Strategy Combining Free Volume Theory and Fragment Contribution Corresponding State Method for Predicting Viscosities of Ionic Liquids

In
this study, we proposed a strategy that combines the fragment
contribution corresponding states (FCCS) and free volume theory (FVT)
method, namely FCCS–FVT, to calculate the viscosities of ionic
liquids (ILs) covering a wide range of temperatures and pressures.
In the method, the FCCS model was used to calculate the critical properties
and densities of ILs, and then based on those values, the FVT model
was applied to calculate the viscosities of ILs. The results indicated
that the FCCS–FVT method shows high accuracy with 6.6% in average
absolute relative deviation of total 2138 data points (25 ILs), which
covers a wide range of temperatures (258.15–573 K) and pressures
(0.06–300 MPa). Moreover, it is more convenient for the FCCS–FVT
method to be applied for quick and accurate calculation of viscosities
of ILs because it needs only three adjustable parameters.