Medical face masks can be recycled thanks to the iCycle process. What motivated your research?
Alexander Hofmann: One deciding factor was our conversations with Procter & Gamble about face masks – P&G is one of our partners in a pilot project where we investigate whether we can use iCycle to recycle face masks. Having said that, we also realized that amid the COVID-19 pandemic, face masks are often carelessly thrown away and not disposed of correctly. Our fear was that face masks are becoming the new wave of dangerous trash. But even if the masks are disposed of properly, they still generate residual waste, which is ultimately incinerated. Since the masks contain polypropylene – which is a plastic –, our objective was to generate higher recycling rates in this setting, meaning to use the masks to produce feedstock for new material.
How does the process work?
Hofmann: Our process uses an auger reactor for pyrolysis. The material is loaded onto a screw conveyor, while oxygen is removed and nitrogen introduced, referring to so-called nitrogen inerting. When we subsequently heat the preparation to over 500 degrees Celsius, the nitrogen atmosphere keeps the material from burning – because it would burn if it contained oxygen. As a result, the plastic is broken down into its molecular fragments. These smaller chemical compounds can then be converted into the vapor or gas phase by increasing the temperature. After the pyrolysis reactor process, the vapors are then cooled to condense, allowing us to extract an oil.