PVC, or polyvinyl chloride, is one of the most common plastics in the United States and the world's third most common by volume.
PVC is found in many of the plastics we use daily. Much of the plastic used in hospital equipment - tubing, blood bags, masks, and so on - is PVC, as is the majority of modern plumbing piping.
It is used or included in the manufacture of window frames, housing trim, siding, and flooring. It coats electrical wiring and is found in shower curtains, tents, tarps, and clothing.
Recycling previously unrecyclable plastic
Researchers at the University of Michigan, led by study first author Danielle Fagnani and principal investigator Anne McNeil, have discovered a way to chemically recycle PVC into usable material, as per ScienceDaily.
The researchers devised a method to use phthalates in plasticizers - one of PVC's most hazardous components - as a mediator for the chemical reaction.
Their findings have been published in the journal Nature Chemistry.
"PVC is the type of plastic that no one wants to deal with because it has its own set of problems," said Fagnani, who completed the research as a postdoctoral researcher in the University of Michigan's Department of Chemistry.
PVC typically contains a high concentration of plasticizers, which contaminate everything in the recycling stream and are typically toxic.
In most cases, plastic is recycled by melting it down and reforming it into lower-quality materials, a process known as mechanical recycling.
When heat is applied to PVC, one of its primary components, known as plasticizers, leaches out very easily, according to McNeil.
They can then be mixed in with other plastics in the recycling stream.
Furthermore, when heated, hydrochloric acid easily escapes from PVC. It could corrode recycling equipment and cause chemical burns to the skin and eyes, which is not ideal for recycling plant workers.
Moreover, phthalates, a common plasticizer, are highly toxic endocrine disruptors, which means they can interfere with thyroid, growth, and reproductive hormones in mammals, including humans.
Fagnani began researching electrochemistry to find a non-heat method of recycling PVC.
Along the way, she and her colleagues discovered that the plasticizer, one of the major recycling challenges, could be used to break down PVC.
The plasticizer improves the method's efficiency, and the electrochemical method solves the problem with hydrochloric acid.
According to Fagnani, PVC is a polymer with a hydrocarbon backbone made up of single carbon-carbon bonds.
Hydrochloric acid rapidly pops off during heat activation, resulting in a carbon-carbon double bond along the polymer's backbone.
However, the research team uses electrochemistry to introduce an electron into the system, causing it to have a negative charge.
The carbon-chloride bond is broken, resulting in a negatively charged chloride ion. Because the researchers are using electrochemistry, they can control how quickly hydrochloric acid is produced by metering the rate at which electrons are introduced into the system.
Industries can then use the acid as a reagent in other chemical reactions. Chloride ions can also be used to chlorinate arenes, which are small molecules.
These arenes have the potential to be used in pharmaceutical and agricultural components. McNeil said the group is still looking for a use for the polymer material that was left over.
According to Fagnani, the study demonstrates how scientists might think about chemically recycling other difficult materials.
McNeil's lab has been working on ways to chemically recycle various types of plastics. Plastics can be broken down into their constituent parts to produce non-degraded materials that industry can use again.
Recycling Is A Vital Part Of The Solution
The more we recycle, the less waste ends up in landfills and incinerators.
We can save money and energy by reusing aluminum, paper, glass, plastics, and other materials, while also reducing the environmental impact of their extraction and processing, as per Stanford University.
Everything comes back to you. Recycling boils down to one person acting. Your recyclable waste material can be used to create new products. Recycling is beneficial to our environment, communities, and economy.
Recycling, in a broad sense, is part of an ethic of resource efficiency - of using products to their full potential.
Natural resources and energy are conserved when recycled materials are used to make new products rather than raw materials.
Because recycled materials have already been refined and processed once, the second manufacturing process is much cleaner and less energy-intensive than the first.
Manufacturing with recycled aluminum cans, for example, uses 95% less energy than producing the same amount of aluminum with bauxite.
Related article: Recycled Plastics Harm Environment by Leaking Hazardous Chemicals, According to Experts