Sci-Tech

Graphene microbots slurp lead from polluted water

Tiny self-propelled microbots can remove up to 95 percent of the lead in wastewater produced by industrial activity.

Artistic impression of the nanobots in action.

American Chemical Society

Humans are pretty effective at messing up everything. Look at all the tech we use. It doesn't come without a cost. Manufacturing electronics and batteries produces contaminants such as lead, cadmium, mercury, arsenic and chromium, none of which is particularly good for living organisms.

To help combat this destructive effect, an international team of researchers has developed a school of tiny microbots, each smaller than the width of a human hair, which is capable of removing lead particles from contaminated water more efficiently than previously developed methods.

The robots are shaped like tiny tubes, in three layers. Graphene oxide on the outside absorbs lead particles from the water. The middle layer is nickel, which allows external control of the robots using a magnetic field. The inner layer is platinum, which gives the robots self propulsion by adding hydrogen peroxide to the water. This interacts with the platinum, which decomposes the hydrogen peroxide into water and oxygen, propelling the microbot forwards.

The team writes in their paper, published in the journal Nano Letters, that a swarm of the microbots can reduce the amount of lead in water from 1,000 parts per billion to just 50 parts per billion, a reduction of 95 percent, in just 60 minutes.

Obviously this is dependent on the amount of water and number of microbots, but what makes it even more impressive is that the robots can be reused. The same magnetic field that controls the microbots can be used to retrieve them. They can then be cleaned and used again.

Moreover, the lead ions that have been cleaned off the microbots can be reused too.

"This is a new application of smart nanodevices for environmental applications," co-author Samuel Sánchez of the Max Planck Institute for Intelligent Systems in Germany told Phys.org.

"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."

The next step in the research is to develop microbots that can clean up a much wider range of industrial pollutants, while trying to reduce the costs of fabrication.