Leaching of metals from printed circuit board powder by an Aspergillus niger culture supernatant and hydrogen peroxide

Abstract

An efficient and rapid metal leaching process for solubilisation of heavy and precious metals from waste printed circuit board (PCB) powder was investigated. The PCB powder was first treated with 0.1 M sodium hydroxide (NaOH) solution to remove the chemical coating. An incubation time of 8 h and 150 rpm shaking speed were found to be optimum for the removal of the chemical coating from the PCB powder (1 g). The NaOH treated PCB powder was further subjected for metal leaching using an Aspergillus niger (A. niger) culture supernatant and hydrogen peroxide (H₂O₂). 100% solubilisation of all the metals was observed. The shaking speed showed insignificant effect on metal solubilisation. The 3.18% H₂O₂ concentration was found to be optimum for metal solubilisation. An increase in temperature (80 °C) reduced the time required for metal solubilisation. Optimization of all these parameters considerably decreased the leaching period to 2 h.