CU Boulder chemists develop future of recycling plastics

Chemists at the University of Colorado Boulder are developing the future of recycling polyethylene terephthalate (PET), a common type of plastic found in packaging and soda bottles. The method relies on electricity and chemical reactions to dissolve the plastic.

The study addresses concerns about the problem of plastic waste around the world. According to the Environmental Protection Agency, the total generation of municipal solid waste in 2018 was 292.4 million tons. This is approximately 23.7 million tons more than the amount generated in 2017.

PET plastic is found in everyday items such as water bottles, blister packs and some polyester fabrics. Mixed with a special kind of molecule and small amount of electric voltage applied, the reaction decomposes acids and alcohols in the presence of oxygen.

This approach works to highlight PET being deconstructed into their molecular components through electrochemical reaction.

Study co-author Oana Luca, who is also an assistant professor in the Department of Chemistry, said a majority of the waste ends up in landfills.

“We pat ourselves on the back when we toss something into the recycling bin, but most of that recyclable plastic never winds up being recycled,” Luca said in a news release.

She is taking steps to discovering how to recover molecular materials, the building blocks of plastics so they can be reused.

The researchers are developing a recycling process that breaks down plastic into its original molecular components, achieving almost 100% atom efficiency.

“The catalyst used for the breakdown of the PET is also regenerated using electricity, thus opening the door to the development of sustainable recycling methods that reduce waste with minimal production of it,” Luca said.

The team studies the basic chemical reactions based on the organic chemistry of PET. The reaction time depends on how much PET is broken down and on how fine it is ground. The appeal of electrochemical reactions applied to this sort of application is that electrochemical methods are inherently scalable.

Luca stated some of the largest industrial processes implemented on scale use electricity such as the chloralkali process for the production of chlorine.

“We are trying to shorten reaction times and are working on developing a version of this electrochemical reaction that operates fully open to air,” Luca commented. “We are also studying the inner workings of the reaction mechanisms, … (and) we’d like to team up with engineers to scale up the reactions.”

Study lead author Phuc Pham noted that it will take time to cut into the current plastic trash issues, but instead of waste lingering for centuries with this new tool it can dissipate in mere hours or days.

“It was awesome to actually observe the reaction progress in real time,” Pham, a doctoral student in chemistry, said in the release. “The solution first turns a deep pink color, then becomes clear as the polymer breaks apart.”