The ubiquitous nature of plastic pollution in our environment is an alarming concern. The breakdown of plastics into smaller sizes, ranging from micro to nano-sized material, raises concerns about their toxicity to the environment and humans. The impact of nanoplastics, which are a thousand times smaller than microplastics on fish, marine life and human life is under intense investigation, however, mitigating options are quite limited.

A team of researchers led by Chemical Engineering Professor Tizazu Mekonnen, at the University of Waterloo, have leveraged their expertise in polymer engineering to tackle this critical challenge. Mekonnen’s research is in polymer sustainability, and it endeavours to reduce the carbon footprint of the plastics industry.

“To mitigate the plastic waste crisis and reduce the environmental impact of plastics production and use, we need to implement a circular economy approach that considers every stage of the plastic journey,” says Mekonnen. “Rationally designed plastics not only can be part of the solution to reduce climate change but can positively impact economic development and job creation for the future generation.”

Mekonnen and Masters student Rachel Blanchard have made a significant proof breakthrough in nanoplastics cleanup from wastewater systems. There were two facets to their research.

The first was to utilize a form of plastic waste with no recycling or treatment options. Mekonnen used a waste polymer, epoxy a thermoset plastic often used in composite materials, adhesives, coatings, and electronics. Epoxy cannot be reused or reprocessed and ends up in landfills or spills into the environment, including water systems.

Using a process called thermal decomposition the researchers converted epoxy thermosets into an extremely large surface area activated carbon, a material capable of immense adsorption.

The second facet of their research was to utilize the activated carbon for the treatment of water contaminated by nanoplastics. For testing, they produced nanoplastics from polyethylene terephthalate (PET) a form of polyester often used in plastic water bottles and clothing such as fleece, which sheds nanoplastics during the washing process. These tiny contaminants pose a greater health risk compared to microplastics as they can penetrate cells and their presence is hard to detect.

The researchers were able to convert a form of plastic waste that is impossible to reuse or convert into a useful material with a high surface area and multiple layers. They then used that product to adsorb nanoplastics from contaminated water. They achieved 94 percent efficiency in removing nanoplastics from the water.

This research is impactful as there are very limited studies that investigate using an epoxy-derived carbon-type adsorbent for nanoplastic recovery. The activated carbon, like a Brita water filter, can be safely disposed of when its adsorbent qualities have been completely saturated. It can also be regenerated for repeated use.

The next steps in this research are to apply this method to other types of plastics and test this proof of concept in real municipal wastewater treatment which contains a variety of other contaminants in addition to microplastics.

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