Silver is well-known for its antibacterial qualities, which has led to the use of silver nanoparticles in devices such as an experimental water filtration system developed by Stanford University. That system is intended as a relatively permanent setup, and it requires a small electrical current. Researchers from Montreal's McGill University, however, have come up with a silver-based water treatment system that could conceivably be used instantly, in any place and at any time. While not intended as a routine method of killing water-borne bacteria, it could be very useful in emergency situations such as disaster relief.
The filters themselves are simply hand-sized sheets of 0.5 mm-thick absorbent blotting paper, that have been coated with microdots of silver nanoparticles. Almost all of the silver remains on the paper after water has percolated through, so recipients of the water would not be consuming harmful amounts of the metal.
Even when sheets with a relatively small amount of silver (5.9 mg per dry gram of paper) were tested, they were still found to kill almost all the E. coli and E. faecalis bacteria present in water samples, resulting in filtered water that met American Environmental Protection Agency (EPA) standards.
The McGill scientists are now looking towards testing the filters under field conditions.
The research was recently published in the Journal of Environmental Science and Technology.
