Dissociation constants of eriochrome black T and eriochrome blue black RC indicators and the formation constants of their complexes with Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II), under different temperatures and in presence of d

The dissociation constants of eriochrome black T, and eriochrome blue black RC, were obtained at different temperatures (20–40 °C) by potentiometric measurements in the presence of different percentage of organic solvent–water media. The thermodynamic parameters of ionization were calculated. The formation constants of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) complexes of the azo indicators were evaluated in 50% ethanol media (v/v). The thermodynamic parameters of complexation were calculated and discussed.