Simple model of adsorption on external surface of carbon nanotubes—a new analytical approach basing on molecular simulation data

Abstract

Abstract Nitrogen adsorption on carbon nanotubes is widelystudied because nitrogen adsorption isotherm measurementis a standard method applied for porosity characterization.A further reason is that carbon nanotubes are potentialadsorbents for separation of nitrogen from oxygen in air. Thestudy presented here describes the results of GCMC simulationsof nitrogen (three site model) adsorption on singleand multi walled closed nanotubes. The results obtained aredescribed by a new adsorption isotherm model proposed inthis study. The model can be treated as the tube analogue ofthe GAB isotherm taking into account the lateral adsorbate–adsorbate interactions. We show that the model describesthe simulated data satisfactorily. Next this new approachis applied for a description of experimental data measuredon different commercially available (and characterized usingHRTEM) carbon nanotubes. We show that generally aquite good fit is observed and therefore it is suggested thatthe observed mechanism of adsorption in the studied mate-rials is mainly determined by adsorption on tubes separatedat large distances, so the tubes behave almost independently.