The role of organic diluents in the aspects of equilibrium, kinetics and thermodynamic model for silver ion extraction using an extractant D2EHPA

• Effect of diluents on Ag+ extraction was studied using the extractant D2EHPA.
• Various diluents which have different dielectric constants were selected.
• Equilibrium data of water + D2EHPA + diluents exhibited type-2 LLE behavior.
• Efficiency and stoichiometry of Ag+ extraction changed in the different diluents.
• rmsd values for modeling and experimental correlations were less than 1%.

The effects of organic diluents regarding the aspects of equilibrium data, kinetics of extraction behavior and thermodynamic model are of great importance in the extraction processes. Therefore, these effects were investigated for silver ion extraction by a liquid–liquid extraction process using D2EHPA as an extractant. Various organic diluents that have different dielectric constants like kerosene, cyclohexane, chloroform and 1-octanol were selected for use in this work. The equilibrium data of solubility and tie-lines for the ternary systems of water + D2EHPA + organic diluents exhibited type-2 LLE behavior at a temperature of 298.2 K and atmospheric pressure. Moreover, the uncertainty propagation calculation was determined to validate the reliability of the data. The extraction efficiency of silver ions for each organic diluent was also investigated; maximum extraction of 94% was obtained for 1-octanol. The extraction behaviors of silver ion with D2EHPA in the different organic diluents were reported as regards their reaction stoichiometry. They were also analyzed by spectroscopic analysis. Results of the thermodynamic NRTL model were obtained and a very good correlation with the experimental LLE data was confirmed by the root-mean square deviation (rmsd) values of 1%.

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