Scientists program microbots to clean polluted water

Testing proves a team of tiny microbots are able to remove the majority of heavy metal toxins from water.

When deployed, the swarm of microbots removed 95 percent of the lead from polluted water in less than an hour -- suggesting the process could replace more expensive water treatment technologies.

"This work is a step toward the development of smart remediation system where we can target and remove traces of pollutant without producing an additional contamination," Samuel Sanchez, a researcher with the Max-Planck Institute for Intelligent Systems in Stuttgart, Germany, said in a news release.

Industries like electronics manufacturing and mining are largely to blame for the presence of contaminants in local waterways -- toxins like lead, arsenic, mercury, cadmium and chromium, all of which put both humans and freshwater species at risk.

The microbots are miniature tubes formed by three layers of material. An outer shell of graphene oxide soaks up the lead. A middle layer of nickel allows the microbots to be maneuvered by electromagnetic fields.

Finally, an inner layer of platinum propels the bots forward. When hydrogen peroxide is added to wastewater, it dissolves the platinum. As a result, oxygen microbubbles are ejected out the back of the tube, pushing it toward magnetic north.

"This is a new application of smart nanodevices for environmental applications," Sanchez said. "The use of self-powered nanomachines that can capture heavy metals from contaminated solutions, transport them to desired places and even release them for 'closing the loop' -- that is a proof-of-concept towards industrial applications."

Sanchez and his research partners shared their success in a new paper, published this week in the journal Nano Letters.