The solution to one of America’s biggest environmental problems could come from iron-based particles that are 1,000 times thinner than a human hair.

Wei-xian Zhang, associate professor of civil and environmental engineering, uses these nanoparticles to clean groundwater that contains toxic organic solvents, pesticides and carcinogenic heavy metals.

In site tests in New Jersey and Florida, nanoparticles made at Lehigh have reduced contaminants by as much as 96 percent in four weeks, says Zhang. This compares to success rates of 25 to 35 percent typically achieved in one year by traditional, more costly cleanup methods.

With as many as half a million sites requiring cleanup, estimates of the cost of remediating America’s groundwater, much of it tainted by industrial pollution, run well over $1 trillion.

Zhang believes his method could cut these costs by as much as 75 percent.

The U.S. EPA’s National Center for Environmental Research has praised Zhang’s work, saying his nanoparticles are “highly reactive, can be scaled to fit the pollution problem and could be used for a wide variety of common contaminants, including chlorinated hydrocarbons, pesticides and explosives.”

Zhang’s work has been featured in Technology Review, Environmental Science and Technology and Chemical and Engineering News.

Zhang’s nanoparticles contain more than 99.9 percent iron and less than 0.1 percent palladium, a catalyst used in catalytic converters and other applications.

The nanoparticles’ size gives them their advantage, says Zhang. Measuring 20 to 50 nanometers in diameter, the particles have a greater proportional surface area than larger quantities of the same catalyst, giving them more reactivity with the toxins. And being small, the particles “flow with the groundwater through the ground, chase the waste and treat it in the ground,” he says.

Zhang has a patent pending on his cleanup technology, and Lehigh has licensed his technology to two environmental remediation companies. He has received funding from NSF and EPA.

“The key to commercializing this process will be to make the material in a large enough quantity to achieve economies of scale,” says Zhang, who is enlisting chemical companies and industrial partners to help overcome that problem.

In 2005, Zhang served as guest editor for an issue of Environmental Science and Technology that was dedicated to nanotechnology research.