Research Specifications

This article focuses on measuring and modeling activity coefficients and some thermodynamic properties of the quaternary system (NaCl + KCl + N,N-dimethylformamide (DMF) + H2O) using a potentiometric technique at (298.15 ± 0.05) K. By employing ion-selective electrodes (Na+-ISE, Cl–-ISE), experimental results were collated for the four series of the mixed electrolyte systems in various ionic strengths for the investigated quaternary system. The electrochemical measurements were carried out over total ionic strengths range from 0.0249 up to about 3.8223 mol·kg–1 in mixed N,N-dimethylformamide + H2O solvents, with various solvent mass percents (wt % = 0.0, 0.10, 0.20, and 0.30) at 298.15 ± 0.05 K. Experimental data were modeled on the basis of the Pitzer approach, and the two and three particles mixing ionic interaction parameters (θNaK and ψNaKCl) estimated for the quaternary electrolyte systems under investigation. Finally, using the optimized parameters (θNaK and ψNaKCl), the thermodynamic properties of electrolyte systems, such as activity coefficients of the constituent’s electrolyte, osmotic coefficients, and the excess Gibbs free energy, were determined for each mass percent of DMF in water for mixtures of sodium and potassium salts with common anion chloride. The resultant activity coefficients demonstrate a decreasing trend upon decreasing dielectric constants and as the mixed solvent medium growing dense and viscous.