Dismantling and electrochemical copper recovery from Waste Printed Circuit Boards in H2SO4–CuSO4–NaCl solutions

Abstract

The worldwide growing of electrical and electronic equipment makes increasingly urgent to find environmentally friendly treatments for e-waste. In this paper, the attention has been focused on i) the eco-friendly dismantling of the electronic components from Waste Printed Circuit Boards and ii) recovering of pure metallic copper, which is the most abundant metal and one of the most valuable in Printed Circuit Boards. After an experimental optimization study, we found that a solution containing 0.5 M H2SO4, 0.4 M CuSO4, and 4 M NaCl can be successfully used to disassemble the electronic components from the boards by leaching of all exposed metals. Air was blown into the leaching solution in order to regenerate Cu2+ ions, which acts as the predominant oxidant specie. The key role in dismantling/leaching process is played by Cl− ion that stabilizes Cu+ through the chloro-complexes formation. The results show that, in this manner, the electronic components can be easier disassembled in undamaged state, allowing the efficient recycling and valorization of the base materials. The feasibility to recover electrochemically the copper from the solution resulting from dismantling/leaching tests was verified through a preliminary cyclic voltammetry study aimed to investigate the copper electrodeposition in sulphate-chloride solutions in the presence of other metal ions such as Ni2+, Fe2+, Zn2+, Pb2+, Sn2+. A two-compartment electrochemical cell operating in either galvanostatic or potentiostatic mode was employed to investigate simultaneous copper recovery and leaching solution regeneration. The results indicate that, in both modes, pure copper can be obtained after the removal of all surface impurities by dipping in acidic concentrated sodium chloride solution. The galvanostatic mode leads to deposit of higher quality, meanwhile the potentiostatic one determines a faster deposition and leaching solution regeneration.