Viscosities and Interfacial Properties of 1-Methyl-3-butylimidazolium Hexafluorophosphate and 1-Isobutenyl-3-methylimidazolium Tetrafluoroborate Ionic Liquids

Room temperature ionic liquids (RTILs) are potential alternative solvents in chemical reaction or separation process. The viscosity of RTIL, interfacial properties of air−RTIL, organic compounds−RTIL, and solid−RTIL are of general importance. The viscosities of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) and 1-isobutenyl-3-methylimidazolium tetrafluoroborate ([iBeMIM][BF 4 ]) ionic liquids (ILs) have been determined from (288.15 to 313.15) K. The surface tension/contact angle on solids of [BMIM][PF 6 ] and [iBeMIM][BF 4 ] ILs have been measured at 298.15 K. The liquid−liquid interfacial tension for [BMIM][PF 6 ] with 21 organic compounds have also been determined at 298.15 K. The relationship between the interfacial tensions and activity coefficients at infinite dilution of solutes in IL is discussed.