Methodological approach for the characterization of printed circuit boards from smartphones by micro X-ray fluorescence

Technological development improved human life style, but the fast progress of electronic applications makes devices quickly obsolete, generating waste difficult to treat (Zhou and Qiu, 2010), the so-called Waste Electrical and Electronic Equipment (WEEE). The generation of WEEE substantially grows up in the last years, resulting a total WEEE production of about 20-50 million tonnes every year (Bachér and Kaartinen, 2017). Some estimations indicate that within Europe the generation of WEEE is about 12 million tons, that is around 23 kg per person (Bachér et al., 2015). United States are the major producers of e-waste with a total generation around 3 million tons (Reis de Oliveira et al., 2012). On the other hand, WEEE can be considered as a “mine” of base metals (i.e. Fe, Al, Cu, Ni, …), precious metals (i.e. Au, Ag, Pt, …) and rare earths (i.e. Pr, Y, Nd, …). Therefore, the importance of a correct and sustainable management of this abundant and valuable kind of waste is undoubted. The possibility to use recycling system to recover materials from WEEE is strictly linked to the product complexity and the related processing costs. Indeed, although recycling could give environmental and social benefits, economic reasons lead the actual applicability of recycling process for material recovery. On the other hand a full characterization of WEEE, clearly highlighted the presence of valuable materials, thus justifying the economic investment finalized to set up more efficient recycling strategies (Cui and Forssberg, 2003). Starting from these premises, a study finalized to analyze Printed Circuit Boards (PCBs) coming from spent mobile phones through micro X-ray fluorescence (micro-XRF), was carried out. Spent communication devices are a large part of the “more valuable” WEEE since most consumers frequently change their mobile phones (Tan et al., 2017; Huang et al., 2008; Schluep et al., 2009) and, at the same time, they constitute the richest device in terms of precious elements contents. The aim of this work was to define a characterization procedure to be used as a preliminary phase in the recycling of EOL PCBs. More in detail, the possibility to utilize the micro-XRF based approach to perform chemical element detection and mapping in dismissed iPhone electronic boards, both entire and milled, was verified