not require electricity