Transport Properties and Ionic Association in Pure Imidazolium-Based Ionic Liquids as a Function of Temperature

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• 作者：B. E. Mbondo Tsamba ; S. Sarraute ; M. Tra茂kia ; P. Husson
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2014
• 出版时间：June 12, 2014
• 年：2014
• 卷：59
• 期：6
• 页码：1747-1754
• 全文大小：299K
• 年卷期：v.59,no.6(June 12, 2014)
• ISSN：1520-5134

文摘

In this work, three transport properties (viscosity, diffusion coefficient, and electrical conductivity) were experimentally determined from 298 K to 343 K in four pure imidazolium-based ionic liquids with two anions and different alkyl chain lengths on the cation: 1-ethyl-3-methylimidazolium methylsulfate, [C₁C₂Im][CH₃SO₄], 1-butyl-3-methylimidazolium methylsulfate, [C₁C₄Im][CH₃SO₄], 1-ethyl-3-methylimidazolium triflate, [C₁C₂Im][CF₃SO₃] and 1-butyl-3-methylimidazolium triflate, [C₁C₄Im][CF₃SO₃]. Higher viscosities, lower diffusion coefficients, and electrical conductivities were measured when the alkyl chain length was increased or a sulfate anion was present. From these experimental data, the ionic association was discussed using the qualitative approach of the Walden plots and the quantitative ionicity concept. An increased ionic association was observed when the alkyl chain length on the cation was increased, while comparable ionicities were measured for both anions. Finally, the applicability of the Stokes鈥揈instein equation (relation between the diffusion coefficient and the viscosity) was also discussed in these systems.