Browsing by Author "Yagmur, E."

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    Examination of gas and solid products during the preparation of activated carbon using phosphoric acid
    (Academic Press, 2018) Yagmur, E.; Inal, I. I. G.; Gokce, Y.; Ghobadi, T. G. U.; Aktar, T.; Aktas, Z.
    Activating agents play significant roles in the preparation of activated carbon (AC) from biomasses and their wastes, which are widely used in AC production. Application methods are also important for the production process. Products give remarkable ideas regarding the method and heat treatment process. The activated carbon was produced from waste tea in accordance with either the conventional method or microwave energy pretreated method using phosphoric acid (H3PO4) as activating agent. The yields of the activated carbons were 51.8% for conventional method and 46.0% for microwave pretreated method. The acid suppressed the formation of tar and promoted the amount of solid and aromatic structure accordance to sp2 hybridisation. Additionally, the waste tea was directly carbonised (without H3PO4) and the yield was 36.3%. Major gas (H2, CH4, C2H6, C2H4, CO2 and CO) products obtained during heat treatment process in a conventional furnace were examined in terms of quantity and quality. The solid products were characterised in terms of surface area, pore size and surface properties. The result of gas analysis showed that phosphoric acid affected formation of activated carbon mechanism and significant reactions occurred during microwave pretreatment process.
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    Highly stable Megalopolis lignite based N and S self-doped hierarchically porous activated carbons for high performance supercapacitors and ash content effects on performance
    (Elsevier, 2022-02) Oglou, Ramadan Chalil; Gokce, Y.; Yagmur, E.; Ghobadi, T.Gamze Ulusoy; Aktas, Z.
    This study proposes that high value-added activated carbon (AC) is produced from lignite (low rank coal) and used as electrode material in supercapacitors. In addition, the effects of the ash content of the activated carbon on supercapacitor performance are determined. The ACs at a temperature of 800 °C are produced in three different impregnation ratios (IR) (IR: 1, 2 and 4: KOH/precursor) using KOH as the activation agent. While the surface area of the AC produced at IR4 is 2531.4 m2 g−1, it is determined as 1321.3 (IR1) and 1989.0 (IR2) m2 g−1 for the others. The pore size analysis of the samples shows that the mesopores are dominant in the IR1 (52.73%) and IR4 (88.74%) samples, while it is observed that the micropores are dominant in the IR2 (69.03%) sample. The IR4 sample gives excellent results. The cell specific capacitances of this sample are determined as 260.47 F g−1 (at 1 A g−1) and 150.3 F g−1 (at 50 A g−1). The amount of ash in the AC samples dramatically reduces the supercapacitor performances and significantly increases the resistances.