US scientists test tiny water purifier powered by light

2016-09-08 22:25


Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

San Francisco - US scientists say they have invented a tiny water purifying device, which is about the size of a person's fingertip and harnesses light to kill harmful bacteria.

In laboratory experiments, the ultra thin 1cm-by-2cm miniature tablet-like device, which was placed in a water container, killed 99.9% of bacteria in just 20 minutes, according to a study published last month in the Nature Nanotechnology journal by a team from Stanford University in California.

"Researchers have always been looking for better ways to harvest sunlight for water disinfection. But traditional photocatalysts [using light to affect a chemical reaction] usually only use the UV part," said project leader Chong Liu, referring to ultraviolet rays, which are invisible to humans.

Liu's team developed a device that harnesses both ultraviolet rays and visible light at an unprecedented rate to kill harmful bacteria, and the results are "very promising", Liu told Al Jazeera.

"The major advantage is that this material can harvest 50% of solar energy. This can greatly enhance the speed of water disinfection. It does not need any additional energy or effort for treating water," he said.

Similar water purifying devices only harness UV rays, and take up to two days to work, according to the Swiss Federal Institute of Aquatic Sciences and Technology.

The device's main component is Molybdenum disulfide, Liu said, which is a silvery black compound similar in appearance and touch to graphite. Sunlight excites electrons in the device, which then react with water and oxygen to kill harmful bacteria, leaving pure water behind.

Liu said the device has the potential to help people in countries hit by energy and water shortages.

More than 660 million people lack access to potable water sources, and at least 1.8 billion people globally use a source of drinking water that is contaminated faecal matter, according to the United Nations. 

Inadequate drinking-water and poor sanitation and hygiene are estimated to cause more than 840 000 diarrhoeal disease deaths each year, according to the World Health Organisation.

More experiments on the device need to be carried out before it is ready for commercialisation, including conducting field tests, which is the next step, Liu, a postdoctoral scholar, said.

"It can be a really simple point-of-use water disinfection device and can help a lot of people without access to clean water," he added.

"The material itself is cheap and the synthesis process is facile. So we assume that the device would be of low-cost."

Read more on:    us  |  research

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

Inside News24


Book flights

Compare, Book, Fly

Traffic Alerts
There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.