New process simplifies recycling of plastics

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have developed a new process claimed to simplify the process of sorting plastics in recycling plants.

A team of researchers led by Prof Heinz Langhals of LMU’s Department of Chemistry have developed a technique that provides for automated recognition of their polymer constituents, thereby improving the efficiency of recycling and re-use of the various types of plastic.

The technique takes advantage of the polymer-specific nature of the intrinsic fluorescence induced by photoexcitation.

‘Plastics emit fluorescent light when exposed to a brief flash of light, and the emission decays with time in a distinctive pattern. Thus, their fluorescence lifetimes are highly characteristic for the different types of polymers, and can serve as an identifying fingerprint,’ Langhals said in a statement. Details of the new method appear in Green and Sustainable Chemistry.

The new technique, which is the subject of a patent application, involves exposing particles of plastic to a brief flash of light which causes the material to fluoresce.