A superhydrophobic particle - that can degrade three types of hard-to-remove pollutants in water, has been designed by scientists at the University of Barcelona in Spain.

Some compounds that end up in aquatic ecosystems pose a risk to the environment and human health. They are sometimes called 'emerging contaminants' - because they are relatively new compounds related to human activity, and include microplastics, oils, dyes, pharmaceuticals and plasticisers.

Such compounds can also be found in wastewater, and removing them represents a scientific, technological and societal challenge. However, most of the wastewater related to these products is still discharged into rivers or the sea without removing the pollutants.

Now, an innovative approach, using two-faced superhydrophobic particles to degrade the pollutants has been proposed. The 'Janus' particles are named after the Roman god who is often depicted looking two ways.

Each has differentiated domains that can eliminate three types of pollutant: organic solvents, stable dyes and microplastics. The researchers say the results open up new possibilities for new superhydrophobic materials that can effectively remove persistent pollutants.

“The use of superhydrophobic materials is an effective strategy to fight environmental pollution," says Oriol Rius, Serra Húnter lecturer at the Univerisity of Barcelona's department of materials science and physical chemistry. "A few years ago, attempts were made to mimic the superhydrophobicity present in nature, as in the case of the lotus flower.

"Recently, however, research has progressed to design new materials with various applications. Superhydrophobic materials stand out for their great versatility, with uses such as the self-cleaning of surfaces, or the removal of oils and organic solvents.”

Two-faced functionality

“The fact that the particle has two clearly differentiated domains gives it multifunctional properties that allow it to eliminate three different types of pollutants: organic solvents, stable dyes and microplastics,” says Professor Núria Llorca. “Since these materials have two different sides, this makes it possible for each one to act differently.

"Specifically, one side has a greater affinity with organic solvents and microplastics, as it is functionalised with a compound called lauric acid. In contrast, the other side does not contain this compound, but allows for the fast and effective degradation of a fairly stable dye.

"These two characteristics make the system capable of eliminating different types of pollutants.”

In the future, the possibility of combining different chemical compositions in a single material could broaden the field of application of these materials with superhydrophobic properties, the research team concludes.

The paper is published in the Journal of Environmental Chemical Engineering.