Thermal properties of graphene oxide prepared from different agricultural wastes

Graphene oxide (GO) extracted from different agricultural wastes such as sugarcane bagasse (SCB), rice straw (RS), lignin (L), mature beech pinewood sawdust (MW) in the presence and absence of ferrocene as a catalyst at 300℃ in a muffle have been prepared, characterized and evaluated by TGA and DTA. TGA decomposition curves of GO showed three decomposition stages for all studied samples except for GO prepared from SCB and MW in the absence of ferrocene, which revealed two decomposition stages. The residual weight of SCB was very low; this indicates its high purity and absence of inorganic residues. The high production of char residue from MW, and L pyrolysis can be ascribed to its lower content of methoxyl group (determined by FTIR). The activation energy (Ea) determined for thermal reduction of GO are found to be from 21.00 to 55.35 kJ/mol. From TGA, it was found that the rate of removal of oxygen-containing functional groups depends on the temperature, which agrees with the experimental findings and thermal degradation kinetics. The free energy change of activation (∆G) of this system is positive. Consequently, the thermodynamics of GO should be non spontaneous.