PET Recycling Goes Electric

Everything, it seems, is going electric, from planes, trains, and automobiles to our kitchen stoves. You may be able to add recycling to that list at some point in the future. Chemists at the University of Colorado (CU) Boulder have developed a new way to recycle polyethylene terephthalate (PET) by combining chemical reactions with an electrical charge. In lab experiments, the advanced recycling technology started breaking apart PET within minutes.

In small-scale lab experiments, the researchers mixed bits of PET with a special kind of molecule then applied a small electric voltage. Within minutes, as shown in the video, the solution containing the small grains of PET undergoes a color change as the PET begins to disintegrate.

The research is described in the journal Chem Catalysis.

Study lead author Phuc Pham explained to Daniel Strain, who wrote about the research on the CU Boulder website, that he and his colleagues ground up plastic PET bottles and mixed the powder into a solution. Next, they added a molecule known as [N-DMBI]+ salt to the solution. In the presence of electricity, this molecule forms a “reactive mediator,” said Pham, that can donate its extra electron to the PET, causing the grains of plastic to come undone.

The researchers are still trying to understand exactly how these reactions take place, but they were able to break down the PET into its basic building blocks, which the group could then recover and, potentially, use to make something new. 

Using only tabletop equipment in their lab, the researchers said that they could break down about 40 milligrams of PET over several hours, writes Strain.

“Although this is a great start, we believe that lots of work needs to be done to optimize the process as well as scale it up so it can eventually be applied on an industrial scale,” Pham said. 

Study co-author Oana Luca is already imagining where this technology could lead. “If I were to have my way as a mad scientist, I would use these electrochemical methods to break down many different kinds of plastic at once,” Luca told Strain. “That way, you could, for example, go to these massive garbage patches in the ocean, pull all of that waste into a reactor and get a lot of useful molecules back.”