Study On Particle Transport In Single-walled Carbon Nanochannels

The inflow control technology has a very broad application prospect in physics,chemistry,biomedicine and other fields.When the size of the channel is reduced to the nanometer scale,the matter transported in it will produce a large number of phenomena that are different from the macroscopic conditions.Understanding these unique phenomena is the main content of the current inflow control.It is of great significance to study and improve the particle transport characteristics in nanoscale channels for the development of the technology of inflow control.In this paper,the ion current and the transport characteristics of water molecules and C60 molecules in a single-walled carbon nanochannel are studied by molecular dynamics simulation.The specific research contents are as follows:(1)Modeling software Nanotube Modeler and visualization software VMD were used to construct straight and bent tube models of single-walled carbon nanochannel,and molecular dynamics simulation was used to study ion current and water transport in the nanochannel.The simulation results show that increasing the electric field intensity and the wall charge density will increase the ionic current in the nanochannel,and the influence of the electric field intensity on the ionic current is greater than that of the wall charge density.Because of the change of L-J potential energy between carbon atoms and water molecules,the transport speed of water in elbow channel is obviously higher than that in straight channel.(2)In order to further study the effect of macromolecules on ion current in the channel,a C60 molecular model was constructed and added to the nanochannel.The results showed that charged C60 molecules would attract ions in the solution to move with them,resulting in an increase in ionic current in the channel.Moreover,the more charges C60 molecules carry,the greater the force they are subjected to in the electric field and the faster they move in the nanochannel,which would cause an increase in ionic current in the channel.The attraction of C60 molecule at the center of nanometer channel to ions in solution changed the radial density distribution of Na+ ion and Cl-ion,and caused current crossing phenomenon.(3)A four-probe experimental bench was designed and built,and the nanochannel was fabricated by using a capillary glass tube,and the diameter of the channel was calculated by theoretical formula.The relationship between the conductivity and the concentration of sodium chloride was studied experimentally.The results showed that when the concentration of solution ranged from 0.5mol/L to 1.5mol/L,the conductivity increased linearly with the concentration of solution.When the solution concentration is greater than 2mol/L,the conductivity basically does not change due to the increase of viscous force in the channel.This phenomenon is consistent with the simulation results.The relationship between channel diameter and conductivity as well as the ion velocity in the nanochannel with different diameters were studied.