Figure 3:  Critical Raw materials within the periodic table (available at here source Rizzo, A.; Goel, S.; Grilli, M.L.; Iglesias, R.; Jaworska, L.; Lapkovskis, V.; Novak, P.; Postolnyi, B.O.; Valerini, D. The Critical Raw Materials in Cutting Tools for Machining Applications: A Review. Materials 2020, 13, 1377. https://doi.org/10.3390/ma13061377)

Plastics are another area where we need to reduce both the environmental impact (Figure 4) and improve their recycling. One approach is a process termed 'chemical recycling' whereby the plastic is broken down into its constituent chemicals which can then be reused to produce more materials. One advantage is that this reduces the use of fossil fuels as a starting material and provides value from plastic waste within a circular economy. For example, it is possible to breakdown a mixture of polyester bottles to form their constituent chemicals in a stepwise process which facilitates their chemical recycling (Carné and Collinson 2011).

Figure 4: Some of the plastic litter at Ivy Cove near Kingswear, Devon, England. Online available at here.

Whilst recycling and chemical recycling are suitable technologies for reducing plastic pollution, the converse approach with packaging is to develop alternative materials that have an overall lower environmental impact. This can be achieved by changing the formulation of the material to use more renewable and biodegradable resources, or to include an active function to the material that extends the shelf-life of foodstuffs. Traditional packaging seeks to provide a barrier to the external environment, whereas active materials delay food spoilage by reducing harmful agents such as microbes and oxygen.  

Biodegradable packaging also differs from traditional plastic packaging as it can break down over time into its constituent chemicals without the need of chemical recycling. It is important to distinguish here that biodegradable is an umbrella term for which compostable materials fall under. Compostable packaging is a type of biodegradable material that is broken down in a specific time frame under specific conditions. At present, researchers at the OU are developing compostable materials that aim to prolong shelf-life by scavenging oxygen and preventing microbial attack. 

The feedstocks used for this material will itself be renewable and derived from waste materials such as chitosan polymer, a waste from the seafood industry, and active additives from agricultural processing wastes, thus contributing to the circular economy. A short video by a current PhD researcher, Katy Woodason, and their motivation behind the project is available below:

Transcript (16.0 KB)

In the above video, Katy discusses whether we can create sustainable alternatives to plastic from food waste.

Sustainable chemistry also appears in OU modules for example students’ synthesis a bioplastic at home using everyday chemicals. They also incorporate a dye so that they can monitor the breakdown of the plastic using a smart phone app.

If you would like to study these topics further then related materials appear in The Open University course S350 Evaluating Contemporary Science, and sustainable chemistry is discussed in S248 Chemistry in life: food, water & medicines and will be in the new module S218.