The use of voltammetry for sorption studies of heavy metals on mineral surfaces in presence of the siderophore desferrioxamine B

The influence of pH, ligand and solid concentration on the determination of dissolved heavy metals in homogeneous solution and in suspension with mineral phases by different voltammetric methods has been evaluated. Sorption studies were conducted with model systems that consisted of montmorillonite or goethite, the hydroxamate siderophore desferrioxamine B (DFOB) as complexing agent, and the heavy metals Zn or Cd. An in situ voltammetric method for the quantitative determination of the heavy metal ion concentration in solution was developped for these model systems. The measured Zn and Cd species included both the free metal ions and their soluble DFOB complexes. Metal ions bound to the mineral phases were not detected. The effect of the organic compound on the voltammetric response was estimated from reference measurements and taken into account for the calibration procedure. This method was useful for the investigation of both kinetics and thermodynamics of adsorption phenomena. Results obtained by using this voltammetric procedure were compared with those from conventional batch studies on sorption, where dissolved heavy metal concentrations were measured by atomic absorption spectrometry. (C) 1999 Elsevier Science B.V. All rights reserved.