Teeny tiny, invisible pieces of plastic are all around us. Microplastics and nanoplastics, as they are called, have been found in our bodies, and in food, water, and air. If things continue as is, the oceans will carry more plastic than fish by weight by 2050, according to the Plastic Soup Foundation.
Researchers have been looking for ways to remove them from the environment. A novel approach now comes from researchers at the University of Missouri. In a study published in the journal ACS Applied Engineering Materials, the researchers report a solvent that removes 98% of the tiny plastic particles from water in the laboratory.
Plastics are designed to be tough and long-lived. But this is a detriment when waste plastic ends up in waterways, where it can break down into small pieces less than five millimeters in size. Those microplastics and nanoplastics are easily ingested by fish and shellfish, and make their way up the foodchain. The myriad chemicals in plastics have been linked to serious health issues.
Around 3% of all plastic produced in the world winds up in the oceans today. That share will likely rise as plastic production increases.
To combat this plastic pollution, Gary Baker and his colleagues at the University of Missouri came up with an efficient way to remove nanometer-sized plastic pieces, which are invisible to the eye, from fresh and salty water.
“The challenge in extracting and detecting nanoplastics from environmental matrices lies in their minuscule sizes, varied shapes, and low concentration,” the team writes in the paper. So they made 10 different chemical solvent mixtures of hydrophobic materials that, like oil, don’t mix with water.
Because plastics are also hydrophobic materials, they are attracted to the solvents. When the researchers poured the solvents into water containing tiny polystyrene plastic beads, the solvents first floated on the surface. When mixed in, they picked up the nanoplastics and then floated back to the top, from where the researchers could remove them.
Three of the solvents worked best, the researchers found. Two were mixtures of a fatty acid called decanoic acid with salts of ammonium and bromide. The third was a mixture of menthol and a thyme extract called thymol.
“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,” said Piyuni Ishtaweera, lead author of the paper, in a press release. She added that the work could foster innovation in plastic filtration strategies.
Source: Piyuni Ishtaweera et al. Nanoplastics Extraction from Water by Hydrophobic Deep Eutectic Solvents. ACS Appl. Eng. Mater. 2024.
Image: Based on photo by Sam O’Keefe via University of Missouri. ©Anthropocene Magazine
