Water purification seems simple enough on paper—just kill or remove all the harmful bacteria in water. However, it's not so easy in the real world. You can boil water, but that requires starting a fire and consuming fuel. You can use a water filter or purifier device, but many of these are bulky or expensive. Finally, you can use purification chemical tablets or even household bleach, but these methods require anywhere from 30 minutes to several hours to work. All of these methods can be effective in the right circumstances, but it never hurts to have new options.

This diagram shows how the new nanostructured water purifier uses sunlight to kill bacteria.

This diagram shows how the new nanostructured water purifier uses sunlight to kill bacteria. Source: slac.stanford.edu

Speaking of new options, a team of researchers at the U.S. Department of Energy's SLAC National Accelerator Lab and Stanford University have just announced the development of a new type of nanotechnology-based water purifier. The device is tiny—about half the size of a postage stamp— and has no moving parts or batteries. To the naked eye, it looks like a tiny rectangle of black glass, but this device is actually covered in “nanoflakes” of molybdenum disulfide material, which are stacked together like the walls of an intricate maze. These layers are only visible under an electron microscope.

An electron micrograph shows the intricate “nanoflakes” which resemble a jumbled fingerprint pattern.

When exposed to sunlight, these nanoflakes act as a photocatalyst, and trigger the formation of hydrogen peroxide (H202) and other “reactive oxygen” molecules. If you're familiar with hydrogen peroxide, you may know that it acts as a powerful disinfectant and ruptures the cell walls of bacteria, killing them. In initial testing, this device killed more than 99.999% of three bacteria strains found in water in only 20 minutes. Granted, that's not quite as effective as other water purifiers on the market, which can meet the NSF/ANSI P231 standard by removing 99.9999% of bacteria, but it's still a promising start. It's also impressively small, light, and fast-acting.

Nanotechnology water purifier 3

Better still, the molybdenum disulfide material is cheap and easy to manufacture, and is already being used extensively as an automotive and industrial lubricant (moly grease). So, once this device is refined further, it could potentially offer a reusable alternative to water purification tablets—just drop it into a full water bottle, expose to sunlight for 20 minutes, and drink.

For more information on this new nanotechnology-based water purifier, click here to read the full report on SLAC.Stanford.edu.

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