Abstract:
This work was carried out to remove impurities in crude biodiesel via the adsorption process with mangosteen shell-derived activated carbon. The effects of KOH to char ratio in the range of 0.5-1.5 and activation temperature in the range of 500-900 oC on property and adsorption property of the obtained activated carbon were explored. It was found that the KOH to char ratio and activation temperature affected importantly the amount of oxygen-containing surface functional groups and textural property of activated carbon as well as the purity of biodiesel. The optimum KOH to char ratio and activation temperature for preparing activated carbon were 1.25 and 800 oC, respectively, which can enhance the generation of carbonyl group and BET surface area up to 11.62 mEq/g and 1,207 m2/g, respectively. By using such activated carbon at the dosage of 9 g/L biodiesel at 120 min adsorption time, the purity of biodiesel up to 97.18 wt.% was obtained, which was comparable with that purified by adsorption with commercial activated carbon and wet washing method. Equilibrium adsorption data fitted well with the Freundlich isotherms and the adsorption mechanism was controlled by the transport of some impurities from the bulk solution to the surface of the AC. The reusability of the mangosteen shell-derived activated carbon was possible for a time after regeneration with hexane and thermal.