Thermodynamic surface properties of [BMIm][NTf2] or [EMIm][NTf2] binary mixtures with tetrahydrofuran, acetonitrile or dimethylsulfoxide

► We report the investigations of surface tensions of binary systems of ionic liquids with aprotic substances. ► DMSO similarly like water has higher surface tension in comparison with ionic liquids under test. ► It seems that surface activity of aprotic substance in mixture with ionic liquid is different than of alcohols. ► Real surface activity of aprotic substance in binary mixtures is always lower than the ideal one.