Molecular dynamics study of an electro-kinetic fluid transport in a charged nanochannel based on the role of the stern layer

Electro-osmotic flow of an aqueous solution of NaCl has been studied using the molecular dynamics simulation. The main objective of this work is to investigate the effects of the electric field and temperature on the flow properties considering the role of the stern layer. By increasing any of the mentioned parameters, the electro-osmotic velocity grows. It is found that the electro-osmotic velocity is a fourth order function of the electric field, while it changes linearly with temperature. Similar trends of change are found for the EDL thickness. By an increase in the studied parameters, a reduction in the stern layer capacity is observed. In this situation, more moving ions are located in the diffuse layer, which are dragging other particles. This is one of the causes that increase the electro-osmotic velocity, a matter which was not predicted by previous researches. A consequence of the stern layer capacity reduction is that in the systems under the influence of higher temperatures or stronger electric fields, charge inversion phenomenon occurs at higher wall charges.