Global water news March 2011

Abstract

American scientists are reporting development and successful initial tests of an inexpensive new filtering technology that kills up to 98% of disease-causing bacteria in water in seconds without clogging. A report on the technology appears in Nano Letters, a monthly American Chemical Society journal. Dr Yi Cui and colleagues from Standford University, in California, explain that most water purifiers work by trapping bacteria in tiny pores of filter material. Pushing water through those filters requires electric pumps and consumes a lot of energy. In addition, the filters can get clogged and must be changed periodically. The new material, in contrast, has relatively huge pores, which allow water to flow through easily. And it kills bacteria outright, rather than just trapping them. The scientists knew that contact with silver and electricity can destroy bacteria, and decided to combine both approaches. They spread sub-micro scopic silver nanowires onto cotton, and then added a coating of carbon nanotubes, which give the filter extra electrical conductivity.

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