Adsorption of benzene from an aqueous solution

Abstract

Adsorption of benzene from aqueous solution on a planar carbon wall is studied by molecular dynamics simulations. The density profile and the orientational behavior of a benzene molecule are determined by two methods. In the first one the center of the benzene molecule is fixed while the molecule can freely rotate and the local density is obtained via integration of the mean force on the center of the molecule. In the second method the density profile is determined directly from a freely moving benzene molecule. It turns out that even in the case of strong adsorption the first method is superior. As regards structure, the benzene molecule is preferably adsorbed in a nearly parallel orientation to the wall, but there is also a certain probability for finding it in more remote positions in an almost perpendicular orientation bridging two water layers.

Keywords:

• Molecular dynamics simulations
• Potential of mean force (PMF)
• Adsorption
• Aqueous solution
• Benzene

Acknowledgements

The authors gratefully acknowledge financial support by Deutsche Forschungsgemeinschaft for the project “Adsorption aus wässrigen Lösungen”, Az Fi 287/13-1, within the priority research program “Molekulare Modellierung und Simulation in der Verfahrenstechnik”. Moreover, we thank the John von Neumann Institut für Computing, Jülich, Germany, for allocation of computer time at JUMP, project ID hvi020.