Green electrochemical upcycling of spent batteries into graphene oxide: Process optimization, structural characterization, and life cycle assessment

As the demand for sustainable practices in materials science intensifies, this study presents an environmentally benign electrochemical route for synthesizing graphene oxide (GO) using graphite rods recovered from spent zinc–carbon batteries. Traditional methods such as the Hummers and modified Hummer's techniques involve hazardous chemicals and concentrated acids, posing significant environmental and health concerns. In contrast, our approach utilizes a neutral sodium sulfate electrolyte for electrochemical oxidation, enabling a safer, cleaner process that eliminates harmful byproducts. Process parameters, including electrolyte concentration, applied voltage, and reaction time, were optimized using Response Surface Methodology with a Central Composite Design to ensure efficiency and reproducibility. The resulting GO was extensively characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and UV–Visible analysis. The results revealed a well-oxidized, mesoporous GO structure that retained its sp² carbon framework while introducing oxygen-containing functional groups in a controlled manner. Furthermore, a comprehensive life cycle assessment highlighted the environmental advantages of this method over conventional synthesis routes, showing significant reductions in greenhouse gas emissions, acidification, eco-toxicity, and ozone depletion potential. This work aligns with the principles of the circular economy and cleaner production, offering a sustainable pathway for value-added carbon nanomaterials from electronic waste.