Recycling oriented characterization of printed circuit boards from mobile phones by micro X-ray fluorescence

A micro X-ray fluorescence-based approach for the chemical characterization of spent printed circuit boards (PCB) from mobile phones was applied. More in detail, twelve spent mobile phones were grouped in three clusters depending on brands, models and release year and a study to evaluate the technological evolution of PCBs over time was carried out. Precious and dangerous elements were investigated and some differences between samples belonging to the different groups were appreciated. For instance, the distribution of gold on the PCB layer was more widespread for the older analyzed samples, and a smaller and smaller quantities of bromine and lead were detected in the more recent models in accordance with the Restriction of Hazardous Substances Directive 2002/95/EC. The analysis of PCB composition can help to correctly manage such a complex waste, maximizing the recovery of base, critical and precious metals and considering the possible presence of harmful elements to be managed carefully. The experimental results showed as, through the proposed approach, it is possible to obtain maps of the distribution of chemical elements on the entire surface of PCBs, useful to set up optimal strategies for their further handling (i.e. classification) and processing (i.e. critical/precious metals recovery).