Interfacial activity of copper(II) complexes with chelating ligands and individual hydrophobic extractants in model extraction systems I. Study of equilibrium interfacial tension at the hydrocarbon/water interface for systems with copper(II) complexes with chelating ligands and individual hydrophobic extractants.

The equilibrium interfacial tensions at the hydrocarbon/water interfaces, as measured at 20 degrees C for copper(II) complexes with the chelating ligands beta-diketone (1-phenyl-1,3-decanedione), 2-hydroxy-5-t-nonylacetophenone oxime, 2-hydroxy-5-t-octylacetophenone and 2-hydroxy-5-t-octylbenzophenone oxime, as well as for individual extractants, are discussed. The interfacial tension and surface excess isotherms were determined and interpreted. The experimentally obtained curves were successfully matched with the Szyszkowski and Frumkin equations. It was found that the tendencies of interfacial tension to be lower at the hydrocarbon/water interfaces for copper(II) complexes and individual chelating ligands are similar. However, the effectiveness and efficiency of adsorption for chelating extractants and copper(II) complexes are quite different, irrespective of the type of hydrocarbon used as the organic diluent. On the other hand, the type of organic phase affects the interfacial activity of the investigated compounds. Moreover, it was shown that the way of preparing the measurement systems with the copper(II) complex influences the results of its interfacial activity.