Everlasting Plastic

Plastic lasts forever; the very reason we use plastic is also one of its biggest downfalls. We designed plastic to be durable for everyday uses such as in containers and clothing. However, now we are trying to find ways to make it decompose so these plastics do not stay in our environment.

What is so special about plastic that prevents it from decomposing?

Most plastic today is made from fossil fuels. When heated with a catalyst, propylene from fossil fuels is turned into polypropylene. Polypropylene contains strong carbon-carbon bonds that are not found in nature. Because of this, before plastics, bacteria rarely came into contact with carbon-carbon bonds, and, therefore, have not evolved to be able to break the bonds (Wolchover, 2011).

Peptide bonds(between carbon and nitrogen) are what nature uses instead of carbon-carbon bonds because they can be formed more easily. These bonds are rarely used in plastic, however, because they are not nearly as strong, meaning that the main benefit of using plastic- its durability- would be defeated (Wolchover, 2011).

Plastic does break down into smaller pieces due to sunlight exposure, oxidation, and friction (Plastic Break Down and Fragmentation, n.d.). Animals eating a bit of the plastic also cause the plastic to break down into smaller pieces. These small pieces are still plastic(called microplastics), however. In fact, when the plastic is smaller, it can actually be more harmful to organisms because they can easily ingest the microplastic. Additionally, since microplastics are often not visible for the human eye, it is hard to control microplastic pollution.

Recent plastic decomposition developments

In the past few years, scientists have found ways to chemically upcycle plastics. Other scientists have found bacteria that can eat plastic and reengineered it to be more efficient. These discoveries could help us to not only keep plastic out of landfills(and microplastic out of our environment), it could also help us to reuse the resources in plastic to reduce our carbon footprint.

Upcycling Plastics

Researchers from the University of California, Berkeley have come up with a process through which polyethylene polymers, found in items such as plastic bags and packaging, can be converted into propylene. To do this, platinum-tin and platinum-zinc catalysts are first used to break two carbon-hydrogen bonds in the polyethylene molecule. This causes a carbon-carbon double bond to form. Because these carbon-carbon double bonds are reactive, when the scientists add a palladium catalyst and ethylene, propylene molecules are formed. Overall, this process turns 80% of the polyethylene molecules into propylene (Sanders, 2022). The propylene itself is a valuable resource, and producing it from polyethylene reduces the carbon footprint of its production.

Plastic-eating bacteria

In 2016, Japanese scientists discovered a bacteria called Ideonella sakaiensis that has digestive enzymes hydrolyzing PET or PETase that allow it to eat Polyethylene terephthalate(PET) plastic. Other researchers from the University of Portsmouth have built upon this research combining the PETase enzyme with MHETase, another enzyme with the ability to break down plastic. In addition to breaking down PET more efficiently, this “super enzyme” has the ability to break down Polyethylene furanoate(PEF) (Dutfield, 2022). Before any of these enzymes can be used on a wide scale, however, more research is needed.

Turning plastic into vanilla

It turns out that we may be eating plastic in the future too(well, we already are today, but this would be purposeful). This is because researchers from The University of Edinburgh in Scotland have found a way to turn plastic into vanillin, the flavoring that gives vanilla its taste and fragrance. These researchers used genetically engineered E. coli bacteria to turn Terephthalic acid(made from breaking down polyethylene terephthalate plastic) into vanillin. When the E. coli was put with Terephthalic acid at 98.6 degrees Fahrenheit, 79% of the Terephthalic acid in the span of one day. Not only would this process help to curb plastic pollution, but it would also help satisfy the growing demand for vanillin. Because the demand for vanillin is so high, we are already producing nearly 85% of it from fossil fuels instead of from natural vanilla beans, so producing the vanillin from plastic should help reduce our carbon footprint (Saplakoglu, 2021).

Summary

Plastic may last forever in the environment, but recent breakthroughs have given us hope that in the future we may be able to limit the amount of plastic that enters our environment through a variety of methods to break down plastic. Until we are able to use these breakthroughs, however, we must make sure to dispose of plastic responsibly. Furthermore, whether we can break down plastic or not, we must try to limit the amount of plastic that we use to reduce its impact on the environment.

Sources

Dutfield, S. (2022, March 23). Plastic-eating bacteria: Engineering and impact. Live Science. Retrieved December 18, 2022, from https://www.livescience.com/plastic-eating-bacteria

Plastic Break Down and Fragmentation. (n.d.). Plastic Soup Foundation. Retrieved December 18, 2022, from https://www.plasticsoupfoundation.org/en/plastic-problem/plastic-environment/break-down/

Sanders, R. (2022, October 3). UC researchers finally may have solved how to recycle plastic bags into something useful. Local News Matters. Retrieved December 18, 2022, from https://localnewsmatters.org/2022/10/03/uc-researchers-finally-may-have-solved-how-to-recycle-plastic-bags-into-something-useful/

Saplakoglu, Y. (2021, June 25). Scientists convert plastic waste into vanilla flavoring. Live Science. Retrieved December 18, 2022, from https://www.livescience.com/vanilla-flavor-plastic-waste.html

Wolchover, N. (2011, March 2). Why Doesn't Plastic Biodegrade? Live Science. Retrieved December 18, 2022, from https://www.livescience.com/33085-petroleum-derived-plastic-non-biodegradable.html