Cleaning polluted water is never easy, especially when that dirty H2O is inside tiny pipes or other hard-to-reach places. But now a team of researchers in Germany have come up with a possible solution. They have developed a new process that could create nanoscale "micromotors" that could travel through the water and treat the pollutants they come across.

The micromotors are simple structures, smaller than the eye can easily see. These little devices are made up of tubular cores of platinum surrounded by iron. When released into polluted water that contains hydrogen peroxide, the micromotors get to work. The platinum converts the hydrogen peroxide into oxygen bubbles, while the iron creates hydroxyl radicals. A hydroxyl is a molecule containing both hydrogen and oxygen — in fact, water is one example of a hydroxyl — but the radical form is a short-lived, highly reactive form that has long been known to react to pollutants, creating chemical reactions that can convert them into less dangerous substances. This dual conversion serves two purposes: the oxygen bubbles become the micromotors' propellant, moving them along, while the hydroxyl radicals help to oxidize organic pollutants and clean the water.

The self-propelling action means the micromotors can degrade more pollutants than other methods. Although they would not be ideal for large bodies of water, the micromotors could be a very good solution for situations that cannot easily be treated by existing methods, say the researchers. Samuel Sanchez, a scientist at the Max Planck Institute for Intelligent Systems and one member of the team that developed the micromotors, said of their discovery, "We aim to clean contaminated capillaries, small pipes and places difficult to reach. We are dealing with applications especially for the microscale and environments hard to get to."  

The research was published last month in the journal ACS Nano. The tiny motors are not ready for active use, but experts say this is the first step toward scaling up research into this functionality.

Meanwhile, many other researchers have been looking into micromotors and related technologies. Previous studies have examined using the structures to clean up oil spills, while others have proposed using fish-like micromotors to test water quality.

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Tiny 'micromotors' could clean polluted water
The nanoscale structures would propel themselves into tight spaces that other treatments can't reach.