Grand canonical Monte Carlo and dual control-volume grand canonical molecular dynamics simulations were carried out for Lennard-Jones model fluids in carbon nanotubes. The object was to investigate the effect of varying the molecular properties upon adsorption and diffusion. The influence of the molecular weight, and of the Lennard-Jones molecule size and interaction strength, upon adsorption isotherms, fluxes and diffusivities was studied. In these simulations, the properties of component 1 in the mixture were held constant, while one of the properties of component 2 was changed systematically. The validity of Graham’s law, which related the fluxes of two counter-diffusing species to their molecular weight, was investigated at the molecular level. Graham’s law was obeyed over the whole range of molecular weights and Lennard-Jones size parameters that was investigated. However, large deviations were observed for large values of the interaction strength. Here, the interaction of the two components in the mixture became so strong that component 1 was dragged along by component 2.

Molecular Simulation of Adsorption and Transport Diffusion of Model Fluids in Carbon Nanotubes. T.Düren, F.J.Keil, N.A.Seaton: Molecular Physics, 2002, 100[23], 3741-51