Keeping resources in the circular economy: iCycle gives face masks a second life

They have been our constant companions for more than a year though they technically only have a limited lifespan: medical-grade face masks. Surgical masks are single-use devices and should be properly disposed of after use. That's a pity, because it means large amounts of valuable feedstock for new material are thrown away after only a short period of time, thus preventing recycling in the process.

Until now. The Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT wants to change that and has set out to develop a process that recycles the feedstock of face masks and recovers the resources for reuse. In this K-MAG interview, Dr. Alexander Hofmann explains how the iCycle process works, describes the materials it is intended for and reveals what happens once the feedstock has been recovered.

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.

What are the applications of the oil that is produced by this process?

Hofmann: Depending on the quality, the oil can be used by the chemical industry. The latter can subsequently use it as a substitute for petroleum to produce plastics.

What challenges did you encounter during development?

Hofmann: When it comes to pyrolysis, it is generally difficult to control the heating rate – especially when it pertains to a larger scale. That is why Fraunhofer has developed a patented combined heat exchanger system enabling heat-supply both via the surface and the inner section of the auger reactor.

Another challenge refers to the quality of products that result from the pyrolysis process. In the case of electronic scrap, the pyrolysis oil tends to contain halogens. These halogens must first be removed to enable the chemical industry to continue its processing. We have also developed and continue to improve respective processes for this scenario.

How do you plan to improve the iCycle process in the future?

Hofmann: One of our goals is to scale up iCycle. Our current demonstrator model can convert around 70 kilos an hour, but our Fraunhofer spin-off aims to up this to 250 kilos an hour. We also want to improve the chemical recycling process, that being the application of pyrolysis oil. Our objective is to find ways and to develop technologies that ultimately enable us to manage the quality of the pyrolysis oil and tailor it to meet industrial requirements.

How does your process support a circular plastics economy?

Hofmann: First, let's review the status quo: Plastics that cannot be recycled receive thermal treatment, meaning they are being incinerated, which results in tons of CO2 emissions. In contrast, we aim to use thermo-chemical technology to break down plastics and reuse them to make new plastic products. This enables us to partially create a carbon circular economy. Needless to say, there is still waste, but this way, the plastic does not entirely generate CO2 emissions. A large percentage can be recycled to provide useful feedstock and thus create a circular economy.