Speeds of sound in ionic liquids under elevated pressures. New experimental data and CP-PC-SAFT modelling.

This study reports synthesis of a new ionic liquid ethyl-1-octyloxymethylimidazolium bis(trifluoromethylsulfonyl)imide ([C 2 imC 1 OC 8 ][NTf 2 ]) and its speed of sound data at 295.15 K ≤ T ≤ 373.15 K and 1 bar ≤ P ≤ 1471.5 bar. In addition, the atmospheric pressure densities of this IL were measured at 292.05 K ≤ T ≤ 423.65 K and determined at 295.15 K ≤ T ≤ 373.15 K and 1 bar ≤ P ≤ 1500 bar. Basing on a representative variety of ILs, it is demonstrated that the CP-PC-SAFT EOS adjusted to their high-pressure density data by a standardized numerical procedure and attached by a simple expression for estimating the ideal gas heat capacities is capable to predict sound velocities in a particularly accurate manner, with AAD around 1% and at times even smaller that the experimental uncertainties. • The new IL [C 2 imC 1 OC 8 ][NTf 2 ] was synthesized. • Its speeds of sound were measured in wide range of T and P conditions. • The parameters of CP-PC-EOS were fitted to the determined densities. • The predictions CP-PC-EOS deviate from the speeds of sound data by ~1%. [ABSTRACT FROM AUTHOR]