Measurement of infinite dilution activity coefficients of n-alkanes in 4-methyl-n-butylpyridinium tetrafluoroborate using gas-liquid chromatography

The infinite dilution activity coefficients of octane, nonane and decane in 4-methyl-n-butylpyridinium tetrafluoroborate (C₁₀H₁₆BF₄N, MW = 237.05) were measured by gas-liquid chromatography (GC) using the ionic liquid as stationary phase. The measurements were carried out at several temperatures between 297 and 344 K under atmospheric pressure. The infinite dilution activity coefficients were affected by the flow rate of carrier gas. The infinite dilution activity coefficients were determined by extrapolating the flow rate of carrier gas to zero. The infinite dilution activity coefficients determined in this work somewhat are larger than those of the literature values because the effect of flow rate of carrier gas was not considered in the literature. The partial molar excess enthalpy at infinite dilution and the heat of solution for the solutes in the ionic liquid were calculated from the infinite dilution activity coefficients. The experimental results were correlated by using the ASOG, which is one of the successful group contribution activity coefficient models. The group interaction parameters were determined by using the Complex method to minimize the deviation between the experimental and calculated values. The correlated results are in good agreement with the experimental results.