Adsorption of Ammonia Gas
The combined adsorption isotherms and strong adsorption isotherms of ammonia are shown in Figs.1 and 2, respectively. The adsorbed amount on BC400 and AC in the combined adsorption isotherms was higher than that of BC700 and BC1000, and that of BC400 was highest. The pore volume of AC from the results of the nitrogen adsorption isotherms
was highest, but the chemisorbed amount on BC400 from the results of the strong adsorption isotherms was the highest. The reason for the high chemisorbed amount on BC400 was due to the presence of more carboxyl groups and phenolic hydroxyl groups as described in previous studies.7–9,22) Although the chemisorbed amount on bamboo charcoal hardly changed by treatment with diluted sulfuric acid, that on AC slightly increased by this treatment. The in- crease of chemisorbed amount on AC was consid- ered because of occurring by oxidation of the sur- face. The AC has an especially high surface area as compared with that of BC, and this result had the same tendency as reported by Maruyama et al.21) Therefore, the treatment with diluted sulfuric acid slightly increased the amount of acidic functional groups for AC but hardly influence that for bamboo charcoal.