Solar nanowire-nanotube filter offers easy access to clean drinking water

It has become imperative then that we develop efficient and cost-efficient ways to decontaminate water

A team of scientists at École polytechnique fédérale de Lausanne in Switzerland has developed a new water purification filter that combines titanium dioxide (TiO₂) nanowires and carbon nanotubes powered by nothing but sunlight.

The scientists first show that the TiO₂ nanowires by themselves can efficiently purify water in the presence of sunlight. But interweaving the nanowires with carbon nanotubes forms a composite material that adds an extra layer of decontamination by pasteurizing the water, killing off human pathogens such as bacteria and large viruses.

The idea is that when UV light from the visible spectrum of sunlight hits the filter, it causes it to produce a group of molecules called Reactive Oxygen Species (ROS). These include hydrogen peroxide (H₂O₂), hydroxide (OH), and oxygen (O₂-), and are known to be effective pathogen killers.

The researchers tested their device with E. Coli, bacteria, the “gold-standard” for bacterial survival studies, but it should work with other bacteria pathogens, such as Campylobacter Jejuni (a common diarrhea-inducing pathogen in the developed world), Giardia Lamblia (a microorganism that causes the intestinal infection giardiasis), Salmonella, Cryptosporidium (causes diarrheal cryptosporidiosis), the Hepatitis A virus, and Legionella Pneumophila (causes Legionnaires’ disease). The device is exceptionally adept at removing all the pathogens from water, and shows promising results even for eliminating micropollutants, such as pesticides, drug residues, cosmetics etc.