LSU researchers are challenging conventional recycling by developing a new, more environmentally friendly method for breaking down plastic while potentially utilizing renewable energy.
In 2018, the U.S. Environmental Protection Agency found that only 8.6% of the 35.68 million tons of plastic made were recycled. Although this percentage has increased, the total number of recycled plastics in the U.S. continues to be less than 10% of what’s generated annually.
Some plastics, such as polyester, are easier to treat than others. Polyolefins, like polyethylene, polypropylene and polystyrene, are the hardest. Yet, they are often mixed together in bins, making recycling these already difficult polymers even harder.
Five years ago, Kerry Dooley, a chemical engineering professor, Dorin Boldor, a biological engineering professor, and James Dorman, a former LSU chemical engineering professor, joined together to research new recycling methods to handle all polyolefins.
“Lots of companies are trying to do polymer recycling in the United States,” Dooley said. “To my knowledge, nobody has tried to do it this way.”
Most companies use pyrolysis, a technique that melts polymers at a very high temperature and burns natural gas. This process is energy intensive and produces greenhouse gases such as carbon dioxide.
Dooley, Dorman and Boldor began working on a “chemical recycling” method. Dooley said they wanted to know how to do it successfully and have it be relevant to future renewable electricity.
The team found that radio frequency induction heating, combined with catalysts and magnetic materials, can melt polymers at a much lower temperature than pyrolysis, using less energy and causing fewer harmful environmental effects.
Dooley said this process is inherently adaptable to intermittent operations like renewable energy. Theoretically, this process could be used with renewable electricity, whereas other processes would continue to rely on conventional electricity.
A priority of the team is to make the system as robust as possible, scaling the process up. Dooley said they will attempt to apply the method to mixed wastes rather than a single type of plastic at a time. They will also tinker with the exact catalysts used and how to feed the polymer, eventually refining the design enough that a company will license the patent.
However, Dooley said the project will die if it does not obtain this license within the next four or five years, as another technology will soon supersede it.
This research is just one of five projects that Dooley is currently involved in, and Doorman has since left the university and is now a program manager with the Department of Energy. However, the team shows no signs slowing down, as they just finished writing another grant proposal.
“Hopefully, people will recognize that we know what we are doing and we have some good ideas. Maybe it’s worth investing a little money in,” Dooley said.
Their impact on the subject can be seen in new literature by other experts. According to Dooly, practically everyone uses catalysts similar to LSU’s research and that their analytic work has also been copied.
“I am confident that eventually there is going to be a lot of chemical recycling of plastics in the United States,” Dooley said, “and I am confident that a lot of that chemical recycling will look something similar to this.”
