How it works
A plastic phoenix rising from the ashes of recycling
PET bottles, polyester textiles and plastic packaging should, ideally, all be recycled. The spin-off company Depoly wants to do it in a more ecologically friendly manner, without any loss of quality.
Illustration: ikonaut
3 — Recycling again and again
Depoly’s clients can use these components to manufacture new plastic products without any loss of quality. Theoretically, the process described here can enable them to do this as often as they would like.
3 — Back to the source materials
The monomers terephthalic acid and mono-ethylene glycol are now present as a powder and a liquid respectively. According to Depoly, they are in the same state as if they had been newly produced.
2B — Everyday catalyst
Since Depoly’s process uses a special synthetic catalyst, the reaction can take place under natural environmental conditions. Chemical recycling normally takes place at temperatures above 200 degrees Celsius, and at between 20 and 40 times atmospheric pressure. But Depoly’s technology works at roughly 25 degrees Celsius and normal ambient pressure. It even works with unwashed, unsorted PET. Some of the chemicals needed for this catalysis are derived from everyday materials. They don’t have to be specially produced in a lab, and can also be used in large quantities at low cost.
2A — Breaking chains
The shredded plastic is then poured into the reactor liquid whose chemicals break down the chemical chains of the PET into their individual components: purified terephthalic acid (PTA) and mono-ethylene glycol (MEG). To this end, Depoly uses alkaline hydrolysis – one of the common methods for chemical recycling.
1 — Collection and shredding
Depoly, an EPFL spin-off company, receives material from waste collection points and from textile and packaging companies that want to dispose of their remnants and scraps. The chemical polyethylene terephthalate – PET for short – is then shredded at the Depoly plant.
