Oil spills into ocean or coastal waters can result in significant damage to the environment via pollution of aquatic ecosystems. Absorbents based on reduced graphene oxide (rGO) foams have the capacity to remove minor or major oil spills. However, conventional chemical synthesis of rGO often uses petrochemical precursors, potentially harmful chemicals, and requires special processing conditions that are expensive to maintain. In this work, an alternative cost-effective and environmentally friendly approach suitable for large-scale production of high-quality rGO directly from used cooking sunflower oil is discussed. Thus, produced flaky graphene structures are effective in absorbing used commercial sunflower oil and engine oil, via monolayer physisorption in the case of used sunflower and engine oils facilitated by van der Waals forces, π–π stacking and hydrophobic interactions, π-cation ( H+) stacking and radical scavenging activities. From adsorption kinetic models, first-order kinetics provides a better fit for used sunflower oil adsorption (R2 = 0.9919) and second-order kinetics provides a better fit for engine oil adsorption (R2 = 0.9823). From intra-particle diffusion model, R2 for USO is 0.9788 and EO is 0.9851, which indicates that both used sunflower and engine oils adsorption processes follow an intra-particle diffusion mechanism. This study confirms that waste-derived rGO could be used for environmental remediation.

    Abstract
    1 Introduction
    2 Experimental details
        2.1 Materials and processes
        2.2 Adsorption kinetics of oils on RGO
    3 Results and discussion
        3.1 XRD, raman and FTIR characterization of As-Prepared RGO
        3.2 SEM, AFM and EDX characterization of As-prepared RGO
        3.3 Contact angle and absorption measurements
        3.4 FTIR spectra
        3.5 Analysis of absorption kinetics
        3.6 Mechanism of RGO growth
        3.7 Effect of temperature and thermodynamic parameters
    4 Conclusion
    References

• G. S. Lekshmi(Centre for Nanoscience and Technology, Anna University)
• R. Tamilselvi(Centre for Nanoscience and Technology, Anna University)
• Karthika Prasad(Faculty of Science and Engineering, Queensland University of Technology)
• Olha Bazaka(School of Science, RMIT University)
• Igor Levchenko(Plasma Sources and Application Centre/Space Propulsion Centre Singapore, School of Engineering, The Australian National University)
• Kateryna Bazaka(Plasma Sources and Application Centre/Space Propulsion Centre Singapore, School of Engineering, The Australian National University)
• Mandhakini Mohandas(Centre for Nanoscience and Technology, Anna University)