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article imageNano device disinfects water using solar power

By Tim Sandle     Aug 17, 2016 in Science
Washington - In many parts of the world there is limited access to clean water. Different devices exist to clean water but these are rarely portable. In a breakthrough, researchers have developed a nano-sized solar powered device.
The new device has been developed at the U.S. Department of Energy’s SLAC National Accelerator Laboratory together with scientists from Stanford University. The device is of a nanostructured design, no larger than a postage stamp.
The device can remarkably disinfect water rapidly and at a faster rate than ultraviolet light technology. The device does so using solar power, optimizing the visible part of the solar spectrum. The device is made up of a large number of tiny grooves (which resemble a fingerprint when examined under an electron microscope). The lines are very thin films composed of nano-flakes of molybdenum disulphide.
Naizam Jaffer (@NaiJaffer) "Researchers develop cheap nanostructured device that uses sunlight to disinfect #water."
The process works by sunlight falling on the device. This initiates the formation of hydrogen peroxide, which is an oxidising disinfectant effective against most microorganisms. In 20 minutes the device was able to reduce a known microbial population by 99.999 percent. Although the device is effective at removing microorganisms it is not capable of removing pollutants such as toxic chemicals. This means ‘cleanliness’ is defined in terms of microbial levels only.
This happens because the molybdenum disulphide functions as a photocatalyst. As light strikes the electrons in the material move away from usual places which causes a chemical reaction to begin. The reaction initiates the “reactive oxygen species” hydrogen peroxide.
MRTecno (@MRTecno) "Postage stamp-sized device can disinfect water in minutes."
Speaking with Controlled Environments magazine, the lead researcher Dr. Chong Liu explains: “Our device looks like a little rectangle of black glass. We just dropped it into the water and put everything under the sun, and the sun did all the work.”
A key advantage, in addition to the size, is that the hydrogen peroxide disinfectant breaks down into harmless substances — oxygen and water — at the end of the process. Another factor to consider is the cost of production, with the key components being relatively inexpensive to manufacture.
The results have been reported to the journal Nature Nanotechnology. The research paper is titled “Rapid water disinfection using vertically aligned MoS2 nanofilms and visible light.”
More about Clean water, Drinking water, Dirty water, Microbes, Contamination
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