May 13, 2011 -- Researchers at the Asian Institute of Technology (AIT) have found a way to eliminate bacterial contamination from water using visible light and zinc oxide nanorods.
The ZnO nanorods, grown on glass substrates and activated by solar energy, have been found to be effective in killing both gram positive and gram negative bacteria. The nanorods were tested on Escherichia coli and Bacillus subtilis bacteria, commonly used as model microbes. In the dark, ZnO dissolves slowly, releasing zinc ions, which have antibacterial properties. Under well-lit conditions, the effect is doubled with both photocatalysis and zinc ions contributing to killing microbes.
"Most studies so far either work on the use of ultraviolet light or involve a suspension of nanoparticles," said Prof. Joydeep Dutta, director of the Center for Excellence in Nanotechnology at AIT. "Since ZnO has now been tested under solar light, instead of the traditionally used UV light, the potential for commercial applications is huge, particularly since the levels of zinc ions removed from the rods to the water are safe for human consumption," added Dutta.