Bioleaching of different types of metals by Exiguobacterium himgiriensis isolated from printed circuit board.

Abstract

The ubiquity of electronic devices has made them indispensable in daily life. Nevertheless, this high priority leads to a surge in electronic waste, or e-waste, which is extremely dangerous for the environment and human health. E-waste contributes to environmental pollution and threatens ecosystems and human health. Management of recycling methods and efficient e-waste is crucial to lower these dangers. Traditional recycling techniques are effective, but often release harmful pollutants. The present study has attempted to use the metal-resistant Exiguobacterium himgiriensis isolated from e-waste, such as the Printed Circuit Board (PCB), to investigate its efficiency in removing heavy metals from these substrates. By using ICP-OES, it has been found that this species of bacterium recovered different types of metals (Co 84.67%, Ni 83.25%, Pb 80.17%, Cu 80.06%, Zn 76.71%, Al 76.13%, Fe 71.74%, and Ag 64.97% respectively) within 5 days under laboratory conditions. Detecting structural and functional group changes in the control PCB and bioleached residue by the FT-IR, FE-SEM, EDS, and XRD techniques confirms the evidence of bioleaching. Bacteria can increase their dissolving capacity and decrease surface tension by chemically changing metals. E. himgiriensis bioleaches PCB samples for 5 days, resulting in rougher, uneven surfaces with fractures and fissures. FT-IR spectroscopy reveals the bacterium's impact on metals, particularly Si, O, and Fe. This study could help reduce environmental pollution and health risks associated with e-waste by developing an economical and environmentally friendly method for bioleaching different metals in PCB.