Environmental impact of the production of graphene oxide and reduced graphene oxide

Abstract

Reduced graphene oxide (rGO) is widely seen as the most promising route for the low-cost mass production of graphene for many applications ranging from ultrathin electrodes to structural nanocomposites. The Hummers and Marcano methods are the two most successful approaches for producing high-performance rGO, but have been criticized for producing toxic emissions. We have applied life cycle assessment methodology to evaluate the environmental impacts of both production routes for GO and rGO in the context of applications requiring bulk materials or thin coatings. We find no current obstacle to the industrial scale production of graphene arising from its environmental impact. The cumulative energy demand is found to have a cap value between 20.7 and 68.5 GJ/Kg, a relatively high value; impact in other categories (such as human toxicity or resource depletion) is lower, and materials inventory does not include critical/strategic materials other than graphite itself. Our study proposes 1 kg of graphene as functional unit, and an application-specific functional unit normalized by conductivity which show that Hummers production method is far more suitable for bulk applications of graphene, with lower embedded energy per kg of graphene production, while Marcano's production method is better suited for thin film electronic applications.

A review on sustainable production of graphene and related life cycle assessment

“…All studies included in this section reported direct contributions from the production of GRMs, however, the system boundaries varied from 'cradle to gate' , [188,[195][196][197][198][199][200][201] 'cradle to installation' [202] and 'cradle to grave' [189]. The functional unit varied across these studies, with the large majority defined in terms of mass, e.g.…”

Graphene and water-based elastomer nanocomposites – a review

“…The utilisation of strong chemicals in most graphene materials production methods remains a demanding challenge to the environment. For instance, the use of H2SO4 and hydrazine in GO and rGO synthesis have been widely criticised as these reagents poses serious ecological threat to both humans, terrestrial and aquatic environment, thus, could trigger freshwater eco-toxicity, cancer effect on humans, as well as NOx emissions [180]. In addition, the utilisation of organic solvents such as sodium dodecylsulphate (SDS) and sodium dodecylbenzenesulphonate (SDBS) in FLG/GNPs production [151], [156], [160] remain a possible cause for human [181] and environmental concern.…”

“…In addition, recent cytotoxicity study (conducted via both in vitro and in vivo) on G-WBEC utilising FLG/Natural rubber (FLG-C-NR) nanocomposite revealed that graphene incorporation within the NR matrix do not compromise its biocompatibility, as no sign of toxicity, nor skin irritation were observed for up to 48 hours exposure [188]. However, majority of the available literature results suggests that graphene toxicity (as well as its susceptible environmental effects) is largely attributable to the overall nature of the surface chemistry (functionalised sites, especially the reactive oxygen species dominant in the derivatives such as GO), particle size, number of layers, concentration of the graphene material [189], [190] and the processing techniques employed in the graphene production [180].…”

Comprehensive Enhancement in Thermomechanical Performance of Melt-Extruded PEEK Filaments by Graphene Incorporation

“…The so far reported works indicate that GO is advantageous for its composites' mechanical properties compared to pristine graphene [26]. However, the known methods to prepare the GO include strong chemicals (nitric or sulfur acids and potassium chlorate) [27] and produce noxious emissions [28]. In contrast, the multilayer graphene or graphene nanoplatelets (GnPs, >8 carbon layers) [29] can be directly prepared by liquid-phase exfoliation (in organic solvents, ionic liquids or water/surfactant) in large quantities [30,31], are inexpensive (<2 $/gram) [32,33], and therefore, would be ideal fillers for the improvement of mechanical and thermal properties of PEEK nanocomposites.…”