In the modern pharmaceutical and chemical industries, solutions of extremely high purity are needed. Current filtration methods are reaching the limits of their abilities, so new filters must be developed. One possible filter is a Y-shaped carbon nanotube (Y-tube). By changing the sizes of the arms of the Y-tube, custom molecular filtration is theoretically possible. Through the use of REBO molecular dynamics simulations, this is tested.
Y-tubes of different size and chirality are used to determine what effect those characteristics have on gaseous diffusion. Gas reservoirs of methane and an isobutane/methane mix are diffused down each Y-tube. In the case of the isobutane/methane reservoir, isobutane, the larger molecule does not diffuse down the smallest arm. However, filtration is not achieved due to steric clogging of the small arm entrance. A reservoir of N-butane/methane is also diffused to investigate the characteristics of a non-spherical molecule.
These results provide a base understanding of diffusion through Y-tubes to support and guide future studies. This research is being performed in conjunction with Purdue University and the University of Illinois, Urbana-Champaign, and is supported by a National Science Foundation grant through the Network for Computational Nanotechnology (grant no. EEC-02288390).