Words by Smiley Team
Two engineers at a Swiss technology institute, EPFL, have discovered an innovative way of recycling plastic more effectively.
Professor Francesco Stellacci, Professor Sebastian Maerkl and PhD student Simone Giaveri combined their expertises in different areas of bioengineering to develop the technique that replicates the natural breakdown of proteins.
“A protein is like a string of pearls, where each pearl is an amino acid,” explained Simone. “Each pearl has a different colour, and the colour-sequence determines the string structure and consequently its properties.
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“In nature, protein chains break up into the constituent amino acids and cells put such amino acids back together to form new proteins, that is they create new strings of pearls with a different colour sequence.”
To mimic this natural process in the lab, the team of researchers selected proteins and divided them into amino acids before putting the amino acids into a special system that reassembled them as new proteins with completely different structures.
Like proteins, plastics are also polymers – structures composed of strings of similar units bonded together. This implies that they could apply the process for breaking down proteins to plastics as well.
Although they have high hopes for their newly-discovered technique, Francesco expects it to take a while longer until they can successfully apply it to plastic.
“It will require a radically different mindset,” he said. “Polymers are strings of pearls, but synthetic polymers are made mostly of pearls all of the same colour and when the colour is different the sequence of colour rarely matters."
However, the engineers believe that this new recycling process may be unique in that it genuinely promotes a circular economy, unlike alternatives, including biodegradable plastics.
“When we use biodegradable plastics, the degradation process leaves residue that must be stockpiled or buried. The more land that is allocated for this means the less land available for farming, and there are environmental consequences to take into account as bio-degradation products necessarily change the area’s ecosystem,” pointed out Francesco.
Estimating that each person uses an average of 30kg a year, the researchers are keen to contribute to beating plastic waste.
"In the future, sustainability will entail pushing upcycling to the extreme, throwing a lot of different objects together and recycling the mixture to produce every day a different new material,” Francesco said, adding: “Nature already does this."
