Poisonous heavy metals contaminating thousands of sites nationwide threaten to enter the food chain, and there’s been no easy way to remove them. An experimental chemical bath and electrochemical filter could now extract heavy metals from the soil and leave fields safe.

According to the Environmental Protection Agency, heavy metals have been found at thousands of locations nationwide. While some have been cleaned up through a combination of federal, state and private efforts, the need remains for new technologies to address heavy metal contamination.

Now a research team led by Stanford materials scientist Yi Cui has invented a way to wash heavy metals from contaminated soils using a chemical process that’s a bit like brewing coffee.

As they describe June 4 in Nature Communications, the researchers started by rinsing contaminated soil with a mixture of water and a chemical that attracts heavy metals. When that mixture percolates through the soil, the chemical pulls heavy metals loose. The team members then collected this toxic brew and ran it through an electrochemical filter that captured the heavy metals out of the water. In this way they cleansed the soil of heavy metals and recycled the water and chemical mixture to percolate through more contaminated ground.

«This is a new approach to soil cleanup,» said Cui, who is a professor of materials science and engineering and photon science. «Our next step is a pilot test to make sure that what works in the lab is practical in the field, and to figure out how much this process will cost.»

So far, his team has cleansed soils contaminated with lead and cadmium, two prevalent and dangerous toxins, as well as with copper, which is only dangerous in high concentrations. Cui believes this process of chemical cleansing and electrochemical filtering will work with other dangerous heavy metals like mercury and chromium, but further lab experiments are needed to demonstrate that.

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Materials provided by Stanford University. Original written by Tom Abate. Note: Content may be edited for style and length.