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Nanotube-Based Water Purifier From Stanford Filters Water Quicker, Kills Bacteria


Dangerous bacteria can often hide in the water you drink, but they’re not harmful until they reach a certain number to become active inside your body. Regular water purifying technologies consume a lot of power, but a team of Stanford researchers have developed a new low-cost, high-speed filter that works differently than other purifiers.

Using cotton dipped inside a silver nanowires and carbon nanotubes solution, the scientists created the filter that doesn’t stop the bacteria pass through. The catch is that the bacteria that gets out of the filter is dead and harmless – the device kills them with an electrical field passing through the carbon-silver coated cotton.

The pores in the nano-filter are large enough that no pumping is needed – the force of gravity is enough to send the water speeding through. In some of the lab tests of the nano-filter, the electricity needed to run current through the filter was only a fifth of what a filtration pump would have needed to filter a comparable amount of water.

“This really provides a new water treatment method to kill pathogens,” said Yi Cui, an associate professor of materials science and engineering. “It can easily be used in remote areas where people don’t have access to chemical treatments such as chlorine.”

The nanotube water purifying device kills over 98% of Escherichia coli (e-coli), a bacteria that would otherwise cause lots of troubles for a person’s health. They only applied 20 volts of electricity for a few seconds to the filter. “Our filter is about 80,000 times faster than filters that trap bacteria,” Cui said.

For totally filtering out bacteria, multiple-staged filters are needed.

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