Low-cost “magic box” could decontaminate water in rural communities

Photo by Shawn

More than a billion people drink water that is contaminated and can spread deadly diseases such as cholera, dysentery, hepatitis A, typhoid, polio and diarrhea.

Most contaminated water could be purified by adding hydrogen peroxide, which safely kills many of the disease-causing organisms and oxidizes organic pollutants to make them less harmful. Hydrogen peroxide disinfects water in a similar way as standard water chlorination, but it leaves no harmful residual chemicals. Unfortunately, it’s difficult to make or obtain hydrogen peroxide in rural settings with limited energy sources.

Now, researchers from Stanford University and SLAC National Accelerator Laboratory have developed a portable device that produces hydrogen peroxide from oxygen gas and water — and it can be powered by a battery or conventional solar panels. You can hold the small device in one hand.

“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 ground water to oxidize organic contaminants that are harmful for humans to ingest,” said Christopher Hahn, PhD, a SLAC associate staff scientist, in a recent news release.

First, the researchers designed and synthesized a catalyst that selectively speeds up the chemical reaction of converting oxygen gas into hydrogen peroxide. For this application, standard platinum-mercury or gold-plated catalysts were too expensive, so they investigated cheaper carbon-based materials.

Next, they used their carbon-based material to build a low-cost, simple and robust device that generates and stores hydrogen peroxide at the concentration needed for water purification, which is one-tenth the concentration of the hydrogen peroxide you buy at the drug store for cleaning a cut. Although this device uses materials not available in rural communities, it could be cheaply manufactured and shipped there.

Their results were recently reported in Reaction Chemistry and Engineering. However, more work needs to be done before a higher-capacity device will be available for use.

“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, first author and a chemistry graduate student at Stanford. “It’s like a magic box. I hope it can become a reality.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine. For more details, please read my SLAC news release.

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