The dynamic behavior of ethanol and water mixtures inside an Au nanotube molecule filter.

Molecular dynamics (MD) simulation was used to investigate the behavior of water and ethanol molecules, which were mixed with five water-ethanol weight fractions (100:0, 0:100, 25:75, 50:50, and 75:25) inside the Au nanotube. To investigate the nano-confinement effect on water and ethanol molecules, the data of both molecules were analyzed by the probability of the number H-bonds per water and ethanol molecule and radial density distribution. Our results reveal that the radial density distributions and the number of H-bonds are significantly influenced by the Au nanotube, and the molecules also display different behavior from those in the bulk environment. In addition, the interaction between water molecules and the Au nanotube is stronger than that between ethanol molecules and the Au nanotube, from the profile of radial density distribution. Finally, both the number of H-bonds per water and per ethanol will be affected by the weight fraction, because the H-bond not only forms between the same material, but also between different materials.