Single-walled and multi-walled carbon nanotubes (SWNTand MWNT) were prepared by catalytic decomposition of methane
and acetylene, respectively. The resulting catalyst/carbon composites were subjected to chemical treatments to obtain samples
which were enriched in nanotubes. Isotherms and frequency response (FR) spectra of N2 and H2 were recorded at 195 and 77 K,
respectively, in the 1–800 Pa pressure range. The adsorption isotherms for N2 were found to obey Henry’s law, while the
isotherms of H2 adsorption indicated some energetic heterogeneity of the sorption sites. Stronger adatom–substrate interaction
was detected for those samples which had been subjected to oxidative treatment. The FR measurements showed that treatment of
MWNT in KMnO4 solution changed the rate-controlling mechanism of mass transport from one of sorption to one of diffusion.
Results substantiated that the surface functional groups, generated by the oxidative treatment, have significant influence on both
the equilibrium and the dynamic N2 and H2 sorption properties of the carbon nanotubes.
Rate spectroscopy , adsorption , diffusion , Carbon nanotubes