Water desalination using graphene nanopores: influence of the water models used in simulations

Molecular dynamics simulations are widely employed to analyze water and ion permeation through nanoporous membranes for reverse osmosis applications. In such simulations, water models play an important role in accurately reproducing the properties of water. We investigated the water and ion transport across a hydroxyl (OH) functionalized graphene nanopore using six water models: SPC, SPC/E, SPC/Fw, TIP3P, TIP4P, and TIP4P/2005. The water flux thus obtained varied up to 84% between the models. The water and ion flux showed a correlation with the bulk transport properties of the models such as the diffusion coefficient and shear viscosity. We found that the hydrogen-bond lifetime, resulting from the partial charges of the model, influenced the flux. Our results are useful in the selection of a water model for computer simulations of desalination using nanomembranes. Our findings also suggest that lowering the hydrogen-bond lifetime and enhancing the rate of diffusion of water would lead to enhanced water/ion flux.