Backyard Talk

Risks & Rewards of Nanoremediation

Michael Crichton’s 2002 novel Prey features a terrifying interpretation of nanotechnology, when swarms of “nanobots” become self-aware and predatory. His book is entirely fictional, but even outside the realm of popular culture, mentions of nanotechnology can stoke our fears about what might happen if science advances beyond our control.

What is nanotechnology? Any technology that works with and manipulates particles between 1 and 100 nanometers in length or width can fall under the nanotech umbrella. Particles of this size are too small to see with the naked eye – they are about the size of a virus or of your DNA. In the real world, predatory nano-swarms don’t top the list of scientists’ concerns. Instead, they are engaged with determining the environmental and health impacts of our increasing use of nanotechnology in medicine, energy generation, communication technology, and even environmental remediation.

In the environmental field, nanotechnology is used to remediate or clean up polluted groundwater, wastewater, soil and sediment. Nanoremediation methods use materials at the nanoscale to reduce pollutant levels at contaminated sites. Nanomaterials have several properties that make them well-suited to this task. They are tiny in size, enabling them to enter very small spaces and travel further and more widely than larger particles. They also have a high surface area relative to their mass, making it easier for them to react with compounds. (Karn et al., 2009).

When nanoparticles interact with toxic compounds, they operate in one of two ways – breaking down the compounds, or immobilizing them. Nanoparticles can cause reactions that transform toxic compounds to less harmful products. They also can bind to the compounds, immobilizing them and preventing them from exerting further harm on the environment. Iron nanoparticles are one of the most commonly used compounds, used to break down or bind and immobilize harmful contaminants (Karn et al., 2009).

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Site remediation with iron nanoparticles. Credit: Lehigh University

According to the EPA, federal, state and local governments, as well as private industry, are expected to spend billions of dollars each year cleaning up hundreds of thousands of contaminated sites over the next three decades. Researchers have concluded that by using nanotechnology in environmental remediation, we have the potential to reduce the cost, time and effort involved with cleaning up contaminated sites (Karn et al, 2009). One major advantage of nanoremediation is its ability to be used as an on-site, or in situ, treatment method. Removing and transporting toxic sediment or soil can involve excessive time and effort, and in situ methods like nanoremediation eliminate this cost.

However, concerns naturally emerge any time we introduce new compounds to the environment. While nanoparticles are designed and used to reduce contaminant toxicity, they may have the potential to generate harmful byproducts, or products that are even more mobile in the environment. While nanomaterials typically stay in or near the site where they are applied, several studies have shown their ability to travel larger distances, carrying with them absorbed contaminants (Karn et al, 2009). Recent research has also investigated the potential for nanoparticles to enter the food chain and bioaccumulate.

Nanoremediation has the potential to revolutionize contaminated site cleanup, but it also carries unknown risks. Balancing these risks and benefits will be critical to the future of environmental management. The good news? We are (probably) safe from predatory nanobots.

Image: National Science Foundation