The Fraunhofer Cluster of Excellence Circular Plastics Economy CCPE and the Fraunhofer Institute for Environmental, Safety and Energy Technology Umsicht have developed an innovative recycling process for used plastics. The pilot project, in which Sabic and Procter & Gamble are also involved, aims to show that disposable face masks are suitable for closed-loop recycling.

The billions of disposable face masks used to protect against the coronavirus pose a major threat to the environment, especially if the masks are thoughtlessly discarded in public, for example in parks, at open-air events or on beaches. In addition to the challenge of finding a sustainable solution for such large quantities of essential hygiene products, the mere disposal of used masks in landfills or incinerators means a loss of valuable raw material that could be used to produce new materials.

"With this in mind, we investigated how used face masks could be returned to the mask production value chain," says Dr. Peter Dziezok, Director R&D Open Innovation at Procter & Gamble. "However, a genuine circular solution that meets both sustainable and economic criteria requires partners. That's why we teamed up with the experts from Fraunhofer CCPE and Fraunhofer Umsicht as well as the technology and innovation specialists from Sabic to find solutions."

As part of the pilot project, P&G collected used face masks from employees and visitors at its production and research sites in Germany. Even though these masks are always disposed of properly, there was a lack of ways to recycle them efficiently. In order to demonstrate alternative approaches, specially designated collection containers were set up and the collected old masks were sent to Fraunhofer for further processing in a special research pyrolysis plant.

Mechanical recycling is not a solution

"Disposable medical devices such as face masks have high hygiene requirements, both in terms of disposal and production. Mechanical recycling would not be a solution here," explains Dr. Alexander Hofmann, Head of the Circular Economy Department at Fraunhofer Umsicht. "Our concept initially involves automatic shredding and then thermochemical conversion into pyrolysis oil. Under pressure and heat, the plastic is broken down into molecular fragments during pyrolysis, which destroys residues of pollutants or pathogens such as the coronavirus. This can then be used to obtain new raw materials for plastic production that also meet the requirements for medical products," adds Hofmann, who is also head of the Advanced Recycling research department at Fraunhofer CCPE.

In the next step, the pyrolysis oil was passed on to Sabic, where it was used as a starting material for the production of virgin polypropylene (PP). The polymer was produced according to the generally recognized mass balance principle, in which the alternative starting material is combined with fossil raw materials in the production process. The mass balance principle is seen as an important bridging solution between today's linear economy and the more sustainable circular economy of the future.

"The high-quality circular PP polymer obtained in this pilot project clearly demonstrates that closed-loop recycling can be achieved through the active collaboration of stakeholders from the entire value chain," emphasizes Mark Vester, Global Circular Economy Leader at Sabic. "The circular material is part of our Trucircle portfolio, which aims to recycle valuable used plastics and save fossil resources."

The final delivery of the PP polymer to P&G, where it was processed into nonwovens, completed the circle. "This pilot project enabled us to better assess whether the circular approach would also be suitable for plastics used in the manufacture of hygiene and medical products," says Hansjörg Reick, Senior Director Open Innovation at P&G. "Of course, the process still needs to be improved. However, the results so far are very promising."

The entire circular project - from collecting the face masks to production - was developed and implemented in just seven months. The use of innovative recycling processes in the processing of other materials and chemical products is being further researched at the Fraunhofer CCPE.