Study of the electrochemical behavior of printed circuit boards (PCBs) leaching solutions using glycine and copper recovery by electrodeposition from leachate solutions

Abstract

The present work focuses on the study of the electrochemical behavior of printed circuit boards (PCBs) leaching solutions using glycine and copper recovery by electrodeposition from leachate solutions. The recovery is done in a minimum number of steps and under ambient conditions of temperature and pressure. Printed circuits boards (PCBs) were pulverized and sieved, which allowed to obtain a PCBs powder of particle size fraction ≤ 1 mm. X-ray fluorescence spectroscopy analysis was used for PCBs powder characterization before and after leaching. The copper leaching has been carried out from PCBs powder in the open air, under ambient conditions of temperature and pressure using a buffer solution of glycine. UV–Vis spectrophotometry and atomic absorption spectrophotometry were utilized to determine the efficiency of copper leaching. Cyclic sweep voltammetry and chronoamperometry were employed to obtain informations on the electrochemical behavior of metals in the leaching solutions and then compared to that of synthetic solutions containing Cu (II) ions. UV–Visible spectrophotometry was used to determine the nature of the formed complex. Electrodeposition technique was applied in order to recover copper in powder form. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were employed to examine the surface morphology and chemical composition of electrodeposited copper. The leaching solutions show exactly the same electrochemical behavior as the synthetic cupric solutions with two reduction peaks and a single oxidation peak, which demonstrates the high selectivity of glycine for copper. The chronoamperometric results confirm those obtained by voltammetry. UV–Visible spectrophotometry showed that the complex formed is [Cu(Gly)2] for the synthetic solutions as well as for the leachate solutions. Selective copper leaching was achieved with an efficiency of 92.5%. The resulting leachate solution was used directly for copper electrodeposition allowing the recovery of metallic copper as a pure product.