On the temperature dependence of several physicochemical properties for aqueous solutions of the ionic liquid 1-butyl-3-methylimidazolium methanesulfonate ([C4mim][MeSO3])

The viscosity, conductivity, proton T1 relaxation, and the self-diffusion coefficients of cation, anion and water are presented for the binary system water-1-butyl-3-methylimidazolium methanesulfonate ([C4mim][MeSO3]) for the temperature and composition ranges of (298.15-343.14) K and ionic liquid mole fractions 0 < xIL < 0.5. The temperature dependence of these properties at fixed compositions was analyzed to obtain Arrhenius activation energies, which were found to be linearly dependent to xIL for xIL greater than about 0.15 for the self-diffusion coefficients, viscosity and proton T1 relaxation times (except for the water proton T1 relaxation times). The specific xIL dependencies of the various Arrhenius activation energies are qualitatively different from what was observed in a prior study of the water-1-ethyl-3-methylimidazolium methanesulfonate ([C2mim][MeSO3]) binary system [J. Mol. Liq. 160 (2011) 166-179]. In particular, the T1 relaxation behavior is markedly different und is discussed in detail along with other comparisons between these two water-IL binary systems.