Determination of the surface area and porosity of carbon nanotube bundles from a Langmuirian analysis of sub- and supercritical adsorption data

• Published in: Carbon (New York) 2009-04, Vol.47 (4), p.948-956
• Main Authors: Esteves, Isabel A.A.C., Cruz, Fernando J.A.L., Müller, Erich A., Agnihotri, Sandeep, Mota, José P.B.
• Format: Article
• Language: English
• Subjects: Adsorption; Alkenes; Bundles; Carbon; Chemistry; Colloidal state and disperse state; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Physics; Porosity; Porous materials; Single wall carbon nanotubes; Specific materials; Surface area; Surface chemistry; Surface physical chemistry
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2008.11.044

In this paper we revisit the problem of how to obtain reliable information on the porosity and surface area of single-walled carbon nanotube (SWCNT) bundles from adsorption data. We report on adsorption measurements obtained on bundles of high-purity electric-arc nanotubes, with various gases (methane, ethane, ethylene, propane, and propylene) spanning reduced temperatures between 0.8 and 1.6, and pressures from 200 Pa up to 8 MPa, exploring low uptakes as well as multilayering conditions. Using these data we demonstrate the applicability of an analytical procedure for interpreting adsorption isotherms of light alkanes and alkenes on SWCNT bundles in quantitative terms. In particular, its use for the reliable assessment of the surface area and accessible pore volume of the bundles is demonstrated. Our results show that the same set of endohedral sites, as well as the same set of external sites, is available on our sample to all adsorbates investigated. We also show a crossover behavior in endohedral adsorption between the alkene and its saturated counterpart when moving from low pressure to near saturation conditions.