Water structure near single and multi-layer nanoscopic hydrophobic plates of varying separation and interaction potentials

Abstract

We have performed a series of molecular dynamics simulations of water containing two nanoscopic hydrophobic plates to investigate the modifications of the density and hydrogen bond distributions of water in the vicinity of the surfaces. Our primary goal is to look at the effects of plate thickness, solutesolvent interaction and also interplate separation on the solvent structure in the confined region between two graphite-like plates and also near the outer surfaces of the plates. The thickness of the plates is varied by considering single and triple-layer graphite plates and the interaction potential is varied by tuning the attractive strength of the 12-6 pair interaction potential between a carbon atom of the graphite plates and a water molecule. The calculations are done for four different values of the tuning parameter ranging from fully LennardJones to pure repulsive pair interactions. It is found that both the solvation characteristics and hydrogen bond distributions can depend rather strongly on the strength of the attractive part of the solute-water interaction potential. The thickness of the plates, however, is found to have only minor effects on the density profiles and hydrogen bond network. This indicates that the long range electrostatic interactions between water molecules on the two opposite sides of the same plate do not make any significant contribution to the overall solvation structure of these hydrophobic plates. The solvation characteristics are primarily determined by the balance between the loss of energy due to hydrogen bond network disruption, cavity repulsion potential and offset of the same by attractive component of the solute-water interactions. Our studies with different system sizes show that the essential features of solvation properties, e.g. wetting and dewetting characteristics for different interplate separations and interaction potentials, are also present in relatively smaller systems consisting of a few hundred atoms.

Solvation of narrow pores of graphene-like plates in simple dipolar liquids: Wetting and dewetting behavior and solvent dynamics for varying pore width and solute–solvent interaction

“…Contrary to the Lennard-Jones potential, in case of WCA repulsive potential, a destruction of the layering of Stockmayer liquid in the vicinity and away from the solutes is observed. Interestingly, the overall solvation characteristics around these solutes in Stockmayer liquid are found to be rather similar to that found for water [54,55,91,92] when the solute-surface interaction is changed from LJ to fully repulsive WCA potential.…”

“…(2)). It was found earlier [94,91] that the use of repulsive part of the Lennard-Jones potential according to the Weeks-Chandler-Andersen (WCA) [90] decomposition scheme mimics the essential aspects of solvation characteristics for purely repulsive carbon-oxygen interaction for hydrophobic solute and water system and, hence, we have also employed this potential for solute-solvent interactions in this work. The form of the repulsive WCA potential is u WCA ðr ij Þ ¼ 4 LJ ½ðr ij =r ij Þ 12 À ðr ij =r ij Þ 6 þ LJ for r ij < r m ;…”

Separation of hydrocarbon mixture of neopentane and n‐hexane using NaY zeolite: Large distinct diffusivity

“…Chandra and coworkers 9 have reported a study of the transport of nitrate and nitrite ions through the graphene nanopores in aqueous medium. They have also reported a study of water structure within the multi‐layer hydrophobic sheets as a function of separation and interaction potentials 10 …”

“…They have also reported a study of water structure within the multi-layer hydrophobic sheets as a function of separation and interaction potentials. 10 The separation of hydrocarbon mixtures are essential in the petrochemical refineries to increase the octane number of the gasoline pool and optimize the feedstock for ethylene production. Recently, several ideas have been discussed to efficiently separate hydrocarbon mixtures using MOF.…”