Thermodynamic Study of the Ternary Electrolyte (1-Butyl-3-methylimidazolium chloride + sodium chloride + Water) System Using Potentiometric Measurements

In this paper, the thermodynamic properties of the aqueous mixed electrolyte system containing 1-butyl-3-methylimidazolium chloride ([BMIm]Cl) and NaCl are reported based on the potentiometric method. The potentiometric measurements were performed on the galvanic cells without liquid junction of the type:Ag-AgCl [BMIm]Cl (m1), NaCl(m2), H2O│IL-ISE, over total ionic strengths from 0.0025 to 2.000 mol kg -1 for different series of salt molal ratios r (r = m[BMIm]Cl/mNaCl = 0.2, 1.0, 2.5, 5.0) and pure [BMIm]Cl in aqeous system at T = 298.2 K. The PVC based [BMIm]-selective electrode (IL-ISE) and Ag-AgCl electrode used in this work were prepared in our laboratory. The experimental results were analyzed with the Harned rule and Pitzer model. The Harned coefficients and the Pitzer mixing interaction parameters (θ[BMIm]Na, ψ[BMIm]NaCl) were evaluated under investigation system. The results show the under-studied system obeys the Harned rule. Furthermore, the obtained parameters by the Pitzer model were used to calculate the values of the mean activity coefficients of NaCl, the osmotic coefficients, the solvent activity, and the excess Gibbs free energies for the whole series of the studied mixed electrolyte systems.