Infinite dilution diffusion coefficients of [Bmim]-based ionic liquids in water and its molar conductivities

Abstract

In this work, we presented new experimental data of diffusion coefficients of four [Bmim (1-butyl-3-methylimidazolium)]-based ionic liquids in water at infinite dilution for temperatures ranging from 303.2 to 323.2 K using Taylor dispersion technique. The investigated ILs were [Bmim][BF 4 (tetrafluoroborate)], [Bmim][MeSO 4 (methylsulfate)], [Bmim][PF 6 (hexafluorophosphate)], and [Bmim][CF 3SO 3 (trifluoromethanesulfonate)]. The molar conductivities of these ionic liquids were also measured and the infinite dilution conductances were determined. The present experimental diffusion coefficients were represented using three correlations; namely, Wilke–Chang, modified Wilke–Chang, and Nernst–Haskell equation. The Wilke–Chang equation underestimated the diffusion coefficient while the Nernst–Haskell equation overestimated the diffusion coefficient. Only the modified Wilke–Chang equation satisfactorily represented the present experimental data.