Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons

In the present study the effects of the duration of carbonization and physi cal activation properties of activated carbon from vegetable materials were investigated. Peanut shells were used to obtain active carbon. These shell s were activated chemically with ZnCl2 and/or CO2 for different times, and the micropore structures of these active carbons were studied by measuring the adsorption isotherms for nitrogen and some hydrocarbons such as benzene , n-butane, isobutane, 2,2-dimethylbutane, and isooctane. As the physical a ctivation time was increased, the primary micropores, which were measured a t 0.01 relative pressure, were reduced, and they were replaced by larger se condary and tertiary micropores which were measured at 0.15-0.01 and 0.30-0 .15 relative pressures. The ratios of the mesopore volume to the micropore volume also increased as the duration of physical activation increased.