Abstract
Pyrolyzed Japanese cedar (Cryptomeria japonica D. Don) bark was activated in a stream of CO2 at 1123-1173K for 1h. Adsorption of N2 at 77K and DRIFTS spectra were measured to investigate the porosity and surface properties of the activated materials. The resultant fibrous activated carbons showed the development of micro porosity which was characterized by large specific surface area greater than 1000m2g-1, small external surface area of ca. 10m2g-1, and total pore volume of 0.45-0.65mlg-1. Pore size of the activated carbon distributed sharply around 0.3-0.4nm radius, indicating that micropores were selectively formed during activation reactions, while the amounts of meso- and macro-pores were negligibly small. Analysis of adsorption isotherms by αs-plot method suggests that surface properties of the activated carbons from the cedar bark are different from those of ordinary carbon black. Peaks appeared in 900-1350cm-1 region in the DRIFTS difference spectra between the activated carbon and the carbon black showed that principal functional groups on the surface of the cedar bark activated carbon were ether groups such as ether bridges between aromatic rings and cyclic ethers containing COCOC groups. It is indicated that the oxygenated functional groups produced on the surface of the activated carbons from the cedar bark may affect the surface characteristics of the activated ones.
