Síntesis verde para la producción de óxido de grafeno reducido a partir de extractos de polifenol derivados del jengibre y la corteza del eucalipto

Abstract

The aim of this research was to reduce graphene oxide (GO) using polyphenols from ginger (Zingiber officinale) and eucalyptus (Eucalyptus globulus) bark. A solid-liquid extraction was performed using 99% ethanol. A polyphenol count was then performed using the Folin-Ciocalteu method, obtaining 0.11 and 0.92 Eq. mg GAE/ml for ginger extract and eucalyptus bark respectively. GO was obtained by the modified Hummers method, with a yield of 94.3%. Subsequently for GO bioreduction, six experiments were carried out considering three concentrations of eucalyptus bark polyphenol 920, 460 and 110 µg/ml a concentration of 110 µg/ml of ginger polyphenol and three contact times (18, 20 and 24 h) for each sample 25 ml of GO was used. The yield of reduced graphene oxide (rGO) was calculated and averaged 20.5 mg. To corroborate a dependence of the rGO yield on polyphenol concentration and time of action, an ANOVA analysis was performed, which indeed indicates the existence of such a dependence. Finally, the samples were subjected to UV-visible, FTIR, EDS and SEM characterisation analyses: UV-visible shows a red shift from a value of 232 nm belonging to GO to values >270nm belonging to rGO. In the FTIR of the GO, characteristic peaks were observed, where the most prominent was the one belonging to hydroxyl groups, while the FTIR analysis of the rGO samples showed how the magnitude of the peaks mentioned above decreased. As for the EDS analysis, the presence of oxygens decreased due to the reduction of GO, obtaining 40.85%, 26.19% and 17.46% for GO, rGO A18 and rGO A24, respectively. Thus, polyphenols have acted as an efficient ecological reducing agent.