Chemists can now separate four common plastics at once. Will it work as well outside their lab?

But the vast majority of the nearly 350 million metric tons of plastic produced every year returns to the Earth, averaging 500 years of slow decomposition into soil and water. Over the last 50 years, roughly 30 million tons have made it into oceans. Another 100 million tons ended up in rivers, lakes and waterways.

But what if there was a way to break down plastics — even the toughest to recycle — into raw chemical ingredients that could be sold and reused? A new study from scientists at Oak Ridge National Laboratory may have cracked the code to disassemble up to one-third of the world’s unrecyclable mixed plastics. Using a new organic catalyst, researchers designed a compound to separate four of the most used types of mixed plastics at a molecular level, even if they’re chemically bound together or contain trace amounts of impurities.

If this chemical recycling process could be used commercially, the mountains of textiles, styrofoam, drink bottles, food wrappers, and more would become new revenue for waste management facilities while saving them hundreds of millions of dollars in dumping costs. “We know some companies like [Eastman Chemical Company] are already investing in a similar type of chemical recycling process and we know the technology is scalable,” Tomonori Saito, a senior synthetic polymer chemist at Oak Ridge, and corresponding author of the study, told EHN.

Every year, specialized plants for removing recyclables from the waste stream called material resource facilities spend upwards of $70 per ton to dump un-recycled waste in landfills. Reducing plastics could slash significant disposal costs, but chemical separation technology is in its infancy.

Saito said scaling his method will require big changes to the way we recycle and a real-world pilot to show that the catalyst could effectively separate the mixed garbage that ends up in landfills.

Chemical recycling plants have begun to crop up in towns around the U.S. in recent years. But many haven’t lived up to their promise and there are significant environmental justice concerns surrounding the practice. Many of the chemicals used in making plastics are endocrine disruptors — meaning they interfere with the proper functioning of hormones — and are linked to health problems such as infertility, hormonal imbalances, and cancer.

The emissions from superheating plastics to their melting point can release a host of these toxics into the surrounding ecosystem, potentially harming human health if not carefully regulated.

Also advocates say that chemical recycling efforts only continue our reliance on plastic — and that the only true way to reduce waste and exposure is to reduce production.

From the lab to real life: A harsh reality

BASF employee with a bottle of pyrolysis oil recovered from plastic waste. Credit: BASF - We create chemistry/flickr

Turning the mess of plastics we send to the curb each week into something useful is tricky. The first step of the process is taking plastics commonly found in artificial fibers, water bottles, autoparts, and cellphones, and mixing them with glass, water and other contaminants. By running it through a combined mill, the plastic is shredded into pellets about the size of rice grains and then mixed with the salt catalyst in large vats. As the plastic heats up to between 130 and 215 Celsius –about 420 Fahrenheit – the chemical bonds are broken and the homogenous molten plastic begins to separate and recrystallize, explained Arif Ariffuzzman, lead author of the ORNL study.

The resulting mixture resembles a suspension of Italian dressing. Researchers were able to “scoop” out of this mixture several chemical ingredients at purity rates above 96%, including caprolactam and dimethyl terephthalate, both needed to produce synthetic fibers and other plastics. As valuable as these substances are, some like caprolactam are extremely harmful to humans, while others have not been studied thoroughly enough to determine their real risks.

“This isn’t just an opportunity for us as chemists,” Arifuzzman, who founded a startup called Re-Du Plastics in Knoxville, Tennessee, to commercialize the catalyst, told EHN. “It’s a chance for waste facilities to simultaneously save money and make money.”

Bob Allen, a senior research fellow at the National Renewable Energy Laboratory, said that the study’s findings hold great potential, but Arifuzzman’s excitement is premature. Trying to simply add the chemical process to our current recycling system, he told EHN, “is like me taking my first three martial arts lessons and thinking I'm ready to fight Connor McGregor.” Allen, who spent 35 years as the head of Polymer Research & Technology at IBM, also points out that the 96% purity rate is not the high mark we may think. “The only way you're going to get to where you need to be is to get hyper-pure,” he said, adding “99%, that’s the magic number and a truism in molecular chemistry.”

“This isn’t just an opportunity for us as chemists. It’s a chance for waste facilities to simultaneously save money and make money.” - Arif Ariffuzzman, Re-Du Plastics

In general, chemical manufacturers need strong supply chains of ingredients, Allen said, pointing to the lack of such networks in the way we currently manage mixed plastic waste. He espouses the circular plastic economy Saito and Ariffuzman are striving for but sees the commercialization of chemical recycling five to 10 years in the future. “If you're going to go through the pain and suffering of permitting and financing a new manufacturing facility, running a process never seen before on planet Earth,” he said, “you’d better be sure you’re working with more than just Mickey Mouse quantities of usable material.”

The final hurdle is to reintroduce the material into the marketplace. Many petrochemical companies refer to the impending shift toward a “circular plastic economy”, where billions of tons of plastic waste can theoretically be salvaged and recycled into manufacturing usable materials.

But some question this goal, as many of the plastics we use every day, like polyethylene and polypropylene, often contain per- and polyfluorinated substances (PFAS), a group of toxic chemicals known as “forever chemicals” since they do not decompose organically in the environment and have been linked to several health problems.

“Ten years ago, we would’ve never claimed they’re recyclable,” Alfredo Alexander-Katz, a professor of materials science and engineering at MIT, told EHN. “But since there’s added pressure to reduce our production and consumption of plastics, particularly in the European Union, they started to call them circular, as if they were meant to be recycled.”

In addition, it’s unclear if the method will work with the real-life conditions of plastics found in landfills, Allen pointed out. “Any commercial chemical recycling process needs to be able to handle mixed plastic waste streams riddled with contaminants,” he said. When I asked Saito if, for example, his catalyst would be able to handle things like spent yogurt cups with specks of curdled dairy in them, he admitted getting usable monomers from the material would be “very difficult.”