In this paper, a kink model for gas separation is presented. Transport of pure nitrogen, oxygen, and their mixture in single-walled carbon nanotubes (SWCNTs) with a kink formed by bending is studied using molecular dynamics simulations. The results show that a nanotube with a specified kink results in transport resistance to nitrogen, while allowing oxygen to pass even though the two gases have very similar molecular sizes. The permeability decreases while the selectivity increases with increasing the bending angle of SWCNTs. The kink model can be used to improve the permeability by changing the diameter of the SWCNTs, while keeping a high selectivity in the gas separation process. The most important is that it is very convenient to obtain the required purity of the oxygen and permeability by adjusting the bending angle of SWCNTs.

• Received 10 May 2008

DOI:https://doi.org/10.1103/PhysRevB.78.035439