Prediction of Viscosity of Ionic Liquids using Different Equations

Recently, research emphasis on Ionic Liquid (IL) characterization, properties, and applications are rapidly growing ever since ILs have been accepted as ―green-chemicals‖ and candidates to replace other non-environmental friendly chemicals including solvents and lubricants. The understanding of physical and chemical properties of Ionic Liquids is crucial in identifying its potential applications in the chemical industry. However, the information of IL transport properties especially viscosity has left much to be desired from the academia and chemical industries as viscosity of ILs are a relatively new area of study, compared to other IL properties, such as density. Previous studies involving IL viscosity estimation are limited and based on non-generalized equations that are not applicable for all ILs.
The objective of this research is to identify the best method to predict or estimate viscosity of ILs so that their suitability in various applications can be known without much hassle. A research on prediction of viscosity of Ionic Liquids is presented in this report. The prediction methods will only require the critical properties and acentric factor of the IL as the parameters to estimate its viscosity. A detailed comparison between 5 different generalized correlations is performed to identify the best IL viscosity prediction method among them. 20 ILs with around 100 data points for each method was studied in this project. Generalized equations are identified through comprehensive research on available liquid viscosity methods. The database of parameters such as experimental viscosity and critical property data of ILs are collected from literature/online resources and the calculation of %AAD is done with comparison to the experimental data. The accuracies of the different equations (%AAAD) are then compared against each other. The method that has been identified to be the best prediction method of viscosity of ILs is the Lewis & Squires Method.