Alphagalileo > Item Display

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

Even today, clean water is a privilege for many people across the world. According to the World Health Organization (WHO), at least 1.8 billion people consume water contaminated with feces, and by 2040, a large portion of the world will endure water stress because of insufficient resources of drinking water. Meanwhile, the United Nations Children’s Fund (UNICEF), around 1,800 children die every day from diarrhea because of unsafe water supply, which causes diseases like cholera.

It has become imperative then that we develop efficient and cost-efficient ways to decontaminate water. And that is exactly what a team of scientists led by László Forró at EPFL have accomplished, with 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.

“In a close collaboration between chemists, physicists, and biologists, we have developed a very efficient water purification device, which does not need any energy source but sunlight,” says Forró. “Our prototype can supply clean drinking water even at remote places to small populations and could be easily scaled-up. It is a great achievement and an important “side-product” of this project is that it has attracted a large number of talented and motivated students who care for environmental issues, for sustainability”.

In their paper, published in the Nature partner journal Clean Water, the researchers showcase a prototype of the filter and make suggestions for further improvements. “I am convinced that it will create a strong follow-up in versatile scientific communities and hopefully funding agencies,” says Endre Horváth, the lead scientist on the project.

Other contributors
  • EPFL Central Environmental Laboratory
  • Stavropoulos Center for Complex Quantum Matter, Notre Dame University

  • Global Water Award of the United Arab Emirates
  • Swiss-South African collaboration grant
  • Karl Zeno Schindler Foundation
E. Horváth, J. Gabathuler, G. Bourdiec, E. Vidal-Revel, M. Benthem Muñiz, M. Gaal, D. Grandjean, F. Breider, L. Rossi, A. Sienkiewicz, L. Forró. Solar water purification with photocatalytic nanocomposite filter based on TiO2 nanowires and carbon nanotubes. npj Clean Water 07 April 2022. DOI: 10.1038/s41545-022-00157-2
Attached files
  • The prototype of the water purificator held by the Master project student Jerome Gabathuler. Credit: L. Forro.
  • The filtering and sterilization process of the water purification device. On the left is an example of microorganisms that commonly contaminate drinking water. The pathogens are trapped at the surface of the nanowire-carbon nanotube composite-based filter. On the right is an illustration of how UV light generates reactive oxygen species on the surface of the filter UV illumination. Credit: Horváth et al.
Regions: Europe, Switzerland, Africa, South Africa, Middle East, United Arab Emirates
Keywords: Science, Chemistry


For well over a decade, in my capacity as a researcher, broadcaster, and producer, I have relied heavily on Alphagalileo.
All of my work trips have been planned around stories that I've found on this site.
The under embargo section allows us to plan ahead and the news releases enable us to find key experts.
Going through the tailored daily updates is the best way to start the day. It's such a critical service for me and many of my colleagues.
Koula Bouloukos, Senior manager, Editorial & Production Underknown
We have used AlphaGalileo since its foundation but frankly we need it more than ever now to ensure our research news is heard across Europe, Asia and North America. As one of the UK’s leading research universities we want to continue to work with other outstanding researchers in Europe. AlphaGalileo helps us to continue to bring our research story to them and the rest of the world.
Peter Dunn, Director of Press and Media Relations at the University of Warwick
AlphaGalileo has helped us more than double our reach at SciDev.Net. The service has enabled our journalists around the world to reach the mainstream media with articles about the impact of science on people in low- and middle-income countries, leading to big increases in the number of SciDev.Net articles that have been republished.
Ben Deighton, SciDevNet

We Work Closely With...

  • BBC
  • The Times
  • National Geographic
  • The University of Edinburgh
  • University of Cambridge
Copyright 2022 by AlphaGalileo Terms Of Use Privacy Statement