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 mine ral phases by different voltammetric methods has been evaluated. Sorption s tudies were conducted with model systems that consisted of montmorillonite or goethite, the hydroxamate siderophore desferrioxamine B (DFOB) as comple xing agent, and the heavy metals Zn or Cd. An in situ voltammetric method f or the quantitative determination of the heavy metal ion concentration in s olution was developped for these model systems. The measured Zn and Cd spec ies included both the free metal ions and their soluble DFOB complexes. Met al ions bound to the mineral phases were not detected. The effect of the or ganic compound on the voltammetric response was estimated from reference me asurements and taken into account for the calibration procedure. This metho d was useful for the investigation of both kinetics and thermodynamics of a dsorption 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 sp ectrometry. (C) 1999 Elsevier Science B.V. All rights reserved.