Eliminating Pollutants with Magnetic Nanoparticles

Microcontaminants such as detergents, medications, cosmetics, and fertilizers are challenging to remove from wastewater. Yet they can also have a detrimental effect on the ecology of the waterways that effluent is released into, and some have an endocrine-disrupting influence on humans.

Conventional treatment techniques include ozonation, reverse osmosis, or granular activated charcoal. But researchers at ETH Zurich’s Institute of Robotics and Intelligent Systems have developed a revolutionary new removal process using magnetic nanoparticles.

The method harnesses the catalyzing effect of particles with a cobalt ferrite core and a bismuth ferrite shell. The researchers explain that while the particles aren’t directly responsible for micropollutant removal, they serve as a catalyst.

In the presence of a magnetic field, some areas of the particle surface become positively charged, while others become negatively charged. As PhysOrg reports, the charges promote the formation of reactive oxygen species in water, which break down the organic pollutants into less harmful compounds. The nanoparticles can then be removed with the help of a magnet.

“Nanoparticles such as these are already used as a catalyst in chemical reactions in numerous areas of industry,” explains ETH Zurich’s senior research scientist Salvador Pané. “Now, we've managed to show that they can also be useful for wastewater purification.”

During the extensive testing process, researchers exposed solutions containing five common medications to magnetic nanoparticles. Two of the substances cannot be removed with conventional ozone-based methods. The treatment technique was able to reduce the concentrations of these micropollutants by 80%.