Carbon letters

  • Volume 24
  • /
  • Pages.62-72
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  • 2017
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  • 1976-4251(pISSN)
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  • 2233-4998(eISSN)
Korean Carbon Society (한국탄소학회)
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Relationships between dielectric properties and characteristics of impregnated and activated samples of potassium carbonate-and sodium hydroxide-modified palm kernel shell for microwave- assisted activation

  • Alias, Norulaina (Centre of Lipids Engineering and Applied Research (CLEAR), Ibnu-Sina Institute for Scientific and Industrial Research (ISI-SIR), Universiti Teknologi Malaysia) ;
  • Zaini, Muhammad Abbas Ahmad (Centre of Lipids Engineering and Applied Research (CLEAR), Ibnu-Sina Institute for Scientific and Industrial Research (ISI-SIR), Universiti Teknologi Malaysia) ;
  • Kamaruddin, Mohd Johari (Faculty of Chemical & Energy Engineering, Universiti Teknologi Malaysia)
  • Received : 2017.04.26
  • Accepted : 2017.07.05
  • Published : 2017.10.31
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Abstract

The aim of this work was to evaluate the dielectric properties of impregnated and activated palm kernel shells (PKSs) samples using two activating agents, potassium carbonate ($K_2CO_3$) and sodium hydroxide (NaOH), at three impregnation ratios. The materials were characterized by moisture content, carbon content, ash content, thermal profile and functional groups. The dielectric properties were examined using an open-ended coaxial probe method at various microwave frequencies (1-6 GHz) and temperatures (25, 35, and $45^{\circ}C$). The results show that the dielectric properties varied with frequency, temperature, moisture content, carbon content and mass ratio of the ionic solids. PKSK1.75 (PKS impregnated with $K_2CO_3$ at a mass ratio of 1.75) and PKSN1.5 (PKS impregnated with NaOH at a mass ratio of 1.5) exhibited a high loss tangent ($tan{\delta}$) indicating the effectiveness of these materials to be heated by microwaves. $K_2CO_3$ and NaOH can act as a microwave absorber to enhance the efficiency of microwave heating for low loss PKSs. Materials with a high moisture content exhibit a high loss tangent but low penetration depth. The interplay of multiple operating frequencies is suggested to promote better microwave heating by considering the changes in the materials characteristics.

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References

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