Determination of the stability constants of some hydroxo and carbonato complexes of pb(II), cu(II), cd(II) and zn(II) in dilute solutions by anodic stripping voltammetry and differential pulse polarography

Abstract

Anodic stripping voltammetry and differential pulse polarography are used to study complex formation between Cu(II), Pb(II), Zn(II) or Cd(II) and hydroxide or carbonate ions under concentration conditions which approximate those in natural waters, i.e. [Me] t < 10 −7 M. Lead(II) and copper(II) form similarly stable carbonate complexes, which suggests that PbCO 3.aq and CuCO 3.aq are the preponderant lead and copper species in natural waters. Carbonate complexes of zinc(II) and cadmium(II) are less stable; hence these metals are present in natural waters —depending on solution variables — as aquo, hydroxo or chloro (sea water) complexes.