Interfacial activity of HDEHP and kinetics of nickel extraction in variousdiluents

The interfacial behavior of HDEHP at various diluents/0.05M (H-2,Na-2)SO4 i nterfaces was examined using the Drop Volume Method. Different adsorption i sotherms such as the Gibbs and Szyszkowski were found as fits well to the e xperimental interfacial tension isotherms. The values of surface excess at saturated interface,calculated according to them by using the concentration of individual species (e.g. organic monomeric species),increase in the ord er: MIBK<chloroform<benzene similar to toluene similar to xylene<CCl4<n-hex ane similar to n-heptane. The interfacial activity data were used to discuss the mechanism and kineti cs of nickel extraction. It was shown that the interfacial mechanism is ver y probable and the extraction limiting step is the reaction between HDEHP m olecules present near the interface and the intermediate 1:2 complex just a s following Ni(H2O)(4)A(2(int,o))+2H(2)A(2(int,o))=Ni(H2O)(2)A(2) . 2H(2)A(2(int,o))+2H (2)O((int,o)) The investigation of the influence of diluent on the extraction rate suppor ts the mechanism suggested.