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PVC (polyvinyl chloride) is one of the most used plastics in the world and unfortunately it’s also one of the most difficult materials to recycle. Now, however, thanks to chemical advances, a team at the University of Michigan has created a process which can turn this non-recyclable material into useful ones.
PVC plastic is used in a range of different areas ranging between clothing and flooring. In the United States, the recycling rate of the material is non-existent due to its harmful constituents.
“PVC is the kind of plastic that no one wants to deal with because it has its own unique set of problems,” explained study first author Danielle Fagnani. “PVC usually contains a lot of plasticizers, which contaminate everything in the recycling stream and are usually very toxic. It also releases hydrochloric acid really rapidly with some heat.”
In order to solve this issue, Fagnani and her team have tested different non-thermal methods and now they have developed a very promising new electrochemistry method. By using electrons to break down the carbon-chlorine bonds in the material, the research team were able to precisely control the flow of hydrochloric acid by using one of the PVC plasticizers to mediate the process.
“What we found is that it still releases hydrochloric acid, but at a much slower, more controlled rate,” Fagnani illustrated.
Thanks to the process, the acid can be collected and used as a reagent in other chemical reactions. This procedure also produces chlorine ions which can be use to chlorinate molecules for use in medicinal and agricultural applications.
This new process does leave other material behind which the team is trying to find use for so some improvement is still possible. However, the researchers claim the work demonstrates how chemical recycling may be used to give problematic materials a second life.
“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 principal investigator Anne McNeil to New Atlas. “In the United States, we’re still stuck at a 9% recycling rate, and it’s only a few types of plastics. 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.”
If you'd like to read the whole study, you can do so here: Nature Chemistry—Using waste poly(vinyl chloride) to synthesize chloroarenes by plasticizer-mediated electro(de)chlorination