Environmental life cycle assessment of synthesis routes for industrial-scale graphene production from waste-based feed stocks

Graphene has gained a lot of attention over the last two decades due to its novel physiochemical properties. Commonly exfoliation, chemical vapor deposition, epitaxial growth, reduction of graphene oxide, etc. are used to synthesize graphene. In addition to these, many sustainable methods of graphene production have been proposed recently that use waste materials as the starting feedstock. In this study, we quantify the environmental impact of some of these sustainable production routes and compare them using life cycle assessment (LCA) tools. We study four different processes of graphene production using a gate-to-gate LCA: with industrial coal tar pitch, rice husk, plastic waste and paper waste as the feedstock. The assessment is done keeping in mind bulk production of graphene at an industrial scale. We find that energy for converting the feedstocks into carbon-rich precursors can have dominating effects on the results. Thus, we present a separate scenario where the environmental impact is calculated without including the energy from fossil fuels in the assessment to simulate the effects of using non-renewable energy sources in the production processes.