Upgraded activated carbons (ACs) are typically synthesized by mixed methods, such as solid–solid mixing and wet impregnation of low-grade ACs with KOH. This study compares the properties of upgraded ACs prepared by different methods using elemental analysis, X-ray photoelectron spectroscopy, N2 adsorption isotherms, and X-ray diffraction. In ACs produced by the solid–solid mixing, the ratio of potassium activator is proportional to the surface area and amount of gas produced. However, in wet impregnated ACs, the potassium ratio exhibits a zero or negative correlation. It is demonstrated that potassium ions in solution are not transferred to K2O and do not contribute to the surface area and pore size, generating less amount and different composition of gases. As such, impregnated ACs exhibit similar surface areas and large pores, regardless of the potassium ratio. The physical properties, such as specific surface areas and pore size distribution, of ACs using wet impregnation were similar to the ACs generated by the water physical activation. It indicated that the KOH does not efficiently act as a chemical activator in the wet impregnation method. Therefore, a certain amount and suitable mixing method of chemical activator play an important role in the property upgrade of ACs.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials and chemical agents
        2.2 Experimental methods
        2.3 Physical and chemical characterization of AC
    3 Results and discussion
        3.1 Properties of upgraded ACs
        3.2 Properties of upgraded ACs
    4 Conclusions
    Acknowledgements 
    References

• Sang Youp Hwang(Department of Plant Engineering, Institute for Advanced Engineering)
• Gi Bbum Lee(Department of Plant Engineering, Institute for Advanced Engineering)
• Ho Kim(Department of Plant Engineering, Institute for Advanced Engineering)
• Jung Eun Park(Department of Plant Engineering, Institute for Advanced Engineering)