pH of Toluene in [Bmim][BF4] and [Bmim][PF6] Ionic Liquids

The pH value of binary mixtures containing toluene and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) ionic liquids over the range of ionic liquids mole fraction (xIL) from (1.0 to 0.60) and temperature range from (293.15 to 340.65) K were measured. The range of the pH values of toluene and [Bmim][BF4] and [Bmim][PF6] were from (3.16 to 4.63) and (5.57 to 7.55), respectively. Comparison showed that the pH of toluene in the two ionic liquids was in sequence: [Bmim][BF4] < [Bmim][PF6]. The temperature dependency of the pH value was correlated using an empirical equation. The correlations gave satisfactory results.