UNIVERSITY PARK, Pa. — A new approach to plastic recycling being explored at Penn State could make the process more efficient by using tiny particles of coal, according to researchers. On the latest episode of “Growing Impact,” researchers discussed how the technique uses laser light to generate heat at the molecular scale, potentially allowing plastics to be broken down into their basic building blocks and reused.
The researchers are investigating whether tiny particles made from Pennsylvania anthracite coal can help drive the chemical reactions needed to recycle plastics.
The research team includes Ben Lear, professor of chemistry and lead investigator on the project; James Adair, professor of materials science and engineering, of biomedical engineering and of pharmacology; and Jonathan Mathews, professor of energy and mineral engineering. The researchers bring together expertise in chemistry, materials science and coal.
Their approach uses nanoscale anthracite particles to convert laser light into heat. Because the particles are extremely small, the researchers can generate heat close to the chemical bonds that hold plastics together. The heat can then break those bonds, potentially allowing plastics to be returned to their basic building blocks, known as monomers.
That could address one of the fundamental challenges of plastic recycling, the researchers said.
“Plastics are designed to be durable,” Lear said. “They’ve been designed to resist the kind of reactivity that would necessarily be involved for recycling.”
Today, recycling can require different types of plastic to be separated, and additives such as dyes and flame retardants can make chemical recycling more difficult. The researchers said they hope their approach could eventually provide a more general way to process complex plastic waste, reducing the need to separate some materials.
“A big problem in polymer recycling is you have these relatively unique polymers,” Adair said. “Polyurethane can’t be processed with, say, polyethylene.”
The researchers said this work also could create a new, higher-value use for Pennsylvania’s abundant anthracite. Rather than using coal primarily as a fuel, the researchers are exploring how it can serve as an advanced material.
“Many of us think that anthracite is too valuable to burn,” Mathews said. “There is an opportunity here to take this abundant natural material and make it far more valuable and have a greater contribution to society.”
The researchers have found that the anthracite particles can function as an effective material for converting light into heat, opening the door to further research into using them for plastic recycling. Their next steps include optimizing the particles and determining which difficult-to-recycle plastics could benefit most from the approach.
In the long term, the team hopes the research could contribute to a more flexible and efficient approach to plastic recycling while creating a new use for a Pennsylvania resource.
“Growing Impact” is a podcast by the Institute of Energy and the Environment. It features Penn State researchers who have been awarded IEE seed grants and discusses their foundational work as they further their projects. The podcast is available on multiple platforms, including YouTube, Apple, Amazon and Spotify.