University of Michigan researchers discover way to recycle polyvinyl chloride

University of Michigan researchers have discovered a way to chemically recycle polyvinyl chloride (PVC) into usable material, according to a study published in the journal Nature Chemistry, a university news release said. 

PVC is one of the most commonly produced plastics in the U.S. and is used in a wide range of products including hospital equipment, plumbing, window frames, housing trim, electrical wiring and clothing. However, it has a 0% recycling rate in the U.S. 

When heat is applied to PVC, one of its primary components, called plasticizers, leach out of the material easily and release hydrochloric acid, which can corrode recycling equipment and cause chemical burns to workers. Moreover, phthalates, a common plasticizer, are highly toxic endocrine disruptors.

Searching for a way to recycle PVC without heat, University of Michigan researchers, led by Danielle Fagnani, a postdoctoral researcher in the university's Department of Chemistry, began exploring electrochemistry. 

The team discovered that the plasticizer that presents one of the major recycling difficulties can be used in the method to break down PVC. The plasticizer improves the efficiency of the method, and the electrochemical method resolves the issue with hydrochloric acid. 

The acid can then be used by industries as a reagent for other chemical reactions. The chloride ions also can be used to chlorinate small molecules called arenes, which can be used in pharmaceutical and agricultural components. There is material left from the polymer, for which the researchers are still looking for a use.

“It’s a failure of humanity to have created these amazing materials which have improved our lives in many ways, but at the same time to be so shortsighted that we didn’t think about what to do with the waste,” said Anne McNeil, principal investigator of the study. 

“In the United States, we’re still stuck at a 9% recycling rate, and it’s only a few types of plastics," she added. "And even for the plastics we do recycle, it leads to lower and lower quality polymers. Our beverage bottles never become beverage bottles again. They become a textile or a park bench, which then ends up in a landfill.” 

The focus of McNeil’s lab has been to develop ways to chemically recycle different kinds of plastics. Breaking plastics into their constituent parts could produce non-degraded materials that industries can incorporate back into production.