Characterization of adsorbent prepared from oil-palm shell by CO2 activation for removal of gaseous pollutants

Characterization of activated carbon prepared from oil-palm shell, an abundant agricultural solid waste from palm-oil processing mills in some tropical countries, by carbon dioxide (CO2) activation was carried out in this paper. The effects of activation temperature on the textural and chemical properties of the activated carbon were studied. It was found that significant weight losses occurred during the activation process due to continual release of volatile matter and carbon burn-off through weak carbon–CO2 oxidation, resulting in an increase of solid density and a decrease of apparent density. Hence, the activated carbons prepared from oil-palm shells possessed well-developed porosities and predominant microporosities, which were verified by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), respectively. The development of microporosity for the oil-palm-shell activated carbon would lead to potential applications in gas-phase adsorption for the removal of air pollutants. Adsorption test results showed a linear relationship between the BET surface area and the adsorptive capacity for both nitrogen dioxide (NO2) and ammonia (NH3) gases. This could be elucidated by the neutral surface functional groups of the oil-palm-shell activated carbon, as detected by Fourier Transform Infrared Spectroscopy (FTIR).