Fast copper extraction from printed circuit boards using supercritical carbon dioxide

Abstract Technological development and intensive marketing support the growth in demand for electrical and electronic equipment (EEE), for which printed circuit boards (PCBs) are vital components. As these devices become obsolete after short periods, waste PCBs present a problem and require recycling. PCBs are composed of ceramics, polymers, and metals, particularly Cu, which is present in highest percentages. The aim of this study was to develop an innovative method to recover Cu from the PCBs of old mobile phones, obtaining faster reaction kinetics by means of leaching with supercritical CO 2 and co-solvents. The PCBs from waste mobile phones were characterized, and evaluation was made of the reaction kinetics during leaching at atmospheric pressure and using supercritical CO 2 with H 2 O 2 and H 2 SO 4 as co-solvents. The results showed that the PCBs contained 34.83 wt% of Cu. It was found that the supercritical extraction was 9 times faster, compared to atmospheric pressure extraction. After 20 min of supercritical leaching, approximately 90% of the Cu contained in the PCB was extracted using a 1:20 solid:liquid ratio and 20% of H 2 O 2 and H 2 SO 4 (2.5 M). These results demonstrate the efficiency of the process. Therefore the supercritical CO 2 employment in the PCBs recycling is a promising alternative and the CO 2 is environmentally acceptable and reusable.