Characterization of different types of electronic waste: heavy metal, precious metal and rare earth element content by comparing different digestıon methods

Electronic waste is one of the fastest-growing waste streams. The content of this waste has critical importance for the development or adoption of new recycling techniques and safe waste management practices. In this study, printed circuit boards and screens of three different types of electronic wastes, such as old mobile phones, smartphones, and laptops were characterized for their heavy metal, precious metal, and rare earth element contents. Three different digestion methods were applied to the samples prior to ICP-OES analysis. Results showed that Cu, Fe, Zn, Ni, Pb, and Al were found to be the main heavy metals in all samples. Nd, Ag, and Au were found as the major precious metals, followed by Pt, La, Dy, Pr, and Ce in the rare earth element category. The contents indicated that there is an urgent need to develop recycling techniques for the recovery of these valuable materials. When the digestion methods were compared to each other, it was found that different methods performed better on different types of metals. U.S.EPA.3050B is advised for Nd, Pd, Pr, Ag, Dy, Pt, Mn, Ce, Cd, Cr, Co, Al, Pb, while U.S.EPA.3051A performed better for Au, Mo, Zn, Cu, and Ni, and MMDM for La.

Graphic abstract