Nanotech-Infused Cotton Provides Fast, Cheap Water Filtration

 

Over 884 million people drink unsafe water, according to UNICEF, making water filtration technology vital to raising living standards around the world. Cotton treated with silver nanowires promises to do just that, by dramatically increasing the speed, and reducing the energy cost, of removing deadly bacteria from drinking water.

The silver nanowires conduct 20 volts of electricity through the cotton water filter , frying any pathogens. Essentially a cross between a bug zapper and a Brita water filter, this new material kills 98 percent of bacteria in a matter of seconds. At that speed, the system purifies water 80,000 times faster than filters that trap bacteria, said Yi Cui, an associate professor of materials science and engineering at Stanford University and inventor of the system.

“The most important thing is the speed. That’s the key here,” Yi told TechNewsDaily.

In addition to purifying water much faster than traditional filters, this system also uses 80 percent less energy than a traditional bacterial water filter, Yi said.

Traditional water filters remove bacteria by forcing the water through very small pores. This method requires a lot of pressure to actually purify the water in a practical amount of time, and that pressure eats up a lot of energy, Yi said.

Conversely, by pairing mechanical filtration with an electric charge, the new system allows for pores so large that water can pass through the filter unassisted by any force other than gravity.

Furthermore, the silver nanowires used to conduct the electricity have natural, chemical, antibacterial properties. This prevents the build up of bacterial films seen in mechanical filtration systems.

The main problem with the new system is the cost. There is no industrial process to manufacture silver nanowires, making the materials for the new filter very expensive. However, Yi remains confident that over time, the price will drop low enough to make this system a cost effective solution for the developing world .

“The price of raw materials is not so low yet. No one is selling silver nanowires,” Yi said.

“But given the synthesis method, and the amount of materials used, the cost shouldn’t be high in the future.”

 

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