BEHAVIORS OF INTERFACIAL-TENSION AND REAC TION-MECHANISM OF SURFACE-ACTIVE SPECIES IN METAL EXTRACTION SYSTEM BY D-2 EHPA

Interfacial tensions of D 2 EHPA in benzene/aqueous solution systems w ere measured by the Wilhelmy plate method. Measurements were carried o ut fora metal ion-free system and for a system with cupric or ferric i on dissolved. In consequence, it is made clear that 1) the adsorption process is very rapid and the extractant can exist as a monomer or its dehydrogenized anion at the interface, 2) in cupric ion extraction sy stems, 1: 2 complexes are formed but no intermediate metal-ligand comp lexes can exist at the interface, and 3) in ferric ion extraction syst ems, 1: 2 intermediate complexes are formed and can adsorb with monome r extractants at the interface. The respective actual behaviors of the interfacial tension are shown to be explained well by Gibbs equation with the aid of the reaction model deduced from present experimental i nsights.