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The effect of the inorganic electrolytes KPF6 and KBF4 on the aggregation behavior and thermodynamic properties of 1-allyl-3-methyl-imidazolium bromide (AmimBr) in aqueous solution was investigated by volumetric and conductometric measurements in different concentration ranges. The density and conductivity of AmimBr + KPF6 and AmimBr + KBF4 mixtures were measured at a temperature of 298 K over a wide concentration range (0.01, 0.015, 0.02 and 0.025 M), with no micelle formation in the system. Two regions were found in the conductivity plots of AmimBr/BF4 mixtures where the cac values for the other systems AmimBr in water and AmimBr + PF6 mixtures were not identified. The cac values decrease in the concentration ranges BF4 (from 0.015 to 0.025 M) between 0.30 M and 0.40 M, indicating the formation of an aggregate structure. In addition, the calculated molar volume, VΦ of the mixtures AmimBr/BF4 and AmimBr/PF6 is larger than that of pure IL. The VΦ values were 280–300 cm3 /mol for PF6/IL and BF4/IL but the value of VΦ of AmimBr in water is about 120 cm3 /mol. We have performed a new calculation with DFT simulations to better explain the IL-PF6 and IL-BF4 interactions.
Fouzai et al. (Mon,) studied this question.