Adsorption of Pb2+ ions on nanosized γ-Fe2O3:: formation of surface ternary complexes on ligand complexation

Adsorption of Pb2+ ions on the combustion derived nanosized gamma-Fe2O3. and its thiourea complex composite is reported. The adsorbents upon adsorption of Ph2+ ions are characterised by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis and infrared spectroscopy techniques. The eluent is characterised by atomic absorption spectroscopy for the estimation of Ph2+ ions. The reduction in the amount of lead after adsorption was estimated to be around 50% in case of complex composite adsorbent and around 15% in case of the gamma-Fe2O3 adsorbents. Orthorhombic PbSO4 precipitated out from the eluent and is reported with a model reaction. Adsorption of lead onto the complex composite is explained through the formation of a surface tertiary complex. The advantage of employing a thiourea -gamma-Fe2O3 complex composite as solid adsorbent for the adsorption of heavy metal pollutants is envisaged in the present investigation. (C) 2003 Elsevier Science B.V. All rights reserved.