Classification of plastic waste originated from waste electric and electronic equipment based on the concentration of antimony

The aim of this research is a preliminary assessment of antimony concentration in plastic fractions deriving from different e-waste. We considered microwave ovens, desktop computers, laptops, mobile phones, a TV case, a PC monitor and LED lamps (63 items in total). The plastic fraction ranged from 8%-wt in computers and microwave ovens, up to 40%-wt in cell phones and 59%-wt in LED lamps. Specific polymers were identified through Near Infrared spectroscopy. The samples followed three parallel procedures: acid digestion with aqua regia; conversion into ashes at 600 °C then acid digestion with aqua regia; leaching according to UNI10802 reference procedure. Plastic components with significant amounts of antimony were the ones derived from desktop computers (25–1900 mg/kg) and from microwave ovens (830 mg/kg), yet their relative amount compared to the total weight of the item was limited. Items with larger plastic fractions showed lower concentrations of antimony (1–6 mg/kg in mobile phones cases and 160–640 mg/kg in plastic components of LED lamps). Leaching tests revealed that the analyzed plastic fractions could be mostly admitted in non-hazardous waste landfills. The analysis of ashed samples highlighted the need to further improve the acidic extraction procedure.