Background: A study was conducted to investigate the effects of activation by CO2, steam and their sequential combinations on the development of pores of activated carbon derived from ZnCl2-treated oil palm kernel shell.
Results & Conclusion: The results show that the combination of CO2 and steam, regardless of their sequence, results in a higher carbon burn-off than the single activating agents. The combination of activation in the sequence of CO2-steam, however, gives the highest value of carbon burn-off and produces activated carbon with the highest total pore volume and BET surface area. Steam activation favours the creation of new microporous structures, while CO2 activation tends to widen existing pores leading to the formation of mesoporous structures. The preferential action of different activating agents can be related to the size of their molecules and the rate at which they dissociate and react with carbon.
Keywords: Activated carbon, pore structure, oil palm kernel shell, steam activation, CO2 activation, ZnCl2.