Potentiometric study of binary complexes of effortil hydrochloride with somedivalent metal ions in aqueous medium

The formation equilibria for the binary complexes of Effortil with Cu2+, Co2+, Ni2+, and Zn2+ metal ions were investigated using potentiometric technique in aqueous medium (t= 37 CAiµ’, I= 0.15 mil. dm-3 NaNO3). The formation of binary complexes was inferred from the pH-metric titration curve. The overall stability constants of the complexes formed were obtained using HYPERQUAD 2008 program using from potentiometric data. The calculated stability constants of the complexes formed have been discussed in terms of both the nature metal ions and Effortil. The stability of the complexes follows the trend Co2+< Zn2+< Ni2+< Cu2+, which is in agreement with the Irving– Williams order of the metal ions. The results showed the formation of ML, MHL, and ML2 complex species. The concentration distribution of the complexes in solution was evaluated as a function of pH and discussed. Evaluation of the effect of temperature of the medium on the dissociation of ligand and the stability of binary systems has been studied. The thermodynamic parameters were calculated and discussed.