A study of interfacial adsorption isotherm at divided interface for novel macrocycles in solvent extraction

摘要

A new aspect of liquid–liquid extraction by using the adsorption isotherm approach at divided interface was described. In order to explain complexation behavior of ligands, extraction of ions in the interfacial region of liquid–liquid phase can be modeled by Langmuir adsorption isotherm. A series of macrocycles of different ring sizes with different type of donor atoms has been synthesized and characterized by several spectroscopic techniques. Solvent extraction method was used to evaluate metal-ion binding properties of the macrocycles. The values of the extraction constants and the complex compositions were determined for the extracted complexes. Macrocycles 2 and 3 as extractant of silver cation from aqueous solution at different temperatures and concentrations was investigated. Kinetics and thermodynamic parameters of the interfacial adsorption were also investigated. The cation-binding affinity of macrocyclic ligand 2 among the other ligands for Ag+ over other cations in both organic solvents was found to be the highest. The Ag+ ion was extracted by 88.3 and 81.7 % to the dichloromethane and chloroform phase with macrocycle 2, respectively. The maximum metal ion adsorption capacity (28 %) was found for macrocycle 2 at 20 °C.