Distribution of Nickel(II), Cadmium(II) and Copper(II) Chelates of 2-(2-Pyridylazo)-5-methylphenol in Two Phases Separated from Micellar Solution of Nonionic Surfactant

Abstract

Several metal chelates of 2-(2-pyridylazo)-5-methylphenol (PAP-5-Me) were extracted from an aqueous phase into a surfactant phase which was separated from a micellar solution of poly(oxyethylene)=4-nonylphenyl=ether with oxyethylene units of 7.5 (PONPE-7.5). On the basis of the distribution curves for the respective chelates, the partition constants of the neutral chelates were determined at 293K at an ionic strength of 0.1 (NaCl). The partition constants were considerably smaller than those expected from the regular solution theory. The partition constants were also dependent upon the kind of metal ions. This fact is probably due to such an ordered structure as liquid crystal in the surfactant phase which can differentiate the size of the metal chelates.