Stanford Researchers Purify Water with Silver


"Nanotechnology and silver purify water faster than any previous method."

Stanford researchers have developed a new kind of filter, a cheap and fast way to purify water in poor parts of the world.

In her Stanford laboratory, Alia Schoen purifies water using a new method thousands of times faster than anything previous. It uses nanotechnology and silver.

Before milk could be pasteurized or refrigerated, people dropped a silver coin into a bottle to preserve it. Silver is lethal to bacteria. You could build water filters out of silver, but It's so costly, it would kill your bank account before the bacteria.

Now, nanotechnology is changing that.

A minute amount of electricity run through microscopic silver amplifies its antibacterial powers. The Stanford's Materials Science Lab is already making the first fabric batteries out of cotton infused with the hottest material in research today: carbon nanotubes.

Professor Yi Chui's team has also infused cotton with microscopic silver nanowires. A member of that team recalls, "We thought it was a crazy idea. . .to combine electricity with nanowires to treat water."

The crazy combination of nanosilver and nanocarbon did the trick. It enables them to filter 98% of the E. coli in a water sample in one pass using so little electricity it can run on 9-volt batteries. Professor Chui, says: "We use a tiny amount. So, it is possible to scale this filter up to a very large size. There's no reason we cannot do thousands of gallons quickly."

In fact, all the water used by one average household in a year (20,000 gallons) could be treated in just one hour with a filter the size of a kitchen sink. Safety and commercialization require still more work, but there is huge potential for poor communities.

"The biggest application," Cui is certain, "will be use in remote areas in third world countries."

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