If you want to make the water suitable for drinking and to clean it from bacteria, it is one of the best ways is to just leave the water in a transparent bottle in direct sunlight and let the UV rays do their work.
However, this method can take from six to 48 hours. Instead, scientists from the National accelerator laboratory SLAC, the US Department of energy and Stanford University have developed a faster alternative.
This device, which is activated by the sun and kills 99.999 percent of bacteria in just 20 minutes.
The size of a rectangular device is about half the size of a postage stamp, and it looks like a piece of black glass, which is placed in a transparent container with water.
In fact, it consists of a glass substrate covered with "nanotechology" molybdenum disulfide. These flakes are placed in profile, so that their edges were directed upwards. Each of these edges, in turn, coated with a thin layer of copper.
When exposed to the visible part of the solar spectrum, both material, molybdenum disulfide and copper, act as photocatalysts, causing water formation of hydrogen peroxide and other disinfectant chemicals. After they kill all the bacteria, all the chemicals dissolve, leaving behind nothing but pure water.
Part of the reason that this method is much faster than the method with UV is that the UV rays pass only 4% of solar energy and visible light is 50 percent.
However, it should be noted that the technology only works with bacterial contamination, not chemical. In addition, while it has only been tested with three bacterial strains, though there is every reason to believe that this method should work with other strains that have not been tested. published
Source: facepla.net/the-news/tech-news-mnu/5523-%D0%BE%D1%87%D0%B8%D1%81%D1%82%D0%BA%D0%B0-%D0%B2%D0%BE%D0%B4%D1%8B.html