Issues of the Environment: U-M researchers determine potential ways to recycle PVC plastics

Overview

  • According to the EPA (Environmental Protection Agency) less than 9% of plastic is recycled in the United States. One type of plastic, PVC (polyvinyl chloride) is technically recyclable, PVC is the least recycled plastic, with less than one-quarter of 1% of post-consumer PVC recovered for recycling. Most curbside recycling programs and recycling centers do not accept vinyl.(Source: https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/plastics-material-specific-data_; https://earth911.com/home-garden/pvc-another-problematic-plastic/#:~:text=Although%20PVC%20is%20technically%20recyclable,worth%20checking%20your%20local%20options).)
  • Currently, no city in Washtenaw County accepts PVC (also known as #3 plastic) for recycling. Recycle Ann Arbor warns residents not to put any #3 plastic into curbside recycling containers They warn, “Just one #3 PVC bottle can contaminate an entire half-ton of water bottles for recycling.”
  • Now, University of Michigan researchers, led by study first author Danielle Fagnani and principal investigator Anne McNeil, have discovered a way to chemically recycle PVC into usable material. The most fortuitous part of the study? The researchers found a way to use the phthalates in the plasticizers—one of PVC’s most noxious components—as the mediator for the chemical reaction. Their results are published in the journal Nature Chemistry.
  • “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,” McNeil said. “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.” (Source: *directly quoted* https://news.umich.edu/u-m-team-recycles-previously-unrecyclable-plastic/)

Transcription

David Fair: This is 89 one WEMU, and welcome to another edition of Issues of the Environment. Now, if you’ve ever looked under your sinks and walked through an unfinished basement, you’ve noticed a lot of piping. And much of it is PVC piping. It is a material used pervasively in all sorts of ways. It’s made of a thick, hard plastic. And while it most certainly serves a useful purpose, it poses a problem when it comes to recycling. I’m David Fair, and according to the Environmental Protection Agency, of the small 9% of all plastics that are actually recycled, PVC plastic is the least recycled. Here in Washtenaw County, PVC, or polyvinyl chloride, is not recyclable at all. Our guest today is behind some groundbreaking research that could make PVC recyclable without producing some hazardous residues. Dr. Danielle Fagnani is a post-doctoral researcher, and she served at the University of Michigan as part of the McNeil Group. And, Danielle, thank you so much for the time today.

Dr. Danielle Fagnani: Yeah. Happy to be here. Thanks for having me.

David Fair: So, what is it that makes PVC plastics so much more difficult to recycle than other forms of plastic?

Dr. Danielle Fagnani: So, there’s two main reasons why PVC is more difficult to recycle. The unique challenges associated with PVC are, one, that it releases HCL–hydrochloric acid–upon heat treatment. So, that’s different from polyethylene, for example. PVC releases HCL, and that’s very corrosive to the recycling equipment and just not something you’d want to happen.

David Fair: Not good for quality or people. Right.

Dr. Danielle Fagnani: Yes, exactly. And then, the other reason why PVC isn’t recycled is because it’s usually formulated with a lot of plasticizer additives. It’s in the PVC. So, if you have any soft PVC formulations, like PVC tubing or even PVC vinyl gloves, it usually contains a lot of Cell-A plasticizers. There are some other plasticizers that are used, but phthalates are among the most common for several decades. And these are highly toxic. And this gets into the recycling stream. It will actually contaminate other plastics. So, you don’t want anything recycled with that present.

David Fair: So, with PVC recycling rates at zero in most areas of the country, what happens to most of it? Is it being reused in any form, or just landfilled?

Dr. Danielle Fagnani: So, it’s mostly being landfilled. One unique thing with PVC, especially if you think about PVC piping, it does have very long-term use, so you’re not often using it for a day and throwing it out. So, there are long-term uses for PVC, which is great. So, that’s not going directly into a landfill. But PVC that does get disposed of will usually end up in the landfill, especially in the US, where the recycling rates are quite low for PVC.

David Fair: Besides taking up space in the landfill, what are the environmental implications for the long-term breakdown of those plastics in our land?

Dr. Danielle Fagnani: Great question. So, the plasticizers that I was referring to, especially the phthalate plasticizers, they can still leach out of the plastic, out of the soft PVC formulation.

David Fair: And get into the groundwater.

Dr. Danielle Fagnani: Exactly. And if that leaches out, that can get into, you know, wastewater streams, into the environment, and that’s not great because, particularly for phthalates, they’re very toxic for human health. They’re known as current disruptors, which leads to a lot of health problems. So, that’s, like, one major issue. It also will slowly break down, and it will form chlorinated byproducts, often dioxins, which are also pretty toxic, pretty hazardous. So, you don’t want those just loose in the environment. It’s much better to be able to collect the PVC and recycle it or controllably degrade it.

David Fair: And that brings us to the subject of our conversation. Issues of the Environment and our conversation with Dr. Danielle Fagnani continues on 89 one WEMU. And, Dr., as you and the rest of the McNeil Group at the U of M began to explore potential remedies, how did you come up with the process by which you could recycle and not release the hydrochloric acid?

Dr. Danielle Fagnani: Great question. So, in the McNeil lab, we were broadly thinking about new ways that we could chemically recycle plastic waste, so to use some sort of chemical reaction to convert the polymer into any other useful product. So, for PVC in particular, we turned to electrochemistry– electrosynthesis. And that inserts an electron into the system. And then, that will lead to a bond-breaking reaction that will slowly release the chloride ions. So, since we’re doing this electrosynthetically, we can control the reaction and release the chloride very, very slowly, compared to if you heat it and you just have it all rapidly degrade. So, we can slowly break these bonds. And then, in the same reaction vessel, same reaction vessel, we get those chloride ions, and then we can actually do a second reaction where we re-use those ions directly. And we can chlorinate another small molecule of our choice. And, often, that molecule can be used as a precursor, for example, like a pharmaceutical ingredient, which often uses some sort of chlorine chemistry.

David Fair: So, through this process, what byproduct will be reusable, and what will still need to be disposed of?

Dr. Danielle Fagnani: So, the chloride portion of polyvinyl chloride is being reused in this process. So, polyvinyl chloride, it’s carbon and hydrogen and chloride. So, we can use the chloride atoms, but there is still left over hydrocarbon backbone. So, the process is, really, we discovered the first stage of development. So, we’re currently looking into ways to improve the process and to find utilization for the leftover hydrocarbon portion. So, that’s work that’s currently ongoing in the McNeil lab. So, we’re using the chloride ions directly. The leftover hydrocarbons: that could potentially be paralyzed, so that they could be burned and used for fuel or…you know, something that we’re thinking about in the lab is how can we find chemical uses for that as well. So, that aspect is still in development.

David Fair: WEMU’s Issues of the Environment conversation on the recycling of PVC plastics continues with Dr. Danielle Fagnani. Now, is this process, as it stands today, rather expensive?

Dr. Danielle Fagnani: That’s a great question. Presumably, it’s probably expensive. And so, I say presumably, and probably because we haven’t really worked out the cost of this process. So, it’s in a lab-scale development stage. So, it hasn’t been scaled up to something larger yet. So, really, what we discovered was a proof of concept: to say that we can reuse TVC in a unique way that it hasn’t been reused as before. So, that’s the first stage. And ongoing work now, there’s a lot to do to improve the efficiency of the reaction, so improving the efficiency will ultimately lower costs, as well as looking at the scalability. How big can we do this? Because we were doing this on a small, very small, scale in the lab, but, you know, a great question is how big? How big can we do this?

David Fair: And if there was a recycling facility like Recycle Ann Arbor or any of the other municipal or private recycling centers across the country and wanted to explore this as the information becomes available, do they have to look at expanding operations, creating a new part of the facility specifically to deal with this? Or is this something that could be integrate into what already exists?

Dr. Danielle Fagnani: So, because of the nature of the chemical reaction that we’re doing–so this is an electro synthetic reaction–in a recycling plant, there would probably be new infrastructure that would be needed because plastics aren’t typically recycled electro synthetically. However, in terms of chemical synthesis in general, there are large-scale reactors that can use electrochemical energy. So, that type of infrastructure is there. But, yeah, it’s not necessarily integrated into recycling plants. So, there would have to be some a lot of discussion, preparation, and work done there.

David Fair: Well, as you and the McNeil Group move towards getting to the practical application and implementation, how long a process do you think that would take?

Dr. Danielle Fagnani: That’s a great question. That’s very hard for me to say right now, because, you know, as I mentioned, this was really the proof of concept is what we discovered. So, to get this scaled up on a practical level will take some work.

David Fair: It remains to be determined.

Dr. Danielle Fagnani: It remains to be determined, probably not literally tomorrow. But, in the future, it’s a possibility.

David Fair: I’m so glad I got to talk with you today, and I appreciate that you would share the information. And I look forward to what it brings in the future.

Dr. Danielle Fagnani: Thank you so much.

David Fair: That is Dr. Danielle Fagnani. She served as first author of what is considered a groundbreaking study out of the University of Michigan on PVC plastics recycling. For more information on the research and today’s conversation, just visit our website at WEMU dot org. Issues of the Environment is produced in partnership with the office of the Washtenaw County Water Resources Commissioner, and we bring it to you every Wednesday. I’m David Fair, and this is your community NPR station, 89 one WEMU FM Ypsilanti.

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