A Local CompositionOP-NRTL-NRF Model for CorrelationMean Activity Coefficients in Aqueous Electrolyte Systems from ThermodynamicProperties

The activity coefficient in electrolyte systems is a key measure of deviations from ideal behavior, essential for simulating the thermodynamic properties of these systems. Accurate modeling and prediction of this coefficient are crucial for understanding the interactions of electrolyte solutions and optimizing industrial and chemical processes. This study introduces the OP-NRTL-NRF (One Parameter Non-Random Two-Liquid, Non-Random Factor) local composition model specifically designed for binary aqueous electrolyte systems. This model redefines interaction parameters based on fundamental principles and simplifies the traditional approach by correlating the mean activity coefficient with a single adjustable correction factor rather than relying on extensive experimental data and multiple parameters. By redefining the binary interaction parameter, this model establishes relationships that describe the variation of excess Gibbs energy in the central cells of anions, cations, and water molecules. The observed changes in Gibbs energy within water molecular cells indicate the formation of hydration bonding structures and ion pairs. This model, optimized for 85 binary aqueous electrolyte systems at 298.15 K using a data set of 1819 experimental points, shows excellent agreement with experimental results and accurately predicts osmotic coefficient values. Additionally, the model has been extended to ternary systems and has been used to calculate the solubility of electrolytes in water solvent for 10 ternary systems, comprising 110 experimental solubility points, at 298.15 K. The results demonstrate good agreement with experimental data, and the model’s ability to predict the behavior of ternary electrolyte systems is reliable.