Polystyrene, a type of plastic that is not biodegradable has long been viewed as detrimental to the environment. So much so that countries across the world have banned the use of polystyrene in various forms.
Last year, England banned single-use plastic cutlery, balloon sticks, polystyrene cups, and food containers. They can no longer be sold in the country. The government says the supply of single-use plastic plates, trays, and bowls has also been restricted.
Recently, scientists at the University of New South Wales in Kensington, Australia have devised a low-energy, sustainable technique to break down a myriad of plastics including polystyrene.
The new technique uses a common chemical compound (also seen in high school experiments) along with sunlight and air to separate seven unique categories of polymers by 90 percent.
The process takes just 30 minutes while the reduction elevates to 97 percent after three hours, the engineers from UNSW noted in a statement.
Plastic degradation aims to reduce tough polymers into reusable, raw materials
Iron trichloride, an inorganic chemical compound also called ferric chloride is employed in the technique which works at room temperature. It is exposed to sunlight and oxygen which breaks down the plastic.
The chemical compound is affordable and widely accessible, making it easier to be adopted by a vast number of people in the field of recycling.
Aiming to tackle microplastics, the technique is designed to reduce tough polymers into reusable, raw materials ultimately.
Dr Maxime Michelas, a researcher from the School of Chemical Engineering said that the process could be significantly beneficial for the world.
“I think it’s very important to degrade the polymer and turn it into another feedstock we can use for other things, or just to reduce the amount of microplastics in the world.”
The photo-oxidative degradation technique has thus far been effective on polymers with polyvinyl chloride, PVC from the common drainpipe, and poly(ethylene glycol), a widely-used polymer that’s found in cosmetics and pharmaceutical products as per the statement.
The compound – polymer has to be immersed in a solvent ahead of the degradation process. It’s then exposed to ferric chloride, the light source which breaks down the solution. The solvent as a result looks clearer.
The team used a dim, purple light in a controlled environment to make the process work. It also worked with sunlight but the process was a bit slower, scientists said.
“Our proposal here is to make the simplest system to degrade polymers ,” stated Dr Michelas.
“The previous system only was able to degrade a limited range of polymers,” he added. “In our study, we successfully expanded the range of polymers, including polyvinyl chloride, poly(meth)acrylates (typically used in various products, such as paint), and polyvinyl acetate.”
Sustainable plastic degradation for waste management services
An engineer noted that the new sustainable plastic degradation process can be employed by waste management services at the site. The remaining product can further be used as raw material for a different product.
“We are creating very simple organic compounds (such as acetone) after the degradation of these polymers,” stated Professor Cyrille Boyer.
“These molecules can then be further degraded by bacteria, for example, and completely removed from the environment or reused as feedstock to create new polymers.”
However, the current process is not compatible with water yet. This presents certain limitations.
Prof. Boyer explained that if it was compatible, the researchers would directly use it in water, and degrade the plastic or the microplastic present in wastewater to form small organic compounds that could be digested by bacteria using a bioreactor.
“We can degrade the plastic, but we don’t control what exact product we are making when it degrades.”
Therefore, the team is looking for new catalysts that can help the process function in water. “If we can find a catalyst that works in water, I think this will open a lot of opportunities,” Boyer says.
The study was published on July 15, 2024, in the journal – Macromolecular Rapid Communications .
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