Even on a pristine looking cottage lake, chances are good that you can find plastic litter, even if you can’t see it. Our pervasive use of plastic, from take-out containers to water bottles, from garbage bags to polyester clothing, has led to the widespread presence of microplastic pollution in water systems. Microplastics have a diameter smaller than five millimetres, and they pose a threat to ecosystems because they can end up in the bellies of freshwater and marine species like fish and birds, and they can collect and transport contaminants. Now, a study by a team of researchers from Australia has shown a way to break down microplastics into organic intermediates through chemically engineered nanocarbon springs.
The team engineered nanocarbon springs that activated peroxymonosulfate, a chemical compound, to form highly reactive radicals that decomposed the microplastics into organic intermediates. The nanocarbons were designed to be magnetic so that they could be removed from the solution after their job was done. The process was tested on microplastics from a variety of facial cleanser brands.
“We used optical microscopes and electron microscopes to witness the evolution of the microplastic during degradation,” says Dr. Xiaoguang Duan, one of the co-authors of the study and a Research Fellow with the School of Chemical Engineering at the University of Adelaide, Australia. The scientists were able to observe the microplastics’ surfaces forming cracks, before breaking into smaller and smaller segments.
The team evaluated the toxicity of the intermediates by mixing them in a solution with algae. “We found that the algae grows quite well,” says Dr. Duan. “That means that the intermediates are non-toxic and that microplastic degradation products can be utilized as carbon sources for algae growth.”
Canada has banned the manufacture, import, and sale of toiletries containing plastic microbeads, manufactured plastic particles that can function as exfoliants, unless they are found in natural health products or non-prescription drugs. Microbeads are used in over-the-counter medication to make pills easier to swallow. However, facial cleansers and scrubs aren’t the only way for plastic to enter waterways. Synthetic clothes containing polyester and nylon shed plastic microfibres into water systems through laundry machines.
The manufacturing industry generates microplastic waste particles, and litter, such as plastic bags and take-out containers, break down over time into smaller plastic pieces. Dr. Duan says that because of the wide variation in types of microplastic pollution, the next step for this research is to evaluate how the their technology can break down different categories of microplastics. The team is also interested in collaborating with biologists to help them assess the potential toxicity of microplastic intermediates on other species in the environment.