An analysis of the composition and metal contamination of plastics from waste electrical and electronic equipment (WEEE)

Abstract

The compositions of three WEEE plastic batches of different origin were investigated using infrared spectroscopy, and the metal content was determined with inductively coupled plasma. The composition analysis of the plastics was based mainly on 14 samples collected from a real waste stream, and showed that the major constituents were high impact polystyrene (42wt%), acrylonitrile–butadiene–styrene copolymer (38wt%) and polypropylene (10wt%). Their respective standard deviations were 21.4%, 16.5% and 60.7%, indicating a considerable variation even within a single batch. The level of metal particle contamination was found to be low in all samples, whereas wood contamination and rubber contamination were found to be about 1wt% each in most samples. In the metal content analysis, iron was detected at levels up to 700ppm in the recyclable waste plastics fraction, which is of concern due to its potential to catalyse redox reactions during melt processing and thus accelerate the degradation of plastics during recycling. Toxic metals were found only at very low concentrations, with the exception of lead and cadmium which could be detected at 200ppm and 70ppm levels, respectively, but these values are below the current threshold limits of 1000ppm and 100ppm set by the Restriction of Hazardous Substances directive.