Scientists Developed a Little Device Capable of Disinfecting Water Faster

A team of scientists from the Department of Energy's SLAC National Accelerator Laboratory an Stanford University has developed a new nanostructured device capable of disinfecting water using the UV rays and visible part of solar spectrum from the sun.

The new device, described in the journal Nature Nanotechnology, is only about half the size of a postage stamp. It can disinfect germy water faster than the UV method and more cost-saving than boiling the water, which consumes precious fuel. In the UV method, the water is contained in plastic bottle left out in the sun so ultraviolet rays can kill the microbes. However, UV rays only carry about 4 percent of the sun's total energy, making the disinfecting process take about six to 48 hours.

With the new device, the visible part of the solar spectrum, along with the UV rays were utilized. By doing so, 50 percent of the sun's total energy is harnessed and put into use. As opposed to the UGV method, the nanostructured device will only take about 20 minutes to kill more than 99.999 percent of the bacteria present in the water.

"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," explained Chong Liu, an associate professor at SLAC/Stanford and lead author of the study, in a statement.

The tiny device is composed of thin films of molybdenum disulfide stacked at the edge, forming a wall-like labyrinth atop a rectangle glass. The thin films of molybdenum disulfide act as photocatalyst that triggers reactions when by an incoming sunlight. These reactions produce reactive oxygen species, such as hydrogen peroxide, that acts as disinfectant, killing bacteria in the surrounding water.

However, the researchers noted their method can't be used to remove chemical pollutants in the water. So far, the researchers only tested the device on three strains of bacteria mixed in water in a laboratory setting. Although, there is no reason to think it would not kill other bacteria and other types of microbes, including viruses.