CO₂ Adsorption Isotherms on KOH, H₃PO₄ and FeCl₃.6H₂O Impregnated Palm Shell Kernel Activated Carbon

Abstract

Commercial sorbents available are expensive as a result of using high cost and non-renewable materials as precursors. It is imperative to select cheap, viable and sustainable carbon source for production of adsorbents for subsequent use in adsorption applications. Palm kernel shell char was obtained by carbonisation process at 730 °C ± 20 °C for 2 h with 10 °C/min heating rate under inert gas flow. The bio-char obtained was further grinded and sieved to 0.5 to 0.85 mm, then treated and synthesised separately each sample by KOH, H3PO4 and FeCl3.6H2O solution with ratio 1 : 1 weight ratio and followed by microwave treatment technique. Samples treated with chemicals used were named as PKS-POT (Palm Kernel Shell with Potassium Hydroxide ), PKS- PAP (Palm Kernel Shell with Phosphoric acid) and PKS-FER(Palm Kernel Shell with Ferric chloride hexahydrate). CO2 gas was used during the adsorption and desorption study. Samples were characterised by Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM) and Fourier transform infraredspectroscopy (FTIR). PKS-POT showed highest BET surface area (208.7037 m2/g) and pore volume (0.06580 cm3/g). PKS-POT’s SEM result also confirms large surface area, pores and more compact of the shell structure which related to high adsorption capacity compared to PKS-PAP and PKS-FER. CO2 PKS-POT, PKS-PAP and PKS-FER adsorption capacities were 2.19, 0.62 and 1.25 mmol/g and no CO2 gas left for the end desorption phase. From the study concluded that sustainable palm kernel shell material was successfully achieved to obtain the high surface area, high porosity and high adsorption sorbent capacity.