Microwave absorption properties of porous activated carbon-based palm oil empty fruit bunch

Abstract

The increased growth of electronics and wireless communication systems causes the urge to find microwave absorbing materials that are lightweight, inexpensive, and environmentally friendly. In this study, we successfully synthesize activated carbon materials from the oil palm empty fruit bunch (OPEFB) as future microwave absorbing material candidates with a porous structure using different kalium hydroxide (KOH) concentrations during the activation process followed by physical carbonization at 800 °C under an inert atmosphere. The prepared porous activated carbon (PAC)-based OPEFB was characterized by several techniques, including x-ray diffraction, scanning electronic microscopy-energy dispersive x-ray analysis, and Brunauer-Emmett-Teller analysis. The microwave absorption properties of the PAC-based OPEFB were measured using one port rectangular waveguides at the X-band frequency range (from 8 to 12 GHz). A minimum reflection loss value of -32.21 dB (more than 99.9% absorption) at 10.64 GHz is obtained for the PAC-based OPEFB with 20% of KOH concentration. The SEM observations confirm the porous structure of activated carbon, and the BET analysis measures the surface area of the PAC-based OPEFB with 20% of KOH concentration of about 693.06 m2/g. The improvement of reflection loss of the PAC-based OPEFB compared to its raw materials is attributed to the better impedance matching, and multiple reflections occur in the porous structure of activated carbon. This study suggests that the PAC-based OPEFB can become a future potential material for microwave absorbers used in electronics and wireless communications devices.