P–V–T properties of binary mixtures of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with anisole or acetophenone at elevated pressures

•The densities were measured with a high-pressure densimeter.•The systems are ionic liquid [C4mim][NTf2] with anisole or acetophenone.•The densities data fitted accurately to the Tait equation.•The excess volumes are all negative over most experimental conditions.•The FOV and the Schotte equations of state are correlated well the excess volumes.

The isothermal densities of pure ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C4mim][NTf2], and its mixtures with anisole or acetophenone were measured by using a vibrating tube densimeter over temperatures ranging from (298.15 to 348.15) K and pressures from (0.1 to 50) MPa. The Tait equation was used to correlate the density data and accurately represents densities varying with pressure at given temperature and composition. The excess volumes were calculated from the experimental data and found that those are all negative, except for (acetophenone + [C4mim][NTf2]) at 298.15 K with containing acetophenone of 0.1 in mole fraction. The modified Redlich–Kister was applied to correlate the excess volumes. The Flory–Orwoll–Vrij (FOV) and the Schotte equations of state were also employed to correlate the density data over entire experimental conditions.