Recently, scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have developed a tiny, solar-powered water purifier resembling a rectangular bit of black glass. The new device does not have a name yet, but is being referred to as a “tablet.”
Access to safe drinking water is a problem for 663 million people in the world. The World Health Organization reports that unsafe water supplies, sanitation and hygiene are responsible for 842,000 deaths every year, 361,000 of which are children under the age of 5.
What sets this device apart from other water purifying gadgets on the market is its use of a wider range of light. According to the Global Citizen Organization, the device absorbs 50 percent of incoming sunlight energy, while other purifiers only absorb 4 percent.
According to project leader Chong Liu, “This can greatly enhance the speed of water disinfection. It does not need any additional energy or effort for treating water.” In an experiment, the tablet took only 20 minutes to function. In contrast, other purifying systems that use only UV rays can take up to almost 48 hours.
On the surface of the tablet is a layer of nanoflakes and a small amount of copper. The nanoflakes’ exposure to sunlight and water excites electrons in the device and results in the release of hydrogen peroxide. This chemical kills bacteria in the water, making it safe to drink. As of now, however, the tablet is only capable of killing E. coli and lactic acid bacteria.
In an experiment published in the Nature Nanotechnology journal, researchers placed the solar-powered water purifier in a container with 25 milliliters of water for 20 minutes. It killed 99.99 percent of the bacteria in the water, an impressive amount for such a short amount of time. Even Liu said, “We didn’t expect it to work that well at first.”
Since the device is new and not ready for the market yet, it has no fixed price. But according to Liu, “The material itself is cheap and the synthesis process is facile. So we assume that the device would be of low-cost.”
More experiments and field tests must be done before the tablet can be distributed. Nonetheless, this solar-powered water purifier has the potential to cheaply and quickly help people who struggle to obtain clean drinking water.
– Karla Umanzor