Researchers at North Carolina State University have published their findings which demonstrate a successful proof of concept for a system which can remove microplastics from water in a single cycle.
The work, which is published in Advanced Functional Materials, has the potential to improve how oceans and other bodies of water are cleansed of microplastics which could negatively impact human and environmental health.
The process relies on the use of soft dendritic colloids, soft particles which can stick to just about any surface even when wet, to attract and capture microplastics. Before releasing the dendritic colloid pellets, the researchers infuse eugenol, a plant-based oil, to one section of the dendritic colloid pellets to act as a dispersant.
"This oil makes the pellets move in the water by the so-called 'camphor boat effect,' decreasing the surface tension on one side of the pellet and driving it forward. This allows our microcleaners to spread out across a larger area, capturing microplastics as they move and descend," said Ph.D. student Haeleen Hong.
To recover the dendritic colloids, the team include small magnesium particle coated in gelatin which cause the pellets to bubble up and return to the surface after reacting with water.
During their proof-of-concept research, the team observed that the particles can “swim” for nearly 30 minutes before returning to the surface with the collected microplastics. Once on the surface, the microplastic-laden droplets can be collected by skimming.
"Potentially, the collected scum can be bioprocessed into more chitosan, which can then be used to create more microcleaners in order to capture more microplastics," added Orlin Velev, Professor of Chemical and Biomolecular Engineering at NC State.