Modifying improved-Hummer's method to synthesize graphene derivatives from waste asphaltene.

[Display omitted] • Graphene derivatives were synthesized from asphaltenes by chemical treatments. • Asphaltenes from different origins were used to verify the synthesis method. • Asphaltene structure is far more susceptible to oxidation than graphite. • Conventional graphite oxidation treatments are not suitable for asphaltene. • Maintaining asphaltene aromatic moiety requires a selective and controlled oxidation. A method for synthesizing graphene derivatives from asphaltene is proposed in this work. The method is based on chemical treatment on which the asphaltene molecules are dispersed in liquid intercalating agents to remove the alkyl side chains, functionalize the aromatic core, and expand the inter-layer distance between the aromatic sheets to facilitate their exfoliation. In this intercalation process, the graphitic surface of asphaltene was oxidized to form asphaltene oxide and then graphene derivative. The results designate that the chemical treatment has caused considerable changes in aliphaticity, aromaticity, oxidation level, sulfonation range, and condensation degree. The novelty in the proposed method is envisaged by the fact that it has been tailored to selectively oxidize the asphaltene molecules and maintain its aromatic moiety. The results also confirmed that the conventional graphite oxidation treatments, such as Hummers' Method and its subsequent improvements, are not suitable because asphaltene is far more susceptible to oxidation than graphite. The method proposed in this study, in comparison with graphite conventional oxidation methods, has less effluents of undesirable chemicals, less time, lower degree of oxidation, less weight losses, and subsequently higher yield. [ABSTRACT FROM AUTHOR]