Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (9): 1625-1633.doi: 10.3866/PKU.WHXB201407031

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Molecular Dynamics Simulation Study of Structural and Transport Properties of Methanol-Water Mixture in Carbon Nanotubes

GAO Wen-Xiu, WANG Hong-Lei, LI Shen-Min   

  1. Liaoning Key Laboratory of Bio-Organic Chemistry, Dalian University, Dalian 116622, Liaoning Province, P. R. China
  • Received:2014-04-16 Revised:2014-07-03 Published:2014-08-29
  • Contact: LI Shen-Min E-mail:lishenmin@dlu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21133005).

Abstract:

Molecular dynamics simulations of a methanol-water mixture (molar ratio 1:1) were performed to determine the differences among the structural and transport properties in three carbon nanotube (CNT) systems: an equilibrium system, a system with an external pressure, and a system with a gradient electric field. The simulations showed that in both the equilibrium system and the system with an external pressure, the methanol-water mixture is clearly immiscible in the CNTs, with the water molecules distributed mainly around the tube axis, and the methanol molecules located near the tube wall; however, in the system with a gradient electric field, the hydrophobic CNTs become hydrophilic, and the phenomenon of methanol-water separation disappears. In contrast, unlike the unidirectional transport observed in the system with an external pressure, the particles move in two directions in the system with a gradient electric field, with a flow one order of magnitude larger than that in the corresponding external pressure system. However, in the system with a gradient electric field, the net flux is small, because the flows for the two directions are similar. There is thus a small flux difference between the system with an external pressure and the system with a gradient electric field.

Key words: Methanol, Water, Carbon nanotube, Molecular dynamics simulation, Flux

MSC2000: 

  • O641