For practical applications of graphene sheets in a variety of fields, mass production of high-quality graphene sheets is necessary. Herein, we reported a cost-effective, green, and simple approach to synthesizing mass production exfoliated graphene (EG) flakes employing electrochemical exfoliation of pencil graphite in neutral aqueous electrolytes. Pencil graphite cores of different grades were applied as anode and cathode electrodes and exposed to the electrolyte solution at a different voltage. Several parameters were examined and optimized, including pencil grade (2,4,6,8 B), applied voltage (10, 15, 20, 30 V), different inorganic electrolytes ((NH4)2SO4, Na2SO4, NaNO3, NaCl, and CH3COONa), and the concentration of electrolytes. The optimal condition was chosen by considering the mass of produced graphene and the conductivity of the graphene solution. The optimal conditions were as follow: pencil grade: 6B; applied voltage: 10 V; electrolyte type: Na2SO4; electrolyte concentration: 0.1 M. Under these conditions, the production yield was > 95% within 3 h and 9 min. The EG was characterized by utilizing FT-IR, XRD, Raman spectroscopy, FE-SEM, Cyclic Voltammetry, and Electrochemical Impedance Spectroscopy (EIS). Characterization indicates that the synthesized EG had an XRD peak at 2θ = 26.6° and an ID/ IG ratio of 0.36. Furthermore, the EG showed good conductivity when tested by cyclic voltammetry and EIS whereas the R2 values were 985.8 and 76.3 Ω for bare GCE and EG/GCE, respectively. In addition, EG effectively removed cadmium (Cd(II)) with an adsorption level of 8.72 mg/g. The results from this study suggest that EG can be scaled up and commercialized in an environmentally friendly and low-cost manner, especially in low-income countries, and using it to rectify metal ions.

    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Chemicals and materials
        2.2 Apparatus
        2.3 Exfoliation process
        2.4 Characterization
        2.5 Electrochemical measurement
        2.6 Adsorption experiments
    3 Results and discussion
        3.1 Types of pencil grades
        3.2 Type of electrolytes
        3.3 Applied voltage
        3.4 Concentration of electrolyte
        3.5 Characterization of graphene obtained by the optimal conditions
        3.6 Applications
    4 Conclusion
    Acknowledgements 
    References

• Fatima Alabdo(Department of Physics, Faculty of Science, Idlib University)
• Waleed Alahmad(Department of Chemistry, Faculty of Science, Chulalongkorn University)
• Untika Pengsomjit(Department of Chemistry, Faculty of Science, Chulalongkorn University)
• Mohammad Halabi1(Department of Physics, Faculty of Science, Idlib University)
• Pakorn Varanusupakul(Department of Chemistry, Faculty of Science, Chulalongkorn University)
• Charoenkwan Kraiya(Department of Chemistry, Faculty of Science, Chulalongkorn University)