A Comprehensive Life Cycle Assessment of Graphene Derivatives Synthesized by a Modified Hummers' Method

The environmental impact of the synthesis of graphene oxide (GO), through a high-yield modified Hummers' method, and its chemical reduction by hydroiodic acid/acetic acid (HI/AcOH) to yield reduced graphene oxide (rGO) on a lab scale was analyzed, across several key life cycle assessment (LCA) indicators in terms of global warming potential (GWP₁₀₀), energy consumption, resource depletion, and other ecotoxicity indicators. The present LCA was performed at the Department of Nursing of the Hellenic Mediterranean University (HMU) based on experimental data from the laboratory at the Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (IESL-FORTH) (Greece), while the results were compared with existing values in the literature to validate the credibility of the analysis. In this study, CO₂ emissions corresponding to the GO synthesis were calculated as 1.78g of CO₂ per gram, which is marginally lower than the reported ones, while CO₂ emissions accounting for the rGO chemical preparation yielded 4.24 g of CO₂ per gram, which is over the range of 1.4-2.7 g of CO₂ found in similar studies. The energy consumption was estimated to be ∼25 kJ per gram and ∼61 kJ per gram to synthesize GO and rGO, respectively, with both being in full agreement with previous investigations. The present analysis provides information on the broader environmental impact as well, including acidification, eutrophication, and ecotoxicity due to the adopted oxidation and reduction procedures. Although further improvements are needed to optimize energy efficiency and management of the waste generated by the chemicals used to carry out oxidation and reduction processes, our study aims to serve as a model toward a straightforward development of graphene derivatives and nanocomposites for emerging nanotechnology applications.