A new way to turn saltwater fresh can kill germs and avoid gunk buildup

[Judi Lynn]

The key to the improvement is keeping device components high and dry
BY MARIA TEMMING 11:00AM, DECEMBER 11, 2018

A new design for sun-powered desalination technology may lead to longer-lasting devices that produce cleaner water.

The trick boils down to preventing a device’s components from touching the saltwater. Instead, a lid of light-absorbing material rests above a partially filled basin of water, absorbing sunlight and radiating that energy to the liquid below. That evaporates the water to create pure vapor, which can be condensed into freshwater to help meet the demands of a world where billions of people lack safe drinking water (SN: 8/18/18, p. 14).

This setup marks an improvement over other sun-powered desalination devices, where sunshine-absorbing materials float atop the saltwater (SN: 8/20/16, p. 22). In those devices, salt and other contaminants left behind during evaporation can degrade the material’s ability to soak up sunlight. Having water in contact with the material also prevents the material from getting hotter than about 100° Celsius or producing steam above that temperature. That limits the technology’s ability to purify the final product; killing pathogenic microbes often requires temperatures of at least 121° C.

In the new device, described online December 11 in Nature Communications, the separation between the light-absorbing lid and the water’s surface helps keep the lid clean and allows it to generate vapor tens of degrees hotter than the water’s boiling point.

More:
https://www.sciencenews.org/article/desalination-saltwater-fresh-water-sunlight?tgt=nr