Enhancement of water flow across a carbon nanotube

Abstract

It is important to investigate how to enhance the flow rate of single-file water molecules across nanochannels. To our knowledge, all the existing methods are based on pressure gradients, external point charges or uniform/graded electric fields. Accordingly, these methods are all based on exogenous tools, and thus bring challenges for both energy-saving and miniaturisation. In contrast, here we manage to reveal an endogenously determined mechanism of flow enhancement. On the basis of molecular dynamics simulations, we investigate water permeation across a single-walled carbon nanotube (SWCNT A) in the presence of another SWCNT (SWCNT B). We find that the flow rate of the single-file water molecules across SWCNT A is enhanced for the case of unblocked SWCNT B compared with the rate for the case of blocked SWCNT B, and that this flow rate is determined by the separation between the two SWCNTs and the diameter of SWCNT B.

Pb2+removal based on the confinement effect in polygonal carbon nanotubes: a molecular dynamics simulation

“…All MD simulations were performed within the canonical (NVT) ensemble, 31 Tersoff force field was used for the carbon-carbon atom interaction computation in PCNTs/G, 32 and the CHARMM force field was used to describe the Pb 2+ ions, 33,34 and H 2 O was modelled using the transferable intermolecular potential 3-point (Tip3p) water model. 33,35 Such combinations of tersoff, CHARMM, TIP3P has been already successfully used by Khadem et al 27 to reproduce some experimental data.…”

Structure and Transport Properties of Water and Hydrated Ions in Nano‐Confined Channels

“…[67][68][69] When the confinement is strong enough, the original HB structure of water is broken up and new microstructures are formed as a result. [12,75] This may result from the ordered structure and the potential well formed in the center of such small tubes. In a single-file structure, the water molecules are tightly chained with HB, and as the liquid recedes from hydrophobic surface, there would be a gap separating the bulk phase from the surface.…”

“…In a single‐file structure, the water molecules are tightly chained with HB, and as the liquid recedes from hydrophobic surface, there would be a gap separating the bulk phase from the surface . When transporting with a single‐file manner, the water molecules cannot cross each other but can form an extremely effective transportation . This may result from the ordered structure and the potential well formed in the center of such small tubes …”

Towards sustainable ultrafast molecular-separation membranes: From conventional polymers to emerging materials

“…This may occur in UMS membranes because of their unique pore size and ultrafast fluid flux. Therefore, advanced fluid dynamics should be developed to consider the unique properties of UMS membranes, in which molecular simulation may play a key role [267][268][269][270][271]. There remains plenty of challenges to overcome to clarify the reasons behind ultrafast mass transfer across UMS membranes, which is the key to providing guidance to the design of advanced UMS membranes.…”