Innovative solvents remove nanoplastics from water

As tiny nanoplastics continue to build up in the world’s bodies of water, the challenge remains to develop a cost-effective solution to remove them while leaving clean water behind. Now researchers at the University of Missouri have created a liquid-based solution that eliminates more than 98% of these microscopic plastic particles from water, which they have described in the journal ACS Applied Engineering Materials.

“Nanoplastics can disrupt aquatic ecosystems and enter the food chain, posing risks to both wildlife and humans,” said Piyuni Ishtaweera, who led the study while earning her doctorate in nano and materials chemistry.

“We’re developing better ways to remove contaminants such as nanoplastics from water.”

The team’s innovative method uses water-repelling solvents made from natural ingredients. Initially, the solvent sits on the water’s surface the way oil floats on water. Once mixed with water and allowed to reseparate, the solvent floats back to the surface, carrying the nanoplastics within its molecular structure.

“These solvents are made from safe, non-toxic components, and their ability to repel water prevents additional contamination of water sources, making them a highly sustainable solution,” Ishtaweera said. The new method is also effective in both fresh and salt water, she added.

The Missouri team tested five different sizes of polystyrene-based nanoplastics, in the process outperforming previous studies that largely focused on just a single size of plastic particles. The researchers simply used a pipette to remove the nanoplastic-laden solvent — leaving behind clean, plastic-free water — but future studies will work to scale up the entire process so that it can be applied to larger bodies of water like lakes and, eventually, oceans.

“Our strategy uses a small amount of designer solvent to absorb plastic particles from a large volume of water,” said Associate Professor Gary Baker, corresponding author on the study. “Currently, the capacity of these solvents is not well understood. In future work, we aim to determine the maximum capacity of the solvent. Additionally, we will explore methods to recycle the solvents, enabling their reuse multiple times if necessary.”

The breakthrough not only offers a practical solution to the pressing issue of nanoplastic pollution but also paves the way for further research and development in advanced water purification technologies. Ishtaweera concluded that “creating effective removal methods fosters innovation in filtration technologies, provides insights into nanomaterial behaviour and supports the development of informed environmental policies”.

Image caption: Gary Baker looks at a bottle of the liquid-based solution. Image credit: Sam O’Keefe.