Low-cost Device to Provide Developing Countries with Clean Water

Water purificationAccess to adequate water and sanitation is a major obstacle that impacts nations across the globe. Currently 1 in 10 people – or 663 million – lack access to safe water. Due to the global water crisis, more than 1.5 billion people are affected by water-related diseases every year. However, many of those disease causing organisms could be removed from water with hydrogen peroxide, but production and distribution of hydrogen peroxide is a challenge in many parts of the world that struggle with this crisis.

Now, a team of researchers from the U.S. Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have develop a small device that can produce hydrogen peroxide with a little help from renewable energy sources (i.e. conventional solar panels).

“The idea is to develop an electrochemical cell that generates hydrogen peroxide from oxygen and water on site, and then use that hydrogen peroxide in groundwater to oxidize organic contaminants that are harmful for humans to ingest,” says Chris Hahn, a SLAC scientist.

This from SLAC:

In this case, researchers in the theory group led by SLAC/Stanford Professor Jens Nørskov used computational modeling, at the atomic scale, to investigate carbon-based catalysts capable of lowering the cost and increasing the efficiency of hydrogen peroxide production. Their study revealed that most defects in these materials are naturally selective for generating hydrogen peroxide, and some are also highly active. Since defects can be naturally formed in the carbon-based materials during the growth process, the key finding was to make a material with as many defects as possible.

Read the full article.

“My previous catalyst for this reaction used platinum, which is too expensive for decentralized water purification,” says Samira Siahrostami, co-author of the study. “The beautiful thing about our cheaper carbon-based material is that it has a huge number of defects that are active sites for catalyzing hydrogen peroxide production.”

This is how the device works: oxygen gas flows through the first chamber and interfaces with a catalyst, reducing it to hydrogen peroxide; then the hydrogen peroxide enters a new chamber, where it is stored in a solution; finally, a catalyst in a third chamber converts the water into oxygen gas, and the cycle starts over.

The device can also run on renewable energy sources available in villages. The electrochemical cell is essentially an electrical circuit that operates with a small voltage applied across it. The reaction in chamber one puts electrons into oxygen to make hydrogen peroxide, which is balanced by a counter reaction in chamber three that takes electrons from water to make oxygen—matching the current and completing the circuit. Since the device requires only about 1.7 volts applied between the catalysts, it can run on a battery or two standard solar panels.

Right now, the device only holds about 10 microliters of hydrogen peroxide. In order to make the device effective, researchers are working to make it bigger.

“Currently it’s just a prototype, but I personally think it will shine in the area of decentralized water purification for the developing world,” said Bill Chen. “It’s like a magic box. I hope it can become a reality.”

PS: Check out some of the work ECS researchers are doing to provide access to clean water around the world.


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