Calorimetry and molecular simulation for the characterization of single- walled carbon nanotubes by CO2 adsorption

A.A. GARCÍA BLANCO; A.G. ALBESA; D. SOARES MAIA; J. VILLARROEL ROCHA; J.L VICENTE; K. SAPAG

Delray Beach

Workshop; 6th International Workshop-Characterization of Porous Materials (CPM-6); 2012

Quantachrome Instrument

In this work, single walled carbon nanotubes (SWNT) were subjected to an acid treatment in the conditions reported in previous studies [1] and characterized by CO2 adsorption at 273 K and N2 adsorption at 77 K. Adsorption isotherms and differential enthalpies of CO2 adsorption were measured in a Tian-Calvet microcalorimeter connected to a volumetric system which allows the simultaneous measurement of adsorption isotherms and enthalpies of adsorption. Additionally, molecular simulations of gas adsorption in SWCNT were performed, using the Monte Carlo method in the Grand Canonical ensemble. Homogeneous, heterogeneous and oxidized bundles of nanotubes were employed as substrate for the simulations, using configurations of nanotubes diameters similar to the diameters experimentally determined. The simulations were performed for the adsorption of CO2 at 273 K. Simulated adsorption isotherms as well as isosteric heats of adsorption profiles were obtained. The correlation between experimental and simulated isotherms gave information about the nanotubes diameter distribution and the nature of adsorption sites, which is important for the characterization of SWCNT.