|Marker materials and spectroscopic methods for sorting plastic waste (NanoTrust-Dossier No60en - June 2023)
Today, plastic is a ubiquitous material with good mechanical, chemical, and thermal properties and therefore used in many industrial sectors. The biggest challenge in recycling plastic waste is to separate the different types of plastic to a high degree of homogeneity. Waste sorting plants use automated sensorbased sorting systems to separate different plastics from each other. Many engineering plastics, such as polyoxymethylene (POM), end up in mixed waste streams, are not detected by sorting systems, and are therefore currently rarely or not at all recycled. Markerbased sorting is an innovative approach to improving recycling rates and achieving the recycling targets of the EU’s Circular Economy Action Plan (CEAP). For this, the marker materials are incorporated into plastics, which can only then be detected by automated sorting systems to subsequently achieve improved homogenisation. However, markerbased sorting is currently not economical because of the expected high implementation costs. Consequently, expensive technical plastics show the greatest potential for markerbased sorting. For example, POM from plastic components of waste electrical and electronic equipmentcould be separated by type and recycled. This dossier provides an overview of advanced materials with spectroscopic “fingerprints” and suitable detection methods that can be usedfor markerbased sorting.