Turning trash into Treasure: Extracting precious metals from e-waste with Electrochemically Exfoliated graphene derivatives

Electronic waste (e-waste) presents a significant opportunity for recovering valuable precious metals (PMs) while mitigating environmental impacts. This study introduces a novel approach to e-waste recycling by utilizing electrochemical exfoliation (ECE) to produce graphene oxide (GO) from discarded dry cells, composed of graphite core, followed by its reduction to reduced graphene oxide (rGO). Since GO and rGO have dynamic physicochemical properties making them suitable candidates for the adsorption and extraction process. The ECE method is both environmentally friendly and cost-effective, offering a green alternative to traditional synthesis methods that involve hazardous chemicals and lengthy processes. GO and rGO were employed as adsorbents to extract gold (Au) and silver (Ag) from the central processing units (CPUs) of old laptops. Characterizations such as X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), UV-visible spectroscopy, Linear sweep voltammetry (LSV), Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), and Field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS) confirmed the structural and morphological properties of the graphene derivatives. Batch adsorption experiments demonstrated that GO and rGO effectively adsorbed PMs, while former showed superior efficiency due to abundant oxygen-containing functional groups and dispersion stability. The promising potential of adsorbents was demonstrated with exceptionally high extraction efficiency and selectivity for PMs rather than heavy metals (Cu). Post-adsorption samples were analyzed using Atomic absorption spectroscopy (AAS), FTIR, XRD, Raman spectroscopy, XPS, and FESEM-EDS mapping, and the mechanism was proposed. This method supports the circular economy by turning e-waste into valuable resources, contributing to more sustainable e-waste management practices.