Canadian scientists create biodegradable plastic from invasive green crabs
Updated: Jun 8
Dr. Audrey Moores and research assistant Thomas Di Nardo at McGill University have recently discovered a new process for creating a biodegradable plastic (1). This process is more sustainable than traditional alternatives, it has some interesting sustainable applications, and could even help manage the invasive green crab population in a Nova Scotian National Park.
The researchers were able to create a new process for converting chitin into chitosan that is more environmentally-friendly. The main problem regarding the production is that chitin does not dissolve easily in most solvents (2). The commercially-used method of creating chitosan is energy-intensive, and the aqueous chemicals involved in the process can be difficult to handle and pose a risk to workplace health and safety (1,2). Following green chemistry principles, Moores and Di Nardo created the desired reaction through mechanically milling and heating chitin and a reactant for several days (1,2). High-quality chitosan can now be produced in a low-energy process that does not rely on dangerous concentrated solutions (2).
This research has further positive environmental applications because a new biodegradable plastic was discovered in the process. Products made using this material would not contribute to long-term pollution, as they would degrade if they entered the environment (3). There is interest in using the bioplastic for single-use items such as bags and food packaging (2). This could help reduce plastic pollution, since millions of tons of single use plastic every year which never fully break down in the environment (4).
Potentially the most exciting element this research is that the chitin used to make the chitosan and biodegradable plastic can come from shelled-animals, such as the shrimp, lobster, crab, fly larva larvae and silkworm larvae shells that were used in the experiment (2). Chitin is the second most abundant naturally produced polymer, but it is largely unused by humans (2). Now, Parks Canada has teamed up with the researchers to use invasive green crabs from Nova Scotia's Kejimkujik National Park Seaside as a chitin source (5). Initially, the crabs will be shipped to Montreal, but eventually the production of the plastic will move to Nova Scotia (5). Green crabs are found in both the East and the West coasts of Canada, and are aggressive predators which eat many species such as clams, mussels, oysters, other crustaceans and small fish. Often, they can out-compete native crab species for food (6). In Kejimkujik Seaside, the crabs cause major destruction to the eelgrass beds that form the habitat for a number of fish species (5). This project will reduce the invasive green crab population in Kejimkujik Seaside and potentially utilize hundreds of crabs that would otherwise be harming the marine ecosystem (5,6).
The breakthroughs made by Dr. Audrey Moores and Thomas Di Nardo at McGill University have multiple positive impacts on the environment. They have created a safer and more environmentally-friendly process for converting chitin into chitosan, they have created a new biodegradable plastic that could help reduce pollution, and by using green crabs for the chitin are contributing to an innovative invasive species management strategy.
(1): Branswell B. The secret to biodegradable plastic is … lobster shells? McGill News. 2019. Available from: https://mcgillnews.mcgill.ca/s/1762/news/interior.aspx?sid=1762&gid=2&pgid=2095
(2): Nardo TD, Hadad C, Nhien ANV, Moores A. Synthesis of high molecular weight chitosan from chitin by mechanochemistry and aging. Green Chemistry. 2019. 21:3276–85.
(3): Rukavina S. McGill researchers use lobster shells to make biodegradeable plastic. CBC News. 2019. Available from: https://www.cbc.ca/news/canada/montreal/mcgill-researchers-use-lobster-shells-to-make-biodegradeable-plastic-1.4920820
(4): IUCN issues brief: Marine plastics. International Union for the Conservation of Nature. Available from: https://www.iucn.org/resources/issues-briefs/marine-plastics
(5): Smith E. Invasive green crab at Keji seaside could soon become biodegradable plastic. . CBC News. 2020. Available from: https://www.cbc.ca/news/canada/nova-scotia/keji-seaside-looks-to-turn-invasive-species-into-biodegradable-plastic-1.5458723
(6): Fisheries and Oceans Canada. European green crab. Department of Fisheries and Oceans. 2020. Available from: https://www.dfo-mpo.gc.ca/species-especes/profiles-profils/europeangreencrab-crabevert-eng.html