Electroviscous Effects in Nanofluidic Channels

This paper presents a systematical study of electroviscous effects in nanofluidic channels using a triple layer model and a numerical framework. A chemical dissociation layer is introduced at solid-liquid interfaces to bridge the surface charge condition with the local properties of both solid surfaces and the ionic liquid. The electrokinetic transport in the electrical double layers is modeled by a lattice Poisson-Boltzmann method. The results indicate that there is an ionic concentration leading to the maximum electroviscosity for a given channel height, pH value, and environmental temperature. For a very high ionic concentration, a smaller channel height leads to a higher electroviscosity. When the bulk concentration reduces from 10(-3)M to 10(-6)M, there is a critical channel height that maximizes the electroviscosity for a given ionic concentration, and the critical height increases with the decreasing ionic concentration. The electroviscosity increases with the pH of electrolyte solutions and is nearly proportional to the environmental temperature. The present study may help to improve the understanding of electrokinetic transport in nanofluidic channels.