Modeling the viscosity of binary eutectic systems at different compositions and temperatures

Deep eutectic solvents (DESs) are considered as promising green alternatives to common organic solvents in various applications. For utilizing DESs in process applications, it is essential to study their viscosity. In this work, the modified Adam-Gibbs (AG) and Vogel-Fulcher-Tammann (VFT) models were combined with 12 mixing rules to calculate the viscosity of 11 L-menthol-based binary eutectic systems (ESs) at various temperatures and compositions. The modified AG and VFT models were adopted to predict the viscosity of pure constituents below their melting temperatures, while the mixing rules were used to estimate the viscosity of ESs. It was found that the VFT model predictions for the viscosity of pure constituents below their melting temperatures were generally higher than those predicted by the modified AG model. Accordingly, when combined with the 12 mixing rules, the modified AG model gave better predictions for the viscosity of ESs than the VFT model. The Grunberg-Nissan mixing rule with one adjustable parameter provided the lowest average absolute relative deviation between the calculated and experimental viscosity.