Swarms of graphene microbots could be used to clean polluted water

11 Apr 2016

New research has developed upon the idea that, in the near future, swarms of microbots controlled by magnetism could be unleashed in polluted water to absorb the toxic chemicals in it.

The planet’s oceans are increasingly becoming the sites of enormous amounts of human-generated waste, with estimates putting the amount of plastic now in our oceans close to 8m tonnes.

While a number of research groups have been contemplating how to best remove this harmful waste from our oceans, one research group plans to use minute microbots to help remove toxic material from industrial wastewater.

Due to the demand for a multitude of devices and other industrial output, the need to dispose of water contaminated with heavy metals like lead, mercury and arsenic is an ever-present problem created during the manufacturing process, with this polluted water often being returned to the environment with harmful consequences.

Publishing its findings in Nano Letters, the research team from the Max-Planck Institute for Intelligent Systems in Stuttgart, Germany has found a way of developing microbots that could remove 95pc of lead from wastewater within the space of an hour.

Graphene bots gif

Magnetic guidance of the microbot. Gif via Vilela, et al.

Completely reusable

Designed in three layers, the microbot tubes outer layer consists of a graphene oxide material that can absorb the lead in the water, followed by the middle layer, which is made from nickel, making these microbots ferromagnetic, so that their direction of motion can be controlled by an external magnetic field.

Finally, the innermost layer is made from platinum, giving the microbots the ability to self-propel themselves through water once hydrogen peroxide is added to the water, which dissolves the platinum and thus propels it forward using the generated oxygen microbubbles.

Once the microbots have had their fill and the water is deemed safe, a magnetic field is used to collect the microbots once again where they will be given a bath in an acidic solution to remove the lead.

The lead-hungry microbots can then be reused again for cleaning up more lead from another source.

Speaking about the future for this technology, the team said that it could one day become automated with it being tasked to perform a number of different functions within a body of water.

“This is a new application of smart nanodevices for environmental applications,” said co-author of the research paper Samuel Sánchez.

“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.”

Wastewater image via Pam Broviak/Flickr

Colm Gorey was a senior journalist with Silicon Republic