Abstract
With increasing pressure on resources, filtration plays a key role in the lives of everyone on this planet. This can, for example, be in terms of desalination to obtain clean drinking water, hydrocarbon separation for gasoline production, or gas separation to meet stringent environmental regulations. In the design of membranes for applications such as these, fast transport of atoms combined with high selectivity is desired, and aligned carbon nanotube membranes show great promise in this respect. In order to design and tailor nanotube-membranes for optimum performance in specific applications, an understanding of the fundamental non-equilibrium flow properties through nanotubes is crucial. The aim of the research described in this thesis is to study these fundamental properties in a systematic fashion, in order to gain a better understanding of the potential that carbon nanotubes have for use in filtration and separation technologies. This research presents a new non-equilibrium molecular dynamics simulation written by this author, capable of reproducing and analysing long-time-scale non-equilibrium flow through carbon structures. Counter-intuitive flow dynamics as well as enhanced flux are demonstrated, and the reasons behind such phenomena are explained. The ability to manipulate the flow on the nano-scale through mechanical means is limited, and this research shows the potential role that nanotubes can play in manipulating the flow and inducing usual flow phenomena. The flow of point-particles is contrasted with that of diatomic molecules, and the level down to which macro-scale laws apply are discussed. Finally, the role of charge on the flow is also highlighted by considering the entry of water into nanotubes. By making these studies, a much greater insight into the potential role of nanotubes in filtration and separation applications is obtained. This research demonstrates that nanotube- membranes have great potential to help overcome the challenges facing the world, today as well as in the future.