High-Pressure Viscosity Prediction of Ionic Liquids Using the Eyring Theory

The predictive capabilities of a recently developed thermodynamic model for the accurate estimation of dynamic viscosity of pure ionic liquids at elevated pressures are discussed here. The viscosity model is based on the Eyring's absolute rate theory for pure liquids where the activation energy for viscous flow was related to well-known thermodynamic quantities readily obtained from simple cubic equations of state of the van der Waals type. The resulting model was successfully validated during the prediction of experimental dynamic viscosities of various imidazolium- and pyridinium-based ionic liquids within a wide temperature range and at high pressures up to 3,000 bar.