Role of functional groups on the microwave attenuation and electric resistivity of activated carbon fiber cloth

Virgin activated carbon fiber cloth (ACFC) samples with select degrees of activation/porosity were treated with nitric and sulfuric acids or with hydrogen. Composition, microwave attenuation constant and electric resistivity results for these samples are provided. On average, acid treatment resulted in a 677% increase in oxygen content, 89% decrease in microwave attenuation constant, and 3200% increase in electrical resistivity when comparing these properties to the corresponding ones in the virgin samples. However, hydrogen treatment resulted in a 72% decrease in oxygen content, 50% increase in microwave attenuation constant, and 63% decrease in electrical resistivity, when comparing these properties to the corresponding ones in the virgin samples. These results indicate that conduction loss dominates over the polarization loss for microwave attenuation in ACFC. Increasing the oxygen content reduces the ACFC’s ability to absorb microwaves and is expected to make ACFC more difficult to heat with microwaves. However, decreasing the oxygen content allows the ACFC to heat more readily by resistive heating. Since microwave and resistive heating techniques depend on the microwave attenuation constant and electric resistivity, respectively, controlling the density of functional groups of ACFC can significantly affect the thermal regeneration of ACFC depending on the method used to heat the ACFC.