Preparation of activated carbons from cork by physical activation in carbon dioxide

Activated carbons (ACs) were prepared by the physical activation of cork wood, virgin cork and adult cork of different particle sizes in carbon dioxide and characterised by elemental analysis, DRIFTS, SEM and N-2 adsorption at -196degreesC. The wood gave results similar to those obtained with other lignocellulosic precursors. On the other hand, the cork, which has a different chemical composition as well as microstructure, gave somewhat unusual results. The cork ACs retained the characteristic honeycomb structure of the precursors and had low C/O ratios with oxygen present in the form of basic carbonyl and ether groups. With increasing activation, the micropore volume approached a limiting value of ca. 0.33 cm(3)/g, while the mean pore width was in the range 0.8-1.1 nm and decreased slightly with increasing burn-off. It was also found that the rate of activation of the adult cork was more than 10-times faster than that of the wood or the virgin cork.